Bulletin of the Geological Society of America Vol. 67. Pp. 1331-1396. 2 Figs.. 10 Pls. October 1966 Stratigraphy, Paleontology

BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA VOL. 67. PP. 1331-1396. 2 FIGS.. 10 PLS. OCTOBER 1966

STRATIGRAPHY, PALEONTOLOGY, AND PALEOGEOGRAPHY OF THE ELLIPTOCEPHALA ASAPHOIDES STRATA IN CAMBRIDGE AND HOOSICK QUADRANGLES, NEW YORK

BY CHRISTINA LOCHMAN

ABSTRACT An Elliptocephala asaphoides fauna from rocks of the "Taconic sequence" of eastern New York is a characteristic "Schodack" faunule comparable in age and composition to those described by Ford from the vicinity of Troy, New York, and by Walcott from northern Washington County. Several new species and a revision of described species show that this fauna is a transitional assemblage composed of some typical Atlantic province genera, some typical Pacific province genera, and several unique genera. Eleven trilobite genera are present, of which the two belonging to Dorypygidae are new. Two new trilobite and one new molluscan species are described. A detailed population study of Calodiscus lobatus (Hall) was possible on the large number of specimens. One limestone pebble with a diagnostic Middle Cambrian fossil and several with Tremadocian fossils were found in Prindle's collection. Outcrops in the Cambridge-Hoosick quadrangles give a limited stratigraphic section; but on the basis of distribution of several trilobite species two faunules of stratigraphic significance can be distinguished within the Ettiptocephala asaphoides fauna. Lack of appreciation of the concept of lateral gradation of lithofacies has caused considerable stratigraphic confusion in the Slate Belt; yet this principle was emphasized by Dale and has been reaffirmed by all recent studies. Fossils and careful attention to details of the lithofacies units in this region show three consecutive Lower Cambrian phases or times of deposition during which one or several major lithofacies units were deposited. When the lithologic units were given formational names by Ruedemann a time-stratigraphic significance was incorrectly attached to them, and the sequences from Rensselaer County and from the Slate Belt were erroneously correlated. The position of first appearance of the lower Elliptocephala asaphoides faunule is the only significant datum level for age correlation in this Lower Cambrian sequence, indicating as it does the approximate age equivalence of all beds at this position and above, regardless of their particular lithofacies expression. The mixed composition of the Ettiptocephala asaphoides fauna demands a revision of paleogeographic concepts. To account for mixing, the enclosing beds must have been deposited in essentially the same geographic relationship they now hold to the Lower Cambrian rocks of adjoining areas. The faunal assemblage also indicates that the major barrier between Atlantic province faunas and Pacific province faunas was a fundamental difference in environment and not, as previously assumed, a continuous land barrier. The Pacific province genera were normal inhabitants of an environment, a shallow submerged coastal shelf, which bounded the western, northern, and eastern shores of the old North American continent, Laurentia. The outer edge of this environment was the landward boundary of the Atlantic province environment, and the intermingling of faunal elements observed in the Ettiptocephala asaphoides fauna could have occurred only in such a boundary area. It is postulated that in eastern New York and adjoining parts of Vermont one or more deeply downwarped basins developed on the shallow coastal shelf and that these basins had narrow connections eastward and southward with the Atlantic Ocean. The benthonic environment of these basins was similar to that of the open ocean and contrasted sharply with the biofacies of the surrounding shallow coastal shelf. Con- sequently, it would be inhabited by an assemblage primarily adjusted to ocean temper- atures, pressures, and salinity and showing affinities to Atlantic province faunas dwelling to the south and east. Few normal benthonic species of the coastal shelf could establish themselves in such an alien environment, although, because of the geographic proximity of the two areas, sporadically drifted individuals might be found. 1331

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CONTENTS

TEXT ILLUSTRATIONS Figure Pag' Page 1. Correlation of Lower Cambrian formations Introduction 1332 of New York, Vermont, and Labrador.... 1353 Historical review 1332 2. Changes in glabellar shape during growth General statement 1333 in the species Calodiscus lobatus (Hall) 1379 Acknowledgments 1333 Stratigraphy and lithofacies 1334 Plate Following page Historical review 1334 1. Porifera. Archaeocyathettus, Pelagiella,' Stratigraphic sequence of the Slate Belt. . . 1335 and Forditta Stratigraphic sequence in the Cambridge 1. Hyoltihdlus micans (Billings) and Hoosick quadrangles 1336 3. Hyolithes, Coleoloides, and Acrotreta 1372 Discussion of fauna 1339 4. Botsfordia, Lingulella, Indiana, Salteretta, Introduction 1339 Hdcionella, and Stenolhecopsis ( Faunal lists—Lochman's localities 1339 5. Serrodiscus, Eodiscus, Pagetia, Bonnia, Faunal lists—Prindle's localities 1341 and Labradoria Preservation of fossils 1343 6. A tops and Elliptocephala Composition of fauna 1344 7. Kootenia, Bonnaria, Fordaspis, and • 1384 Etched material 1347 Calodiscus Ecology of fauna 1348 8. Calodiscus, Fordaspis, Kochiella, Ptycho- Correlation of fauna 1349 parella, and Parabolina Paleogeography 1352 9. Relation of time-stratigraphic units to Introduction 1352 lithofacies units in the Lower Cambrian Faunal evidence 1353 "Taconic sequence" of eastern New York Lithofacies evidence 1360 Facing page Reconstruction of paleogeography 1362 and western Vermont 1394 Later Cambrian and Ordovician events.... 1366 10. Lower Cambrian paleogeography of Conclusions 1367 eastern New York and New England.... 1396 Systematic paleontology 1368 Porifera 1368 TABLES Archaeocyatha 1368 Table Page Annelida 1369 1. Correlation of the Elliptocephala asaphoides Brachiopoda 1370 fauna 1350 Mollusca 1371 2. Stratigraphic range of the species of the Arthropoda 1376 Elliptocephala asaphoides fauna 1351 Problematica 1395 3. Comparison of three equivalent late Lower References cited 1395 Cambrian faunal assemblages 1354

INTRODUCTION zer Emmons in 1844, were members of this fauna and were Primordial (Cambrian) in age. Historical Review In 1886 C. D. Walcott started mapping and In the last three decades of the nineteenth collecting through Rensselaer and Washington century the region along the east side of the Counties, New York, and Bennington County, Hudson River in Rensselaer and Washington Vermont. During the rest of the century the counties, New York, was the scene of intensive United States Geological Survey was interested Stratigraphic and paleontologic activity de- in this area. Walcott (1887) demonstrated the signed to solve the so-called "Taconic con- age equivalence of faunas from the limestone troversy." In a series of papers published from breccias around Troy, the "Upper Taconic 1871 to 1885 S. W. Ford carefully described formation of Emmons" in Washington County, and the slates of Parker's Quarry, Georgia, fossils collected from limestone breccias and Vermont; and in 1891 correctly assigned these thin limestone beds interbedded in black shales faunas to the Lower Cambrian. T. Nelson Dale exposed from Troy southward to Schodack (1893), in his report on the Rensselaer grit Landing, Columbia County. Ford showed that plateau of New York, described the Lower Atops irilinealus and Elliptocephala asaphoides, Cambrian locality at Ashley Hill and listed a two trilobites collected and described by Ebene- small fauna identified by Walcott. In 1899 T. N.

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Dale published the first coherent stratigraphic Slate Belt. A corrected Lower Cambrian section succession and detailed lithologic description of for the Cambridge-Hoosick quadrangles is pre- Lower Cambrian rocks in the Slate Belt of sented. "Schodack" faunules can be correlated eastern New York and western Vermont. Dale with Lower Cambrian standard faunal zones of was assisted in the field by L. M. Prindle who both the Pacific and the Atlantic provinces. found most of the 343 Cambrian and Ordovician This study deals primarily with Lower fossil localities. The area mapped extended from Cambrian fossils and enclosing strata in a re- the latitude of Hortonville, Vermont, south- stricted area; but it re-emphasizes the need for ward to Cambridge, New York. a thorough and detailed examination of Lower During the second decade of the twentieth Cambrian faunules, lithofacies, and stratigra- century Dr. L. M. Prindle extended the geologic phy over the region from northern Vermont to mapping southward across the Cambridge and Dutchess County, New York. Such an examina- Hoosick quadrangles; and in 1932 Prindle and tion should entail the co-operation of several Knopf published a preliminary map and discus- specialists, should extend over 10 or more years, sion of the 30-minute Taconic quadrangle in and should employ the most modern methods which the locations of additional Cambrian and and interpretations in considering the complex Ordovician collections were given. stratigraphic, structural, and lithologic prob- In 1938 the writer first visited the region with lems involved. Ford's and Walcott's contribu- L. M. Prindle and R. Balk and collected from tions were collecting and describing fossils several Lower Cambrian localities known to during a time when the concepts of intergrading Prindle. In 1948-1949 L. D. Bonham (1950, lithofacies and ecologic control of fossil animals Ph.D. thesis, Univ. of Chicago) mapped the were not fully appreciated. Once the existence structural geology of the 7^-minute Hoosick of Lower Cambrian strata in the region had Falls quadrangle. During this time Bonham, been proved for the benefit of the "Taconic Balk, and the author made additional Cambrian controversy", further interest in relating pale- and Ordovician fossil collections from the known ontology to stratigraphy and lithofacies waned. Prindle localities and from several new locali- No Ordovician material has been studied. ties. R. Balk (1953) made several large col- Collections from both shales and limestones lections from Ashley Hill, Kinderhook quad- made during Bonham's mapping are at New rangle, New York. York State Museum, and Prindle's Ordovician collections are stored at the United States General Statement National Museum.

This paper describes and discusses the Lower A cknowledgments Cambrian fossils from all the collections, including those made by Prindle that retained Many persons have contributed to this paper. adequate locality labels. The Lower Cambrian Dr. L. M. Prindle took the writer to many of assemblage of these beds is a characteristic his best collecting localities. Dr. G. A. Cooper "Schodack" faunule and can be compared to made available for study all Prindle's Lower the assemblage described by Ford and to the Cambrian collections from this area, as well as several faunules of the Slate Belt incompletely several of Walcott's types. Drs. Winifred known from Walcott's descriptions. A Middle Goldring and R. H. Flower spent several days Cambrian limestone pebble and several of in the field with the author. Drs. R. Balk and Tremadocian age were found in Prindle's col- L. D. Bonham furnished several collections. lections. The large faunule from Ashley Hill is Mr. C. F. Kilfoyle kindly loaned several of described for the first time; and generic and Ford's types from the New York State Museum. specific assignments of most "Schodack" forms Dr. W. H. Bucher sent additional material col- have been corrected and brought up to date. lected from Ashely Hill by J. C. Craddock. With precise and modern definition of the Dr. Robert Balk drafted Figures 1, 6, and 7. several faunules thus obtained, the writer has Photographic expenses were partially defrayed clarified the relationships between time-strati- by a grant from the Penrose Bequest of the graphic units and lithofacies as developed in the Geological Society of America, and the pho-

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tography was done by Mr. Charles Treseder, slate; Unit C—the Eddy Hill grit; Unit D—the New Mexico Institute of Mining and Tech- Schodack shales and limestones; Unit E—the nology. Zion Hill quartzite. Working from Dale's 1904 chart, Ruedemann named divisions A through STRATIGRAPHY AND LITHOFACIES E—the Nassau beds; division G—the Diamond Rock quartzite; and division H—the Troy Historical Review shale. Ruedemann's one error was that, although he defined the Bomoseen grit as Dale's Lack of appreciation of the concept of lateral Unit A of the Slate Belt, he assumed that Dale's gradation of lithofacies has caused considerable division F of the Rensselaer County Lower confusion among stratigraphers in the Slate Cambrian series was the stratigraphic equiva- Belt; yet this principle was emphasized by Dale lent of Unit A. Apparently this error was caused and has been reaffirmed by recent studies by Dale's reference to the lithologic similarity (Kaiser, 1945; Fowler, 1950). of these units. Ruedemann comments (Gushing Dale (1899, chart facing p. 178) recognized and Ruedemann, 1914, p. 71) that the grit of only three major Lower Cambrian stratigraphic Unit F "was found full of carbonaceous units in the Slate Belt: (1) lower Unit A, the blotches, suggesting seaweeds, and large worm olive grit; (2) middle Unit B, the Cambrian trails." Heavier grit beds alternate with more roofing slates; and (3) a top unit in which he slaty beds, and the unit is immediately overlain places Units C, D, and E in vertical position but by and intimately associated with calcareous indicates in footnote 1 that "C, D and E are sandstones of Unit G—The Diamond Rock intermittent. Any one or two of them may be from which fossils of the lower Elliptocephala wanting. One of them generally, if not always, assemblage have been obtained (R. H. Flower, between the Ordovician (F) and Lower Olenellus personal communication, 1954). Lithologically (B)." Although the wording is old-fashioned, Unit F more nearly resembles Unit C, the this statement can only be interpreted as Eddy Hill grit, in several distinctive features. recognition of the lenslike nature of the litholo- Called the Black Patch grit by Dale, Unit C was gies of Units C, D, and E, and Dale's discus- described as a grayish grit or sandstone charac- sions confirm this conclusion. terized by black shaly patches and associated Dale (1904a) published a table giving the nodules of calcareous-cemented quartz sand- sequence of Lower Cambrian units which he stone that contain fragments of Olenellus (that recognized in Rensselaer and Columbia Coun- is, Elliptocephala). Units F and G of Rensselaer ties, New York. On page 14 he comments that County and Unit C of the Slate Belt lie strati- "a metamorphic olive grit, usually weathering a graphically above a series of red and green light bright red, crops out at a few points, and shales and interbedded calcareous quartzites is also typical of this formation in Washington and below a series of colored and black shales County," and refers the reader to his petro- with calcareous quartzites, limestones and lime- graphic discussion of the olive grit of Unit A. stone breccias carrying Elliptocephala faunules. On page 15 he similarly comments on calcareous Paleontologically Units F and G and Unit C sandstones and associated limestone breccias, occur at or just above the first appearance of and refers the reader to his discussion of Unit E. trilobites of the Elliptocephala assemblage. Although Dale meant a general similarity of Consequently the Nassau beds of Dale's lithologies and not stratigraphic equivalence of Rensselaer County section are the stratigraphic units between the two regions, these references equivalent of the Mettawee slate of the Slate proved most unfortunate. Belt; no graywacke stratigraphically equivalent In 1914 Ruedemann (in Gushing and Ruede- to Dale's Unit A has been observed in the mann) named many of Dale's lithologic units. Rensselaer sequence. Stratigraphic equivalence One error in this paper caused most of the subse- of the Nassau beds and the Mettawee slate has quent confusion. Working from Dale's 1899 been determined independently by R. H, chart and utilizing Dale's best-exposed locali- Flower (Personal communication, 1954). ties as type localities, Ruedemann named Unit Stratigraphic position of the Bird Mountain A—the Bomoseen grit; Unit B—the Mettawee grit and associated green and purple phyllites is

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unknown. Dale (1893, p. 337), Kaiser (1945, p. Elliptocephala faunule is the only significant 1090), and Fowler (1950, p. 40^1) each sug- datum level for age correlation in this Lower gested different positions for the beds. However, Cambrian sequence. It indicates approximate if they lie stratigraphically below the type age equivalence of all beds at this position re- Bomoseen grit position as believed by Fowler, gardless of lithofacies expression. By this time they must not be called the "Nassau formation" several animals with preservable exoskeletons since that would imply correlation with the and shells had invaded the optimum bottom type Nassau beds of the Rensselaer County habitats throughout the basin of deposition. At sequence which are much higher. some places, as at locality Y 6, the animals appear to have lived on the muddy bottom Stratigraphic Sequence of the Slate Belt represented by the argillaceous limestones in which the fossils now occur. Elsewhere the Dale's three major stratigraphic units of the organic debris as well as the quartz sand grains Lower Cambrian sequence may be ac- and arkose have been carried to and distributed cepted as time-stratigraphic units which are over the mud bottoms by the sporadic strong conformable, have transitional boundaries, and currents. record several phases of a single depositional The third and latest phase of sedimentation cycle (PI. 9). The earliest phase is represented is recorded in Dale's Units C and D, and pos- by Dale's Unit A—the Bomoseen grit—a series sibly Unit E. Fundamentally this third phase is of green or purple grit beds with interbedded only a continuation of the second phase. Off- massive quartzites, slightly calcareous quartz shore deposition of muds continued, and oc- conglomerates, and a few slates. Fowler (1950, casional strong currents carried quartz sands, p. 46) reported that toward the east the Bomo- arkosic grits, and organic debris into the mud seen may become thinner or be missing. The sites. It is, however, the record of a time when significance of this earliest phase cannot be detailed sedimentary lithologies varied more determined since the bottom of the Bomoseen from place to place within the Slate Belt. This has never been observed. The thickness of the variability is caused by introduction of two new Bomoseen ranges from 50 to 500 feet; this unit elements: (1) common and frequent intercala- represents an interval of graywacke deposition tion of the shales, sandstones, and grits with not repeated on a comparable scale in the Lower thin limestone beds, lenses or nodules, and Cambrian of the Slate Belt area. Although the masses of limestone pebbles to form breccias lithology of Unit A is variable, the magnitude and conglomerates. The carbonate was derived of the development of grit beds at this position from the exoskeletons of the Elliptocephala is believed to have stratigraphic significance. faunules now successfully established through- The second phase of sedimentation is recorded out the province; and (2) development of in Unit B—the Mettawee slates—a series of anaerobic portions of the sea floor where pyrites purple, green, and gray shales interbedded with formed and muds acquired a black color from lenses of calcareous quartzite and arkosic grits. the high organic content. Minor swells and Limestone conglomerates that contain a typical swales on the sea floor, probably tectonically lower Elliptocephala faunule occur in a gray or produced, could have formed and maintained green shale matrix near or at the top of Dale's these conditions. Well-oxygenated floors of the Unit B. During this second phase fine elastics swells were sites of a teeming biota while the were the main material available for deposition anaerobic floors of the swales were covered by in this area. Occasional strong currents carried dead and dying organisms washed in from the quartz sands and/or arkosic debris from the surrounding swells. Similar conditions of sedi- beach area into the offshore mud sites. Shale mentation characterize some Cambrian de- colors suggest the prevalence of oxygenated posits of the Baltic region; these deposits have bottom waters. The rather abrupt appearance been studied in great detail by Hadding (1932). of the first opisthoparian trilobites associated Unit D—the Schodack shale and limestone— with an olenellid genus, Elliptocephala., is typical was described by Dale as widespread lenses of of Upper Olenellus zone faunas. Consequently, black shales that contain limestone beds and the position of first appearance of the lower limestone pebble conglomerates and are inter-

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calated with thin beds of calcareous quartzite, cluded in the discussion of the Lower Cambrian feldspathic grit, and gray shales. Dale noted cycle of deposition because the various sand- that Unit C developed sporadically at the begin- stones which have received this name or been ning of the third phase. Unit C, the Eddy Hill correlated with it in the Slate Belt probably are grit, consists of 10-to-40-foot lenses of arkosic not all the same age. These quartzites are mas- grits incorporating pebbles and blobs of black sive-bedded sandstone lenses, 25-100 feet organic mud and fossiliferous calcareous sand- thick, overlain by Ordovician black shales. One stones. Only the greater thickness of the lenses calcarenite lens in the Hoosick Falls quadrangle distinguishes these grits from the thinner grits contains crinoid stems (Bonham, 1950, Ph.D. in Unit D. The indicated conditions of sedi- thesis, Univ. of Chicago) indicating at least an mentation explain why black shales of Unit D Upper Cambrian, probably a Lower Ordovician, would grade laterally into gray, green, and age. These sandstones were called Eagle purple shales which were the mud deposits of Bridge quartzites and placed in the top of the the well-oxygenated swell floors. Dale appreci- Lower Cambrian sequence by Prindle and ated the lens shape of the black shales and Knopf (1932, p. 278). Although some of these records several localities where gray, green, and massive quartzites are of Lower Ordovician purple shales are interbedded with or overlie age, others may represent a thicker than usual black shales. calcareous quartzite lens intercalated with Dale's Unit H in the Rensselaer County shales of the third phase of Lower Cambrian sequence indicates maintainance of aerobic deposition. The position of any such quartzite bottom conditions with continued deposition of would be variable and might occur some green and purple shales for some time after the distance below the top of the Lower Cambrian first appearance of the lower Elliptocephala shale deposition. Any pre-Ordovician erosion faunule in the Diamond Rock quartzite. This is surface would have been held up by these more comparable to conditions in the Slate Belt massive quartzites. where the lowest fossiliferous limestones are interbedded with gray, green, and purple shales Stratigraphic Sequence in the Cambridge and and calcareous sandstones which Dale placed in Hoosick Quadrangles the top of his Unit B. Kaiser (1945) and Fowler (1950) both used the presence of black shale as Understanding of the relationships between their only criterion for the recognition of the lithofacies, time-stratigraphic units, and Schodack beds, and green and purple shale for position of the Elliptocephala asaphoides recognition of the Mettawee. This usage is faunules in the classic Slate Belt area is requisite entirely correct since both names as originally for an appreciation of the lithology and stra- applied by Ruedemann (Gushing and Ruede- tigraphy of the Lower Cambrian beds in the mann, 1914) referred only to beds defined as Cambridge and Hoosick quadrangles. lithofacies units. However, they seriously err in Prindle and Knopf (1932, p. 275-278) present trying to handle these two lithofacies units as a Stratigraphic succession of Lower Cambrian time-stratigraphic units (called by them "for- rocks not supported by subsequent field exami- mations") in their mapping and discussions. nation. The lowest unit, called "Shales and Only the 200 ± feet of Mettawee lithofacies grits of Lower Cambrian age" is described (p. between the Bomoseen grit and the first ap- 275) as "chiefly gray to olive-green and purple pearance of the lower Elliptocephala faunule is shales speckled with tiny flakes of mica and con- believed to have a time-stratigraphic signifi- taining limestone lentils that carry Lower cance, that of the second phase of deposition. Cambrian trilobites. These dull-green shales are The third phase of deposition is also a time- interlayered with beds of grayish quartzite or stratigraphic unit; but sediments laid down in grit and in places, as east of Moon Hill, they the Slate Belt area during this time were of grade upward into greenish and purplish grits or Mettawee lithofacies, Schodack lithofacies, graywacke and slate." Fossils from five locali- Eddy Hill lithofacies, and Diamond Rock ties are listed. Fossils from the first three lithofacies in lateral gradations. localities are now referred to the lower Ellip- Unit E, the Zion Hill quartzite, is not in- tocephala faunule and those from the last two

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localities are believed to be an upper Ellipto- phase of sedimentation in this southern region cephala faunule. Prindle and Knopf (1932, p. than it does in the more northern regions. 276) state that "these shales and grits are Prindle and Knopf's second unit, called the approximately equivalent to the horizon of the Mettawee slate, is described (1932, p. 276) as Bomoseen grit of Ruedemann, or the horizon A "a series of purple and green slates or shales. It (olive grit) of Dale." This correlation is incor- grades conformably into the grayish-green rect since the fossils indicate a correlation with shales and grits and appears to occupy a higher strata in Dale's sequence which lie above the horizon than the grits and shales, although the horizon of first appearance of the Elliptocephala section may be overturned. These slates have fauna. Consequently, strata from which yielded no fossils in the Taconic quadrangle, but Prindle got these fossils are time equivalents of they are Lower Cambrian because they underlie the uppermost beds of Dale's Unit B and the conformably rocks that carry Lower Cambrian superjacent beds of Units C and D. Variable fossils." Apparently Prindle and Knopf were lithology of the strata is characteristic in both uncertain of everything about this unit except areas. In Hoosick quadrangle the strata carry- the lithofacies. Certainly the green and purple ing the lower Elliptocephala faunule cited by shales of the Mettawee lithofacies occur in the Prindle and Knopf (1932, p. 276) are thin Cambridge and Hoosick quadrangles, and at shaly limestones intercalated with gray, green, several localities are intercalated with the and purplish shales at locality Y 9. At locality fossiliferous limestones, lime nodules, and lime- Y 10 and vicinity limestone pebble conglomer- stone pebble conglomerates that contain the ates are interbedded with gray wackes, the upper Elliptocephala asaphoides assemblage. Thus, lens of which is overlain by a black shale con- these green and purple shales are the time taining limestone nodules. These graywackes equivalents of the third phase of deposition. were cited by Dale (1899, p. 180) as typical of Structural relations observed by Bonham the Bomoseen grit, but he apparently did not (1950, Ph.D. thesis, Univ. of Chicago) indicate notice the intercalated limestone conglomerates. that some of the colored shales underlie gray- Fossils collected by Prindle, Bonham, and the wacke lenses assigned to the Eddy Hill grit author from both the limestone conglomerates horizon and grade laterally into the grits. and the overlying limestone nodules belong to These strata are at about the same strati- the lower Elliptocephala faunule and indicate graphic position as the upper beds of Dale's that these graywackes are more nearly the time- Unit B which are interbedded with limestone stratigraphic equivalents of Unit C—the Eddy conglomerates in which the lower Ellipto- Hill grit. In Dale's sequence the various strata cephala faunule first appears. However, in the of comparable age, the lower Elliptocephala Hoosick and Cambridge quadrangles no ap- faunule, are gray and green shales intercalated preciable thickness of green and purple shales with limestones and limestone pebble con- of Mettawee lithofacies is exposed below the glomerates and with the overlying lenses of fossil horizon. Thus most of the strata of the Eddy Hill grit and calcareous quartzites. Most second phase of sedimentation comparable in of the upper Elliptocephala faunule in Dale's age to the greater part of Dale's Unit B in the sequence occurs in limestones interbedded in Slate Belt can not be observed. black shales of his Unit D, whereas, the fossils Prindle and Knopf's third unit, called the of localities P 13 and Moon Hill, believed to be Schodack formation, (1932, p. 277) is "made up of comparable age, occur in limestone pebbles of thinly bedded black shales containing thin and thin lenses of dirty limestone interbedded beds of impure blue limestone that carry frag- in green and purple shales and grits. Dale does ments of Lower Cambrian trilobites in the north part of Hoosick quadrangle. These record green and purple shales and grits at a fossils in the limestone establish the age of the comparable stratigraphic position at several formation as Lower Cambrian. The black localities within the Slate Belt. However, con- shales themselves have so far yielded only ditions at localities P 13 and Moon Hill in sponge spicules found by Dale. No graptolites Hoosick quadrangle suggest that the Mettawee have been found. The formation is the equiva- lithofacies occurs more frequently in the third lent of the Schodack shale and limestone de-

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scribed by Ruedemann from the Capital district pear to be fairly widespread in the central and of New York, and horizon I and J of Dale's northern portions of the Slate Belt, but beds of Rensselaer Co. section, or D of the roofing- comparable age seem to have a limited and slate section. The formation is in apparently sporadic distribution in these southern quad- conformable contact with the underlying rangles. Distribution in this area suggests that Mettawee slate." Prindle and Knopf erred also some of the upper strata of the third phase of in trying to handle the black shale of the sedimentation were removed by pre-Ordovician Schodack lithofacies as a time-stratigraphic erosion. unit. Prindle's fossil localities in the north Within this Lower Cambrian succession the part of the Hoosick quadrangle are in the same lateral gradations among the colored shales, area as those cited for the "Shales and grits of grits, black shales, limestone beds, lenses, and Lower Cambrian age" which were said to be pebble conglomerates can readily be observed. Bomoseen equivalent. Except for one locality Southward from Eagle Bridge colored shales believed to carry an upper Elliptocephala underlie and also grade laterally into gray- faunule, Prindle's localities in the north part of wackes which are at the approximate age po- Hoosick quadrangle and adjoining southern sition of the Eddy Hill grit. In this area colored part of Cambridge quadrangle yielded fossils shales occur also as lenses within larger masses belonging to the lower Elliptocephala faunule. of coarse dark shale (Bonham, 1950, Ph.D. The outcrops of beds of this age, trending thesis, Univ. of Chicago). At Y 12 gray-green northeast-southwest from Shushan to Cam- shales grade laterally into black shales; at Y 10 bridge and beyond, show a lateral color change grit lenses and limestone conglomerates in in the shales from the purples, greens, and grays green shales and blue-gray limestone nodules of localities Y 9, Y 10, and Y 14 to grays and in black shales are intimately interbedded; and blacks at locality Y 12 and Y 13, and finally to at Y 9 and vicinity gray, green, and purple a coal black shale matrix with blue-gray shales grade into thin similarly colored lime- fossiliferous limestone pebbles at locality Y 16. stone beds. Fossiliferous limy deposits occur The lithology of the latter locality is typical of throughout most of the succession with the the Schodack lithofacies. The coal black shales possible exception of the lowermost colored outcrop at least as far southwest as Prindle's shales. Earlier workers frequently referred to locality near West Cambridge; but northwest them indiscriminately and inaccurately as at locality Y IS fossiliferous limestone is associ- limestone conglomerates. In this paper three ated with gray, green, and purple shales. Thus types of indigenous lime deposits are dis- it is possible to delineate roughly the bound- tinguished in the Lower Cambrian shales: aries of one of the many sites of black shale (1) shaly, gray, green or purple limestone deposition in the Slate Belt during the third beds, 1 inch or so in thickness but traceable phase of sedimentation. linearly 25-50 feet, alternate with thin beds of At an outcrop 1.3 miles N. 5° W. of Post shale which are pyritiferous in places. The lime- Corners, Prindle and Knopf's uppermost unit, stone beds were formed by the addition of the Eagle Bridge quartzite, contains crinoid carbonates from shells and exoskeletons of the stem plates (Bonham, 1950, Ph.D. thesis, animals enclosed; outcrops at Y 9 and vicinity Univ. of Chicago). On the basis of these fossils are good examples. and the structural mapping a probable Ordo- (2) Limestone lenses and nodules range from vician age for all the quartzite lenses in this 6-8 inches in diameter to 10 feet thick by 30 area seems reasonable. feet wide and are usually surrounded by gray In summary, outcrops in the Cambridge and or black shales. Layers of the smaller nodules Hoosick quadrangles reveal only a limited have often been confused with pebble con- stratigraphic succession of Lower Cambrian glomerates. The nodules are reasonably beds; i.e., strata equivalent to lithofacies of the fossiliferous and frequently contain a notice- third phase of sedimentation and to the upper able amount of rounded and frosted white part of the second phase as compared to Dale's quartz sand. These nodules were originally sequence for the Slate Belt. Strata carrying masses of organic and inorganic debris collected fossils of the upper Elliptocephala faunule ap- and carried to their present position by cur-

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rents. The outcrop at Y 12 shows good examples The writer proposes naming this fauna the of average-sized nodules. At locality Y 15 the Elliptocephala asaphoides assemblage for one blue-gray crystalline limestone lens, 10 by 30 of its most abundant and characteristic species. feet, surrounded by green-gray and purplish In the early faunal lists of Dale and Walcott shales, appears to represent a clear water site this fossil was erroneously called Olenellus, and on a well-oxygenated bottom where organic this incorrect use appears in some recent papers remains accumulated for some time. (Fowler, 1950) although Walcott corrected the (3) Limestone pebble conglomerates occur in identification in 1910. This assemblage can be a shale or shaly grit matrix. The limestone divided into an upper and a lower faunule pebbles, usually small, subangular or partially based on stratigraphic distribution of several rounded, dear blue-gray to rather muddy, and trilobite species. fossiliferous, are derived from the break-up and redeposition of thin limestone beds. Faunal Lists—Lochman's Localities In this Lower Cambrian succession in Cam- bridge and Hoosick quadrangles shales typical All types and additional specimens used in of the Mettawee lithofacies and the Schodack the ontogeny series and for locality references lithofacies and grits typical of the Eddy Hill in this paper are at the U. S. National Museum. lithofacies are intercalated with lime deposits The Lower Cambrian duplicate material and that contain the same fauna. This relationship the Ordovician collections made during Bon- indicates the contemporaneity of the three ham's mapping of the area are at the New York lithofacies. Consequently, throughout this State Museum. A few brachiopod species are paper the names Schodack, Mettawee, and commented on in this paper, but most of the Eddy Hill are used to refer to lithofacies units brachiopod material from Lochman's collections as first defined; and the time-stratigraphic units has been given to Dr. W. Charles Bell for will be referred to as the second and third future study. phases of sedimentation. Y 6 Three-quarters of a mile southeast of Post Corners, on knoll capped by 760-foot contour; DISCUSSION or FAUNA and the southward continuation of these beds, half a mile east of road junction at 623-foot ele- Introduction vation, east of house and north of road, Hoosick The greatest care has been employed in Falls quadrangle, 1948—Mettawee lithofacies working up this material because limestone Botsfordia caelata (Hall) Hyolithdlus micans (Billings) beds, limestone nodules, and limestone pebble Hexactinellid sponge spicules conglomerates are found in the unfossiliferous Indiana dermatoides (Walcott) Hdcionella subrugosa (d'Orbigny) shales. Fossils from each pebble of the pebble ElHptocephala asaphoides Emmons conglomerates were kept separate, and the as- Serrodiscus speciosus (Ford) semblages checked against those obtained from Calodiscus lobatus (Hall) the limestone beds and the limestone nodules. Y 7 West side of Moon Hill, about 1 mile north of Possibility of artificially mixing faunas has Petersburg, N. Y., Hoosick quad., 1938—Met- thus been eliminated, and all but three collec- tawee lithofacies tions represent a single faunal assemblage of late Botsfordia caelata (Hall) Hyolithdlus micans (Billings) Early Cambrian age. This is the assemblage Hexactinellid sponge spicules that was described by S. W. Ford from the Satterella pulchdla Billings limestones and limestone-pebble conglomerates Edcionella subrugosa (d'Orbigny) Pdagiella primaeva (Billings) in the vicinity of Troy, New York, and, since Hyolithes americanus Billings Gushing and Ruedemann's 1914 publication, Elliptocephala asaphoides Emmons has been referred to as the "Schodack" fauna. Serrodiscus speciosus (Ford) Calodiscus lobatus (Hall) This name is inappropriate as the term Scho- dack refers to a lithofacies, and this faunal Y 9 Same locality as Y-6. 1938 collection assemblage occurs in beds of the Diamond cf. Ptychopardla sp. Rock, Eddy Hill, and Mettawee lithofacies, as Hyolithellus micahs (Billings) Elliptocephala asaphoides Emmons well as in beds of the Schodack lithofacies. Serrodiscus speciosus (Ford)

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Coleoloid.es prindlei Lochman, n. sp. 10P13 #170, hill a quarter of a mile southwest Kutorgina cingulata Billings of Cambridge, New York Botsfordia cadata (Hall) Bonnia sp, undet. Stenothecopsis schodackensis Lochman, n. sp. Botsfordia caelata (Hall) 10P63, hill overlooking Cambridge on the south, Y 17 1.2 miles north of Cambridge, Cambridge west a quarter of a mile quadrangle—Schodack lithofacies Botsfordia cadata (Hall) Stenothecopsis schodackensis Lochman Hyolithellus micans (Billings) operculum Hexactinellid sponge spicules 10P69 #473, half a mile southwest of Cambridge, Hdcionella subrugosa (d'prbigny) New York = Lochman Y 16 Hyolithellits micans (Billings) Hyolithellus micans (Billings) Calodiscus lobatus (Hall) Serrodiscus speciosus (Ford) Faunal Lists—Prindle's Localities Pdagiella primaeva (Billings) Elliptocephala sp. undet. This material represents all collections made by L. M. Prindle from the old Cambridge (30- The four boxes that contain the Prindle material minute) quadrangle and the adjoining Hoosick listed below have no labels, but this material prob- (30-minute) quadrangle. The collections are ably came from locality 10P69; lithology and faunal now stored at the United States National assemblage are similar, and Prindle (Private communication) made a large collection from locality Museum. Prindle's notebook and locality num- 10P69. bers are given just as they appear on the labels now with the collections. An asterisk indicates Hyolithellus micans (Billings) those collections cited in Prindle and Knopf Fordaspis nana (Ford) Elliptocephala asaphoides Emmons (1932) so that the reader may compare earlier Hyolithes americanus Billings temporary identifications with those given in Elliptocephala asaphoides Emmons Serrodiscus speciosus (Ford) this paper. The author's locality number is also Fordaspis nana (Ford) given. Helciondla subrugosa (d'Orbigny) Calodiscus lobatus (Hall) cf. Nisusia festinata (Billings) Cambridge Quadrangle— Indiana dermatoides (Walcott) cf. Ptychoparella sp. 10P26 tit 243, Hill half a mile north of Cambridge, New York 10 Keith 2, 1J£ miles west of Cambridge, New Calodiscus lobatus (Hall) York Sept. 24 Serrodiscus speciosus (Ford) Nisusia festinata (Billings) Elliptocephala sp. undet. cf. Kutorgina sp. undet. Hyolithellus micans (Billings) tubes and 10P22 #211, 2^ miles southwest of Cambridge, opercula New York 10P24a #241, half a mile north of Cambridge, Oboldla crassa (Hall) New York Hyolithellus micans (Billings) Hyolithellus micans (Billings) 10P17 #196, western base of ridge at a point Labradoria cambridgensis Lochman, n. sp. about three-quarters of a mile N.20°E. of cf. Calodiscus sp. undet. Coila, New York = Lochman Y 17 Linguldla granvillensis Walcott Hyolithellus micans (Billings) Elliptocephala sp. undet. Elliptocephala asaphoides Emmons 10P1S #186, hill just north of Cambridge, Calodiscus lobatus (Hall) New York 10P28 #257, west of road, west side of valley Calodiscus meeki (Ford) 2 miles northeast of Cambridge = Lochman Elliptocephala asaphoides Emmons Y13 10P32, hill north of Cambridge, north by a Elliptocephala sp. undet. quarter of a mile Hdcionella subrugosa (d'Orbigny) Acrotreta taconica (Walcott) Fordaspis nana (Ford) Fordaspis nana (Ford) 10P28b—near # 257, at road, near house Elliptocephala sp. undet. Elliptocephala sp. undet. Hdcionella sp. The following three localities may represent only Calodiscus lobatus (Hall) one locality, or else several collections made along 10P30 #274, about 2J4 miles southwest of the line of intermittent shale exposures on the west, Shushan, 1000 feet west of Railroad north, and east sides of the 760-foot hill (720-foot Elliptocephala asaphoides Emmons on old map) on which the Mary McClellan hospital 10P29 #270, about 1% miles southwest of Shushan, 700 feet west of road = Lochman is located. Y12

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Serrodiscus speciosus (Ford) Helcionella subrugosa (d'Orbigny) Hdciondla subrugosa (d'Orbigny) Hyolithellus micans (Billings) Hyolithellus micans (Billings) Obolella crassa (Hall) Calodiscus lobatus (Hall) cf. Scenella retusa Ford Forditta troyensis (Walcott) *10P59 #453, about 1^ miles north of Center Fordaspis nana (Ford) White Creek and 350 feet east of road = Botsfordia caelata (Hall) Lochman Y 10 Kutorgina cingulata (Billings) Hexactinellid sponge spicules Nisusia festinala (Billings) Fordaspis nana (Ford) Elliptocephala asaphoides Emmons Calodiscus lobatus (Hall) About 3^£ miles northeast of Cambridge, New Serrodiscus speciosus (Ford) York on ridge east of valley. 1923 Hyolithellus micans (Billings) Pagetla connexa (Walcott) 10P80 #522, about 2% miles northeast of Post Hyolithes sp. undet. Corners Elliptocephala sp. undet. Nisusia festinata (Billings) Acrotreta taconica (Walcott) 10P47 #402, about 1 mile northeast of Post Corners The two boxes containing the Prindle material Elliptocephala asaphoides Emmons listed below have no labels, but this material prob- 10P51 #418, east side of slate pond about 1J£ ably came from the above locality as the lithology miles north of Center White Creek and faunal assemblages are similar. Elliptocephala sp. Hyolithellus micans (Billings) Calodiscus lobatus (Hall) Helcionella subrugosa (d'Orbigny) Pagetia connexa (Walcott) Fordilla troyensis Walcott Acrotreta taconica (Walcott) Botsfordia caelata (Hall) Acrotreta taconica (Walcott) Calodiscus lobatus (Hall) Obolella crassa (Hall) 10P55 »4:29)4, 1J6 miles southeast of Post Calodiscus lobatus (Hall) Corners Pagetia connexa (Walcott) Serrodiscus speciosus (Ford) Hoosick Quadrangle— Hyolithellus micans (Billings) 10P44 #376, about three quarters of a mile Elliptocephala sp. west of Centre Cambridge, New York *Hill southeast of Post Corners = Lochman Y 9 Obolella crassa (Hall) Serrodiscus speciosus (Ford) Hyolithellus micans (Billings) Obolella sp. Acrotreta taconica (Walcott) Hyolithellus micans (Billings) 10P23 # 225, half a mile south of northern limit P13 about half a mile northwest of Petersburg, of Hoosick sheet New York July 1913 Calodiscus lobatus (Hall) Coleoloides prindlei Lochman, n. sp. Coleoloides prindlei Lochman, n. sp. Hexactinellid sponge spicules Serrodiscus speciosus (Ford) Elliptocephala sp. Helcionella subrugosa (d'Orbigny) Helcionella subrugosa (d'Orbigny) Fordaspis tumida (Walcott) Hyolithellus micans (Billings) Hyolithellus micans (Billings) Calodiscus lobatus (Hall) *10P9 #134, about 2^ miles southwest of cf. Kootenia sp. undet. Hoosick Falls, New York Archaeocyathellus sp. Serrodiscus speciosus (Ford) Fordaspis nana (Ford) 12P100 half a mile southeast of Eagle Bridge. *West side of Moon Hill, about 1 mile north of Oct. 9 Petersburg, New York = Lochman Y 7 cf. Ptychoparetta sp. Helcionella subrugosa (d'Orbigny) Elliptocephala sp. Elliptocephala asaphoides Emmons Helcionella subrugosa (d'Orbigny) cf. Hyolithes Kootenia cf. marcoui (Whitfield) 10PSO #414, about 1% miles north of Post Cor- Hyolithellus micans (Billings) operculum ners Fordaspis nana (Ford) 10P45 #389—S.49°E. to Pleasant Hill. This locality cannot be found on either quad- 10P90 § 60, about three quarters of a mile north rangle, spelling of the hill on Prindle's label of Eagle Bridge looks as transcribed above. It may refer to a Elliptocephala asaphoides Emmons local name in the vicinity of Petersburg. Hyolithellus micans (Billings) Kootenia cf. K. marcoui (Whitfield) Serrodiscus speciosus (Ford) Calodiscus lobatus (Hall) Calodiscus lobatus (Hall) Helcionella subrugosa (d'Orbigny) 10P41 #320 Middle Cambrian pebble. Three Fordaspis sp. undet. quarters of a mile west of Coila, New York Eodiscus cf. E. punctatus (Salter)—(PI. 5, *P7 #67, hill 1 mile northwest of North Hoosick figs. 22, 23) Elliptocephala asaphoides Emmons small cranidium cf. Agraulos sp. undet 2— Calodiscus lobatus (Hall) Cobbold (1913)

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small brachiopod—^Obolus sp. Lower Cambrian limestone nodules and beds, fragmentary cranidium cf. Ptychoparia (Lio- stracus) lota n. sp., Cobbold (1913) and that each piece is different from the other. Two pieces of black, dense, lithographic lime- Preservation of Fossils stone constitute this collection. The best specimen is a large fragmentary cephalon of Eodiscus All the fossils occur in limestones although close, if not identical, to E. punctatus (Salter) certain of the thin beds, as at locality Y 6, are which is a diagnostic species of the Paradoxides argillaceous. Emmons' original specimens of hicksi zone of the Atlantic province. On the Elliptocephala and Atops and some of Walcott's reverse of this piece is a small incomplete specimens which are nearly complete exo- cranidium similar to that figured by Cobbold skeletons appear to have come from similar (1913, PL 2, figs. 14a, b, c) as Agraulos sp. muddy limes. Only one specimen of a complete undet. 2 from the P. intermedius fauna of the exoskeleton, of Serrodiscus, was obtained from Comley Breccia-Bed. On the second piece there the collections here described. is one small Obolus-\ike shell and a crushed im- Fossils are largely disarticulated pieces of pression of a trilobite head. Reconstruction of trilobite exoskeletons, broken shells of brachio- discernible features suggests a cranidium simi- pods, and worms, and snails. The fragile exo- lar to that figured by Cobbold (1913, PL 2, skeletons of large adults of Elliptocephala are figs. 16a, b, c) as Ptychoparia (Liostracus) lata known only from fragments. Identifiable n. sp. from the same fauna. This fauna belongs cephala are 1 inch or less in length, most are to the P. hicksi zone (Cobbold, 1920). about 5 mm. The larger shells of Botsfordia and Two of Prindle's collections, each now con- the calcareo-phosphatic tubes of Hyolithellus sisting of one small piece of dark limestone, micans are always broken. Comminution of all contain Lower Ordovician fossils and should the more frangible specimens of the assemblage not be confused with similar appearing material indicate that this material was moved by cur- from the Lower Cambrian. Most of Prindle's rents and waves for some time and distance Early Ordovician fossiliferous material consists before deposition. In contrast, all disc-shaped or of large fragments of an asaphid trilobite, pieces oval-shaped specimens, as the opercula of of cephalopods, and of large coiled gastropods Hyolithellus micans or the pygidia and cephala in a light-gray medium-grained limestone. The of Calodiscus and Serrodiscus, are usually com- two collections mentioned here are of special plete and show current orientation in their interest as they represent a different facies and deposition. possibly a different horizon from the material The absence of fossils in the shales can be of the other collections which came from large largely attributed to the slow silt accumulation on the sea floor. All organic matter was exposed outcrops of limestone in quarries. The small to the activity of bottom scavengers as well as limestone pieces of these two collections ap- chemical dissolution. Bottom scavengers, be- pear to have been isolated nodules or pieces longing to several worm phyla and primitive from thin beds in dark shales. The localities lie Arthropoda, must have been numerous during within areas mapped as Ordovician shale by Cambrian and, no doubt, were adjusted to both both Prindle and Bonham. aerobic and moderately anaerobic bottom con- 10P20a #205—about three quarters of a mile ditions. Thus the fossil collections, almost ex- southwest of Cambridge, New York clusively, were masses of organic debris small cranidium cf. Parabolina sp. undet. (PI. fortuitously covered by sand or silt carried by 8, fig. 23) fragment of bryozoan the same currents which moved them. cephalon of "Agnoslus" sp. All enclosing strata have been subjected to 10P36 # 295—hilltop about 2}£ miles north of dynamic metamorphism of different degrees. Cambridge, New York; The limestone material was squeezed while fragment of calcareo-chitinous test with distinctive markings. plastic and/or fractured; many of the fractures were healed by calcite veins. The resulting dis- Microscopic examination shows that both tortion of fossils necessitates caution in deter- pieces differ lithologically from characteristic mining specific characters. The author had

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attempted to negate its influence by preparing Genera of the Eodiscida are the second most the largest possible number of specimens for common members of the assemblage. Specimens each species. Each suite is mounted on large in the collections indicate that the adult of cards so that variations in growth sizes and Serrodiscus speciosus (Ford) reached a length of variations in appearance of equal size indi- 28-30 mm, but most adults of Calodiscus and viduals may be easily compared. With such Pagetia were small and did not exceed 15 mm. material it is mandatory to form a species Again the large number of individuals of a few concept from as many specimens of a popula- species, usually one for each genus, is striking, tion as possible rather than from a single holo- and metaspid as well as holaspid molts are type specimen. abundant. This abundance enabled the author to show conclusively that types of cephala Composition of Fauna which were called Calodiscus agnostoides Kobayashi do not constitute a valid biological Of 11 trilobite genera identified in this fauna species but are metaspid cephala of Calodiscus only six are important members of the assem- lobatus (Hall). Serrodiscus speciosus and blage. The Olenellida are represented only by Calodiscus lobatus are common and abundant Elliptocephala asaphoides Emmons, a monotypic members of the fauna at most localities and genus whose known distribution is from eastern appear to have a stratigraphic range of the life New York and western Vermont to eastern span of the assemblage. Both genera occur Massachusetts. Elliptocephala occurs in great throughout the Atlantic province; Serrodiscus numbers everywhere in the area studied, and is reported from as far south as Spain and apparently persisted in comparable abundance Morocco. Although five valid species of Calo- throughout the time range of the fauna. It may discus have been reported from eastern New have been an indigenous Olenellid which was York, only one cephalon in these collections rigidly adapted to an environment peculiar to can be referred to a second species, C. meeki this region, or it may have been a southern (Ford). The apparent exclusive development of olenellid genus which was at the northern limit C. lobatus (Hall) in this area, as compared to of its range in the New England Cambrian seas. the assemblage obtained around Troy, may Fossil remains suggest that it was one, if not have stratigraphic rather than ecologic sig- the, dominant member of the assemblage as nificance and indicate that most collections in well as the largest adult form, reaching a total the Cambridge-Hoosick region came from length of at least 7 inches. strata lying in the lower half of the Ellipto- The other large member of this fauna is cephala asaphoides fauna! range. Atops trilineatus Emmons. This species appears The presence of Pagetia in this assemblage is to have been a less common but more wide- interesting biologically and geographically. A spread member of the assemblage. Species of new species, Pagetia prindlei, has been described Atops and/or Pseudatops Lake, 1940, have been from several collections. Diagnostic characters identified from the Callavia zone of Newfound- of the adult cephalon of this species are features land and from the late Lower Cambrian beds of which occur only in the smaller metaspid North Wales and Shropshire, England. These cephala of P. connexa (Walcott). Moreover, the forms are considered the earliest representa- two species are mutually exclusive of each other tives of the Conocoryphidae and had a sturdier in occurrence. These two phenomena lead to exoskeleton than the Olenellida. This circum- the postulation that P. prindlei is the earliest stance suggests that the fewer fossils obtained known species of Pagetia and that P. connexa give a true picture of the species' minor po- is a direct descendant. Thus the first appear- sition in the assemblage, and is not an accident ance of Pagetia was in this late Lower Cambrian of preservation. Because of the reticulate orna- fauna of eastern New York. These two species, mentation of the exoskeleton fragments of both in physical appearance and stratigraphic Pseudatops reticulatus (Walcott) could be con- position, were forerunners of the widely dis- fused with fragments of Elliptocephala, but tributed Middle Cambrian Pagetia species. It Atops trilineatus can easily be distinguished by is doubtful whether Pagetia is closely related to the granular ornamentation of its exoskeleton. other Lower Cambrian genera of the Pagetiidae.

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Pagetides appears to have originated inde- genus are in the pygidium, whereas the cra- pendently in the Pacific province biofacies. It is nidium is similar to Bonnia. In the southern very common in the late Lower Cambrian as- Appalachian Lower Cambrian faunas Resser assemblages of the Saint Lawrence valley, is sociated a Bonniella pygidium with a Bonnaria- known from the Parker shale of Vermont, and like cranidium in his species Bonniella vir- by a few cranidia in "Schodack" limestone near ginica. Consequently, the relationship of these Middle Granville, Washington County, New two genera is uncertain. York (Rasetti, 1948), apparently the southern Bonnia, known from one cranidium, is re- limit of the genus. Pagetides shows similarities ported here for the first time in the Ellipto- to Hebediscus and to certain Middle Cambrian cephala asaphoides assemblage, although it Eodisats species. occurs in abundance in the upper Lower Four genera in the assemblage belong to the Cambrian of the Saint-Lawrence Valley. Geo- Dorypygidae, Kootenia, Bonnia, and two new graphic distribution of Bonnia indicates that it genera Fordaspis and Bonnaria. The genera ap- was a member of the contemporaneous Pacific pear closely related and are rather primitive, province assemblage, and that it had a marked which suggests that this family was of mono- preference for a clear water biofacies. With re- phyletic origin and that its inception was in the spect to the single specimen reported here, it late Early Cambrian. Fordaspis nana (Ford), seems probable that this individual was carried the genotype, occurs in abundance in the by storm waves or currents into this region author's material as well as in some of Ford's from its normal biofacies to the north. Bonnia collections from Troy. A second species, F. swantonensis Resser occurs with its normal tumida (Walcott), occurs in abundance in some faunal assemblage at Mallets Bay, Vermont of Walcott's Washington County collections. (Kindle and Tasch, 1948). Ecologic conditions From known material these two species appear rather than age difference are responsible for mutually exclusive in occurrence, a situation its near absence from the Elliptocephala also believed to have stratigraphic significance. asaphoides assemblage. The largest cranidium is 5 mm long, and the Kootenia does not occur in most of the largest pygidium (doubtfully referred to the author's material, but is present in several of species) is 6 mm long. The average adult may Prindle's collections. It has also been found at have reached a length of 30 mm. The small size some of Walcott's localities in Washington and generalized appearance of Fordaspis sug- County and near Troy, although S. W. Ford gests primitiveness, but the genus appears to did not report it in his collections. Three species, show some specialization in the excessive con- K.fordi (Walcott), K. marcoui (Whitfield), and vexity of the glabella. There is a striking K. troyensis Resser are recognized as valid, and similarity between the metaspid cranidia of appear to be moderately abundant normal Fordaspis, before the tumid glabella develops, members of the Elliptocephala assemblage. and the holaspid cranidia of Bonnaria. The Some cranidia and pygidia are 10-12 mm long, similarity suggests that the two genera had a which indicates that the average adult exo- common ancestor and that Bonnaria, with en- skeleton could have been 40 mm or more in larged anterior glabellar lobe and longer dis- length. Thus Kootenia was generally larger than tinct glabellar furrows, shows the more primi- Fordaspis or Bonnaria. Faunal associations tive structure of the cranidium. The small adult indicate that the Kootenia species were mem- cranidia of Bonnaria indicate that the adult bers only of the upper Elliptocephala faunule, exoskeleton was about 30 mm. long. Bonnia, which accounts for the absence of the genus Kootenia, and Bonniella were also derived from the ancestral stock about this same time, but from any collections from the Cambridge- two of these genera are poorly represented in Hoosick area. Kootenia appears always to have the Elliptocephala asaphoides assemblage. had a remarkably wide environmental tolerance Bonniella desiderata, the genotype, is from the and/or adaptability. It is the only member of Dunham formation of Vermont. There is no the late Lower Cambrian trilobite assemblages evidence of its presence in the Cambridge- of the northern Appalachian regions that was Hoosick material. Diagnostic features of the equally at home in the biofacies peculiar to the

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Atlantic province faunas and in that peculiar prevalence of reticulate surface markings of the to the Pacific province faunas. exoskeleton on Lower Cambrian trilobites is The almost total absence of Ptychoparid striking as it is rarely observed in the much genera from the Elliptocephala asaphoides larger trilobite assemblages of the Middle and assemblage probably is the feature that has Upper Cambrian. Its prevalence in the Lower overemphasized its similarity to Atlantic Cambrian suggests that it had some biologic or province assemblages. Only a few fragmentary ecologic significance. cranidia of Ptychoparella sp. occur. The con- A variety of phyla are represented among the dition of these specimens strongly suggests non-trilobite members of the Elliptocephala that these were alien fragments that drifted asaphoides fauna. Indigenous benthonic forms into the area. In one of Walcott's collections are: Helcionella subrugosa and Scenella relusa of from Washington County a few specimens of the Gastropoda; Fordilla troyensis, probably a Kochiella fitchi and Antagmus adamsi have been Pelecypoda; hexactinellid sponges, usually found with abundant Pagetia connexa. This called Protospongia; Hyolithellus micans of the ratio contrasts markedly with that in the late Annelida; Indiana and Stenothecoides, probably Early Cambrian biotas of comparable age from primitive Branchiopoda; and Botsfordia, Lin- the Pacific province in which primitive Ptycho- guella, Acrotetra, andOio/eHoof theBrachiopoda. parid genera frequently dominate the assem- Four genera of pelagic planktons, Hyolithes, blage. The ptychoparid material reported from Pelagiella, Coleoloides, and Salterella, may be the Elliptocephala asaphoides assemblages seems considered indigenous to the open ocean waters best explained as extraneous exoskeletal frag- which had access to this area. The Archaeo- ments moved southward and eastward by cyathids and the larger brachiopods, such as waves and currents into an alien environment Rustella, Nisusia, and Kutorgina, are poorly from the normal biofacies to the north. This and sporadically represented in the Cambridge- biofacies was inhabited by the Olenellus thomp- Hoosick area. This fact, contrasted with their soni assemblages recorded from the Dunham, somewhat better representation at localities to Monkton, and Parker formations of Vermont. the west and the north, indicates that they The eleventh trilobite of the assemblage is must be alien elements drifted into the area by Labradoria cambridgensis, a new species, known currents. Both groups are sessile benthos and only from a few cranidia. The genus was previ- required an ecologic habitat characterized by ously reported from the Forteau formation at clear, sunlit, well-oxygenated, shallow water L'Anse au Loup, Labrador. The few specimens and a firm bottom. Six species of Archaeo- in Prindle's collection may also represent ex- cyathids are described from the Elliptocephala traneous drifted fragments. The affinities of asaphoides fauna. Ajacicyathus profundomimus Labradoria are unknown, and no guess can be occurs from Labrador to Virginia, but the made until a pygidium can be associated. five species of Archaeocyathellus comprise a Hupe (1953, p. 160) suggests placing Labra- compact group not closely related to any other doria in a family with the southeast Asian species of Archaeocyathids. This is in sharp genus Yinites Lu 1946. However, since Hupe's contrast to the prolific Archaeocyathid fauna discussion indicates complete unfamiliarity from Newfoundland which has close affinities with either genus, his classification cannot be with species from Silver Peak, Nevada. Archaeo- considered valid. cyathellus appears to have been an endemic Several genera of this faunal assemblage, as genus of the eastern New York region. well as of other Lower Cambrian assemblages, The position of the small shell, Stenothecopsis commonly show a reticulate outer surface of schodackensis, is uncertain. Cobbold (1935) the exoskeleton. This network of narrow ridges and Poulsen (1942) referred it doubtfully to or reticulation occurs on all genera of Olenel- the Crustacea; but the conical shape, closed lida, on the species referred to Pseudatops, on apex, thin phosphatic material, and small size species of Bonnia, probably on Kootenia, and comprise characteristics most like those found on well-preserved specimens of Serrodiscus in small sessile solitary individuals of the speciosus in the author's collections. The Entoprocta and the Phoronidea. Its much

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greater abundance at locality Y 11 suggests and silicified specimens was obtained from lo- that it, like the Archaeocyathids and the larger cality Y 11 that limestones from all collections brachiopods, required a firm sandy bottom. were subsequently etched. Many additional The Elliptocephala asaphoides assemblage of specimens of the smaller species of the fauna the Cambridge-Hoosick area is a mixed fauna were obtained by this means (i.e., number of transitional in composition between the At- localities was doubled for sponge spicules); the lantic and the Pacific province biotas. Ellipto- worn and comminuted condition of most cephala, Atops, Bonnaria, Fordaspis, Pagelia, brachiopod and trilobite specimens was veri- and possibly Kootenia may have developed in fied; and interesting data on lithology of the this region, and three remained restricted to it. limestone nodules were obtained. Pseudatops, Elliptocephala (in eastern Massa- Etched specimens are preserved in one of chusetts), Calodiscus, and Serrodiscus found the three types of material: typical Atlantic province biofacies an equally (1) Many retain original shell material and compatible environment. Bonnia, the Ptycho- show colors of the nacreous layer. Shells of parid genera, and Labradoria occur in large Stenothecopsis and tubes of Hyolithellus micans numbers in most Pacific province regions and are most fragile, but often their coloring and assemblages; but are represented here by rare fine surface markings are preserved. The larger and sporadic specimens which were apparently opercula of Hyolithellus are thick and stained the remains of occasional individuals washed orange, apparently by iron oxide; but the into an alien environment to which they could smaller opercula (0.25-0.5 mm in diameter) are not adapt. Only Kootenia was adapted to both paper-thin, fragile, and translucent, and already biofacies. The trilobites were the most sensitive show the distinctive muscle scar pattern. These to the difference in biofacies. Among the smaller opercula are rarely obtained except brachiopods the environmental response is re- from etched material. Of the many valves of flected at the specific rather than the generic Botsfordia, Linguldla, and Acrotreta obtained, level as few species have been recorded from some were the fragile immature shells 0.5 mm both provinces. Fordilla is an indigenous form. or less in size. The Branchiopoda genera occur elsewhere only (2) Silicified specimens of Elliptocephala, in the Atlantic province biotas. Strangely, Calodiscus, and possibly Atops were identified, Hyolitkellus micans and Helcionella subrugosa, but other genera may be represented in the presumably benthonic forms, show widespread masses of jumbled silicified fragments re- distribution throughout the two provinces covered. Sponge spicules, fragments of the comparable only to that of the planktonic porous walls of Archaeocyathellus, valves of genera. H. subrugosa was probably a generalized Botsfordia caleata, and small gastropod molds gastropod species which, like Kootenia, had a have all been silicified. There is a direct relation wide ecologic tolerance. HyolUhellus micans between the number of silicified fossils and the may be a similar widely tolerant animal or amount of quartz sand grains in the enclosing only a form name for a type of worm tube. limestone and associated beds. Limestones This faunal assemblage, mixed both artificially from locality Y 11 furnished abundant silicified and naturally, has proved invaluable for corre- specimens; from localities Y 16 and Y 17 lime- lation purposes; and has permitted a reasonably stone nodules that showed some quartz sand exact correlation of the late Lower Cambrian furnished a moderate number of specimens; faunas of the Atlantic and the Pacific provinces. and the thin muddy limestones of locality Y 6 yielded only a few quartz sand grains, two Etched Material silicified cephala of Calodiscus, and a few sponge spicules. Etching with acetic acid was initiated in (3) Badly worn fragments of sponge spicules, order to obtain perfect specimens of Hyo- trilobite genal spines, tubes of Byolithes and lUhellus micans opercula, flat discs 1 to 2 mm Coleoloides, gastropod molds, and brachiopod in diameter of a brittle calcareo-phosphatic shells were recovered as black or dark brown material. Such a variety of calcareo-phosphatic phosphatic nodules and pellets. Though of

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little use as identifiable fossils, these fragments variation in sea-bottom conditions and prob- are interesting ecologically. They indicate that able opacity of the water during the third phase silt deposition in this region was slow and that of sedimentation. To the west in the classic the remains of organisms lay exposed on the region along the eastern side of the Hudson sea floor for a considerable time during which Valley the sediments contain the highest per- they were subjected to both chemical and centage of sandstones and fragmental limestones. mechanical attack by the sea water. The limestone conglomerates reach a maximum Dr. M. S. Sun, New Mexico Bureau of Mines, development in thickness and coarseness. Here kindly made a series of microchemical tests on also are found most the larger calcareous bra- samples of sponge spicules, trilobite fragments, chiopods and the archaeocyathids. However, opercula of Hyolitkellus, Botsfordia shells, and fragments and scattered specimens of these several kinds of the problematica which were species show that these are transported rather also recovered by etching. All were determined than individuals in situ. The physical appear- to be calcium ortho-phosphate—Ca3(P04)2- ance of the limestone breccias or conglomerates X-ray diffraction pictures identified the mineral suggests that these fossils were shallow-water species as fluorapatite. Many Problematica had reef debris incorporated in layers of limy ooze a porous texture, and could be divided into a disrupted by submarine sliding. Deposits of the nodular group and a flattened group. The shallow-water reef environment must have lain flattened forms were suspected of being badly a short distance to the west, but they are no- worn pieces of Botsfordia shells. A microscopic where exposed today. Known sediments appear prismatic structure shows that they are of or- to have been deposited in the deeper-water ganic origin. The nodular specimens, rem- areas of the lower slopes and marginal floor of iniscent of bone, are similar to W. C. Bell's a contiguous basin on which the unstable illustrated specimens etched from the Upper masses finally came to rest. Cambrian Bonneterre dolomite of Missouri.1 The sandstones contain subangular grains as Microscopically the nodular pieces show a con- well as well-rounded frosted grains as large as cretionary rather than a prismatic structure; 1 mm in diameter. The major source of sand they are actually small phosphatic nodules or was from the west, the Precambrian conti- concretions which formed on the sea bottom. nental land mass; but apparently a limited local supply was also available from scattered Ecology of Fauna islands such as Stissing Mountain. In western areas lime ooze derived largely from organic Some of the ecologic conditions controlling debris accumulated when the sand was not the life patterns of this assemblage can be re- being deposited. Black and colored shales ap- constructed. It is difficult to evaluate the sig- pear locally and sporadically with the limes and nificance of the small number of genera and sands in the Rensselaer County sections. To species constituting the assemblage. The num- the east and north the shales increase rapidly bers of fossil species is controlled largely by the to a dominant position in the section which ability of the animals to produce preservable indicates that the basin floor was predom- exoskeletons. The numerous tracks, trails, sea- inately a soft mud bottom. However, the water weed markings, and Problematica recorded was not constantly turbid. Frequent phosphatic throughout the region in the shales of the nodules in the etched material suggest slow and second and third phases of sedimentation sporadic rate of mud accumulation. Only (PL 9) suggest the presence of a large fauna and locally and temporarily, as after a storm, was flora without preservable hard parts. all the water turbid. Gradually the silt would Ecologic data can be derived from the litho- settle onto the quiet deep basin bottoms, and facies, etched material, and regional distribu- the overlying waters would clear. Only water tion of certain genera and species. The litho- immediately above the bottom would become facies patterns indicate considerable local opaque when the mud was disturbed by bottom dwellers. The distribution of colored shales 1 At the December 1946 meeting of the Paleonto- indicates that scattered sites of well-oxygenated logical Society; for abstract see Bell (1946) bottom areas were always present during the

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third phase of sedimentation. The in situ as- arkosic, and calcareous—are interbedded with semblage of Y 6 shows vagrant benthos equally argillaceous sediments throughout the Cam- at home on soft mud bottoms well out in the brian and the Lower Ordovician terranes. This basin and on mud and sand bottoms near is one of the most prominent features of sedi- basin margins. Elliptocephala, Calodiscus and mentation of these strata from southeastern Serrodiscus, and Helcionella are the common New York to the Saint Lawrence Valley. Epi- vagrant benthos; Hyolithellus was probably a sodic passage of strong currents over the sea semimobile animal capable of leaving its tube; bottom is required to introduce these masses of sponges and inarticulate brachiopods, sessile quartz sand and arkose into the sites of silt benthos, presumably utilized shells and exo- deposition. Such currents, produced by storm skeletons of other animals as sites of attach- and/or oversteepening of the marginal slopes of ment on mud bottoms. the basin, would cause slumping and frag- It is more difficult to reconstruct the biota mentation of limestone layers on the slopes. inhabiting the moderately anaerobic bottoms Most breccia would come to rest near the base of the swales where the black shales of the of the slope, but smaller fragments could be Schodack lithofacies formed. At present such carried far out into the basin. Limestone bottoms are inhabited by mud eaters and pebbles in the Cambridge-Hoosick area are scavengers without preservable exoskeletons; it always small and subangular to rounded. The is not improbable that such animals were in- presence of Archaeocyathellus, Kutorgina, and habiting these sites in the Cambrian. Nisusia in sandy limestone nodules at localities Planktonic species, Pelagiella, Hyolithes, Y 12 and Y 13 indicates that the currents oc- SaUerella, and Coleoloides, appear fully adapted casionally carried both sand and reef debris to their specialized type of life in the normal eastward into the basin. Arkosic grits and marine near-surface or surface waters. Their quartz sands are associated with the pebble sporadic occurrence in the collections and their conglomerates in the Hudson Valley and the oriented deposition reveal their planktonic Cambridge-Hoosick area. The floor of the origin. These species are especially useful as basin may have been 600 feet below sea level, they are widely distributed throughout the or it may have been several times that deep. northern Appalachian region. They are equally abundant in faunal assemblages of the Atlantic Correlation of Fauna province biofacies and of the Pacific province biofacies, which shows that the surface waters Recent publications of Rasetti (1951) and had free access to all portions of the provinces Lochman (1953) indicate that the Lower from New England and the Maritime Provinces Cambrian faunal zones presented in the North northward over the Saint Lawrence Valley and American Correlation Chart (Howell et al., Labrador. 1944) are untenable, and a revision com- The presence and distribution of fossils from patible with the present known facts has been a shallow-water reef environment indicate that made. Table 1 gives the correlation of the the entire region from the Hudson Valley east- Elliptocephala asaphoides fauna with the stand- ward to the Cambridge area comprised a basin ard faunal zones as they are now recognized for that was deeper than the adjoining western both the Pacific province and the Atlantic reef region, but data of the actual water depth province. For the Pacific province the entire are not available. Tracks and trails on shale Lower Cambrian is termed the Olenellus surfaces were once considered evidence of faunizone and is divided into two subzones. In shallow water, but undersea photography has the lower subzone Olenellus, Nevadia, Paede- shown that these can be made and preserved at umias, and Wanneria are present, associated considerable depth. In this region of deposition with primitive brachiopods, worm tubes, there is no justification for the assumption that Hyolithes, and archaeocyathids. In the upper only shallow-water waves could shatter the subzone the various Olenellida genera are as- limestone beds to produce the pebble con- sociated with many opisthoparian genera, some glomerates. mollusks, and larger brachiopods as well as all Masses of coarse detritus—arenaceous, the nontrilobite genera found in the lower sub-

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zone. No further zonal subdivisions of the Callavia-zone time (Hutchinson, 1952; Schu- Lower Cambrian are possible now, but more chert and Dunbar, 1934); but in northwestern detailed study of the stratigraphic succession of Europe strata of the Holmia zone may be some-

TABLE 1.—CORRELATION OF THE ELLIPTOCEPBALA ASAPHOIDES FAUNA Cambridge-Hoosick Pacific province quadrangles Atlantic province Hupe's zones in Morocco

"Austinvillia faunule of Quebec"

Protolenus Zone VIII upper Upper faunule o 7nne VII *

subzone 1 Zone VI It | :§ lower Callavia ^ Q ;§i 5 faunule

ZoneV

Holmia Zones I-IV

Lower

Olenellus

subzone

fossils, in the upper subzone at least, may per- what older. Hupe (1952) published a succession mit finer subdivisions. of Lower Cambrian faunal zones for Morocco. For the Atlantic province three zones seem His zone VI, from which Callavia is recorded, recognizable—the Holmia, the Callavia, and the may be considered the approximate time Protolenus. The Callavia and Protolenus as- equivalent of some of the Callavia zone; and semblages contain Eodiscida and opisthoparian his zones VII and VIII probably occupy the genera, which suggests that these two zones ensuing time interval through the Protolenus may be the time equivalent of the upper zone. Hup6's zones I-V, lying below the ap- Olenellus subzone. The mixed composition of pearance of Callavia, occupy a position which the Elliptocephala asaphoides assemblage veri- would indicate at least some time equivalence fies this suggestion. In the North American with the Lower Olenellus subzone of the Pacific portion of the Atlantic province there appears province. However, the continuation of the to have been little or no deposition prior to same genera and species through two or more

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TABLE 2.—STRATIGRAPHIC RANGE (WHEREVER KNOWN) or THE SPECIES OF THE ELLIPTOCEPHALA ASAPHOIDES FAUNA Faunal list Lower faunule Upper faunule

Elliptocephala asaphoides Emmons A to ps trilineatus Emmons Pseudatops reticulatus (Walcott) Serrodisctts speciosus (Ford) Calodiscus lobatus (Hall) Calodiscus schucherti (Matthew) 7» ? Calodiscus meeki (Ford) "? ? Calodiscus walcotti Rasetti ? ? Pagetia prindlei, n. sp. Pagetia connexa (Walcott) Pagetides elegans Rasetti ? ? Fordaspis nana (Ford) Fordaspis tumida (Walcott) Kootenia troyensis Resser Kootenia marcoui (Whitfield) Kootenia fordi (Walcott) Bonnaria clavata (Walcott) Bonnaria salemensis (Resser) p Bonnia sp. undet. p Ptychoparella sp. undet. Kochiella fitchi (Walcott) Antagmus adamsi (Billings) Labrador-id cambridgensis n. sp. Prozacanthoides eatoni (Walcott) A rchaeocyathellus Hexactinellid sponges Helcionella subrugosa (d'Orbigny) Fordilla troyensis Walcott ? Modiolopsisf prisca Walcott Hyolithes americanus Billings Hyolithes communis Billings Hyolithes impar Ford Pelagiella primaeva (Billings) Scenella retusa Ford Hyolithellus micans (Billings) Coleoloides prindlei n. sp. Salteretta pulchella Billings • r Indiana dermatoides (Walcott) Stenothecoides labradorica Resser Stenothecopsis schodackensis n. sp. Obolella crassa (Hall) Bicia gemma (Billings) Acrotreta taconica (Walcott) Lingulella granuillensis Walcott Botsfordia caelata (Hall) Kutorgina cingulata (Billings) Nisusia festinata (Billings) Billingsella salemensis (Walcott)

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of these zones shows that Hup6 is dealing with This entire region remains to be reworked by assemblages which North American paleon- modern methods. Assemblages from many of tologists call faunules. A faunule is an as- Walcott's Washington County localities, as semblage of genera and species more limited in USNM 20a, 33, 34, 35, 36, and 38a (Walcott, time and space than the assemblage called 1912), appear to be a typical upper Ellipto- faunizone. The same species of Fallatopsis cephala faunule. occurs from zone I through zone III, and the genus continues through zone IV. The appear- PALEOGEOGRAPHY ance in zone IV of Hebediscus attleborensis and Strenueva marocana indicates a close time rela- Introduction tion to the Callavia zone of the North Atlantic province. Consequently, there is some doubt Throughout eastern New York and Vermont that the Fallatopsis strata of Morocco extend two stratigraphic sequences of Lower Cambrian as far back into the early Early Cambrian as rocks, based primarily upon lithofacies dif- certain strata of the Lower Olenellus subzone ferences, have long been recognized. The of the Pacific province. Taconic sequence is characterized by pre- The Elliptocephala asaphoid.es fauna is corre- dominant graywackes and shales and the lated with most of the upper Olenellus subzone presence of the Elliptocephala asaphoides of the Pacific province and with the Callavia fauna; the Valley sequence is characterized by and Protolenus zones of the Atlantic province. predominant dolomites, limestone, and ortho- However, the writer believes that the upper quartzites and the presence of the Olenellus faunule of the Elliptocephala asaphoides as- thompsoni fauna. Several hypotheses of Cam- semblage is not so late as some faunules which brian paleogeography have been advanced have been described from the Protolenus zone during the past SO years to account for the and the top of the upper Olenellus subzone. Two close juxtaposition of these two sequences smaller faunule divisions based primarily on throughout this region. the mutually exclusive occurrence of species of Dale (1899; 1904b) postulated rapid lateral several trilobite genera can be recognized changes between contemporaneous sediments of within the larger assemblage. The relationships the two sequences during the Lower Cambrian of the species of Pagetia and Fordaspis indicate and the Ordovician; he suggested that the sand- that these faunules have stratigraphic sig- stones and limestones of the Valley sequence nificance. Table 2 shows the range of each passed laterally into the graywackes, sand- species in the assemblage. Pagetia prindlei and stones, and shales of the Taconic sequence. He Fordaspis nana are considered characteristic of believed that during Cambrian and early the lower faunule; Pagetia connexa, Fordaspis Ordovician the sea floor, unstable throughout tumida, the three species of Kootenia, Acrotreta the region, was subjected to frequent oscilla- taconica, and Lingulella grantnllensis are usually tions. This may have caused rapid lateral associated in the upper faunule. More detailed gradations, which resulted in nondeposition of work may also indicate a stratigraphic sig- Middle and Upper Cambrian strata and pro- nificance for the various species of Calodiscus. duced variable overlaps of Ordovician strata on In the Cambridge-Hoosick quadrangles most underlying Lower Cambrian beds. collections represent the lower Elliptocephala Schuchert proposed a second hypothesis faunule. Only those from Prindle's localities, which embraced conditions for the entire northwest side of Moon Hill, near Pleasant Hill, and eastern Appalachian region, Greater Acadia, about 3J

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their map (Fig. 2), the geosynclines are be- workers were based on several assumptions now lieved to have been foreshortened by folding known to be false: (1) that the Elliptocephala and faulting. asaphoides and Olenettus thompsoni assemblages For the eastern New York and Vermont area were totally different and had no significant Keith (1923), in order to derive sediments of the genera or species in common; and (2) that the

Northwesttrn Vermont ond adjoining southern Quebec* NW

FIGURE 1.—CORRELATION OF LOWER CAMBRIAN FORMATION or NEW YORK, VERMONT, AND LABRADOR

Taconic sequence from depositional sites lithofacies of one sequence were entirely dif- within Schuchert's Acadian geosyncline, postu- ferent from the lithofacies of the other sequence. lated westward movement of all such strata along numerous thrust planes. This would en- Faunal Evidence tail 50-100-mile displacement of these strata A comparison of the three assemblages as from an original site east of the Green Moun- they are now known (Table 3) shows that the tains. Most of the faults and the reality of such Elliptocephala asaphoides fauna has 4 species movement have not been proved in this region. and 6 genera of trilobites, 2 species and 4 Prindle and Knopf (1932), also following genera of brachiopods, and 4 species and 4 Schuchert, considered that the lithofacies of genera of other phyla in common with the the two sequences were totally different and so Atlantic province assemblage; and 4 species and postulated their deposition in separate basins. 6 genera of trilobites (at least 4 are strays), 13 To explain close geographic juxtaposition of species and 10 genera of brachiopods, and 7 sections of the two sequences in the Slate Belt species and 9 genera of other phyla in common area, they postulated that all sections of the with the Pacific province assemblage. The Taconic sequence had been carried westward somewhat greater affinities with the latter ap- on numerous low-angle thrust planes and that pear to agree with the geographic juxtapo- the roots of the Taconic sequence lay east of sition of this region to the edge of the coastal the Green Mountains Precambrian mass which shelf area of the Pacific province. This compila- may or may not be the land barrier originally tion had to be based2 largely on Walcott's early separating the two sites of deposition. •With corrections from the studies of Rasetti These postulates of Schuchert and later (1948) and Shaw (19S4).

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Olendlus ?? wakotti (S. & F.)) = Elliptocephala asaphoides Em- Elliptocephala mons *0lenellus ? sp. Olendlus vermontanus (Hall) *0lenettus thompsoni (Hall) Olenellus thompsoni (Hall) Olendlus thompsoni. crassimargi- natus Walcott Olendlus hermani Kindle & Tasch Olendlus logani Walcott Callavia broggeri (Walcott) *Callavia bicensis Walcott Callavia burri Walcott Callavia crosbyi Walcott Wanneria? sp. undet Paedeumias transitans Walcott Paedeumias sp. undet. Pseudatops reticulatus (Walcott) Pseudatops reticulatus (Walcott) A tops trilineatus Emmons Bathynotus holopygus (Hall) Serrodiscus speciosus (Ford) Serrodiscus speciosus (Ford) Serrodiscus bettimarginatus (S. & F.) Serrodiscus serratus R. &. R. Serrodiscus silesius R. &. R. Calodiscus helena (Walcott) Calodiscus lobatus (Hall) Calodiscus schucherti (Matthew) Calodiscus meeki (Ford) Calodiscus walcotti Rasetti Hebediscus attleborensis (S. &. F.) "Hebediscus" manuelensis (Walcott) Weymouthia nobilis (Ford) Weymouthia nobilis (Ford) Weymouthia caudatus (Delgado) Pagetia prindlei Lochman, n. sp, Pagetia connexa (Walcott) Pagetides parkeri (Walcott) *Pagetides degans Rasetti Pagetides elegans Rasetti Austinvittia n. sp. of Shaw

Fordaspis nana (Ford) Fordaspis tumida (Walcott) Kootenia Iroyensis Resser Kootenia marcoui (Whitfield) Kootenia marcoui (Whitfield) Kootenia fordi Walcott *Bonnia sp. undet. Bonnia senecta (Billings) Bonnia panula (Billings) Bonnia busa (Walcott) Bonnia bicensis Resser Bonnia brennus (Walcott) Bonnia brennoides Rasetti Bonnia similis Rasetti Bonnia occipitalis Rasetti Bonnia sculpta Rasetti Bonnia bubaris (Walcott) Bonnia crassa Resser Bonnia tensa Resser Bonnia swantonensis Resser 1354

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TABLE 3. (Cont.) Atlantic province assemblages Elliptoccphala asaphoides assemblage Pacific province assemblages •Indicates stray from Pacific Province •Indicates stray from Pacific Province •Indicates stray from Atlantic Province Bonnaria hispanica R. & R. Bonnaria clavata, (Walcott) Bonnaria salemensis (Resser) Bonniella desiderata (Walcott) Dolichometopsis minor Rasetti Dolichometopsis bicensis Rasetti Zacanthopsis virginica Resser Prozacanthoides eatoni Prozacanthoides sp. undet. (Walcott) Protypus hitchcocki (Hall) Protypus typicus (Resser) Protypus marginatus Rasetti Protypus reticulatus Rasetti Labradoria cambridgensis Labradoria misera (Billings) Lochman Labradoria elongata Resser Periomma typicalis Resser Kochiella fitchi (Walcott) Kochiella *Ptychopardla sp. undet. Ptychoparella walcotti Resser Ptychoparella kindlei Resser Ptychoparella?? gaspensis Kindle Ptychoparella? vermontensis Resser Crassifimbrat georgiensis (Resser) Perimetopus arenosus (Billings) Antagmus adamsi (Billings) Antagmus adamsi (Billings) Antagmus typicalis Resser Strenuella strenua (Billings) Antagmus? simplex Resser Strenuella strenua nasuta (Walcott) "Solenopleura" bombifrons Matthew Trachyostracus howleyi (Walcott) "Solenopleura" harveyi Walcott Ellipsocephalus sp. *Ajacicyathus profundomimus Ajacicyathus profundomimus Okulitch Okulitch

*Archaeocyathellus rensselaericus Ajacicyathus rimouski Okulitch Ford * Archaeocyathellus walcotti Okulitch * Archaeocyathellus dwighli (Walcott) *Archaeocyathellus rarus (Ford) *Archaeocyathellus'} uniporosus Okulitch Archaeocyathus atlanticus Billings Protopharetra dunbari Okulitch Cambrocyathus profundus (BilUngs) Cambrocyathus loupensis Okulitch Cambrocyathus amourensis Okulitch Cambrocyathus orthoconicus OkuHtch Cambrocyathus dissepimentalis OkuUtch

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TABLE 3. (Cont.) Atlantic province assemblages Elliptocepkala asapkoides assemblage Pacific province assemblages 'Indicates stray from Pacific Province •Indicates stray from Pacific Province •Indicates stray from Atlantic Province Metethmophyllum labradorensis (Okulitch) Archaeosycon billingsi (Walcott) Archaeosycon vesiculosum Okulitch Exocyathus canadensis Okulitch Exocyathus regularis Okulitch FordUla troyensis Walcott Modiolopsis? prisca Walcott Hdciondla subrugosa (d'Orbigny) Hdcionella subrugosa Hdciondla subrugosa (d'Orbigny) Belciondla erecta (Walcott) (d'Orbigny) Hdcionella acuticosta (Walcott) Hdcionella laevis (Walcott) Hdciondla pauper Billings Hdcionella abrupta (S. & F.) Scenella reticulata Billings Scenetta retusa Ford Scendla varians Walcott Pdagietta aMeboroensis (S. &. F.) Pdagiella primaeva (Billings) Pdagiella primaeva (Billings) Pelagiella primaeva (Billings) Pdagidla atlantoides Matthew Hyolithes americanus Billings Hyolithes communis Billings Hyolithes communis Billings Hyolithes impar Ford *Hyolithes impar Ford Hyolithes frinceps Billings Hyolithes princeps Billings Hyolithes quadricostatus S. & F. Hyolithes similis Walcott Hyolithes terranovicus Walcott Hyolithes bUlingsi Walcott Hyolithdlus micans (Billings) Hyolithdlus micans (Billings) Hyolithdlus micans (Billings) Hyolithdlus micans rugosa Walcott Helenia bdla Walcott Coleoloides typicalis Walcott Coleoloides prindlei Lochman, n. sp.

*Salterdla pulchdla Billings Salterdla pulchdla Billings Salterdla rugosa Billings Salterdla obtusa Billings Stromalocystites walcotti Schuchert Eocystitesf sp. Stenothecoides labradorica Resser Stenothecoides labradorica Resser Stenothecopsis heraultensis Stenothecopsis schodackensis Cobbold Lochman, n. sp. Indiana secunda Matthew Indiana dermatoides (Walcott) Indiana lippa (Matthew) Beyrichona tinea Matthew Beyrichana rotwndata Matthew Beyrichona ovata Matthew Bradoria benepuncta (Matthew) Bradoria cambrica (Matthew) Bradoria minor (Matthew) Bradoria oculata (Matthew) Walcotdlafusiformis (Matthew)

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TABLE 3. (Cont.) Atlantic province assemblages EUiptoeephala asaphoides assemblage Pacific province assemblages •Indicates stray from Pacific Province 'Indicates stray from Pacific Province 'Indicates stray from Atlantic Province Beyrickona papilio (Matthew) Hipponicharion minus Matthew Hipponicharion cavatum Matthew Botsfordia caelala (Hall) Botsfordia caelata (Hall) Botsfordia pretiosa (Billings) Botsfordia pretiosa (Billings) Bicia gemma (Billings) Bicia gemma (Billings) Bicia whiteavsi Walcott Oboldla attantica Walcott Oboldla, crassa (Hall) Oboldla crassa (Hall) Oboldla, minor Walcott Oboletta chromatica Billings Obolella chromatica Billings Micromitra (Palermo) bella Micromitra (Paterina) bella Micromitra (Paterina) bella (Billings) (Billings) (Billings) Micromitra (Paterina) labradorica Micromitra (Paterina) labradorica Micromitra (Paterina) labrodorica (Billings) (Billings) (Billings) Micromitra nisus (Walcott) Obolus prindlei (Walcott) Obolus cf. prindlei (Walcott) Lingulella franklinensis (Walcott) Lingulella granvillensis Walcott Lingulella granvillensis Walcott Acrotreta taconica (Walcott) *Nisusia festinata (Billings) Nisusia festinata (Billings) Nisusia (Jamesella) amii Walcott Nisusia (Jamesella) oriens Walcott Kutorgina granulata Matthew Kutorgina cingulala (Billings) Kutorgina cingulala (Billings) Acrothele matthewi lata Matthew Acrothele nitida (Ford) Acrothele prima (Matthew) Yorkiaf washingtonensis Walcott Yorkia wanneri Walcott Acrotreta gemmula Matthew Acrotreta emmonsi Walcott Billingsella salemensis (Walcott) Billingsella salemensis (Walcott) Billingsella orientalis (Whitfield) Rustella edsoni Walcott Quebecia circe (Billings) Quebecia sp.

studies of fossils from the sections of Vermont; chusetts, but Pseudatops reticulatus, Serrodiscus the sections near Forteau Bay, Labrador; speciosus, Calodiscus, and Bonnaria have wider northwestern Newfoundland (Schuchert and distribution in the Acado-Baltic province. Most Dunbar, 1943); and from USNM loc. 41, Con- genera and species listed in common with the ception Bay, Newfoundland. None of these im- Pacific province represent stray specimens car- portant Lower Cambrian sections and fossil ried by currents into an alien environment. localities has received the thorough collecting Only Kootenia marcoui, Prozacanthoides eatoni, and modern study which it deserves. Figure 1 and Antagmus adamsi are believed native to presents a tentative correlation of some of both environments. Only a single specimen of these sections. Callavia bicensis Walcott is known as a stray Trilobites in the Atlantic province assem- from the Atlantic province into the Pacific blage show greater similarity to those in the province regime of the Saint Lawrence Valley. Elliptocephala fauna and suggest an environ- Members of the Eodiscida were probably semi- mental similarity between the two regimes. sessile benthos, burrowing through bottom Elliplocephala sp. and Weymouthia nobilis are sediments and lying partially or entirely con- otherwise known only from eastern Massa- cealed in them. Such forms would have some

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protection from currents, and consequently Elliptocephala fauna should be considered few strays are known though the numbers of strays. This genus probably did not success- individuals in the Elliptocephala asaphoides fully invade the boundary region of eastern fauna were large. New York and Vermont. However, Antagmus Among the opisthoparian trilobites the affini- adamsi, originating in the Pacific province, did ties of the Atopidae are definitely with the invade the boundary area. The few specimens Atlantic province assemblages. Bathynotus is of Kochiella fitchi could represent successful rigidly restricted to the Pacific province al- invaders or may be only strays. Kochiella, first though distributed from Labrador to Vermont. described from northwest Greenland, is abun- Genera of the several other families appear to dant in the Cordilleran portion of the Pacific have been early branches of stocks which province, but has not been reported from gradually adapted to several environments. In faunas of this province in the Saint Lawrence the Dorypygidae, Bonnia and Bonniella became region. adapted to the shallow shelf area of the Pacific Strenuella, Strenueva, Protolenus, and Mic- province. In spite of its wide geographic range macca are common genera of the Callavia and and large numbers of individuals and species, Protolenus zones of the Atlantic province en- Bonnia appears to have adapted to an ex- vironment. They are known from eastern clusively clear-water habitat within this en- Newfoundland, Nova Scotia, New Brunswick, vironment, possibly to a semireef habitat. and several localities in eastern Massachusetts, Bonnia specimens are rare in the dominantly USNM loc. 9n, North Weymouth and Hoppin clastic sediments of the Pacific province. Hill, North Attleboro. From the Massachusetts Fordaspis was indigenous to the eastern New localities Callavia, Elliptocephala, Strenuella, York region. Bonnaria, represented by species Hebediscus, and Weymouthia have been re- in Virginia and Spain, may have been a south- ported, but because of metamorphism of the ern genus at the northern limit of its range in strata and limited outcrops this faunule is in- New York. Only Kootenia, a generalized and complete. The eastern Massachusetts localities highly adaptable genus, appears to have lived lie farther southeastward or oceanward than as a normal vagrant benthos in both environ- the Slate Belt localities but are separated in ments. Among the Bathyuriscidae, Zacanthopsis latitude by only 1°. Consequently, a more sig- and Dolichometopsis were restricted to the nificant comparison can be made with the Pacific province; but Prozacanthoides, probably Massachusetts faunule than with the Maritime originating in the coastal shelf area, invaded Provinces faunas. Had the Slate Belt and the the boundary region of eastern New York and Massachusetts strata been deposited in the appears with Kootenia in the upper faunule of Acadian geosyncline under a single environ- the Elliptocephala fauna in northern Washing- mental regime the same genera in each assem- ton County. Protypus appears restricted to the blage might be expected to be dominant. The Pacific province. Labradoria is too poorly known compositional differences between the two to furnish conclusive evidence. It may have assemblages would be expected if the two had invaded the boundary region like Prozacan- always held the same relative geographic po- thoides, or the two known cranidia may be sition in an ocean partially accessible to the strays. coastal shelf of the continent. The Ellipto- The ptychoparids originated in the Pacific cephala asaphoides assemblage, now located province environment. Ptychoparella, Antag- close to the Pacific province environment, has mus, Kochidla, and several other genera are a mixed trilobite fauna of indigenous genera, common throughout the province. Fragments genera from the Pacific province, and genera of Ptychoparella cranidia are reported from known only from eastern Massachusetts and several of Walcott's localities in the Slate Belt the Maritime Provinces. Not a fragment of a as well as from the Cambridge-Hoosick area. Pacific province trilobite has ever been reported Since the adjoining parts of the Pacific province from the Massachusetts localities; Ellipto- were inhabited by many individuals of Ptycho- cephala is rare; Callavia becomes prominent; parella, the 20 or so cranidia recorded from the Weymouthia, very rare in New York, is more

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common; and Serrodiscus is well represented by Elliptocephala fauna occur also in the Pacific a different but related species. Stremtella and province assemblage, but only a few are found Hebediscus, characteristic of the Atlantic in the Atlantic province. These species, Bots- province, appear. It seems that sea bottoms fordia, Micromitra (Paterina), Lingulella, Obo- inhabited by the trilobite genera typical of the lella, Acrothele, are all small generalized forms American and European Atlantic province whose widespread occurrence in Cambrian beds assemblages were farther oceanward than that suggests tolerance of a wide range of physical area inhabited by the Elliptocephala fauna. An and chemical conditions. Distribution of open-ocean environment is indicated. Scattered larger-shelled forms, Nisusia, Rustella, Que- islands of different sizes formed archipelagoes becia, Billingsella, indicates a preference for like the Dutch East Indies. Water temperature shallow clear waters. These forms were normal and salinity would be relatively constant over inhabitants of the Pacific province. They occur large areas, and the normal ocean temperature in limestone breccias around Troy, mainly and salinity would dominate the environment along the western edge of the boundary region even in the coastal waters of the islands. Both and nearest their normal habitat. Nisusia larvae and adults could have developed wider festinata is so poorly represented in the Cam- tolerance of depths and pressures. In contrast, bridge-Hoosick area that it is believed that the boundary-area environment of the Ellipto- these specimens are strays from the western cephala fauna was, like the fauna inhabiting it, localities. Only Kutorgina cingulata appears to a mixed environmental domain. Ocean tempera- have lived in both environments. tures and salinities, and greater pressures and Hyolithellus micans, the chitinous tubes and opacities resulted from the oceanward connec- opercula of a presumably benthonic annelid, tions and the greater depth of the sea floor in has universal distribution in all faunas of the the area. Nevertheless, these waters were also northeastern Appalachian region and is also subjected to contamination by coastal-shelf common in the northwestern European sec- water currents which were less saline and car- tions. The nature of the fossil is such that ried organic and inorganic debris from the several different species may be represented; continental land masses. but it seems certain from the distinctive pat- Archaeocyathids were reef-building sessile tern of muscle scars on the opercula that the benthos inhabiting clear shallow waters, and forms studied here belong to a related group of numerous archaeocyathid reefs are known in species of one genus. Widespread distribution of Pacific province formations from Labrador to Hyolithellus, a presumably semisessile benthos, Georgia. No reefs have been found in the Lower and of Helcionella subrugosa, a gastropod and Cambrian deposits of the Atlantic province, presumably a vagrant benthos, is more charac- and archaeocyathids occur only in the Ellipto- teristic of planktonic than benthonic forms. It cephala asaphoides fauna. All the material con- appears that adults of these two forms de- sists of small fragments of individual cones. veloped a tolerance for a wide range of environ- Six species, each represented by a few specimens, mental conditions and that the larvae may have are described from localities around Troy, New been planktonic in near-surface waters of York, but only a few specimens of one species the sea. have been obtained from a single locality in the Pelagiella and Hyolithes are regarded as adult Cambridge-Hoosick area. All archaeocyathids plankton and as such must have been normal of this fauna are stray individuals broken from inhabitants of near-surface waters of the open a reef apparently located a short distance west ocean. Since they are carried by waves and of the deposition site of the Schodack limestone currents, they would be washed into and de- breccias of the Troy region. Ajacicyathus pro- posited in all regions which were connected fundomimus, a Pacific province species, ranges with the open ocean. Pelagiella primaeva is from Labrador to Virginia, but the genus abundant in all assemblages. It may be sig- Archaeocyathellus is unique for this region and nificant that the greatest number of Hyolithes appears to have no close relations. species has been described from the Atlantic Several brachiopod genera and species in the province assemblage; three from the Ellipto-

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cephala fauna (one in common with each of the barrier between two domains but by a biofacies other assemblages) and three from the Pacific barrier. province (again one in common with each of the other assemblages). This distribution sug- Lithofacies Evidence gests that communication between the open ocean and the coastal shelf was partially re- Careful examination of the total lithofacies stricted, presumably by scattered island groups picture for sections within both the Taconic which oriented and restricted the surface sequence and the Valley sequence reveals that currents. the difference is one of percentage and not of Salterella may or may not have been plank- rock types. Orthoquartzite is present through- tonic. Its distribution indicates that the genus out the Taconic sequence outcrops and, al- developed as a normal habitant of coastal-shelf though the beds in the Slate Belt region are waters and that in the Pacific province en- usually a few inches to a few feet thick, locally vironment it had spread around the North they may thicken rapidly. Along the east side American continent in Late Lower Cambrian of the Hudson Valley, quartzites are common time. The few scattered fragments of S. pul- and conspicuous throughout the sequence chella reported from the Elliptocephala assem- (Dale, 1904a). The arkosic component of the blage were probably strays from the Pacific grits appears to be unique to the Taconic se- province environment. quence, but the arkoses are everywhere associ- The faunal evidence suggests some of the ated with quartz sands similar to the quartzite physical requirements for the paleogeography beds of the sequence. Quartzites of the Taconic of the region studied. The Pacific province and the Valley sequences show the same general genera were normal inhabitants of an environ- characteristics and could have originated from ment which circled the shores of the North Precambrian rocks exposed on offshore islands American continent—the environment of a and peninsulas related to the mainland mass of shallow submerged coastal shelf. The outer the Canadian Shield. edge of this environment impinged upon the The percentage of variegated and black shales inner or landward edge of the region inhabited is high in the Taconic sequence, but shale in by the Elliptocephala fauna. The waters of this lesser amounts is also present in formations of region were communicating with those of the the Valley sequence. The Dunham is described Atlantic province environment. The inter- as a gray, buff-weathering, siliceous dolomite. mingling of faunal elements from both prov- Some beds are massive, others are thinner and inces in the Elliptocephala asaphoides fauna separated by red shale and sand partings. The could develop only in such an intermediate Mallet, a member of the middle part of the region. There must have been some movement Dunham (Fig. 1), contains sandy thick-bedded of currents and waves between the environ- gray dolomites, thin dolomites with shale part- ments; so a continuous land barrier could not ings, flaggy dark shaly dolomite, and an intra- have separated them. Distribution of the plank- formational breccia. Thus the Mallet shows a ton species suggests that scattered island groups local increase in rock types regarded as char- lay along the oceanward side of the inter- acteristic of the Taconic sequence. The Mallet mediate region. The Atlantic province deposits member grades upward through intraforma- everywhere are south-southeast, or oceanward tional conglomerates into the Monkton dolo- from those of the coastal shelf. The Atlantic mitic quartzites which carry the Olenellus province environment must have been con- thompsoni fauna (Kindle and Tasch, 1948). To trolled by conditions of the open ocean and the northeast and the southeast the Mallet and consequently differed markedly from that of the Monkton grade laterally into typical Dun- the shallow submerged coastal shelf. Since ele- ham dolomites. The gradual change of the ments of both assemblages could live in the Monkton quartzites to sandy dolomite beds intermediate region, it is believed that the dis- which in turn interfinger with and grade into tinctions between the Atlantic and Pacific prov- purer dolomite beds is recorded by Cady (1945). ince assemblages were produced not by a land Farther northeast and southeast beds of the

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Dunham dolomite lens out into shales or slates feet of alternating coarse sandstones and red, of the Lower Parker slate (Shaw, 1954, p. 1039). green, and black shales, are unfossiliferous ex- This formation consists of 600 feet of arenace- cept for specimens of Botsfordia pretiosa in the ous, micaceous shale of which the lower 450 upper part. The lithofacies of these beds is feet, at least, carries the Olendlus thompsoni similar to the Mettawee facies of the Taconic fauna. All easternmost Vermont sections show sequence. Rasetti (1946, p. 691) comments on a marked development of shales (Fig. 1). The the great lateral variation in lithology, even Vermont sections show the most rapid lateral within short distances, and on the impossi- gradations and the highest percentages of argil- bility of correlating beds on a lithologic basis. laceous material within an accepted Valley Another undisturbed section, Villa Guay, 12 sequence. miles northeast of Chaudiere Falls, was de- In the third phase of deposition of the scribed by Rasetti. It is largely Ordovician Taconic sequence abundant limestones occur strata, but at the base 11 feet of gray shale and as thin impure limy layers, nodules and lenses, thin limestone lenses carries an Austinvillia and pebble conglomerates in the Slate Belt. faunule. This fauna and the others reported Here and there, as at locality Y 15, purer and from the limestone boulders of Early and thicker lenses of blue-gray limestone occur. In Middle Cambrian age belong to the Pacific the Hudson Valley, limestone breccias may be province, but occasionally an assemblage of quite thick, but individual limestone beds are mixed composition is noted (Laverdiere, 1949). usually thin. Lateral gradation of all rock types These two sections indicate, as does the Parker is conspicuous in the Taconic sequence. How- shale of Vermont, that late Lower Cambrian ever, thick glacial cover and limited exposures strata of the dominantly argillaceous facies make it impossible to show that the shales and characteristic of the Taconic sequence were de- limestone conglomerates of the Taconic se- posited locally within the domain of the Pacific quence interfinger laterally with dolomites or province environment as well as in the Atlantic sandstones of the Valley sequence. The compo- province. sition of the Elliptocephala asaphoides fauna The Forteau Bay, Labrador, sections begin proves that the sites of deposition of the Metta- with a transgressive sandstone, the Bradore wee and Schodack lithofacies were in com- formation; the lower beds are reddish arkose munication with those of the northwestern and sandstone with small-pebble conglomerate; Vermont formations. higher beds of pink or gray nearly pure quartz Faunal evidence suggests that the eastern sand are cross-bedded and contain only the New York and Vermont region occupied an tubes of Scolithus linearis; and the top bed is a area intermediate between the Atlantic and the white fine-grained sandstone 15-25 feet thick. Pacific province environments. The lithofacies The overlying Forteau formation consists of indicate that in this region rapid lateral litho- great lenses of archaeocyathid reefs grading facies changes may have occurred. laterally into and interbedded with sandy To obtain a regional perspective for the crystalline and oolitic limestones. Shales, a paleogeographic reconstruction the lithofacies small percentage of the strata, occur as partings of Lower Cambrian formations in the vicinity between the limestone beds or as filling of de- of Quebec, at Forteau Bay, Labrador, and in pressions in the reefs. To the north the reefs northwestern Newfoundland are considered. thin and gradually disappear, and the lime- Until recently the Lower Cambrian at Que- stones become more even-bedded and muddier. bec was known only from fossiliferous limestone Schuchert and Dunbar (1934, p. 19) suggest boulders in Ordovician shales, and it was tacitly that the archaeocyathid reefs in this area de- assumed that the original sequence was largely veloped as barrier reefs in front of a low north- carbonate. Rasetti (1946) described two un- ern land mass. disturbed sections of Lower Cambrian strata, Fifty miles to the south Lower Cambrian both in thrust sheets which now lie some dis- strata crop out in the Highlands of Saint John, tance northwest of their original sites of depo- Newfoundland. The base of the section is not sition. At Chaudiere Falls the older beds, 1500 exposed, but the lowest 150 feet, cross-bedded

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red arkose and sandstone, is referred to the such an island was simply an upwarped portion Bradore formation. The overlying 386 feet, of the coastal shelf. interbedded fossiliferous sandy and shaly lime- Farther oceanward such islands would be stones with several horizons of archaeocyathid expected to decrease in size, but the sediments reefs, is assigned to the Forteau formation. Ap- show increased silt at the expense of limestone, proximately two-thirds of the Forteau is com- while the arenaceous material remains about posed of limestone, but shale is conspicuous in the same. Active volcanic islands seem indi- the lower half and again near the top. Quartz cated. Weathering of volcanic lavas and pyro- sand is abundant in some of the limestones; 350 clastic material would produce siliceous muds feet of Hawke Bay quartzite forms the top of as well as quartz sands. Tuffs, basalts, and the section. This formation is cross-bedded, greenstones are associated with sediments rippled, conglomeratic sandstone interbedded assigned to the Lower Cambrian (Fig. 1; Balk, with a few thin fossiliferous black or green shale R., 1953, map, p. 820-822, and PI. 8); but no zones and numerous thin limestones and lime- sections known show the interfingering of vol- stone-pebble conglomerates. Conspicuous sun- canic deposits with fossiliferous Lower Cam- cracked, rippled beds suggest that the site of brian sediments. Such sections do appear in the deposition was extensive shoals bordering a low Middle Cambrian of Cape Breton Island, and Precambrian island mass. they become increasingly conspicuous in the Eighty miles farther south a third Lower Ordovician strata throughout the northern Cambrian section crops out in the vicinity of Appalachian region. Bonne Bay, Newfoundland. The 2200 feet of Late Lower Cambrian sections, characterized fossiliferous strata consists of interbedded thin by a high percentage of argillaceous and impure nodular limestones, thick units of black arenaceous material, occur in a belt from New- and variegated shales, and pink and yellow foundland southwestward to Vermont, New quartzites in a proportion of 8 per cent lime- York, and into Pennsylvania. All those sections stone, 40 per cent mudstone, and 52 per cent farthest southeastward or oceanward from the sandstone. No archaeocyathid reefs were postulated position of the continental shore found, but other elements of the Olenelltts line carry only fossils characteristic of the At- thompsoni fauna that occur throughout the lantic province environment. Those sections section are the same as those in the northern farthest to the northwest, nearest the shore line, sections. The lithofacies change was sufficient carry fossils of the Pacific province environment. to prevent Schuchert and Dunbar from recog- All known sections in an intermediate position nizing with certainty any of the northern contain fossils from both environments. The formations. geographic extent of this belt suggests several These three sections present a picture of scattered island groups composed of Pre- varying depositonal conditions across the cambrian granite and gneisses on which vol- Pacific province coastal shelf, especially the canoes were developing. These island groups marked increase in argillaceous material south- were about 500-600 miles off the Lower Cam- ward or oceanward. Schuchert concluded that brian continental shore line. these clastic sediments were derived from the New Brunswick geanticline without explaining Reconstruction of Paleogeography why this narrow land could furnish a greater volume of elastics than the larger Canadian A reconstruction of the paleogeography of Shield. Faunal evidence indicates that this the Slate Belt (PI. 10) during the Lower Cam- continuous land barrier did not exist; but it brian must be based on the known faunal and suggests groups of scattered islands oceanward. lithofacies data and should also fit into a larger The Hawke Bay sections are best interpreted regional picture that explains the apparent as deposits formed on extensive shoals around repetition of basic conditions along the north- an offshore island mass that genetically was a eastern and western sides of the Atlantic Ocean. part of the main continental mass. Rocks ex- The problem of the relationship of the two types posed on this island were probably largely Pre- of sequences is not unique to the Slate Belt. cambrian granites and gneisses. Presumably Cambrian strata in Great Britain show the two

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lithofacies sequences and the two faunal assem- waters derived from a northeast flowing tropic blages although most of the sections belong to ocean current, like the present Gulf Stream, (6) the Atlantic province environment. In contrast, little range of diurnal and seasonal changes in most of the sections of the United States south the physical and chemical conditions of the of New York belong to the Pacific province environment—approximating the more stable environment; but at Cedar Bluff, Alabama conditions of the open ocean, and (7) a sporadic (Butts, 1926), and Marathon Uplift (Wilson, influx of quartz sands and arkose carried in by 1954) faunas of the Atlantic province occur hi turbidity currents from the continent or islands, a dominantly argillaceous section. Finally, the and a slow steady supply of siliceous muds concept of the Lower Cambrian paleogeog- drifted into and settling in the basin from an raphy should also explain conditions in the eastern source of weathered volcanic rocks. later Cambrian and the Ordovician. The organic debris now associated with the grit The faunal evidence suggests that the dis- and sand lenses indicates that the turbidity tinctness of the faunal assemblages is at- currents did bring some organic and mineral tributable to biofacies barriers and not to a nutrients into the basin, but otherwise the continuous land barrier. Gross lithology was bottoms had a limited food supply. Items (3) to not a significant factor of the biofacies barrier. (6) of this environment are the factors which The sites of deposition of accepted Valley se- were the biofacies barriers to most of the normal quence formations and the domain of the Pacific province species which inhabited the Pacific province faunas may be called conti- surrounding shelf areas. nent-dominate environment. The details of this The easternmost sections of northern Ver- environment were (1) hard sand bottoms and mont (Fig. 1) show that the initial cycle of soft mud or lime-ooze bottoms, (2) clear to downwarping of the Atlantic coastal plain of moderately turbid waters, (3) shallow depths, the Canadian Shield began in earliest Lower out to about 200-foot depths, (4) well-lighted Cambrian and brought marine waters as far waters, (5) cool to temperate waters, (6) wide westward as central Vermont. Locally a green- range of diurnal and seasonal changes in the stone and associated siliceous muds occur at physical and chemical conditions of the en- the base of the section; but otherwise the early vironment, and (7) a limited sporadic supply of Lower Cambrian is a typical transgressive se- sand and arkose from the western Precambrian quence of sediments, the Mendon formation, continent and from scattered Precambrian lying unconformably on the Precambrian. The islands, and a constant and increasingly more successive members of the Mendon (Brace, important supply of siliceous, micaceous muds 1953, p. 30-32) record in their lithologies the from weathered volcanic rocks to the east. The deposition of basal transgressive conglomerates, land-derived waters introduced organic and graywackes, and quartz sands on the inundated mineral nutrients into the environment. plain; the gradual clearing of the water and the The sites of deposition of the Taconic se- deposition of carbonates; and, finally, depo- quence formations and the domain of the sition of arenaceous shales indicating the Elliptocephala fauna were in an elongate basin building of the sea bottom up to and above extending northward into the Pacific province wave level and the regressive encroachment of and bounded on the east by an island archi- the shore sediments. Locally a disconformity pelago. The basin connected both to the south between the highest Mendon beds and the over- and southeast with the Atlantic Ocean waters lying Cheshire quartzite has been noted by and the Atlantic province proper. The biofacies Osberg (1952, p. 38). The transgressive sands of details of this environment were a mingling of the Cheshire quartzite mark the beginning of the features of the two province environments. the second cycle of downwarping of the coastal This basin was characterized by (1) predom- plain which during upper Olenellus-zone time inant soft-mud bottoms with scattered local carried the shore line northwestward to the hard bottoms developed on sands and grits, (2) Saint Lawrence Valley and produced a deep clear to moderately turbid waters, (3) depths embayment north of the Adirondack peninsula. from 300 to 600 feet, (4) poorly lighted waters The transgressive sediments deposited on this with little if any plant life, (5) warm temperate shallow submerged shelf are the sand-carbonate

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fades called the Valley Sequence. In north- It is uncertain whether the present linear ar- western Vermont these beds grade laterally rangement of the dolomite shoal areas and of eastward into a dominantly arenaceous, argil- the downdropped basins with the "Taconic" laceous sequence overlying the Mendon forma- sequence reflects the initial orientation of these tion (Fig. 1). The Olenellm thompsoni fauna in structures. Subsequent structures developed by the argillaceous beds supports the lateral the folding and faulting of the several Paleozoic gradation and indicates that these siliceous orogenies definitely paralleled the buttress of muds were being deposited on a portion of the the Adirondacks. It is quite possible that from continental shelf area dominated by the Pacific the earliest Cambrian compressional forces province environment. The muds were being were being exerted upon the Adirondack but- derived from an eastern island source. Upwarped tress by the circum-Atlantic seismic-volcanic Precambrian granites and gneisses of the coastal belt to the east, and that the faulting of the shelf probably formed the cores of these islands. basins was an initial response to the pressure. If these Precambrian rocks had been the sole Whether the faulting started soon after source of the sediments the section would have initial subsidence or appreciably later is not been a dominantly sand-carbonate lithofacies known since the base of the "Taconic" sequence similar to that of the western, shoreward areas is everywhere concealed. The oldest deposits, and to that at the Highlands of Saint John, the Bomoseen and/or the Bird Mountain grits, Newfoundland. Such an abundance of siliceous, were Precambrian debris carried by turbidity or micaceous muds, extending in time of depo- storm currents from the sites of active faulting. sition from the Upper Olenellus subzone to the For the sequence known now they also represent Middle Cambrian Albertella zone (Shaw, 1954), the time of most active and widespread faulting, demands a large constant-supply source. but there is no proof that it was the first. Subse- Debris from volcanoes developing on these quently, within the main area of the Slate Belt offshore islands is indicated as the most logical and adjoining Hudson Valley (1) the earth source. movements, though continuing throughout the In eastern New York and adjoining southern Lower Cambrian, become more local and inter- Vermont, the Adirondacks formed a broad mittent, allowing time for an appreciable thick- peninsular bulge that acted as an immovable ness of the slowly settling muds drifted from buttress against the gradually submerging the northeast to accumulate between lenses of coastal shelf. Not far offshore several islands grit and quartzite (second phase of deposition); marked upwarped portions of the coastal shelf— and (2) the Precambrian rocks of the coastal- Stissing Mountain may be a remnant, and the shelf floor are less and less often exposed during present Green Mountain axis, the site of islands faulting as the sedimentary cover becomes and shoals which were the southern continu- thicker—the quartz sands become more promi- ation of the offshore-island groups of north- nent than the grits in the lenses of the second eastern Vermont. In the shallow coastal waters phase of deposition—and finally thin impure along the shores of the Adirondacks and the limestones with minor amounts of quartz sands various islands a characteristic sand-carbonate and arkose are the materials involved in the lithofacies would develop. In this southern movements during the third phase of deposition. region the continued downwarping of the shelf, Such a change suggests that the basins reached crowded between the Adirondacks and the their maximum depths early in their develop- persistently upwarping island masses, tended to ment, and that sedimentation, slow as it was, produce sinking, ever-deepening basins as con- gradually raised the floor levels. At least one trasted to the shallow widely submerged coastal important exception to this orderly develop- plain of the northern Vermont and southern ment is revealed by the sediments at two locali- Quebec region. It is postulated that the per- ties, Moon Hill and P 13, just north of Peters- sistent upwarping of the islands (apparently burg, New York. Here fossils of the upper associated with the volcanic activity to the Elliptocephala asaphoides faunule occur in a few northeast) and the sinking of the basins pro- thin limy lenses intercalated in purple and gray duced stresses which ultimately led to faulting shales and arkosic grits. The percentage of along the sides and northern ends of the basins. arkosic grits is so high in these sections that

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Prindle and Knopf were misled into correlating curred. The greatest problem in the paleogeo- the strata with the Bomoseen grit although the graphic reconstruction is the thrust zone along fossils indicate that these beds were deposited the east side of the Hudson valley—Logan's late in the third phase of deposition. Prindle and Line and its southern extensions. West of this Knopf were also influenced by these sections thrust zone, concealed by Ordovician strata or into assigning an Early Cambrian age to the by the Lower Cambrian sediments, now lie the Rensselaer grit. It is possible that the mass of sites of the Lower Cambrian shore line, the off- the Rensselaer grit may represent extensive shore lagoons of the coastal shelf, the archaeo- deposits dumped at the base of a major fault cyathid reefs, and the fault zones of the western- zone along which movements, of a magnitude most downdropped basins. This now concealed that kept Precambrian rocks exposed on the up- belt may have been narrow—10 to 20 miles in thrown side, continued throughout the Early width as along the east shore of Florida—or it Cambrian. The proximity of these two fossil may have exceeded 50 miles. The greater localities to accepted outcrops of Rensselaer abundance of both strays and migrant indi- grit favors such an interpretation. viduals from the Pacific province in the Ellip- The downwarping and faulting carried the tocephala collections from northwestern Wash- basin floors to greater depths—300-600 or more ington County and the greatest number of feet—and imparted to them features totally archaeocyathid fragments in the strata at Troy alien to the dolomite shoals. Their environment and Ashley Hill justify the assumption that the would be allied to that of the open-ocean region site of deposition of these sections was in the in that (1) the waters above the bottom were westernmost basins. The sporadic strays and much darker and the temperature controlled by few archaeocyathids of the Cambridge-Hoosick the [ocean currents and waves, (2) all physical collections indicate that this region lay either and chemical conditions of the environment on the eastern side of such a basin or in a side were less variable, (3) the food supply was basin partially connected with the western limited in amount and restricted in kind, (4) the ones. accumulation of fine mud on these bottoms was It is assumed that the sloping continental so slow that normally all organic material was shelf continued east of the "Taconic" sequence destroyed by the hungry animals before the basins and the inner island group bounding silt could bury it (the fossil collections mainly them on the east. No Cambrian deposits of represent masses of organic debris accumu- either lithofacies are known in west and central lated and rapidly deposited, probably by tur- Massachusetts. The easternmost Lower Cam- bidity currents), and (5) the floors were soft brian sections of New England cropping out in and muddy except for the occasional and eastern Massachusetts are fine-grained red and shifting deposition sites of the arkosic grits and green shales carrying a nearly typical Atlantic the quartzites. Such an environment was in- province fauna. These argillaceous sediments compatible to all animals which had become may have been derived either from the west or reasonably well adapted to normal conditions of the east. Their source seems also to have been the coastal-shelf bottoms or carbonate shoals the weathered debris from volcanoes rather and reefs, but this environment was more than soil materials from a large Precambrian similar to that of the Atlantic Ocean with which land mass such as Schuchert's borderland it was connected to the south and southeast. Novascotia. It is postulated that these scattered Consequently these basins could become the volcanoes were developing on a series of sinking habitat of any reasonably tolerant Atlantic Precambrian islands. Thus in the northern province benthos who could gain access to Appalachian region the Lower Cambrian was them. the time of inception of a series of volcanic Fault zones bounding the basins are assumed archipelagoes which became most noticeable in to have been about a mile wide. Such regions the record of the Ordovician deposits. It is would have received the thickest deposits of postulated that these archipelagoes developed arkose grits and limestone breccias; and across on the oceanward side of a broad circum- these zones, in a width of several miles, a rapid Atlantic seismic belt extending from about 53° lateral change in lithofacies would have oc- N. Lat. in the British Islands southwestward at

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least to 28° N. Lat. in Texas. The belt may have veloped on the margin of a shoal as its lower turned due south and connected with the beds are a shoal dolomite, overlain by a seismic Atlantic province sites of deposition in Argen- breccia of pebbles and boulders derived from tina, but no indication of such connections has the shoals. These conglomerates are overlain by been found in Central America. The volcanic fine-grained dark shales indicating that the portion of this belt appears to have held an surface of deposition now lay much deeper. The average position of 500 miles from the conti- very late Upper Cambrian conglomerates of the nental shore line. Hungaia magnifica fauna appear to be a similar fault breccia in a basin facies. The overlying Later Cambrian and Ordovician Events Tremadocian fauna at the base of the Highgate formation is a characteristic mixed fauna with Until the completion of this work it had been a conspicuous Atlantic province element. generally thought that Lower Ordovician This evidence suggests that the topographic strata in this area rested with apparent con- features of this entire area remained essentially formability upon the Lower Cambrian beds, the same from the Early Cambrian to near the and Dale (1904b) believed that no Middle or end of the Early Ordovician. During Middle Upper Cambrian deposition occurred. Now two Cambrian portions of the shoals were built up small collections of Middle Cambrian fossils are to, or raised above, sea level while other portions known, Eodiscus punctattts in a Prindle col- continued to receive slowly accumulating lection and a specimen of "Agnostus" desideratus carbonate oozes. The continental shore line re- recorded by Walcott. These specimens indicate mained stable or may even have pushed ocean- the continuance of an intermediate environ- ward. Slow and intermittent silt accumulations ment in which species from both provinces with occasional limestone conglomerates con- could mingle. No Upper Cambrian is known, tinued in the basin areas. Seismic movements but several specimens of a Tremadoc trilobite were sporadic and slight so that only the surface were found in another Prindle collection. In- limestones along the shoal edges and slopes were tensive and thorough collecting from small disturbed. The Middle Cambrian faunas of the scattered limestone lenses in the shales of the basin facies continue to show a mixture with Slate Belt area should furnish additional Atlantic province forms dominant. The supply material. of silt was limited, and much of the mud may Both north and south of this immediate area have been derived from the reworking of Lower more extensive deposits of Middle and Late Cambrian material by turbidity currents. The Cambrian age are known. In Dutchess and areal extent and thickness of any one deposit Columbia counties these beds are limestones seems to have been already limited at the time and dolomites of the shoal facies, and the few of deposition. known fossils belong to the Pacific province. To The beginning of the Late Cambrian was the north no Middle Cambrian of the shoal marked by a moderate movement of the ocean facies has been identified. Numerous small floor associated with the sporadic lowering of scattered patches of pebble conglomerates and the shoals and the downwarping of the coastal shales of the basin facies carrying a mixed fauna shelf. The seas spread westward onto the are known largely through the efforts of B. F. Adirondack peninsula where a sand-carbonate Howell. Several horizons of the Middle Cam- sequence was deposited. To the east some lime- brian are present. Some Upper Cambrian de- stone conglomerates and shales accumulated posits of both the shoal facies and the coastal very sporadically and locally along the margins shelf facies with Pacific province faunas are and on the floors of the basins. The silt supply known. Four formations, the Mill River con- from the eastern volcanic islands was very glomerate, Skeels Corners formation, Rockledge limited. Toward the end of the Late Cambrian conglomerate, and Hungerford slate, are inter- a new cycle of crustal movements began and bedded shales and pebble conglomerates of a continued through the Early Ordovician. Lime- basin facies. The vast majority of the fossils stone conglomerates, breccias, and arkosic grits belong to the Pacific province and occur in the become common in the section and indicate ex- Rockledge. This formation apparently de- tensive faulting. Tuffs and igneous flows are now

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sporadically interbedded with the fossiliferous basal Ordovician series of northern Vermont. sediments. These Early Ordovician deposits Sporadic records of local angular unconformities suggest a movement of the entire seismic belt in regions of apparent conformable relations north-northwest against the coastal belt. The are consistent with the postulated paleogeo- Gorge, Highgate, Grandge, and Corliss forma- graphic conditions. Local tilting of the floor of tions were deposited at the edge of the shoals the basins is to be expected; and, consequently, and on their flanks; conglomerates are common any later deposits would be unconformable to with thin limestones and interbedded shales. the earlier, compacted sediments. An angular All the faunas are of the dolomite facies and unconformity can be produced in a submarine show an interesting composite assemblage of position as readily as in a subaerial one. American Pacific province genera and genera of the dolomite facies in northwest Europe. CONCLUSIONS Certain basal Highgate beds, however, were accumulated on the floor of a basin and carry a Much of the difficulty in interpreting the rela- Tremadoc fauna with elements from the At- tions of the Lower Cambrian formations of lantic province environment. eastern New York and adjoining Vermont has Postulation of a subaerial exposure of the thus arisen from the development of these deep basin sites between Upper Cambrian and basal basins in the coastal shelf area of this region. Ordovician does not seem justified, but oscil- These basins not only interrupted the orderly lations of the coastal shelf and shoals seem lateral gradation of lithofacies across the shelf likely. Where a gap in sedimentation appears in area from shore line to the inner edge of the a geologic sequence, it is usually attributed to seismic-volcanic belt but also introduced close subaerial exposure and erosion without detailed to the continent an entirely different environ- consideration of the contact or the areal rela- ment for the benthos—a biofacies regime tions of the formations. In this particular ordinarily found on the floors of the continental region, considering the evidence just presented, shelf beyond the inner islands of the volcanic it is logical to assume that the dominant topo- archipelago. Moreover, the more numerous graphic units remained the same. On floors of fossiliferous sections in this region show the deep basins the formation of datable deposits close juxtaposition in which the two lithofacies depended entirely on the sporadic accumulation and biofacies originally developed. In several of organic debris and enough clastic material to other areas remnants of the basin facies are cover and protect it. New supplies of silt were now so fragmentary that their original relation- at a premium since it had a distant source. ships are not readily ascertained. Downfaulted basins remained deep (300-600 This faunal study has covered only a limited feet) from their initial development in early region and, although it helps to point the way Early Cambrian at least until the end of the to the solution of several problems in the area, Chazyan. The present sporadic occurrence of it emphasizes the lack of detailed information Middle and Upper Cambrian deposits of the on the Elliptocephala asaphoides fauna through- basin facies may be attributed to inital spotty out the region as a whole. The old localities in deposition because of deficient silt supply. Washington County and along the east side of Without a protective silt covering all organic the Hudson Valley should all be restudied and material on these bottoms is destroyed since it recollected—many more localities may be is the only source of food for animals dwelling found. Attention must be paid to the detailed at these depths. As fresh supplies of clastic stratigraphy of the sections and the relation- material become available, deposits of ever- ship of sedimentation to the fossils in the light increasing thickness and areal extent appear. of modern concepts. Large new collections Although at many outcrops the contact of should be obtained to give an idea of the lateral basal Ordovician shales with Lower Cambrian and vertical distribution of genera and species shales appears conformable, Bonham has re- in representative assemblages throughout the ported an angular unconformity at one locality region. Walcott's fossil lists supply all the infor- in the Hoosick quadrangle, and unconformities mation now available on most localities in have been reported in the late Upper Cambrian- Washington County. Except for type speci-

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SYSTEMATIC PALEONTOLOGY Original description.—Okulitch cited original description of Ford in toto and added a modern diag- Phylum PORIFERA nosis of the species. Remarks.—The species is represented by a single HEXACTINELLID SPONGE SPICULES— recognizable fragment from the top of a cone which cf. PROTOSPONGIA shows the characteristic single row of pores along (Plate 1, figures 11-18) each furrow. Restricted and rare occurrence of Archaeocyathellus suggests that their habitat differed Sponge spicules were recovered from etched ma- from that of more common members of the fauna. terial from 10 localities, and were also found in the In the Cambridge area recognizable fragments in the limestone matrix from 4 localities. Both long stout matrix were obtained only from locality Y 13 which hexaxial spicules and single slender rods were found furnished the largest assemblage of fossils; but a few in the matrix. At least one ray of hexaxial spicules small broken pieces were obtained by etching from was usually broken. The spicules are composed of Y 12. From Ashley Hill locality in the Hudson calcite. Valley (Y lla) many silicified fragments referred to In one mode of preservation the central portion is Archaeocyathellus spp. (PI. 1, figs. 2, 3) were ob- preserved in silica, and the number of rays can be tained in etched material. Greater abundance of determined. Most of the distal portion of each ray fossil fragments in the Hudson Valley indicates that was broken off, and sutures between the rays were the Archaeocyathellus reefs lay in clearer water areas filled with silica when rays were replaced. Thinness just west of the Hudson Valley localities. of the proximal portion of the rays, compared to Horizon and locality.—Lower Cambrian, Iocs. those in calcite or phosphatic material, indicates Y lla, 13. inexact silica replacement. Most specimens pre- Figured specimen.—USNM 125739 served in black phosphatic-appearing material are single rays of the proximal portion; only one specimen shows most of the rays. These water-worn Archaeocyathellus walcotti Okulitch phosphatic specimens must have lain on the sea (Plate 1, figure 4) bottom a long time after death of the sponge, and then were moved by currents before ultimate burial. Archaeocyathellus walcotti OKULITCH, 1943. Geol. No generic name has been assigned to these Soc. America Special Paper 48, p. 61, pi. 3, figs. spicules. Two genera, Chancelloria and Protospongia, 2-5 are commonly referred to hexactinellid sponges of Original description.—Okulitch gives a modern the Cambrian, but since this material gives no clue diagnosis of the species and cites Walcott's earlier as to shape or general spicule arrangement in the discussion of forms now placed in this species. body determination can not be made. In his 1887 Remarks.—-Three specimens known, two small list Walcott referred loose sponge spicules to Proto- fragments and a third larger fragment of the apical spongia. portion 17 mm in length and about 2 mm in diag- Horizon and locality.—Lower Cambrian, Iocs. Y eter at the widest part, appear to be external lime- lla, 12, 13, 16, 6, 7, 10, 11, 14, 17. stone molds, and only the appearance of the outer Figured specimens.—USNM 125743, 125744a, wall is preserved. Largest specimen shows the low 125744b, 12S744c annulations on the surface, the shallow longitudinal furrows, and three or four rows of small pores be- Phylum ARCHAEOCYATHA tween the furrows. These features place the form in Okulitch's species. Order AJACICYATHINA Among etched material many silificied fragments appear to be the outer wall of Archaeocyathellus. Family AJACICYATHIDAE The most common type shows small, closely spaced, Genus Archaeocyathellus Ford (1873) oval pores; at least six rows can be counted in some specimens, but none retains more than one pariety Archaeocyathellus rarus (Ford) so the total rows possible is not known. Okulitch records from 3 to 10 for A. walcotti, and it seems (Plate 1, figure 1) likely that these are fragments of that species Protocyathus rarus FORD, 1878. Am. Jour. Sci., 3d (Archaeocyathellus spp., PI. 1, figs. 2, 3, USNM ser., v. 15, p. 124 125740).

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A few fragments of comparable dimensions show bent, and irregular in shape, and only toward the coarser pores. One type contains three rows of ellip- apertural portion does the tube tend to straighten. tical pores as large as 1 mm, and from Okulitch's Unlike Coleoloides, the tubes are scattered at ran- description can be referred to the inner wall of A. dom through the limestone nodules. The largest walcotti. A second type is stirrup pores and might tube, a straight fragment, is 10 mm in length, and possibly be referred to this species also. The few the average specimen is 5 mm or less. Fragile other specimens are not structurally diagnostic character of the shell seems to have been responsible enough for sure placement. for fragmentation during deposition and collecting Horizon and locality.—Lower Cambrian, Iocs. Y of the material. lla, 12, 13. Three fragmentary tubes show a coarser annula- Figured specimens.—USNM 125741 tion on the outer surface. Walcott in 1890 recognized a variety, H. micans rugosa, based on a single Phylum—cf. ANNELIDA tube which showed coarse annulations between which were fine longitudinal striae. Specimens Genus Hyolithellus Billings (1872) collected by the author show no trace of longitudinal Hyollthellus mlcans (Billings) striae, although the largest specimen is the same size as Walcott's type. Although poor preservation (Plate 2, figures 1-21) may account for absence of striae, the writer is Hyolithes micans BILLINGS, 1872. Canadian Natural- reluctant to refer these specimens to Walcott's ist, 2d ser., v. 6, p. 215, figs. 3a, b on p. 213 variety or to describe a new variety. Hyolithellus micans (Billings) WALCOTT, 1886. U. S. The opercula of Hyolithellus micans range from Geol. Survey Bull. 30, p. 142, pi. 14, figs. 2, 2a-e. 1890, U. S. Geol. Survey 10th Ann. Rept., 0.25 mm to more than 2 mm in diameter; smaller p. 624, pi. 79, figs. 1, la-e ones consist of a single paper-thin lamina, whereas Hyolithellus micans (Billings) SHIMER AND SHROCK, the larger are composed of many layers. Regardless 1944. Index Fossils of North America, p. 525, of size, they all show the eccentrically placed apex pi. 214, figs. 32-36 surrounded by closely spaced concentric growth Original description.—Walcott (1886) repeated ridges on the upper surface, and on the under sur- Billings' complete description of the species and face the distinct and rigid pattern of five pairs of added his observations about the outer surface muscle scars which originate from a point exactly markings. opposite the apex on the upper surface. In the largest Remarks.—The collections contain many frag- individuals there is a tendency for the short front mentary tubes referrable to this species. The largest pair of muscles to encroach upon their dividing tube fragments show smooth interior shell and ex- septum, so that it no longer completely separates terior marked by fine crowded annular ridges with the muscles. This feature may be largely a matter a few ridges slightly stronger. Shell appears to be of individual variation. The striking bilateral sym- composed of many fine laminae of a calcareo-phos- metry maintained by the muscle scar pattern of this phatic material which etches readily in acetic acid. operculum indicates that the soft parts of the animal Laminae are apparently added progressively layer must also have had bilateral symmetry. by layer since the minute opercula and apical por- Although the close relationship of Hyolithellus tion of the tubes, where recovered, are both paper remains obscure, the species, especially by means thin; but the adult opercula, often 2 mm or more in of the opercula, constitutes an excellent guide fossil diameter, and the apertural portion of larger tubes for beds of late Lower Cambrian. Since they are are thicker and stronger in texture. Some tube frag- obtainable by etching with acetic acid, the recovery ments from etched material appear to retain only and correct identification of Hyolithellus is possible one lamina and show a scattering of oval holes or from material in which the trilobites may be too pores through the lamina. Probably this is the struc- fragmentary or poorly preserved for identification. ture of each individual layer, but superposition of Horizon and locality.—Lower Cambrian, Iocs. Y 6, layers in complete tubes gives the solid appearance 7, 9, 10, 11, lla, 12a-e, 13, 14, 15, 16, 17. Prindle's normally observed. The marked similarity in com- Iocs.—see list. position of all specimens suggests that these frag- Figured specimens. ments represent a single species. Opercula, USNM 126769 Tubes of HyoUthellas micans are distinguished Etched tubes, USNM 126774; Y lla from Coleoloides prindlei by composition, the black Etched tubes, USNM 126773; Y 12 or brown calcareo-phosphatic Hyolithellus contrast- Tubes in matrix, ing with the shiny white calcitic Coleoloides; by their USNM 126772; Y lla surface markings; and by the tube shape. Hyo- USNM 126770; Y 16 lithellus, particularly in the apical portion, is curved, USNM 126771; Y lla

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Genus Pelaglella Matthew (1895) Figured specimens.— USNM 126765a-c. Prindle Pelagiella primaeva (Billings) Order NEOTREMATA (Plate 1, figures 19-21) Superfamily ACROTRETACEA Platyceras primaeoum BILLINGS, 1871. Canadian Naturalist, 2d ser., v. VI, p. 220 Genus Acrotreta Kutorga (1848) Platyceras primaeoum Billings, WALCOTT, 1886. Acrotreta taconica (Walcott) U. S. Geol. Survey Bull. 30, p. 130, pi. 12, figs. 5, 5a; 1887, Am. Jour. Sci., 3d ser, v. 34, p. 188; (Plate 3, figures 9-12) 1890, U. S. Geol. Survey 10th Ann. Rept., p. 618, Linnarssonia taconica WALCOTT, 1887. Am. Jour. pi. 74, figs. 11, lla Sci. (3d ser), v. 34, p. 189, pi. 1, figs. 18, 18a-d Original description.—Billings' original descrip- Acrotreta sagittalis taconica (Walcott) WALCOTT, 1912. U. S. Geol. Survey Mon. 51, p. 707, pi. 71, tion, repeated by Walcott (1886) with supplemen- figs. 1, la-o (for synonymy to date) tary remarks, gives an adequate picture of the species. Original description. — Walcott's description covers Remarks.—Of the five specimens from the author's all known features of the valves except the perfora- material and one from Prindle's collections only one tion of the ventral valve which is shown in material retains the shell and shows the narrow spiral ridges figured by Walcott in 1912 and in etched material on the surface. Other specimens are steinkerns. studied by this author. The largest (PI. 1, fig. 19) specimen obtained, Remarks. — This species is represented by several though broken, apparently had a diameter of 4 mm flattened fragmentary valves from one, possibly two, or more at the aperture, and is the largest specimen of Prindle's localities (label lost from one box, but known. the assemblage suggests that both boxes of material Horizon and locality.—-Lower Cambrian, Iocs. Y 7, came from the same locality). These valves show lla, 12d, 12<% 13, 14. Prindle loc. 473. both dorsal and ventral exteriors and interiors and Figured specimens. average around 2 mm in size, but a large distorted USNM 12S74S; Y 13 dorsal valve measures 3.25 mm, which is about the USNM 12S747; Y 14 size mentioned by Walcott. None of the fragile USNM 125746; Prindle #473 fragments of dorsal and ventral valves obtained from the etched material of Y lla was larger than Phylum BRACHIOPODA 1 mm. Muscle scars on both valves agree in all de- Class INARTICULATA tails with those figured by Walcott. In 1912 Walcott decided to refer this form to the Order ATREMATA species A. sagittalis (Salter), a form which occurs in Superfamily LINGULACEA the Lower Lingula flags of South Wales. However, Walcott's specimens show differences in muscula- Genus Llngulella Salter (1866) ture which can be considered of specific value, and Lingulella granvillensis Walcott it seems advisable to consider this Lower Cambrian Schodack form a distinct species rather than a (Plate 4, figures 20-22) variety of a late Middle Cambrian and Upper Cam- Lingulella granvillensis WALCOTT, 1887, Am. Jour. brian species. Sci. (3d ser), v. 34, p. 188-189, pi. 1, figs. 15-15a-c Horizon and locality. — Lower Cambrian, Iocs. Y Linguletta granvillensis Walcott WALCOTT, 1912, lla. Prindle's Iocs. — see list. U. S. Geol. Survey Mon. 51, pt. I, p. 504, pi. 22, Figured specimens.— USNM. 125729a, b. figs. 1, la-d (synonymy to date) Original description.—Walcott repeated his de- Superfamily SIPHONOTKETACEA scription in Monograph 51. Genus Botsfordia Matthew (1891) Remarks.—Complete valves, 1-2 mm long, and Botsfordia caelata (Hall) many fragments of larger valves can be identified in several of Prindle's collections. The valves of this (Plate 4, figures 3-6) species are not as common as those of Botsfordia Orbicula caelata HALL, 1847. Nat. History New cadata, and their sporadic occurrence suggests a York, Paleontology, v. 1, p. 290, pi. 79, figs. 9a-c Botsfordia. caelata (Hall) WALCOTT, 1912. U. S. Geol. normal habitat different from that of the more com- Survey Mon. 51, p. 603, pi. 59, figs. 1, la-q, 3, mon members of the fauna. Their association indi 3a-b (synonymy to date) cates that their age was the same. Description. — Walcott (1912) gave a complete Horizon and locality.—Lower Cambrian, see list description which adequately covers the various of Prindle Iocs. valves found in the author's material.

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Remarks.—This is the most abundant brachiopod Geol. Survey Bull. 30, p. 128-129, pi. 12, figs. 1, la-e (synonymy to date) species in the faunal assemblages from most of the Stenothecaf rugosa (Hall) WALCOTT, 1890. U. S. author's localities. It appears to have favored a Geol. Survey 10th Ann. Rept., p. 617, pi. 74, figs. somewhat clearer water habitat than the forms 1, la-i Oboletta crassa and Acrotreta taconica. The two Helcionella rugosa (Hall) GRABATT AND SHIMER, 1909. North American Index Fossils, v. 1, p. 607, latter species are abundant in several of Prindle's fig. 810b collections, and the limestone pieces in which they Helcionella rugosa (Hall) RESSER, 1938. Smithson. occur are high in black argillaceous material. The Misc. Coll., v. 97, no. 10, p. 12 thin-shelled young valves and the thick-shelled Helcionella subrugosa (Orbigny) KNIGHT, 1941. Geol. Soc. America, Special Paper 32, p. 142, large valves etch out well. Large valve fragments pi. 3, fig. 1 are most common and indicate that the shells have Hdcionetta subrugosa (Orbigny) SHTMER AND been moved and wave sorted. The largest valves SHROCK, 1944. Index Fossils of North America, obtained by the author are about 9 mm long, and, p. 439, pi. 175, figs. 5-10 Helcionella halli RESSER, 1938. Smithson. Misc. unlike most, have been replaced by silica. Coll., v. 97, no. 10, p. 12 The distinctive ornamentation of the outer sur- Helcionella walcotti RESSER, 1938. Smithson. Misc. face is often preserved. Coll., v. 97, no. 10, p. 13 Horizon and locality.—Lower Cambrian, Iocs. Y 6, Helcionella curticei RESSER, 1938. Smithson. Misc. Coll., v. 97, no. 10, p. 13 7, 11, Ha, 12, 13, 14, 16. Prindle's Iocs.—see list. Helcionella fordi RESSER, 1938. Smithson. Misc. Figured specimens.—USNM 126752, 126753, Coll., v. 97, no. 10, p. 13 126754a, b. Description.—Walcott repeats Hall's original de- Class ARTICULATA scription and adds significant remarks (1886). Knight's description of the genus is based largely Superfamily KTTTORGINACEA upon this species and should be followed for the Genus Kutorgina Billings (1861) modern terminology. Remarks.—Although not exceptionally abundant, Kutorgina clngulata (Billings) this species is represented by shells of a wide size Oboldla (Kutorgina) cingulata. BILLINGS, 1861, Geol. range—some large fragments indicate a length of Survey Canada, Paleozoic Fossils, v. 1, p. 8-9, three-quarters to 1 inch. Several immature shells figs. 8, 10 about 2 mm in length at the aperture show the Kutorgina cingulata (Billings) WALCOTT, 1912. U. S. numerous fine growth lines, but the strong concen- Geol. Survey Mon. 51, p. 580, pi. 5, figs. 1, la-s tric ribs are not yet developed. Fine radiating ridges Description.—Walcott gives a complete descrip- rarely appear. One small fragment of the apex of a tion of the species. moderate-sized shell retains a minute globular proto- Remarks.—Several shells in the author's material conch and some of the inner nacreous shell layer. and in Prindle's collections have been tentatively Compression of the matrix has crushed and broken referred to this species. However, a careful study of most shells. Other shells, crushed down from the these specimens is to be made by Dr. W. C. Bell. dorsal surface, are flattened around the aperture The species is cited here for a record of the localities. for 0.5 mm. Concavity of the posterior profile of Horizon and locality.—Lower Cambrian, Iocs. Y one specimen has been exaggerated by this means. Ha, 13, 16. Prindle's Iocs.—see list. Etched material from Y Ha yielded small steinkerns, presumably of this species, preserved in sand Phylum MOLLUSCA grains or a phosphatic material which filled the empty interior of the shells. No internal muscle Class GASTROPODA scars are preserved. Horizon and locality.—Lower Cambrian, Iocs. Y Subclass ISOPLEURA 6, 7, lla, 12b, 12c, 12d, 13, 14, 16, 17. Prindle's Order MONOPLACOPHORA Iocs.—see lists. Family TRYBLIDIIDAE Figured specimens. USNM 126756 Genus Helcionella Grabau and Shimer (1909) USNM 126757 Helcionella subrugosa (Orbigny) USNM 126758 USNM 126759 (Plate 4, figures 9-19) USNM 126760 Metoptomat rugosa HALL, 1847. Pal. N. Y. v. 1, p. USNM 126761 306, pi. 83, figs. 6a-c Hdcion subrugosa (Hall) D'ORBIGNY, 1850. Prod. USNM 126762 paleont. strat. univ., v. 1, p. 9 USNM 126763 Stenotheca rugosa (Hall) WALCOTT, 1886. U. S. USNM 126764

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Class Cf PELECYPODA Fordilla troyensis Walcott, SHIMER AND SHROCK, 1944, Index Fossils of North America, p. 660, Genus Fordilla Barrande (1881) PL 279> figs' S> 6 Fordilla troyensis Walcott Description—-Ford gives a complete original description which is repeated by Walcott (1886). (Plate 1, figures 5-10) Remarks.—The specimens in the author's ma- „. , , . , „ ,„,., terial are like Ford's types in shape, narrow dorsal Bivalve of uncertain class; gen. nov. FORD, 1873, ,. ,. . , ,,,.,,. , j Am. Jour. Sci. (3d ser) v. 6, p. 139 hm8e ^ wltth sma11 anteriorly placed umbo and Fordilla BARRANDE, 1881. Acgphales. fitudes Loc. numerous fine concentric ridges. A few limestone et Comp., 8°, p. 391-393, pi. 361 external molds also show faint striae radiating from Fordilla troyensis WALCOTT 1886. U. S. Geol. Sur- ^ umbo The 21 specimens were obtained only vey Bull. 30, p. 123-125, pi. 11, figs. 3, 3a-c; , , ., .... ,. u , . , , iU 1890, U. S. Geol. Survey 10th Ann. Rept., P- 615, from the three locahtles which furnished the most pi. 73, figs. 2, 2a-c abundant material. Only one shell, 0.75 mm long,

PLATE 1.—PORIFERA, ARCHAEOCYATHELLUS, PELAGIELLA, AND FORDILLA Figure 1. Archaeocyathettus rarus (Ford). A single fragment showing the single row of pores along each furrow, X5, USNM 125739; Y 13 2, 3. Archaeocyathettus spp. Examples of silicified fragments etched out with acetic acid, X10, USNM 125740; Y lla 4. Archaeocyathellus walcotti Okulitch. A fragmentary specimen showing four rows of pores between furrows, X5, USNM 125741; Y 13 5-10. Fordilla troyensis Walcott. 5, 8, well-preserved limestone mold of exterior of shell, X10, X5, USNM 125742a; Y 16. 9, largest shell, partially broken, X5, USNM 125742d. 6, 10, two additional well- preserved molds of the exterior, X5, USNM 125742b, USNM 125742c; all Y 16. 7, small well- preserved shell with patches of the shell material, X5, USNM 125748; Y lla 11-18. Hexactinellid sponge spicules. 11, 13-16, phosphatic spicules and central discs etched free with acetic acid, X20, USNM 125743; Y 7. 12, 17, 18, calcite spicules in matrix, X10, USNM 125744a, USNM 125744b, USNM 125744c; Y 16 19-21. Pelagiella primaeva (Billings). 19, steinkern showing very faint growth lines and single revolving lira, X5, USNM 125745; Y 13. 20, specimen which has very faint revolving lirae near keel, X5, USNM 125747; Y 14. 21, large steinkern, X10, USNM 125746; Prindle #473

PLATE 2.—HYOLITHELLUS MICANS (BILLINGS) Figure 1-21. Byolithellus micans (Billings). 1, 2, 8, exterior view of adult opercula. 4, exterior with worn apical region and an interior. 3, 5, 6, 7, 10, interior view of adult opercula showing the characteristic five pairs of muscle scars. 9, immature opercula consisting of a single translucent shell layer, all specimens etched free with acetic acid, X10, USNM 126769; Y lla. 11, 12, limestone mold of exterior of a tube showing the annular markings, X5, XlO, USNM 126772, Y lla. 13, portion of a curved tube, X10, USNM 126770; Y 16. 18, limestone mold to which patches of the original chitinous shell material adhere, X5, USNM 126771; Y lla. 15,16,19, three etched fragments from apertural portion of tubes, XlO, USNM 126773; Y 12. 14, two etched specimens, the upper replaced by silica, the dark lower one of original shell material showing numerous scattered pores, XlO. 17, 20, etched tubes showing size range, XlO. 21, straight and curved etched fragmentary tubes, X5, all USNM 126774; Y lla

PLATE 3.—BYOLITBES, COLEOLOIDES, AND ACROTRETA Figure 1-8. Hyolithes americanus Billings. 1, one large specimen showing flat surface and two medium-sized shells showing the angled (convex) side. 2, reverse of large specimen in 1, both XI, USNM 125715a, b; Y 16. 6, 3, well-preserved apical fragment showing outer surface striae on shell, X5, XlO, USNM 125716; Y lla. 4, 7, two opercula differently oriented, 4, showing the conical dorsal side, 7 centered just dorsal of the broken apex to show crenulated ventral side and nearly straight margin, X3, X5, USNM 125717, USNM 125718; both Y 16. 5, apertural fragment, X5, USNM 125719; Y 16. 8, Continued on following page

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------PQRIFERA, ARCHAEOCYATHELLUS, PELAGIELLA. AND FORDILLA

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IIYOLITIIELLUS MICANS (BILLINGS)

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------HYOL1THES, COLEOLOIDES, AND ACROTRETA

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RUTSFORDIA, LI-IGULELI,A, INDIANA, SALTERELLA, IIELCIONELLA. AND STENO'I'£fECOPSIS

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retains the original shell material, which appears to Horizon and locality.—Lower Cambrian, Iocs. Y be calcareo-phosphatic. This shell is blue black and lla, 13, 16. is moderately thick. The other specimens, 3-4 mm Figured specimens. long, are preserved either as limestone external USNM 12S742a; Y 16 molds on which the concentric ridges appear as USNM 12S742b; Y 16 grooves, or as external casts covered with a thin USNM 12S742c; Y 16 carbonaceous film. In the writer's material no USNM 125742d; Y 16 valve pairs occur together. USNM 125748; Y lla Although considerable material was etched from all three localities furnishing the shells, no additional Class INCERTAE SEDIS valves were obtained. This suggests that Ford was /«0oni probabl, ,,y correct.. i.n statint ... g tha., ftt th, e shel, „l was calcite, - . Genus Coleoloides Walcott v(1889 ') The calcareo-phosphatic appearance of the author's Coleoloides prindlei n. sp. small shell is believed caused by an outer chitinous „ , , . „ „., layeri . Succ- ih. a layei r coulud bi. e thi.e source ofr th^i.e car- (Plate 3. figures 17-20) bonaceous film retained on many specimens. Original description.—Shell slender, largest diam- Considering the nature of this material it would eter 1.5-2 mm, elongate, cylindrical, tapers slowly seem unwise to arbitrarily reject Fordilla as a mem- to tip; complete shell probably near 60-75 mm in ber of the Pelecypoda. length (largest fragment in material 25 mm); surface

8a, mold of broken specimen with patches of shell material, sketch of characteristic cross section taken from broken end, X3, USNM 125720; Y lla 9-12. Acrotreta taconica (Walcott). 9, 10, internal mold of dorsal valve, X5, X10, USNM 125729a. 11, 12, exterior of ventral valve, X5, X10, USNM 125729b; Prindle, about 3% miles northeast of Cambridge, N. Y., on ridge east of valley 13-16. Hyolithes communis Billings. 13, 15, two limestone molds suggesting the characteristic oval cross section, X3, X2, USNM 125721, USNM 125722; both Y 16. 14, mold with patches of shell material showing concentric striae, X3, USNM 125723; Y lla. 16, fragment of crushed shell showing faint vertical ridges, X2, USNM 125724; Y 13 17-20. Coleoloides prindlei n. sp. 17, fragment of tube showing crowded narrow vertical ridges, X10, USNM 125727; Y 16. 18, mold of tube with patches of calcite shell material, X 10, USNM 125726; Y lla. 19, a crushed tube, X10, USNM 125728; Y 16. 20, holotype, numerous tubes showing some orientation on rock, X5, USNM 125725; Prindle—P 13, about half a mile northwest of Peterburg, N. Y.

PLATE 4.—BOTSFORDIA, LINGULELLA, INDIANA, SALTERELLA, HELCIONELLA, AND STENOTHECOPSIS Figure 1-2. Stenothecopsis schodackensis n. sp. 2, holotype in matrix, X10, USNM 125749; Y 16. 1, eight paratypes of varying sizes etched from matrix, X10, USNM 126750; Y 13. USNM 126751; Y 16 3-6. Botsfordia caelata, (Hall). 3, interior of a large silicified shell, X5, USNM 126752; Y lla. 4, well- preserved exterior of a shell, X10, USNM 126753; Y lib. 5, 6, two fragments showing characteristic surface markings, X10, USNM 126754a, b; Y 11 7, 8. Indiana dermatoides (Walcott). Limestone mold of carapace with fragments of original shell material adhering along upper and lower edges, X6, X3, USNM 126755; Y 16 9-19. Helcionetta subrugosa (d'Orbigny). 9, 14, side and dorsal of medium-sized shell, X3, USNM 126756; Y lla. 10, a crushed shell, X5, USNM 126757; Y 16. 19, largest shell, X3, USNM 126758; west side of Moon Hill about 1 mile north of Petersburg, N. Y. 12, immature shell, X15, USNM 126759; Y 16. 15, dorsal view of shell in which direction of apex appears to be reversed, X6, USNM 126760; Y 16. 16, flattened aperture of shell from ventral surface, X5, USNM 126761; Y 13. 13, dorsal of small well-preserved shell, X5, USNM 126762; Y 16. 11, profile of shell, X5, USNM 126763; Y lla. 17, 18, profile of very small shell, X5, X10, USNM 126764; Y 13 20-22. Lingulella gramiillensis Walcott. 20,22, typical exteriors, X5, X10, USNM 126765a, USNM 126765c. 21, interior of a valve, X5, USNM 126765b; Prindle #241, half a mile north of Cambridge, N. Y. 23, 24. Stenothecoides labradorica Resser. Single specimen found, X5, XlO, USNM 126766; Y 15 25-27. Salterdla pttlchdla Billings. 25, 26, two halves of broken shell showing concentric bands and central tube, X5, USNM 126767a, b; Y 7. 27, fragment of large tube showing fine concentric striae, XlO, USNM 126768: Y 12d

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of shell layers crowded with fine parallel longitudi- Byolithes americanus BILLINGS, 1872. Canadian Naturalist, 2d ser., v. VI, p. 215, figs. 2a, b, p. 213 nal, occasionally interrupted, ridges and intervening Byolithes americanus Billings, WALCOTT, 1890. U. S. grooves approximately subequal in width. Shell con- Geol. Survey 10th Ann. Rept. p. 620, pi. 75, figs. sists of thin, apparently calcium carbonate, laminae 2, 2a-f (for synonymy to date) on which the ridges and grooves appear. Not certain Byolithes americanus Billings, SHTMT.R AND SHROCK, 1944, Index Fossils of North America, p. 525, pi. whether actual outer surface of shell is preserved in 215, figs. 1-6 any of these specimens. Hyolithes americanus Billings, SINCLAIR, 1946, Jour. Remarks.—This species is similar to Coleoloides Paleont. v. 20, p. 73 typicalis from Newfoundland but does not show the diagnostic spiralling of the ridges around the shell. Billings' description.—"Length from twelve to Walcott states in his original description of Coleo- eighteen lines, tapering at the rate of about four lines to the inch. Section triangular, the three sides loides that "in form this shell is like that of Hyo- lithettus micans." This statement can be misleading. flat, slightly convex or slightly concave, the dorsal In form both are similar in that they are tubes, but (ventral) and lateral edges either quite sharp or in the Schodack material Coleoloides is a straight acutely rounded. Lower lip rounded, projecting about two lines in full grown individuals. Surface tube composed of thin laminae of calcium carbonate, whereas Hyolithdlus (especially in the younger por- finely striated, the striae curving forwards on the tions) is an irregular tube, and is composed of cal- ventral (dorsal) side, and passing upwards on the careo-phosphatic material. Although of acknowl- sides at nearly a right angle, curve slightly back- edged uncertain affinities the two genera have wards on the dorsum (ventrum). In a specimen usually been placed close together. The difference eighteen lines in length the width of the aperture is in early growth and shell material indicate to this about six lines and the depth about four, the pro- author that the two genera are not related. portion being slightly variable. The shell material and the most common mode of "The operculum has a very well-defined conical occurrence of Coleoloides suggest that the genus ventral (dorsal) limb, the apex of which is situated occupied a habitat similar to that of Byolithes and above the center, or nearer the dorsal (ventral) than may have been related to that genus. Although a the ventral (dorsal) side. The dorsal (ventral) limb few solitary specimens have been obtained, the forms a flat margin, and is so situated that when usual occurrence is in masses of one or two shell the operculum is in place the plane of this flat border thickness with the shells roughly oriented. This must be nearly at right angles to the longitudinal indicates that the animals were pelagic during most axis of the shell. In an operculum six lines wide the or all of their life. Tubes of Hyolithellus never show height of the lower limb to the apex of the cone is this feature. two and a half lines, and the width of the flat border, This is the first record of Coleoloides in any of the which constitutes the dorsal (ventral) limb, about Schodack faunas of New York and apparently from one line." any locality other than Newfoundland. It is possible Remarks.—Most Byolithes specimens in this ma- that the genus is actually well represented in late terial can be assigned to this species. In actual Lower Cambrian faunas of eastern United States, numbers they are not too abundant and occur only but has been misidentified as Byolithellus, as were at three localities. At Y 16 some specimens reach a some of these specimens in previous identifications. length of 1% inches, but are preserved only as Horizon and locality.—Lower Cambrian, Iocs. Y carbonaceous imprints of the original shell. At the lla, 12b, 13, 14, 16. Prindle's Iocs.—see list. other two localities the shells and opercula retain Types. some shell material; on some of these the concentric Holotype, USNM 125725; Prindle, about half a striae of the surface can be seen. The best-preserved mile northeast of Petersburg, N. Y. shells show the distinct triangular cross section, the Paratypes most diagnostic feature of the species, but many USNM 125727; Y 16 specimens have been flattened and broken so that USNM 125726; Y lla their cross section is more oval in shape. Although USNM 125728; Y 16 two species of Byolithes are recognized by the author, they may represent a single biological species. Both Genus Hyollthes Eichwald (1840) species, recorded also from the Troy region and from Quebec, always occur together at the same Hyollthes amerlcanus Billings localities and only in this distribution. Walcott, dealing with suites of better-preserved material, (Plate 3, figures 1-8) recognized considerable variation within the species. Thecaf Iriangvlaris HALL, 1847. Paleont. New York, Recognition of two or three species serves no strati- v. 1, p. 313, pi. 87, figs, la-d graphic use, and no distinctions can be made in the

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surface markings of the shells. The two species are Figured specimens. recorded here under their accepted names in order USNM 125721, USNM 125722; Y 16 to call attention to their occurrence, but because of USNM 125723; Y lla limited material it is not possible to undertake a USNM 125724; Y 13 serious revision of the group. Triangular fragments of phosphatic shells in the Genus Salterella Billings (1861) etched material have also been tentatively referred to this species. Salterella pulchella Billings Horizon and locality.—Lower Cambrian, Iocs. Y lla, 13, 16, 7, 12, 14. (Plate 4, figures 25-27) Figured specimens. Salterella pulchella BILLINGS, 1861. Geology of Ver- USNM 125715a, b; Y 16 mont, v. 2, p. 955 USNM 125716; Y lla Salterella pulchella Billings, SHIMER AND SHROCK, USNM 125719; Y 16 1944. Index Fossils North America, p. 531, pi. USNM 125720; Y lla 217, fig. 4 Salterella cf. S. pulchella Billings LOCHMAN, 1952. Opercula, USNM 125717, USNM 125718; Y 16 Smithson. Misc. Coll., v. 109, no. 1, p. 87, PI. 16, fig. 1 Hyolithes communis Billings Original description.—"Elongate, conical, gently (Plate 3, figures 13-16) curved, from six to eight lines in length and from one to one and a half in width at the aperture. Hyolithes communis BILLINGS, 1872, Canadian Naturalist, 2d ser., v. VI, p. 214, figs, la, b, p. 213 Surface ornamented with small encircling striae Hyolithes communis Billings, WALCOTT, 1890, U. S. just visible to the naked eye. Geol. Survey 10th Ann. Rept. p. 620, pi. 77, figs. "This species is larger than S. rugosa, always a 3, 3a-g (synonymy to date) little curved, not so abundant, and when weathered Hyolithes communis Billings, SHIMEK AND SHROCK, 1944, Index Fossils of North America, p. 525, does not present the sharp imbricating annulations pi. 215, figs. 34-41 of that species." Hyolithes communis Billings, SINCLAIR, 1946, Jour. Remarks.—Four fragmentary specimens, the Paleontology v. 20, p. 73 largest 8.5 mm long, have been referred to this species. The stronger concentric annulations are Descripion.—The original description of Billings conspicuous, but the surface preservation is too poor is complete. It was repeated by Walcott (1886). to show the finer annulations. Only the largest frag- Remarks.—A few shells referred to this species are ment indicates shell curvature. The largest speci- distinguished by the narrow oval or elliptical cross men has been broken and shows the round, cen- section of the shell and a blunt-tipped lower end. trally located inner tube characteristic of Salterella. No cross section is as circular as that figured by Horizon and locality.—Lower Cambrian, Iocs. Y 7, Billings, but this can be attributed partly to the fact 12d, 13. that Billings was showing an aperture and in these Figured specimens. specimens the section is farther down the shell, and USNM 126767a, b; Y 7 partly to the known flattening of these specimens. USNM 126768; Y 12b Several specimens have well-preserved exteriors and one shows a few fine longitudinal ridges. As discussed in detail by Walcott (1886) it is diffi- Genus Stenothecoides Resser (1938) cult to point out any valid constant specific difference between H. communis, H. emmonsi Ford (which Stenothecoides labradorica Resser Walcott reduced to a variety of H. communis), and (Plate 4, figures 23, 24) H. impar Ford. Two small limestone internal molds (PI. 3, figs. 13,15) which are more tubular and nearly Stenotheca rugosa WALCOTT (part), 1886. U. S. Geol. circular in cross section might be considered more Survey Bull. 30, p. 129, pi. 12, fig. 4 like those shells referred to H. impar. However, they Stenothecoides labradorica Resser, RASETTI, 1954. Jour, of Paleontology, v. 28, p. 65, pi. 11, figs. are placed here since no more diagnostic features 1-2, 5 (Synonymy to date) can be determined and certainly a filling of the interior of an H. communis shell could produce such Description.—"Largest shell 8.8 mm. long, 3.7 a specimen. Phosphatic and silicified internal molds mm. wide and about 3 mm. high. Transverse profile from etched material show the septa of the interior. almost flat at the sides, resulting in a fairly sharp Horizon and locality.—Lower Cambrian, Iocs. Y keel along the median line. Shell rather pointed at lla, 13, 16. the anterior end and somewhat more rounded pos-

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teriorly. Sides with unequal curvature, apex slightly Remarks.—The single complete specimen of this asymmetric." species, slightly smaller than Walcott's cited dimen- Remarks.—Only a single specimen, 3.5 mm in sions, is 5 mm long by 2.5 mm high. Patches of the length, has been obtained from the material, but it punctate outer surface adhere to the black lime- tends to substantiate Rasetti's tentative conclusion stone internal cast. In reflected light the round that the poorly preserved and small (2.1 mm) holo- muscle scar is visible on the posterior surface as a type of Stenothecoides troyensis Resser might be slightly raised area since a small amount of the shell referrable to S. labradorka. The author's specimen, also adheres to the area. Two silicified fragments, though the overhanging apex has been broken off, which show the characteristic pitted surface, are is fairly well preserved and 1.5 mm larger; and there also assigned here. is no doubt about its specific identity with shells Horizon and locality.—Lower Cambrian, Iocs. Y identified as 5. labradorica. The sharp keel along 6, lla, 16. the median line and the asymmetry of the shell are Figured specimen.—USNM 126755 distinct. Horizon and locality.—Lower Cambrian, loc. Y IS. Class TRILOBITA Plesiotype.—USNM 126766 Order OLENELLIDA Phylum ARTHROPODA Family OLENELLIDAE Walcott, 1891 Subclass ARCHAEOSTRACA Genus Elliptocephala Emmons (.1844) Genus Indiana Matthew (1902), emended Ulrich and Bassler (1931) Elliptocephala asaphoides Emmons Indiana dermatoides (Walcott) (Plate 6, figures 2-21) Elliptocephala asaphoides EMMONS, 1844, Taconic (Plate 4, figures 7, 8) System, p. 21, figs. 1, 2, 3 Leperditia (I) dermatoides WALCOTT, 1887. Am. Elliptocephala asaphoides EMMONS. Walcott, 1910, Jour. Sci., (3d ser) v. 34, p. 192-193, pi. 1, figs. Smithson. Misc. Coll., v. 53, no. 6, p. 269, pi. 24, 13, 13a; 1890, U. S. Geol. Survey 10th Ann. figs. 1-10; pi. 25, figs. 1-8 (for synonymy to date) Rept., p. 626, pi. 80, figs. 1, la Leperditia dermatoides Walcott MATTHEW, 1891, Description.—Walcott gives a complete descrip- Am. Geology, v. 8, p. 290 tion of the exoskeleton of the species. Leperditia dermatoides Walcott COBBOLD, 1921, Quart. Jour. London Geol. Soc., v. 76, p. 368 Remarks.—Every locality yielded Olenellid exo- Indiana dermatoides (Walcott) CHAPMAN, 1918, skeleton fragments; such fragments were abundant Proc. Royal Soc. Victoria, new ser., v. 31, p. 109 at localities Y 11, lla, and 13. These macerated Indiana dermatoides (Walcott) ULRICH AND BASS- pieces must represent the accumulation of piles of LER, 1931, Proc. U. S. Nat. Mus., v. 78, art. 4, p. 75, pi. 9, figs. 16, 17 organic debris on the sea floor, and probably give an exaggerated idea of the superabundance of individ- Original description.—"Outline of the valves uals. Although the fragments are generically and elongate, suboval, with the extremities of the hinge specifically unidentifiable, it is probable that all line rounded, subangular; moderately convex, slop- belong to this single species since all the identifiable ing more rapidly to the ventral than the dorsal protaspids and holaspid cephala in the material can margin; in many specimens, however, it is difficult be ascribed to the species. The largest cephalon, to determine the ventral from the dorsal margin, badly broken, is about 25 mm long, but most identi- owing to their almost equal curvature and similar fiable cephala are about 5-6 mm. Fragments show rounding of the ends; the hinge line is arched and that individuals often reached a size comparable to but slightly marked. It is difficult to determine the that of Walcott's topotype, USNM 18350a, but anterior and posterior ends of the valves in many were broken before deposition. of the specimens, but in others the narrower end is Well-preserved fragments from localities Y 13 considered as the anterior, and a small, rounded and Y 16 show the distinctive surface ornamenta- depression on the inner side of the valve places the tion of narrow ridges in a semi-polygonal or irregular muscular scar well toward the posterior end. The network, each area with a small granule in the scar is barely visible on the outer surface. middle. On the lateral portions of the exoskeleton "The test is finely punctate, and so thin that it the reticulate pattern continues until it merges wrinkled in some instances like a membrane or skin. with the imbricating ridges, but the granules are Length of undistorted specimen, 6 mm; greatest usually absent. height, 3.5 mm." Elliptocephala asaphoides Emmons is known only

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from the late Lower Cambrian beds of eastern New abundant food supply of both vegetable and animal York, in an area extending from northern Washing- origin. The similarity of the coastal shelf faunas of ton County to northern Dutchess County. The Greenland, Canada, and the United States indicates genus, represented by this single species, is now that the shelf regime was dominated by cool currents well enough known to show that it is valid and dis- following the continental shores southward on both tinct from other Olenellids. The specimens occur in the east and the west sides of the North American impure limestone beds, limy shales, and sandstones, continent. as well as in limestone nodules representing lenses Horizon and locality.—Lower Cambrian, Iocs. Y of organic debris. There can be no doubt that the 6, 7, 9, 10, 11, lla, lib, 12b-f, 13, 14, IS, 16, 16a. animal inhabited this site of deposition during life Prindle's loc.—see list. and was adapted to the particular local environ- Figured specimens. ment. Late Lower Cambrian deposits of equivalent USNM 125696; Prindle #274 age and comparable lithology occur to the north in USNM 125697; Prindle #270 Vermont (the Parker shale and the Monkton quart- USNM 125698, 125699, 125704, 125706; Y 6 zite) and to the south in Pennsylvania (the Kinzer USNM 125707, 125708; Y lla formation). All these formations have several genera USNM 125700, 125701, 125712, 125714; Y 13 and many species of Olenellids in common—the USNM 125703, 125709, 125710, 125711; Y 16 characteristic assemblage of the Olenellus thompsoni USNM 125705; Y 12b fauna. This faunal assemblage was adapted to a USNM 125702; Y lib different local environment than the one controlling USNM 125713; Y 14 the ElUptocephala asaphoides fauna, but composition of the various deposits shows that gross lithologic Order EODISCIDA differences were not the critical ecologic features of the environment. A difference in water depth, and Family EODISCIDAE Raymond, 1913 probably water temperature, suggested by geographic distribution, faunal composition, and faunal Genus Calodiscus Howell (1935) affinities of the two assemblages, are believed to be the controlling environmental factors. The Ettipto- Calodlscus meek! (Ford) cephala asaphoides fauna probably lived on bottoms (Plate 7, figure 25) 400-600 feet or more below the surface under a regime controlled by oceanic waters. Such a habitat Microdiscus meeki FORD, 1876, Amer. Jour. Sci., 3d implies little or no seasonal or diurnal variation, ser., v. 11, p. 371 Calodiscus meeki (Ford) RASETTI, 1952, Jour. increased pressure, little or no light, a lower oxygen Paleontology, v. 26, p. 442, pi. 51, figs. 19-21 content and less abundant food supply. The distri- (for complete synonymy) bution pattern of the Atlantic province fauna suggests that this fauna was a warm-water assemblage, Description.—Ford gave a good original descrip- indigenous to the western Atlantic tropics, which tion of the species. was carried into higher latitudes by a north-north- Remarks.—A single cephalon in one of Prindle's eastward flowing warm current. Such a current was collections shows the characteristic tubercles in the similar to the Recent Gulf Stream but broader and marginal furrow of this species. There is one Calo- probably warmed because of the greater width of discus pygidium close to the cephalon and some tropic and temperate climate zones during the Cam- fragments of ElUptocephala, but no other fossils from brian. This warm current would have followed the this collection. The pygidium has all the specific oceanward side of the island archipelagoes, but occa- characters of C. lobatus (Hall), but it is impossible sional basin inlets would have permitted a small to say whether this type of pygidium should also be branch to penetrate toward the continent. Thus associated with the cephalon of C. meeki (Ford) as some members of the Atlantic province assemblage it appears to be here. Since Ford records the holo- were carried close to the alien environment of the type cephalon of C. meeki associated with cephala shallow coastal shelf. of C. lobatus it could belong to the latter species. The Olenellus thompsoni faunal assemblage was The single cephalon has been broken and dis- adapted to the shallow coastal waters around the torted laterally, which probably caused the pro- entire North American continent. This fauna lived nounced convexity of the cheeks, but the surface is on bottoms a few inches to a few hundred feet below well preserved. There are two pairs of tubercles in the water surface—a habitat characterized by di- the marginal furrows and a single one near the left urnal and seasonal variation, an abundance of sun- genal angle. The anterior glabellar lobe is broken, light, slight pressure, considerable movement of the but the glabella is conical as in the holotype. The water producing a high oxygen content, and an anterior border furrow is not as wide as in the holo-

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type, but this feature probably is attributable to population suite he could not show continued grada- compression of the specimen. This specimen has a tion from cephala of the fully mature "lobatus" short blunt occipital spine, whereas the occipital types—A, At to the smaller cephala of the imma- ring in the holotype is broken, which may or may ture "agnostoides" types—O, D (Fig- 2). Thus not be significant. Rasetti's description of C. agnostoides is adequate Apparently the holotype cephalon of C. meeki for cephala from 0.375 mm in length through ap- (Ford) is the only other specimen of this species proximately 1.25 mm. Rasetti mentions (p. 442) that known as neither Ford, Walcott, nor Rasetti men- C. agnostoides may be an immature form because tion or figure specimens. Consequently it is difficult the holotype cephalon is only 1.2 mm in length, but to picture the amount of intraspecific variability excludes the possibility of relationship to C. lobatus which may exist. The writer believes, however, that because he has cephala 1.0 mm in length showing this additional cephalon can be confidently re- "lobatus" features. That the small cephala of the ferred to the species. Rasetti (1952, PL 51, fig. 17) "agnostoides" type are immature individuals of the figured one fragmentary cephalon which he named same species represented by the predominately C. cf. agnostoides (Kobayashi). This cephalon has a larger cephala of the "lobatus" type can be shown glabella of similar shape and furrows as C. meeki only by a population study with a large suite of and an occipital spine like the specimen described individuals. Between molt stages of cephala, 0.75 here. No tubercles seem present in the marginal mm-1.25 mm long, an individual occasionally shows furrow, but surface preservation is poor, and the retardation or acceleration in acquisition of the ma- front part broken. This cephalon is about 3 mm ture type of cephalon (Fig. 2). long, the holotype cephalon of C. meeki (Ford) is Associated thoracic segments are narrow, straight, 2.75 mm long, and the specimen described here is pleuron with short, straight, bluntly pointed end, 1.625 mm long (including occipital spine) by 2 mm pleural furrow deep and wide on outer half, bifur- wide. cating on inner half into two shallow grooves bound- Formation and locality.—Lower Cambrian, Prin- ing a central triangular raised area. dle no. 186—Hill just north of Cambridge, N. Y. Discussion of ontogeny.—The collections furnished Figured specimens.—Plesiotype, cephalon, and more than 350 cephala and 170 pygidia, the vast associated pygidium, USNM 126778 majority from two localities, Y 16 and Y 13. The 175 cephala and 84 pygidia used for this study are Calodiscus lobatus (Hall) preserved in limestone, and many show some crushing or distortion. Six cephala not used in the popu- (Plate 8, figures 1-11) lation study are retained to show extremes of distortion. The material from Y 16 probably is the Agnostus lobatus HALL, 1847, Paleontology New population of a single species as the collection came York, v. 1, p. 258, pi. 57, figs. 5a-f Calodiscus lobatus (Hall). RASETTI, 1952, Jour. from limestone nodules at one horizon. The material Paleontology, v. 26, p. 441, pi. 51, figs. 1-11 (for from Y 13 represents a similar assemblage, and the complete synonymy) specimens from 12 other localities included in the Brevidiscus? agnostoides KOBAYASHI, 1943, Proc. count do not produce any anomalous effects. In all Imp. Acad. Tokyo, v. 19, p. 39 Calodiscus agnostoides (Kobayashi). RASETTI, 1952, the collections, from approximately 20 localities, Jour. Paleontology, v. 26, p. 442, pi. 51, figs. 12-16 only one cephalon can be referred to any other species of Calodiscus. Description.—The population study discussed be- The cephala have been placed in size groups with low indicates that Rasetti's description is adequate a 0.125-mm interval in length between groups. This for cephala approximately 1.0 mm and longer and interval accomodates most accurately all specimens, for pygidia as short as 0.375 mm. The outer surface but it is not possible to decide whether it represents of the best-preserved specimens shows fine granula- a natural molt interval. Both the 0.125-mm interval tions and a minute occipital spine on some indi- and a 0.25-mm interval have been used in arranging viduals of both types of cephala. In the large suite the pygidia. Fewer pygidia than cephala were suit- of specimens now available the intraspecific varia- able for this study because of the fragile nature of bility mentioned by Rasetti (1952, p. 441) can be the pygidia. Only complete pygidia or those with more closely traced from type Ai, a cephalon with axis and one full pleural lobe were considered. The subconical glabella and two pairs of faint incomplete strong convexity leads to easy fracture along the glabellar furrows (Rasetti, 1952, PI. 51, fig. 9), axial furrows, and many such fragments were dis- through a cephalon similar in every respect to type carded. Ai but with a complete posterior glabellar furrow, The cephala have been tabulated (Fig. 2) to indi- to a cephalon of type Qi (Fig. 2). Since Rasetti did cate distribution of the five major types with not have cephala of these two latter types nor a reference to size. In number of specimens there is a

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noticeable tapering at each end of the series, with the count. They show transition between type Qi peak abundance (27 individuals) at 1.0 mm; and and type Ai. the majority occur hi the 0.75-1.5 mm size range (5) Occasional specimens of the "agnostoides" which appears to represent late adolescence to early type show a small occipital node (Rasetti, 1952, maturity. Since the maxima are the same for both PI. 51, fig. 14). Although it appears most frequently cephala and pygidia, this feature may reflect a real on cephala of type Q, a few specimens of all the condition of the species population, i.e., a. greater other types, even type A, do bear an occipital node. abundance of young adults (and their molts) than In this species the node must be interpreted as a older individuals. However, poor preservation of feature of the metaspid cephalon rarely retained in larger specimens is also a factor in their small num- the holaspid stage. ber in the material. Rasetti recorded 2.2 mm as the These facts can logically be interpreted only as length of the largest cephalon in his material, and evidence of the ontogenetic development of a single 2.25 mm is the largest in this material. species of Calodiscus. The single type of pygidium The facts presented by this study are: associated with both "lobatus" and "agnostoides" (1) Pygidia 0.375-2.0 mm long have all the char- type cephala could be considered significant. How- acteristics of pygidia which have always been ever, pygidia of two related species often are indis- assigned to C. lobotus (Hall). In specimens shorter tinguishable while specific differences exist between than 0.75 mm only four axial segments, three pleural the cephala. Therefore, evidence from the cephala segments, and three pairs of marginal spines can be is the determining factor in this study. readily detected, but at 0.75 mm pygidia of complete Since all factors of preservation and sorting should adult character appear. be equal for exoskeletons of two similar species of (2) Among cephala 0.375-0.625 mm in length the same genus, it is reasonable to assume that the only the "agnostoides" type is known (Fig. 2). species represented by the larger number of adult Among cephala 0.75-0.875 mm in length, 29 are individuals should also be represented by a larger "agnostoides" type, and only three can be assigned number of smaller individuals (if the same char- to the "lobatus" type. Of 27 cephala, 1.0 mm in acters are retained). The (Fig. 2) complete disap- length, 18 are "lobatus" type, 5 are "agnostoides" pearance of "lobatus" type specimens shorter than type, and 4 are type Dii an intermediate variant. 0.75 mm and the sudden marked reduction in indi- This represents a sudden and striking reversal of viduals of the "agnostoides" type at 1.0 mm are proportion. As cephalon length increases this pro- biologically and mechanically inexplicable if one portion is maintained, with only a few cephala up holds that two distinct species are present. The to 1.75 mm which can be referred to any variant of material can be interpreted only as an ontogenetic the "agnostoides" type. series of a single species. Every transitional phase (3) In a breakdown of distribution of cephala from type Q to type A is present and abundant among the five major types: all cephala 0.375 mm material shows acceleration and retardation among in length are type Q (probably a metaspid stage), the individuals at their molt stages. The sudden which is characterized by bulbous anterior glabellar inversion of proportion between the two major lobe, giving an hour-glass shape to the glabella, types at 1.0 mm in length is most significant. In and two pairs of complete glabellar furrows. Type earliest molt stage (0.375 mm) only the most imma- O still predominates at 0.5 mm where type Q ture type O is known, and hi the ensuing molt appears (in which anterior glabellar lobe is rounded stages (0.5-0.875 mm) the "agnostoides" types but not swollen, and the sides of glabella are paral- predominate. At 0,75 mm and 0.875 mm a few indi- lel). Type Qi, similar to type Q except that the viduals appear which by acceleration have acquired sides of anterior glabellar lobe converge, appears characters of the "lobatus" type. The tabulation among specimens 0.625 mm in length. Rasetti does shows that this acceleration is sporadic. At 1.0 mm not mention or figure such cephala, but this type is molt the average (or normal) individual acquired the interpreted here as a normal variant in one con- characteristics of the "lobatus" type cephalon, but a tinuous series. It appears somewhat later than types few retarded individuals retain the "agnostoides" O and Q and is prominent from 0.625 mm through type—a proportion of 18-5. In the molt stage of 1.5 0.875 mm. Then it with these two types sinks into mm (the last where numbers of specimens is ade- an inconspicuous position among the larger cephala quate) the proportion has become 13-2. Retarded where the variants of the "lobatus" type dominate. individuals should gradually acquire adult char- (4) A third variant of "lobatus" type cephalon is acters at subsequent molts. After the 1.25 mm molt similar to type Ai except that the posterior glabellar no well-preserved cephalon can be assigned to the furrow is complete. Six such cephala, the smallest most immature type O—Rasetti's largest cephalon 1.0 mm in length, have been included in type Ai in is 1.2 mm. Two cephala in the author's material, one

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1.5 mm (not counted), the other 1.75 mm, may and, while many seem essentially undeformed, the have the swollen anterior glabellar lobe of type Q; majority were distorted in an unbelievable variety but both are so poorly preserved that positive of ways. At the other six localities less abundant identification of this feature cannot be made. The specimens still show some distortion, but at Y13 1.75 mm specimen is shown with ? on the chart to and Y16 the outer surface of the exoskeleton is well- indicate maximum size such a retarded individual preserved and there is one complete specimen with might attain. Other individuals of the "agnostoides" thoracic segments in place. Specimens from these type after the 1.0-mm molt are three of type rj two localities probably were not moved far from and four of type Qi- Thus in this material, after the their natural habitat. 1.0-mm molt stage, there are only nine (possibly 11) The best preserved cephala show a series of 8 retarded individuals of any variant as against 67 rounded tubercles along each side of the marginal normal individuals. Only by such a total population border. The most posterior pair are just anterior to count can the real status of retarded individuals be the genal angle, and the anterior three pairs forward determined. of the front of the glabella. Various authors have Rasetti (1952, p. 442) believed that C. agnostoides shown from 10 to 5 pairs—in ordinary specimens the could not be the immature form of C. lobatus because number easily discernible is 5 while additional pairs in his material there were cephala 1.0 mm in length (the more anterior ones) are harder to see. Border is with characters of C. lobatus. His material contained normally medium wide, rounded, and only slightly the same overlap of normal and retarded individuals widened in front of the glabella; but distortion often between the molt stages of 1.0 mm and 1.25 mm, flattens the anterior border, increasing its apparent but without a population count he could reach no dorsal width. The glabella is long and conical, and, other conclusion. Rasetti records no cephala of the with excellent preservation, shows four pairs of short "lobatus" type smaller than 1.0 mm, but material diagonal glabellar furrows. Several peeled cephala studied here indicates that rare accelerated indi- have two faint short furrows on each side of the viduals may appear as early as the 0.75-mm molt glabella hi the position of the occipital furrow, but stage. Rasetti suggested that C. agnostoides might in most cephala this furrow is definitely obsolete. be the immature cephala of C. meeki (Ford). This Few cephala show the short genal spines mentioned author believes that the "agnostoides" type of by Rasetti—actually they are hi intergenal position cephalon is the standard appearance of the metaspid whereas the genal angles are rounded. This portion stages of all species of Calodiscus. of the cephalon is usually broken as the spines seem Formation and locality.—Lower Cambrian, Iocs. to pull away in the matrix. Y 7, 6, 11, lla, 12a-e, 13, 14, 15, 16. Prindle Iocs.— Several small spines on the edge of the marginal see lists. border were noticed in five pygidia. The plesiotype Figured specimens.—USNM 125692 a-k figured by Rasetti (1952, PL 52, fig. 3) indicates that marginal spines were normal in the species. Genus Serrodlscus R. and E. Richter (1941) However, their small size and the frequent crushing of the vertical border under the rolled-down edge Serrodlscus speciosus (Ford) of the pleural regions makes the recovery of the (Plate 5, figures 13-21) spines on most specimens impossible. The axis of the largest pygidium shows 11 segments separated Microdiscus speciosus FORD, 1873, Am. Jour. Sci., 3d. ser., v. 6, p. 137, figs. 2a-b. by shallow furrows and a small terminal portion, Eodiscus (Serrodiscus) speciosus (Ford). R. and E. but on most pygidia not more than nine segments RICHTER, 1941, Abh. senckenberg. naturf. Ges., can be distinguished. On some specimens reflected no. 455, p. 27, pi. 1, figs. 15-21; pi. 4, fig. 61 light suggests a comparable number of furrows ex- Serrodiscus speciosus (Ford). RASETTI, 1952, Jour. Paleontology, v. 26, p. 444, pi. 52, figs. 1-11 tending across the pleural platforms, but no specimens show the actual impress of these furrows, and Description.—Ford's description of the species on most the pleural platforms are smooth. must be supplemented by Rasetti's additional ob- On specimens from localities Y 13 and Y 16 the servations on the marginal pygidial spines and the outer surface of the exoskeleton is not punctate as short genal spines of the cephalon. that term is now used, i.e., having small rounded Remarks.—At locality Y 6 specimens of this holes sunk below the surface of the test. The surface, species are common—several hundred were easily except the furrows, is covered with a fine network obtained; their occurrence with abundant Olenellida of small ridges with a mesh of 1/15-1/20 mm. Tiny fragments in the thin impure limestone lenses sug- areas between the ridges are rounded to oval and gests that these tests were concentrated by mechan- were what Ford referred to when he called the sur- ical action. The surface of all specimens is worn, face "punctate." On an unworn portion of the

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largest pygidium, an internal mold, scattered gran- several faunules in the Lower Cambrian Schodack ules apparently represent fillings of tiny pores on lithologic unit, the relationship of the two species of the inner surface of the exoskeleton. Pagetia from this unit suggests the presence of two Abundant specimens permitted study of varied faunal subzones. appearances caused by distortion and also the ar- The limestone pieces that contain the specimens rangement of a growth series. Cranidia range from of Kochiella fitchi (Walcott), USNM loc. 34, also 1.25 mm in length by 1.5 mm in width to approxi- contain numerous cranidia and pygidia of P. con- mately 9 mm by 9.5 mm, and pygidia from 2.5 mm nexa. The metaspid cranidia of P. connexa, 0.5 mm, in width by 2 mm in length to 14 mm by 12,5 mm. 0.75 mm, and 0.85 mm in length show a rimlike The largest pygidium indicates that individuals of border without longitudinal grooves and a distinct this species could reach a length of at least 28 mm. deep marginal furrow exactly as is developed in the Most specimens are about 7 mm in length, the same holaspid cranidium of Pagetia prindlei. At a length dimensions as Ford's types. This appears to be the of 1.0 mm the border begins to widen and flatten most suitable size for transportation and burial but is still without grooves (Rasetti, 1948, PL 1, without too much damage. The specimens are appar- fig. 24) which appear only when the cranidia are ently all in the holaspid stage since, throughout the about 1.25 mm in length. Similarity of the metaspid size range, specific characteristics, except the mar- cranidium of P. connexa to the holaspid cranidium ginal tubercles on the cephalon, are discernible. of P. prindlei suggests that P. connexa may be a The smallest cephalon on which faint tubercles are direct descendant of P. prindlei and consequently discernible is 4.5 mm in length by 5.5 mm in width. is characteristic of a later, stratigraphically higher Formation and locality.—'Lower Cambrian, Iocs. faunule than the one commonly represented in this Y 6, 7, 9, 12f, 13, 16. Prindle Iocs.—see list. material. Figured specimens.—USNM 125736 a-g Metaspid cranidia of P. connexa are figured (PI. 5, figs. 1-3) which occur with the holotype cranidium Family PAGETIIDAE Kobayashi, 1935 of Kochiella fitchi. Horizon and locality.—Lower Cambrian, Prindle's Genus Pagetia Walcott (1916) Iocs.—see list. Figured specimens. Pagetia connexa (Walcott) Cranidia, USNM 125730 a-c; Prindle—3^ miles northeast of Cambridge, N. Y. (Plate 5, figures 1-6) Cranidia, with K. fitchi (Walcott). USNM 17455, Microdiscus connexus WALCOTT, 1887. Am. Jour. USNM 123582; USNM loc. 34 Sci., 3d ser., v. 34, p. 194, pi. 1, figs. 4-4b Pagetia connexa (Walcott) RASETTI, 1948. Jour. Pagetia prindlei n. sp. Paleontology v. 22, p. 13, pi. 1, figs. 22-27 (synonymy to date) (Plate 5, figures 7-10) Original description.—Walcott's original descrip- Description.—Cranidium nearly semicircular; tion must be supplemented by Rasetti's recent work glabella conical, moderately and evenly convex; on the species which showed the presence of palpe- glabellar furrows and occipital furrow obsolete; bral lobes and facial sutures on the cephalon and an long slender horizontal occipital spine; apparently axial terminal spine on the pygidium. no ocular ridges; dorsal furrow deep, well-defined at Remarks.—The material consists of about 10 sides, shallowing and merging with broad anterior cranidia from one (possibly two) of Prindle's locali- furrow; no pre-glabellar area; anterior border nar- ties. Although all specimens are incomplete and row, rimlike, apparently no crenulations. Fixed appear crushed and squeezed, the palpebral lobes cheeks wider than glabella, strongly convex; small are discernible. All or a portion of the long occipital eye opposite center of glabella; posterior limb not spine and outer portions of the posterior limbs are known. Free cheeks narrow straight strips at edge frequently missing. of cephalon opposite center of glabella. Thorax not The single occurrence of Pagetia connexa (Wal- known. Pygidium subtriangular, strongly convex, cott) from these two quadrangles and its common axis long, narrow with prominent nearly terminal occurrence at certain of Walcott's localities in spine; dorsal furrow narrow, shallow but distinct Washington County, where it is associated with all around axis; one clear and three faint segments other species of trilobites not recorded from this and long terminal portion; pleural lobes 1J£ times material, raises the question of whether its distri- width of axis, strongly downsloping, narrow con- bution is a matter of facies control or stratigraphic tinuation behind axis; marginal furrow narrow, control. Although no section shows superposition of shallow; border narrow, horizontal, serrate with 6,

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probably 7, pairs of short blunt spines. Outer surface tion of the species (Am. Geol., p. 115, 1855) is apparently smooth. repeated by Walcott (1886). Remarks.—Three poor and three fairly well pre- Remarks.—The peeled limestone mold and the served cranidia and one associated pygidium are impression retaining the test of a specimen of the referred to this species. The cranidia and the py- left cheek, 30 mm wide by 28 mm long, were re- gidium show a feature not recorded in any species covered. The specimen lay on the upper edge of a of Pagetia. The pygidium has characteristic shape limestone nodule, and the glabella and right cheek and terminal axial spine (now broken off) of Pagetia, had been removed by erosion. Distinctive features but differs from that of P. connexa (Walcott) in of this fragment permit identification. The moderate fewer distinguishable axial segments and the serrate convexity of the cheek is unbroken by any trace of border. Cranidium shows the characteristic glabella eye; the marginal furrow is well denned. On the and long occipital spine of Pagetia, but the narrow, right edge of the specimen two indentations suggest rimlike border without crenulations is unique. It the outer limit of the glabellar furrows against the also lacks any pre-glabellar area, but this feature dorsal furrow, although no well-defined dorsal fur- occurs in several cranidia referred to P. connexa row is discernible. In front of the anterior indenta- (Walcott) by Rasetti (1948, PI. 1, figs. 24, 25). tion the low ridge which curves backward for a short Poor preservation of the posterior half of all cranidia distance may be the outer part of the ocular ridge. and strong convexity of cheeks makes delineation of Anterior median portion of cephalon is poorly pre- facial suture difficult. Neocobboldia dentata (Lermon- served and was damaged during collection; but there tova) from the late Lower Cambrian Protolenus is a suggestion that the outer edge of the medium- zone, Lena River, Siberia, is the only other species wide border was beginning to bend upward from its of Pagetiidae in which the border of the pygidium lateral flat position. A small laterally projecting has spines. genal spine occurs 4 mm forward of the genal angle. Horizon and locality.—Lower Cambrian, Iocs. Y Hollow tubercles of varying sizes are thickly set 12b, 13, 16. over the surface of the cheek, widely spaced and Types. smaller on the marginal furrow. A row of large Holotype, cranidium, USNM 125731 tubercles edging the visible border are closely spaced Paratypes, cranidia, USNM 125732, 125733a on posterior and more widely spaced on lateral and Paratype, pygidium, USNM 125733b anterior parts. This fragment represents the largest individual of Atops trilineatus yet recorded. Em- Order OPISTHOPARIA mons' holotype cephalon is about 25 mm wide by 12.5 mm long, and Walcott's well-preserved topo- Family CONOCORYPHIDAE Angelin, 1878 type, figured by Howell and Stubblefield (1950, PI. 1, fig. 3), has a cephalon 29 mm wide by 14 mm long. Genus Atops Emmons (1844) The complete cephalon represented by this fragment would have been about 87 mm wide by 42 mm long. Atops trilineatus Emmons Horizon and locality.—Lower Cambrian, loc. Y 10. (Plate 6, figure 1) Figured specimen.—Left cheek, mold and impression, USNM 125695 Atops trilineatus EMMONS, 1844, Taconic System, p. 20, fig. 1, pi. ii, fig. 3 Ptychoparia trilineata (Emmons). WALCOTT, 1886, Family DORYPYGIDAE Kobayashi, 1935 U. S. Geol. Survey Bull. 30, p. 203, pi. xxvii, figs. 1, Ic (for synonymy to 1886) Bonnarla new genus Conocoryphe trjlineata (Emmons). WALCOTT, 1887, Am. Jour. Sci. v. 34, p. 187; ibid. WALCOTT, 1889, U. S. Geol. Survey 10th Ann. Rept., p. 647 Cranidium quadrate; glabella narrow, parallel- Atops trilineata Emmons. MATTHEW, 1899, Trans. sided posteriorly, expanding rapidly to a broad Royal Soc. Can. 2d ser., v. 5, sec. 4, p. 89 anterior lobe; glabellar furrows present or absent; Atops trilineatus Emmons. HOWELL, 1935, Bull. occipital ring and furrow; dorsal furrow deep; pre- Am. Paleontology, v. 11, p. 30-31 Atops trilineatus Emmons. KOBAYASHI, 1935, Jour. glabellar furrow faint; no pre-glabellar area; narrow Fac. Sci., Imp. Univ. Tokyo, sec. II, v. IV, pt. 2, flat border; fixed cheek—palpebral area convex, p. 220 downsloping, about two-thirds width of glabella; Conocoryphe trilineata Ford. RESSER, 1936, Smith- son. Misc. Coll., v. 95, p. 14 palpebral lobe medium size, approximately opposite Atops trilineatus Emmons. HOWELL AND STTJBBLE- center of glabella; posterior area same length as PIELD, 1950, Geol. Mag. v. 87, p. 3, pi. 1, figs. 3,4 occipital ring, of medium width, broad posterior furrow. Free cheek short and broad with a short, Description.—Emmons' most complete descrip- pointed genal spine, ocular platform broad, marginal

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furrow faint. Thorax and pygidium not known. lachian region and from Spain. The species is known Outer surface granular. only by small, and usually poorly preserved, cranidia Genotype.—Bonnia salemensis Resser whose maximum length is 8 mm and average length Remarks.—A new genus is here established to is 2-3 mm. These cranidia have been referred to embrace a few species described from the Appa- Protypus, Corynexochus, Bonnia, Bonniella, and

PLATE S.—SERRODISCUS, EODISCUS, PAGETIA, BONNIA, AND LABRADORIA Figure 1-6. Pagetia connexa (Walcott). 1, 2, 3, numerous cranidia and pygidia on the two limestone pieces carrying the types of Kochiella fitchi (Walcott), X10, USNM 174S5, USNM 123582; USNM loc. 34. 4, 5, 6, three fragmentary and crushed cranidia associated with Acrotreta taconica at one locality, X10, USNM 125730a-c; Prindle—about 3J^ miles northeast of Cambridge, N. Y., on ridge east of valley 7-10. Pagetia prindlei n. sp. 7, holotype, most complete cranidium, XlO, USNM 125731; Y 16. 8, 9, paratypes, two fragmentary cranidia, XlO, USNM 125732, USNM 125733a; Y 12b, Y 13. 10, paratype, associated pygidium, X10, USNM 125733b; Y 13 11. Bonnia sp. undet. Single fragmentary cranidia known in this fauna, XlO, USNM 125734; Prindle # 170—hill a quarter of a mile southwest of Cambridge, N. Y. 12. Labradoria cambridgensis n. sp. Holotype, largest cranidium, X 10, USNM 125735; Prindle #241, half a mile north of Cambridge, N. Y. 13-21. Serrodiscus speciosus (Ford). 13, one of smallest cephala with marginal tubercles not preserved, X5, USNM 125736f; Y 6. 14, well-preserved but crushed pygidium, X3, USNM 125736b; Y 13. 15, 16, dorsal and side view of pygidium showing small spines along right margin, X3, X6, USNM 125736e; Y 6, 17, 20, cephalon with well-preserved outer surface showing reticulation, X3, X6, USNM 125736c; Y 16. 18, large crushed cephalon, X3, USNM 125736d; Y 13. 19, partially enrolled specimen with thoracic segments, X3, USNM 125736a; Y 16. 21, largest known pygidium, X2, USNM 125736g; Y 13 22, 23. Eodiscus cf. E. punctatus (Salter). Single fragmentary cephalon showing characteristic surface punc- tation, X2, X4, USNM 125737; Prindle *320—three-quarters of a mile west of Coila, N. Y.

PLATE 6.—ATOPS AND ELLIPTOCEPHALA Figure 1. A tops trUineatus Emmons. Dorsal view of left cheek of cephalon showing very small genal spine, XI, USNM 125695; Y 10 2-21. Elliptocephala asaphoides Emmons. 9, largest fragmentary cephalon, XI, USNM 125696; Prindle #274. 2, somewhat crushed cephalon retaining convexity, X2, USNM 125697; Prindle #270. 4, 5, impression and mold of cheeks in very shaly limestone, X1, USNM 125698; Y 6. 6, 7, fragmentary cheeks showing genal caeca, X2, USNM 125699, USNM 125700; Y 6, Y 13. 3, smaller cephalon, X6, USNM 125701; Y 13.13, early holaspid cephalon showing convexity, X6, USNM 125702; Y lib. 15, 8, 18, 17, small holaspid cephala showing characteristic kinds of crushing and distortion, XlO, X5, USNM 125703, 125704, 125705, 125706; Y 16, Y 6, Y 12b, Y 6. 10, 12, well-preserved metaspid cephala, X5, USNM 125707, 125708; Y lla. 11, 19, 21, fragments of thoracic segments showing characteristic markings of the outer surface, XlO, X5, X4, USNM 125709, 125710, 125711; Y 16. 14, fragmentary hypostoma showing dentate posterior margin, X3, USNM 125712; Y 13. 16, late protaspis, X15, USNM 125713; Y14.20, small discrete plate cf. metastoma, X3, USNM 125714; Y13

PLATE l.—KOOTENIA, BONNARIA, FORDASPIS, AND CAWDISCUS Figure 1-10. Kootenia troyensis Resser. 1, 2, plesiotype, dorsal and side view of Walcott's first figured cranidium, erroneously called Solenopleura nana Ford, X5, USNM 15425. 3, dorsal view of very fragmentary cranidium in Walcott's original lot with USNM 15425, X5; both USNM loc. 27. 6, 7, dorsal and side views of holotype cranidium, designated by Resser in 1937, X5, USNM 94342 (USNM 17451- Continued on following page

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------SEItllODISCUS, EODISCUS, PAGETIA, BONNIA, AND LABKADOIUA

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------A TOPS AND ELLIPTOCEPHALA

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------KOOTENIA, BONNARIA, FORDASPIS, AND CALODISCUS

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- - CALODISCUS, FORDASPIS, KOCHIELLA, PTYCUOPARELLA, AND PAKABOLINA

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Bonniaspis. No pygidium has been positively asso- the two genera to which the species have been most ciated with any of the cranidia, and it is probable recently referred, in shape of the glabella; the pos- that the pygidium is small. terior half is narrow, sides nearly parallel, and the Bonnaria differs from both Bonnia and Bonniella, anterior half is markedly swollen so that the sides

222v). 5, 4, paratype, dorsal and side views of larger cranidium figured by Walcott, X5, USNM 174Sl-222w. 8, 9, paratype, dorsal and side views of small associated pygidium, X5, USNM 17451- 222y. 10, paratype, larger associated pygidium, XS, USNM 174Sl-222x. All USNM loc. 38c 11, 12. Bonnaria salemensis (Resser). 11, plesiotype, small well-preserved metaspid cranidium, X10, USNM 12677Sa; Y 16. 12, plesiotype, somewhat larger metaspid cranidium, X10, USNM 126775b; Y 12d 13-18. Kootenia cf. K. marcoui (Whitfield). 15, 16. 17, three small cranidia showing generic features at this size, X10, USNM 126776a, 126776b, 126776c; Prindle #389—S. 49° E. to Pleasant Hill. 13, 14, two fragmentary pygidia, one suggesting marginal spines, XS, USNM 126777a, 126777b. 18, squeezed and fragmentary cranidium, XS, USNM 126777c. All from Prindle—Moon Hill, 1 mile north of Petersburg, N. Y. 19, 20. Fordaspis tumida (Walcott). Dorsal and side views of holotype and only known specimen, X5, USNM 17452; USNM loc. 33 21-24. Fordaspis nana (Ford). 24, dorsal view of holotype cranidium, XS, NYSM 4803. 23, 22, dorsal and side view of a paratype cranidium, XS, NYSM. 21, dorsal view of a second paratype cranidium, XS, NYSM. All from Troy, N. Y. 25. Calodiscus meeki (Ford). Single cephalon and associated pygidium obtained from the material, XS, USNM 126778; Prindle—* 186, hill just north of Cambridge, N. Y. 26, 27. Cf. Fordaspis nana (Ford). Side and dorsal views of a large pygidium from Ford's collection, X5, NYSM 4804; Lansingburgh, N. Y.

PLATE 8— CALODISCUS, FORDASPIS, KOCHIELLA, PTYCHOPARELLA, AND PARABOLINA Figure 1-11. Calodiscus lobatus (Hall). 1, cephala 1 mm and 2 mm in length, USNM 125692a; Y 16. 8, cephalon, 1.5 mm, somewhat flattened and showing two complete glabellar furrows, USNM 12S692b; Y 15. 10, cephalon 1.375 mm, normal adult, USNM 12S692c; Y 16. 11, cephalon 1 mm showing retarded condition with swollen anterior glabellar lobe, USNM 125692d; Y 16. 3, cephalon 1 mm with normal adult glabella, USNM 125692e; Y 13. 4, cephalon 0.875 mm showing advanced condition with essentially adult glabella with two glabellar furrows, USNM 12S692f; Y 13. 6, typical metaspid cephalon 0.75 mm with swollen anterior glabellar lobe, USNM 125692g; Y 16. 7, smallest metaspid cephalon 0.375 mm, USNM 125692h; Y 16. 9, metaspid pygidium 0.75 mm, USNM 125692k; Y 16. 5, holaspid pygidium 1.25 mm, USNM 125692J; Y 12. 2, holaspid pygidium 2 mm all showing the same specific characters, USNM 125692i; Y 13. All X10 12-22. Fordaspis nana (Ford). 12, 22, side and dorsal views of large cranidium, USNM 125691a; Y 13. 21, well-preserved cranidium 2.75 mm in length, USNM 125691b; Y 13. 17, a cranidium 1.75 mm, USNM 125691c; Y 13. 18, 19, two cranidia about 1.25 mm in length showing some broadening of the front of the glabella, USNM 125691e, USNM 125691d; Y 13. 15, metaspid cranidium 0.75 mm showing very broad anterior lobe of glabella and weak development of glabellar furrows, USNM 125691f; Y 13. 13, 14, two free cheeks showing narrow ocular platform and short blunt genal spine, USNM 12S691h, USNM 125691g; Y 13, Y 16. 20, metaspid pygidium 0.5 mm with one thoracic segment, USNM 1256911; Y 13. 16, metaspid pygidium 0.75 mm, USNM 125691J; Y 12d. All X10 23. Parabolina sp. undet. Single cranidium, USNM 125687, X10; Prindle—#205, about three-quarters of a mile southwest of Cambridge, N. Y. 24, 25. Cf. Ptychopardla sp. 24, most complete but squeezed cranidium, X5, USNM 125690; Y lla. 25, a fragmentary cranidium, X5, USNM 125689; Prindle— #320, three-quarters of a mile west of Coila, N. Y. 26-28. Kochidla fitchi (Walcott). 27, holotype, a metaspid cranidium 0.85 mm in length, USNM 17455. 26, plesiotype, a fragmentary pygidium on opposite side of piece carrying holotype, USNM 123582a. 28, plesiotype, holaspid cranidium 3 mm in length, USNM 123582b. All X10; USNM loc. 34 29. Unidentified fragment cf. Tremadocian, XS, USNM 125688; Prindle—*295, hilltop about 2 miles north of Cambridge, N. Y.

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diverge rapidly. Structure of the fixed cheeks and metaspid cranidia of Fordaspis nana (Ford) by the the frontal area is essentially the same as that in shape of glabella and glabellar furrows and by con- Bonnia, suggesting a close relationship; but no vexity of glabella, which is already tumid in Fordas- species of Bonnia shows the peculiarly shaped gla- pis nana but in Bonnaria salemensis is only slightly bella. In Bonnia the anterior divergence of the dorsal convex along the posterior two-thirds and curved furrows is gradual and continuous from occipital down sharply in front to pre-glabellar furrow. In furrow to pre-glabellar furrow. these small cranidia the anterior lobe has not swollen The following species are assigned to Bonnaria: forward too much, and pre-glabellar furrow and Ptychoparia? clavata Walcott, Bonnia salemensis narrow border are visible. In the holotype cranidium Resser, both from Washington County, New York; the anterior lobe of the glabella tends to overhang cranidium doubtfully referred to Bonniella virginica the border. Resser, from Austinville, Virginia; and Bonniella? The species, B. salemensis, is recognized here, and hispanica Richter and Richter from Andalusia, the author's specimens referred to it because preser- Spain. vation of the holotype cranidium of B. clavata (Wal- cott) is so poor that its accurate generic assignment Bonnaria salemensis (Resser) is impossible. Cranidium of B. clavata, USNM 17454a, is 1.2 mm long by 2.2 mm wide. This would (Plate 7, figures 11, 12) place it in the first or second moults of the holaspid. It could be a distorted specimen of Fordaspis nana Corynexochus davatus WALCOTT, 1916 (part). Smith- son. Misc. Coll., v. 64, no. 5, p. 316, pi. 55, fig. 4b (as suggested by poor development of glabellar Bonnia salemensis RESSER, 1936. Smithson. Misc. furrows); a poor specimen of Kootenia marcoui (with Coll., v. 95, no. 4, p. 10 anterior part of glabella distorted); or a cranidium of B. salemensis on which the glabellar furrows were Description.—Cranidium quadrate; glabella elon- not preserved. Identity of B. clavata cannot be re- gate, sides parallel only along posterior third, then solved until a large amount of topotype material diverging continuously to rounded anterior lobe; has been obtained. three pairs of glabellar furrows, posterior pair complete, second pair short, shallow, straight, front pair The holotype cranidium of B. salemensis, USNM 17454b, is 2.2 mm long and approximately 3 mm short, curved forward; dorsal furrow well defined along sides; occipital furrow narrow, distinct; wide. Since the metaspid cranidia collected by this occipital ring of medium width (sag.), flat; no pre- author show the same features as this holaspid glabellar area, marginal furrow in front of fixed specimen, the writer feels certain of the specific and generic validity of those features. cheeks only, coinciding with pre-glabellar furrow in front of glabella, very narrow, flat border; fixed Horizon and locality.—Lower Cambrian, Iocs. Y cheek—palpebral area slightly convex, down-sloping 12, 13, 14, 16. about two-thirds width of glabella; palpebral lobe Plesiotypes. medium size, opposite center of glabella; narrow, USNM 126775 distinct palpebral furrow,—posterior area same USNM 126775a length (tr.) as occipital ring; broad posterior furrow. USNM 126775b Free cheek short, wide with small genal spine, marginal furrow very faint. Pygidium not known. Outer Genus Bonnia Walcott (1916) surface apparently finely granular. Remarks.—A description of the holotype cranid- Bonnia sp. undet. ium is given here since Resser did not describe it at (Plate 5, figure 11) the time he assigned a new specific name to it. Cranidia of B. salemensis Resser show marked re- Remarks.—From all the collections only a single semblance to the cranidium which Resser doubtfully fragmentary cranidium could be surely identified as referred to Bonniella iiirginica, and it seems prob- Bonnia. The specimen is 2.25 mm long, allowing for able that the two forms may prove to be the same broken anterior border, and the glabella, although species. expanded anteriorly, is not as broad as a specimen About 18 small cranidia obtained from the of Bonnaria salemensis of comparable size. On this writer's collection range in length from 0.5 to 0.875 cranidium are two pairs of shallow glabellar furrows mm, and thus are in the metaspid stage. All show and a faint diagonal ocular ridge on the left fixed the unique shape of glabella, strong glabellar fur- cheek, and outer surface is densely covered with fine rows, and a few retain the small free cheek with a granules. Approximate position of palpebral lobes small genal spine. The size overlap shows that these can be made out, but they, the posterior limbs, and cranidia can be accurately distinguished from the the anterior border are broken off. From the features

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preserved, it seems likely that the cranidium is an- that Walcott never saw Ford's specimens of Soleno- other specimen of S. swantonensis Resser, but posi- pleura nana Ford, but assigned his specimens to tive identification cannot be made. the same species as result of erroneous reading of Horizon and locality.—Lower Cambrian, hill one- Ford's description. When Resser (1937) correctly fourth mile southwest of Cambridge, N. Y. assigned Walcott's specimens to the genus Kootenia, Figured specimen.—USNM 125734 he states (p. 16) that Ford's type specimen is not available. So he also was unaware that two species Fordaspis Lochman, n. gen. and two different genera were involved. Since none of the subsequent workers saw Ford's specimens, it Cephalon ovate, elevated; glabella obtusely coni- is incorrect to say that Solenopleura nana Ford was cal, sides nearly parallel, converging slightly to ever confused with the genus Kootenia, but only rounded front; three pairs of short, shallow glabellar that the specific name was so confused. With respect furrows only at sides; occipital furrow deep; occipi- to cranidia and free cheek there are practically no tal ring narrow, low; pre-glabellar area present or similarities between the two species; shape of the absent, narrow anterior marginal furrow, faint along glabella, structure of the frontal area, width and mid-length, narrow anterior border; fixed cheeks— shape of the fixed cheeks, and position of the palpebral area horizontal, approximately two-thirds palpebral lobes are all different (see discussion under width of glabella; palpebral lobes under medium Kootenia troyensis Resser). In the pygidia both have size, anterior to center of glabella; narrow, slightly pairs of marginal spines, though the number is dif- curved ocular ridge,—posterior area broadly tri- ferent, and five axial rings, but Kootenia troyensis angular, strongly convex, approximately same width has only three pleura. Pygidium of Kootenia as it is (tr.) as occipital ring. Free cheek set at steep, down- now known shows great variation in all these fea- sloping angle; narrow ocular platform; narrow mar- tures so that it is quite difficult to draw any conclu- ginal furrow; medium wide lateral border with short sions from it; and it is believed at best to indicate slender lateral genal spine. Pygidium semicircular; only general familial relationships. axis tapered nearly full length; 5 axial rings (may This paper (PI. 7, fig. 24) illustrates for the first have median spines or nodes); 5 pleura in adult, time the holotype cranidium, NYSM 8403, of deep interpleural grooves, narrow pleural furrows; Solenopleura nana Ford. 6 pairs of small flat marginal spines; narrow marginal furrow; narrow flat border. Outer surface covered Fordaspis nana (Ford) with fine granules; furrows may have small granules or be smooth. (Plate 7, figures 21-24; Plate 8, figures 12-22) Genotype.—Solenopleura nana Ford 1878 Solenopleura nana FORD, 1878. Am. Jour. Sci. 3d Remarks.—Two species may now be referred to ser., v. 15, p. 126 this genus, F. nana (Ford) and F. tumida (Walcott). not Solenopleura nana Ford WALCOIT, 1886, U. S. This genus in cranidial structure is similar to Geol. Survey Bull. 30, p. 214-215, pi. 27, fig. 3; Bcmnia from which it differs in the more forward 1891, U. S. Geol. Survey 10th Ann. Rept. p. 658, pi. 98, figs. 1, la-e, 2 position of the palpebral lobes, the slight con- not Kootenia nana (Ford) RESSER, 1937. Smithson. vergence of front of glabella, the presence of a Misc. Coll., v. 95, no. 22, p. 16 pre-glabellar area in one species, and the greater number of segments in the pygidium. The expanded Original description.—"... of this species I have front of the glabella in the metaspid stage strongly a number of specimens of the head, but they are all suggests a common ancestor for both genera; while more or less imperfect. The largest and best pre- Bonnia retained and developed the expanded an- served specimen consists of a nearly perfect glabella terior lobe of the glabella, Fordaspis developed an and the greater portion of the fixed cheeks, and is expanded posterior portion. Free cheeks of the two but two lines in length. The glabella is nearly four- genera are the same in structure. Adult pygidium fifths the total length of the head and is especially of Bonnia is more compact, usually showing three characterized by its great relief. It is obtusely coni- to four pleura, three axial rings, and a reduction in cal, slightly widest behind, and is well defined all number of marginal spines (but as many as three around by the dorsal furrows. In a specimen two pair have been observed). It is interesting to note lines in length its highest point is nearly one and that a species like B. bubaris (Walcott) (Rasetti, one-half lines above the base of the fixed cheeks. It 1948, PI. 4, figs. 16-24) approaches the last metaspid is marked on either side by two or three faint fur- stages of Fordaspis in many features of both crani- rows. The fixed cheeks are notably convex, but their dium and pygidium. relief does not exceed one-third of that of the gla- With respect to Kootenia, it should first be noted bella. The eyes are situated slightly in advance of

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the mid-length and are connected with the front of given in the supplementary description was ob- the glabella by an obscure ocular fillet. The distance tained from the specimens of cranidium, free cheek from the eye to the glabella is nearly equal to the and pygidium in the writer's material. However, width of the glabella at the midlength. The front had Walcott noted carefully the features detailed by margin is narrow and is bounded by a feebly convex Ford, he could not have referred his specimens, rim, inside of which there is a narrow furrow which which represent a different genus and species, to gradually deepens on either side of the median line Ford's species. Critical cranidial features of Soleno- in passing outward. Between this furrow and the pleura nana Ford are: (1) glabella is exactly obtusely glabella there is a somewhat angular ridge which conical, with sides parallel most of the length, con- widens in passing outward to the sutures. verging slightly around the front; (2) glabella's "The course of the facial suture is nearly the same great relief makes it tumid throughout posterior with that of Solenopleura brachymetopa of Angelin portion which appears to overhang the occipital . . . but is directed slightly more inward in front of furrow and ring, and the anterior portion, though the eye. The neck furrow is continuous all across. less swollen so that the profile slopes downward The exact form of the neck-segment cannot be from the posterior, is still strongly convex; (3) 3 made out, owing to the damaged condition of all the pairs of short shallow glabellar furrows reach only a specimens at this point. It is seen, however, to be short distance up the steeply rising sides of glabella, less elevated than in the majority of the species, and on specimens with well-preserved exterior sur- not rising above the surface of the fixed cheeks. face are primarily delimited by smooth strips in the The entire surface is covered with a fine regular granular area; furrows become deeper as the surface granulation." of specimen approaches the limestone cast of the Supplementary description.—Occipital furrow interior; (4) position of palpebral lobes anterior to narrow, distinct, single on mid-length, dividing into center of the glabella is definite; (5) on all 50 two branches at sides, one curving forward under holaspid cranidia collected by the author and on all swollen back of glabella to dorsal furrow, other nine of Ford's specimens the frontal area consists continuing straight to side; occipital ring narrow, of a narrow, flat, downsloping pre-glabellar area; a low, with very small median tubercle; fixed cheeks— narrow, shallow, anterior marginal furrow, faint palpebral area moderately convex, horizontal, about across the mid-length but distinct at the sides; and two-thirds width of glabella; palpebral lobes less a narrow, slightly convex, anterior border, just a than medium size, slightly curved, narrow; distinct little narrower than the pre-glabellar area. This palpebral furrow,—posterior area broadly triangular, division is already visible in cranidia 1.0 mm in strongly convex, same width (tr.) as occipital ring. length. Free cheek narrow, short, set at a steep, down- The largest cranidium now known, in the writer's sloping angle to the cranidium; ocular platform a material, is 5 mm in length. Ford's holotype, his narrow curved strip with eye along inner margin; largest specimen, is broken and is 3.5 mm in length narrow distinct marginal furrow; border convex, but may have been 4 mm when complete. Cranidia somewhat wider than platform with a short slender average 1.5-3 mm in length. In the author's collec- laterally directed genal spine. tion the anterior portion of the glabella of cranidia Pygidium semicircular, wider than long; axis 1.25-0.75 mm tends to be slightly expanded. This slightly narrower than pleura, moderately convex, tendency is most noticeable in the smaller metaspid tapered nearly full length to narrow rounded end, cranidia; and in the smallest specimens there is a divided by narrow deep furrows into an anterior marked similarity to cranidia otBonnariasalemensis. half ring, 4 rings and a terminal portion on the However, no cranidia referred to F. nana show the anterior of which a fifth ring is not fully separated; strong glabellar furrows of B. salemensis, and, with dorsal furrow narrow; pleural platforms strongly a complete sequence, the two types of cranidia can convex, downsloping; 4 narrow pleura separated by be separated. narrow interpleural grooves and crossed by narrow In the author's material the association of free shallow, parallel pleural furrows; very narrow mar- cheek and pygidium with the cranidia appears cer- ginal furrow; border narrow, flat with 6 pairs of tain. However, all these pygidia, 0.5-0.875 mm small margin spines on 1.0 mm pygidium; median long, are still in the metaspid stage of development. posterior margin smooth. Outer surface of test The description here is based on these pygidia, covered with fine granules, which may be of small taking into account as far as possible any features of size or absent in the furrows. immaturity. The smallest pygidia show only five Remarks.—Ford's original description is here re- pairs of marginal spines, four axial rings with a fifth peated since it is detailed and exact in so far as his ring distinguishable but unseparated from the ter- specimens could furnish. Additional information minal portion, and four pleura. The larger pygidia

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suggest six pairs of marginal spines, five set opposite sloping border with six pairs of small flat marginal the endings of the interpleural grooves, and the sixth spines, each spine aligned with the end of an inter- pair just crowding in on each side of the posterior pleural groove; posterior median margin smooth. center line. There are still only four pleura on each Entire outer surface covered with fine granules. side. None of the specimens gives any indication of Remarks.—The pygidium, NYSM 4804, is from median axial nodes or spines. "limestone conglomerates near Lansingburgh" ac- Fordaspis nana (Ford) differs from Fordaspis cording to an old label. This is the specimen from lumida (Walcott) in the possession of a well-defined which Ford wrote his description and made his pre-glabellar area. Although Fordaspis tumida (Wal- sketch which was subsequently published by Wal- cott) is known by only one specimen, this difference cott in 1886 and 1891. There are, however, several appears to be real and a valid specific character. discrepancies between the sketch and description None of the author's 50 specimens and none of and the type pygidium, and at no time is actual size Ford's specimens show any tendency toward a re- given of the specimen sketched. Unfortunately duction or loss of the pre-glabellar area. This specific Ford's sketch is apparently a restored figure, so that difference may have stratigraphic significance. characteristic damaged spots on the pygidium can- Horizon and locality.—Lower Cambrian, Iocs. Y not be used for checking identity of the specimen. 12,12d, 13,14, 15,16. P. 13. Prindle's Iocs—see list. A new description has been written for pygidium Types. NYSM 4804. The specimen has only five axial rings Holotype cranidium, NYSM 4803 and terminal portion (one less than indicated by Plesiotype cranidium, NYSM Ford); there are six pairs of small flat marginal Plesiotypes, cranidia, USNM 125691a-f spines on each side, but the posterior median margin free cheeks, USNM 125691g, h is smooth, not denticulated as in the drawing. pygidia, USNM 12569H, j According to Ford the pygidium was associated with cranidia of Atops trilineatus and Hyolithes americanus, which influenced Ford's original assign- cf. Fordaspis nana (Ford) ment. When Walcott obtained complete specimens (Plate 7, figures 26, 27) of Atops trilineatus he knew that the assignment was incorrect, and referred the pygidium to his Conocephalites (Atops) trilineatus Emmons FORD, specimens of Solenopleura? nana (now Koolenia) in 1875. Am. Jour. Sci. 3d ser., v. 9, p. 205 which he has pygidia with marginal spines. The Ptychoparia trilimata Emmons WALCOTT, 1886. present restudy and description of Walcott's speci- U. S. Geol. Survey Bull. 30, p. 203-205, pi. 27, mens show that this pygidium, while similar in some fig. lb Solenopleura? nana Ford WALCOTT, 1891. U. S. features to that of Kootenia, should not be included Geol. Survey 10th Ann. Rept., p. 658, pi. 98, fig. le in Walcott's species. This pygidium is distinctive in its large size (as Original description.—"It is nearly semicircular compared to much of the Schodack material) and in form, the axis strong, composed of seven seg- the excellent surface preservation. The fine granula- ments, with a row of obtuse spines along the middle; tion is characteristic also of the surface of Fordaspis lateral lobes composed of five segments each, with nana (Ford), and when compared with the positively distinct intervening grooves; marginal-rim nearly associated pygidia in the writer's material pygidium flat, widest toward the front, and distinctly and NYSM 4808 shows several similarities. The number regularly notched or denticulated all around. The of axial rings, pleura, and pairs of marginal spines surface of the border is finely granular." is the same; on both, the rings and pleura are broad New description.—Pygidium semicircular, 10 mm and convex and the furrows deep and broad; and wide by 6 mm long; axis of medium width, convex, the border very narrow and flat. The one difference extending nearly full length leaving only a narrow is the definite row of median axial nodes or spines posterior border, tapered to apparently a rounded on pygidium NYSM 4808, and the apparent absence end; 5 axial rings and terminal portion separated by on the writer's metaspid pygidia. broad distinct furrows, all 5 rings had a short median This one difference in detail plus the facts that spine or node apparently diminishing in size to the the pygidium is larger than any cranidium of low broad node on the fifth ring, the only one intact; Fordaspis nana (Ford) now obtained and no py- dorsal furrow shallow; pleural regions same width gidium of this kind is directly associated with the as axis, convex, downsloping; 5 pleura separated by cranidium of Fordaspis nana (Ford) led the writer broad deep interpleural grooves; trace of a shallow to discuss the pygidium separately and indicate pleural furrow on axial sides of pleura only; marginal that its reference to Fordaspis is still uncertain. The furrow narrow, distinct; narrow flat, slightly down- author believes that this is an adult pygidium of

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Fordaspis nana and that the row of axial nodes made remain questionable. The holotype cranidium was their appearance in the holaspid stage. unmarked and in Walcott's original description and Horizon and locality.—Lower Cambrian, Lansing- subsequent reference to the species he gives at least burgh, N. Y. eight localities for the species. Possibly the first one Type.—Plesiotype, pygidium, NYSM 4804 listed, USNM loc. 33, "limestones interbedded in the shaly slates near Rock Hill schoolhouse (No. 8), Fordaspis tumida (Walcott) east of North Greenwich," Cambridge quadrangle, Washington County, is the type locality, but there (Plate 7, figures 19, 20) is no way to be certain. Solenopleura?? tumida WALCOTT, 1887. Am. Jour. Although there is only one cranidium this species Sci. 3d ser., v. 34, p. 196, pi. i, figs. 2-2a; 1891, is considered valid because it differs in several fea- U. S. Geol. Survey 10th Ann. Rept., p. 658, pi. 98, tures from the 59 known cranidia of Fordaspis nana figs. 3-3a (Ford). None of these cranidia indicate any varia- Original description.—"This species differs from tion in the direction of Fordaspis tumida (Walcott) Solenopleura? nana, with which it is associated at which is distinct in the absence of the pre-glabellar several localities, in having a more tumid glabella, area, the regular convexity of the tumid glabella, narrower frontal lobe, and in the absence of an and the apparent absence of a node on the occipital ocular spine. Some specimens of S.? nana have al- furrow. Walcott reports Fordaspis tumida associated most as tumid a glabella, but usually it is less ele- with Solenopleura? nana at several localities; but all vated. The generic reference is provisional, as both specimens which Walcott so labeled are specimens S.f tumida and 5.? nana appear to belong to a genus of Kootenia troyensis Resser rather than Fordaspis distinct from the typical species of Solenopleura." nana (Ford). The old localities of Walcott in Wash- Supplementary description.—Cranidium subquad- ington County should be recollected and their rate; glabella obtusely conical, sides parallel to faunal assemblages studied in detail. slightly converging rounded front, tumid with regu- Horizon and locality.—Lower Cambrian, possibly lar convexity from back to front; three pairs of short USNM loc. 33. shallow glabellar furrows; occipital furrow deep Type.—Holotype cranidium, USNM 17452 with two branches at each side, anterior branch running diagonally forward under overhanging pos- Genus Kootenia Walcott (1889) terior of glabella; occipital ring narrow, low, smooth; no pre-glabellar area; narrow anterior marginal The genus Kootenia is represented in the Lower furrow at sides only, curving forward into the Cambrian faunal assemblages of Washington narrow pre-glabellar furrow; narrow, slightly con- County by three species, K. fordi (Walcott) 1887, vex, horizontal anterior border; fixed cheeks— K. marcoui (Whitfield) 1884, and K. troyensis palpebral area horizontal, convex, slightly more than Resser 1937. Although the plesiotype cranidium of half the width of glabella; palpebral lobes under K. marcoui collected by Walcott is poorly preserved, medium size, distinctly anterior to center of glabella; it appears similar to the cranidium of K. fordi. The narrow palpebral furrow; faint ocular ridge curves holotype pygidium of K. marcoui is characterized by slightly to well behind front of glabella; posterior small median spines or nodes on the first three axial area broadly triangular, same width (tr.) as occipital rings, a very low node on the fourth ring, and seven ring, crossed by broad posterior furrow. Outer sur- pairs of marginal spines. The cotype pygidium of face finely and evenly granular. Free cheek and K. fordi has fewer segments in both axial and pygidium not known. pleural regions and small spines or nodes on the first Remarks.—Although Walcott's original descrip- three axial rings, but has only six pairs of marginal tion would suggest that this species was represented spines. The types of these two species were not in his material by several specimens, only a single examined; only K. marcoui is sparsely and ques- unmarked cranidium in a tray labeled "K. tumida" tionably represented in one of Prindle's collections. could be located at the U. S. National Museum. More complete material may show that the two This cranidium has been compared with the figure species are synonymous. of Walcott's holotype by Drs. Cooper and Palmer Although K. troyensis Resser is not represented and the writer, and all agree that this cranidium is in any of the collections, a complete study was made apparently the holotype of Solenopleuraf? tumida of all the U. S. National Museum types of this Walcott. Dr. Cooper has now placed on the label species because it has been confused in the literature the USNM catalogue number 17452 ?. This cranid- with the species Fordaspis nana- (Ford). K. troyensis ium is illustrated by a photograph for the first time shows distinct specific differences from either of in this paper. The type locality of the species must the other two Schodack species of Kootenia.

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Kootenia troyensis Resser Museum. Two cranidia from USNM loc. 27, Troy, N. Y., were identified by Walcott (1886) as the (Plate 7, figures 1-10) species Solenopleura nana Ford. The name was Solenopleura nana WALCOTT, 1886, U. S. Geol. Sur- written in ink on a strip of paper pasted to the back vey Bull. 30, p. 214-215, pi. 27, fig. 3 of each specimen, and USNM 15425 assigned to the Solenopleuraf nana WALCOTT, 1887, Am. Jour. Sci., lot. The larger more complete cranidium was figured 3d ser., v. 34, p. 196, pi. i, figs. 1-ld; 1891, U. S. Geol. Survey 10th Ann. Rept., p. 658, pi. 98, figs. by a dorsal and profile view in 1886 (PI. 27, fig. 3). 1, la-Id, 2 In 1937 Resser reassigned Solenopleura nana Ford Kootenia nana RESSER, 1937, Smithson. Misc. Coll., to Kootenia. Through oversight he claimed that v. 95, no. 22, p. 16 Ford's "specimen is not available", and so chose this Kootenia troyensis RESSER, 1937, Smithson. Misc. Coll., v. 95, no. 22, p. 17 cranidium first figured by Walcott as the lectotype of Kootenia nana (Ford). However, since Ford's Description.—Cranidium subquadrate; glabella holotype and paratypes are at the New York State rectangular, sides parallel in small specimens, diverg- Museum, studied and illustrated here for the first ing slightly in large specimens to broadly rounded time, the specific name nana Ford belongs to them. front, moderately and evenly convex; four pairs of Thus Walcott's first figured cranidium, which is a glabellar furrows, posterior two pairs long, curving specimen of Kootenia, is left without a specific name. diagonally backward, third pair moderately long, The second cranidium in Walcott's 1886 lot from straight, front pair short, straight; dorsal furrow USNM loc. 27 is figured for the first time as figure 3 distinct; occipital furrow broad, shallow; occipital of Plate 7. When this specimen was loaned to the ring nearly flat, narrow at sides expanding on mid- author for study, it was in a box with the type label length into a short triangular occipital spine; no pre- "Kootenia troyensis, USNM 94342"; it is definitely glabellar area; marginal furrow a broad shallow not the cranidium to which Resser assigned this concave band, slightly wider than anterior border, name and number in 1937. The fragmentary speci- paralleling border and maintaining a constant width men consists only of the glabella, part of the left (sag.), border a narrow curved convex rim; fixed fixed cheek, and a broken occipital spine, and is cheek—palpebral area convex, horizontal, slightly specifically unidentifiable. The tumid glabella and more than half the width of glabella; palpebral the apparent branching of the occipital furrow sug- lobes medium size, back of center of glabella; narrow gests that this fragment probably is a Fordaspis palpebral furrow; faint diagonal ocular ridge, pos- specimen; and it should be kept distinct from Wal- terior area narrow (sag.), almost same width (tr.) as cott's figured Kootenia cranidium, USNM 15425, occipital ring. Free cheek not known. from the same locality. Pygidium broadly triangular, axis of medium In 1887 Walcott referred several cranidia and width, convex, sides tapering only slightly to broad pygidia from Washington County to Solenopleuraf blunt end, extending nearly full length; five axial nana Ford, and figured the dorsal and profile views rings and terminal portion with faint sixth ring of a small cranidium, USNM 17451-222v, and the occasionally on anterior part, a low median node dorsal and profile views of a small pygidium, USNM appearing on anterior three rings in larger speci- I7451-222y, both from USNM loc. 38c. The profile mens; dorsal furrow shallow; pleural platform about of a broken cranidium figured by Walcott (1887, half the width of axis anteriorly; three broad pleura PL 1, fig. lb), cannot be located for certainty among separated by backward curving interpleural grooves; the known material. In 1887 USNM 17451 was marginal furrow shallow, narrow; border narrow, assigned presumably to the material from loc. 38c, flat with four pairs of short marginal spines. and this material is still available for study at the Outer surface of test densely covered with fine U. S. National Museum; but the material from the granules which are commonly arranged in clusters locality 2 miles south of North Hebron, also men- of small irregular wrinkles. tioned by Walcott, apparently did not receive a Remarks.—This is the first description of speci- number and has not been found. Presumably it mens of this species, and several paratypes are being should also be at the U. S. National Museum. figured for the first time. The nomenclature of this In 1891 Walcott repeated his 1887 discussion of form has been involved because Walcott confused this species and all the illustrations published previ- his specimens of this species with Ford's species ously, but, in the legend to figure 2 of Plate 98, he Solenopleura nana. Restudy of the types of the stated that this smooth variety of the cranidium is latter species shows that it belongs to a different referred with doubt to the species, apparently not genus, Fordaspis. appreciating the fact that the outer surface is not Kootenia troyensis Resser is known from three preserved on the glabella. cranidia and two pygidia at the U. S. National In 1937 Resser designated the small cranidium

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USNM 174Sl-222v as the type of a new species Kootenia cf. K. marcoui (Whitfield) Kootenia troymsis, but he did not describe its diag- (Plate 7, figures 13-18) nostic specific characters nor make clear wherein he Dikdlocephalusf marcoui WHITFIELD, 1884. Am. thought it differed from cranidium USNM 15425, Mus. Nat. Hist. Bull., v. 1, p. 150, pi. 14, fig. 7 or the other cranidia USNM 17451, in the lot from Kootenia cf. K. marcoui (Whitfield) RASETTI, 1948. USNM loc. 38c. He assigned a new number, USNM Jour. Paleontology, v. 22, p. 14, pi. 2, fig. 7 (for 94342, to this cranidium. However, in February synonymy to date) 1954, when this material was loaned to the writer, Remarks.—Two of Prindle's collections contain Dr. Cooper found this cranidium in a box labeled specimens which are definitely referable to the Kootenia nana (Ford) with the other cranidia and genus Kootenia. Several fragmentary and distorted pygidia, USNM 17451, of Walcott's original lot cranidia and pygidia and one free cheek occur in the from USNM loc. 38c; and an unidentifiable frag- material from the west side of Moon Hill. Poor ment from Troy, New York (see above), was in a preservation of this material as well as of the type box labeled "Kootenia troyensis, USNM 94342". pygidium prohibits exact specific determination. Careful comparison of cranidium USNM 17451- Fragmentary pygidia collected by the writer show 222v with cranidium USNM 15425 and with other small spines on the first three axial rings and a node cranidia in the lot of USNM 17451 shows conclu- on the fourth, but the number of marginal spines is sively that all are conspecific (PL 7, figs. 1, 6, 5) and unknown because the border is not preserved on represent individuals which range from 3 to 8 mm any specimen. The cranidia agree in all determmable in length. Since the earlier illustrated cranidium, features with the poor cranidium from Parker USNM 15425, is now without a species name, the Quarry assigned to this species by Walcott. These name troyensis assigned by Resser to the cranidium, cranidia average about 7 mm in length, and one is USNM 17451-222v, is the first name available for only 2.25 mm. Outer surface ornamentation on the this species of Kootenia. pygidia consists of fine granules arranged in clusters The specimens of K. troyensis differ in several forming larger granules or the characteristic small respects from both K. marcoui (Whitfield) and K. wrinkles. fordi (Walcott). With respect to the cranidium K. The second collection, 10P45 #389, contains one troyensis may be distinguished by (1) regular curva- fragment of a large Koolenia cranidium and three cranidia 1.25 mm in length, one of which is well ture of the anterior margin and the frontal area, preserved. It shows that the characteristic generic (2) greater width (sag.) of the marginal furrow, and specific features are already present in a and (3) presence of a short triangular occipital spine. cranidium of this size, and, if well preserved, such The two pygidia USNM 17451-222x and 17451-222y cranidia can be identified as to genus and species. seem to be correctly associated with these cranidia The fourth specimen is 0.5 mm in length and appears and are, in the writer's opinion, conspecific. They to be a metaspid. It is tentatively associated with are distinguished by the five axial rings, four pleura, the other specimens. and only four pairs of short marginal spines. A fifth Horizon and locality.—Lower Cambrian, west side posterior pair of minute spines illustrated by Wal- of Moon Hill, 1 mile north of Petersburg, N. Y., cott (1891, PL 98, fig. Ic) cannot be detected on and 10P45 #389, S. 49° E. to Pleasant Hill. either specimen. On the smaller pygidium (3 mm in Figured specimens. length) axial rings are quite smooth, but on the Cranidia, USNM 126776a-c, 126777c larger pygidium (4.5 mm in length) the first three Pygidia, USNM 126777a, b axial rings have small median nodes. This suggests that in Kootenia the axial spines did not appear Family PTYCHOPAKODAE Matthew (1887) until several moults after the individual reached the Kochiella Poulsen, 1937 holaspid stage. Possibly the same is true in Ford- Hamptonella Resser, 1937 aspis. Horizon and locality.—Lower Cambrian, USNM Genotype.—Kochietta tuberculata Poulsen; late loc. 27; USNM loc. 38c. Lower Cambrian, Cape Kent formation, Cape Types. Kent, Northwest Greenland Remarks.—Examination of the holotype, up to Holotype cranidium, USNM 94342—In 1954 still now the only known specimen, of Ptychoparia fitchi numbered USNM 17451-222v; loc. 38c Walcott, 1887 and discovery of several additional Paratype cranidium, USNM 17451-222w cranidia and a pygidium on the same piece of lime- Paratypes, pygidia, USNM 17451-222y, 17451-222x stone revealed that this species, the genotype of Plesiotype, cranidium, USNM 15425 Hamptonella Resser, 1937, is a species of Kochiella.

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Consequently, Hamptonella becomes a junior sub- The limestone piece carrying the metaspid holo- jective synonym of Kochiella. type cranidium (0.85 mm in length) is half of a small limestone block which was broken either dur- Kochlella fitchi (Walcott) ing collection or preparation, but both pieces were retained and numbered USNM 17455. Subse- (Plate 8, figures 26-28) quently the number on the second piece was changed to USNM 123582 and placed in a separate box with Ptychoparia fitchi WALCOTT, 1887. Am. Jour. Sci., a poorly preserved shaly piece. 3d ser., v. 34, p. 197, pi. 1, fig. 6 Ptychopariaf fitchi Walcott WALCOTT, 1891. U. S. On the other side of the piece carrying the holo- Geol. Survey 10th Ann. Rept., p. 650, pi. 96, fig. 5 type cranidium is a flattened fragmentary trans- Hamptonella fitchi (Walcott) RESSER, 1937. Smith- verse pygidium, 5 mm wide by 3 mm long, showing son. Misc. Coll. v. 95, no. 22, p. 13 the same fine granulation that characterizes the Original description.—"This species is founded on holotype cranidium. Near it is the impression of a a minute head that occurs in association with cranidium, the replica of which occurs on the second Microdiscus connexus and several other species of limestone piece. This cranidium is a larger holaspid the lower horizon of the Taconic slate series. The cranidium of the same species as the holotype elongate unfurrowed glabella, wide fixed cheeks cranidium. This holaspid cranidium and the pygid- and strongly granulose surface all unite to give it a ium are now figured as plesiotypes. This cranidium facies unknown in any other species with which I is 3.5 mm in length by 4.25 mm in width across the am acquainted." palpebral lobes and shows, in addition to all features New description.—Cranidium subrectangular, found on the holotype, the development of the wider than long; low, broadly conical glabella, front peculiarly wide anterior marginal furrow character- truncate; three pats of short shallow glabellar istic of Kochiella. This type furrow appears on all of furrows; dorsal furrow well-defined at sides, shallow Poulsen's specimens, the smallest of which is 4.5 across front; occipital furrow distinct; occipital ring mm in length. On the reverse side of the second piece low, triangular in shape; pre-glabellar area narrow, are two fragmentary metaspid cranidia of this downsloping; hi metaspid, anterior marginal furrow species. Both have the frontal area broken so the broad and deep, slightly wider than anterior border; size at which the wide marginal furrow was fully in holaspid anterior marginal furrow broad and developed cannot be ascertained. These two distinct, twice width (sag.) of anterior border on cranidia do, however, have better-preserved gla- mid-length because of posterior inbending of the bellas than the holotype, and show at least three narrow groove along its posterior edge; anterior pairs of glabellar furrows. All four cranidia, includ- border narrow, slightly convex; fixed cheek, anterior ing the holotype, and the pygidium have been area wide (sag.), convex, downsloping; palpebral flattened and distorted, and surface of the plesiotype area slightly convex, horizontal, same width (tr.) as cranidium has been smeared so that granulation is glabella; palpebral lobes less than medium size, present only in isolated patches. convex, just posterior to center of glabella; palpebral The only other trilobite specimens on these two furrow narrow, deep; narrow distinct ocular ridge pieces are the cranidia, pygidia, and thoracic seg- curving forward to dorsal furrow a short distance ments of Pagetia. connexa (Walcott). back of front of glabella; posterior area narrow Horizon and locality.—Lower Cambrian, USNM (sag.), IJ^ times length (tr.) of occipital ring; deep, loc. 34, 2 miles south of North Granville, N. Y. broad posterior marginal furrow. Free cheek and Types. thorax unknown. Holotype, metaspid cranidium, USNM 17455 Pygidium short, transverse; axis low, tapered Plesiotype, holaspid cranidium, USNM 123582b rapidly to narrow end, nearly full length, number Plesiotype, pygidium, USNM 123582a of segments unknown; pleural regions slightly wider Two unfigured metaspid cranidia, reverse side of than axis, gently convex; three moderately wide USNM 123582 (sag.) pleura delimited by faint interpleural grooves and crossed by faint diagonal pleural furrows; no Genus Ptychoparella Poulsen (1927) marginal furrow; narrow border. Well-preserved outer surface of both cranidium and pygidium cf. Ptychoparella sp. covered with fine granules. (Plate 8, figures 24, 25) Remarks.—Description is based on the diagnostic specific and generic features discernible in the Remarks.—In the author's material there are six metaspid holotype cranidium and the holaspid or seven fragmentary and poorly preserved cranidia plesiotype cranidium and pygidium. which are Ptychoparid in character. None, however,

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is well enough preserved to warrant a positive species. L. cambridgensis resembles L. elongata in generic determination. Ptychoparid specimens rarely the broadly conical glabellar shape with the second occur with members of the Elliptocephala asaphoides and third glabellar furrows less strongly developed, faunal assemblage. Walcott (1887) records only two but is similar to L. misera in the presence of a species in his complete list from Washington County. narrow pre-glabellar area. However, the Schodack Ptychoparids do occur abundantly in other later species differs from both Labrador species in (1) Lower Cambrian faunas of comparable age. It absence of the ocular ridge and a noticeable narrow- appears that they were normal habitants of a ness of the fixed cheek at this point, (2) apparent shallow-water coastal environment; whereas the incompleteness of the second glabellar furrow, (3) characteristic Elliptocephala asaphoides assemblage palpebral area which is horizontal rather than down- were habitants of offshore bottoms in deeper waters. sloping, and (4) reticulate surface ornamentation It is assumed that the few Ptychoparid fragments which is formed by minute granules. Because of represent stray moults or individuals drifted into an limited material of all species involved, and the fact alien environment. that preservation alone might be responsible for The specimens are tentatively referred to Ptycho- differences 2 and 3, the Schodack species should be parella rather than Antagmus as they seem to have referred to Labradoria. Additional material repre- rather wide horizontal fixed cheeks and a prominent senting the genus should make the assignment more conical glabella. certain. Horizon and locality.—Lower Cambrian, Iocs. Y Horizon and locality.—Lower Cambrian, Prindle 9, lla, 13. Prindle's Iocs.—see list. #241, half a mile north of Cambridge, N. Y. Figured specimens.—Cranidia, USNM 125689, Holotype— Cranidium, USNM 125735 125690 Phylum Unknown Family INCERTAE SEDIS Genus Stenothecopsis Cobbold (1935) Genus Labradoria Resser (1936) Labradoria cambrldgensis n. sp. Stenothecopsis schodackensls n. sp. (Plate 5, figure 12) (Plate 4, figures 1, 2) Description.—Cranidium narrow; broadly conical, Description.—Largest specimen is 1.75 mm in low glabella, three pairs of glabellar furrows, pos- height (average height is 1 mm). The brittle cal- terior pair deep, complete, second pair deep, at careo-phosphatic shell, thick for the specimen's sides only, anterior pair shallow, at sides only; dorsal size, consists of an inner, dull-appearing layer and furrow well defined; occipital furrow wide, deep; an outer layer of nacreous material. Outer surface occipital ring low; broad, median node may be of outer layer now is black, possibly from carbon of present; narrow, convex, downsloping pre-glabellar a thin chitinous outermost layer, but reflected light area; narrow, convex horizontal anterior border and shows up the colors of the nacreous layer under the a narrow distinct anterior marginal furrow; fixed black coloring. cheek, palpebral area not quite half the width of Apex of the cone is a fine point, and the early out- glabella, horizontal; palpebral lobes arcuate, oppo- line is more or less circular. With growth the shell site center of glabella, larger than medium size; no becomes more and more rectangular in shape until ocular ridge apparent; posterior area narrow (sag.), at the aperture the two longer sides may be as much about half the length (tr.) of occipital ring; narrow as three times the length of the short sides. Outer posterior marginal furrow. Outer surface of glabella surface is covered with strong parallel ridges which and palpebral area covered with a fine reticulation may run straight across the sides or curve slightly of narrow ridges. upward toward the apex. In larger specimens these Free cheek, thorax and pygidium not known. ridges are so coarse as to give a terraced effect to Remarks.—One small (2.375 mm by 2.1 mm) well- the shell. Between the coarse ridges, two or more preserved cranidium and several crushed cranidial finer ridges may be distinguished. Most specimens fragments represent this species, but it is afforded show a smooth apertural opening at the lowest recognition because the single complete cranidium coarse ridge, but a few rare specimens indicate that can be readily compared with the few other de- this is a broken line and not a true aperture. On scribed species of the genus. Only three cranidia these rare specimens vertical ribs develop on the from the Forteau formation of Labrador previously last 0.25 mm of the shell, and the pattern becomes represented this genus, named by Resser in 1937, at cancellate. which time he distributed the three cranidia into 2 Remarks.—The genus Stenothecopsis has been re-

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corded only in Lower Cambrian from the Departe- of the fragments had a prismatic structure and were ment Herault in south France by Cobbold, and in ascertained as the fragments of brachiopod shells Middle Cambrian from Bornholm Island, Denmark, such as the valves of Botsfordia caelata. The nodular by Poulsen. The marked similarity in shell texture, fragments which have a porous texture show a coloring, shape, size, and surface markings leaves no microscopic concretionary structure. It is believed doubt that the three recorded occurrences are shells that they are small phosphatic nodules or concre- of closely related animals which may properly be tions which formed on the sea bottom. Both types placed in one form genus. Cobbold referred the of fragments occur in etched material from most of genus questionably to the Crustacea, and Poulsen the collections. followed him. However, the steep-sided cone shape Horizon and locality.—Lower Cambrian, Y 7, 10, of the shell is unlike any carapace found in primitive 11, lla, 12, 13, 14. Crustacea, and a more reasonable assignment would be to some phylum where cone-shaped exo- REFERENCES CITED skeleton is common and size is always between 1 and 2 mm. Apparently each cone was occupied by one Balk, Robert, 1953, Structure of graywacke areas and Taconic Range, east of Troy, New York: individual, and there is no evidence from the shell Geol. Soc. America Bull., v. 64, p. 811-864 that it was attached, although the individual ani- Bell, W. C., 1946, Etching "corneous" brachiopods mals could have been connected by a gelatinous (Abstract): Geol. Soc. America Bull., v. 57, p. stolon. The Entoprocta or the Phoronidea seem the 1177 Brace, William F., 1953, The geology of the Rut- most likely phyla for possible relationships; but it land area, Vermont: Vt. Geol. Survey Bull. 6, must not be overlooked that the Mollusca may be 1-120 p. a possibility. The cone shape is common for Mollusca Butts, Charles, 1926, The Paleozoic rocks of Ala- shells, and many workers believe it was the shell bama: Geol. Survey Ala. Special Rept. 14, p. 41-230 shape of the ancestral mollusk. It has been common Cady, Wallace M., 1945, Stratigraphy and structure practice to exclude from the Mollusca any form not of west-central Vermont: Geol. Soc. America showing a calcium carbonate shell. However, the Bull., v. 56, p. 515-588 ancestral mollusk could have first produced calcareo- Cobbold, E. S., 1913, The trilobite fauna of the Comley breccia-bed (Shropshire): Geol. Soc. phosphatic shells, and then calcium-carbonate shells, London Quart. Jour., v. 69, p. 27-50 such as occurs among the Brachiopoda. The appar- , 1920, The Cambrian horizons of Comley ent existence in the shell of Stenothecopsis of three (Shropshire) and their Brachiopoda, Pteropoda, layers may be significant. Gastropoda, etc.: Geol. Soc. London Quart. Jour., v. 76, p. 325-386 Three localities which furnished most of the fossil , 1935, Lower Cambrian faunas from Herault, material also yielded most of these specimens. France: Ann. and Mag. of Nat. Hist., ser. 10, Though brittle and hard to handle, the shells etch Bd. 16, p. 25-48 out well with acetic acid. Poulsen (1942) obtained Gushing, H. P., and Ruedemann, R., 1914, Geology of Saratoga Springs and vicinity: N. Y. State his four specimens by elutriation of clay. Possibly by Mus. Bull. 169, 177 p. use of these two methods specimens of Stenothecopsis Dale, T. N., 1893, The Rensselaer grit plateau in will be found more frequently. The quadrate shape New York: U. S. Geol. Survey Ann. Rept. 13, of the more mature part of the shell is a generic pt. 2, p. 291-340 , 1899, The slate belt of eastern New York and feature, and Poulsen was not justified in making western Vermont: U. S. Geol. Survey Ann. each of his specimens a different species based on Rept. 19, pt. 3, p. 153-300 slight changes in shape of the assumed aperture. , 1904a, Geology of the Hudson Valley between Comparison of the author's specimens with Poul- the Hoosic and the Kinderhook: U. S. Geol. Survey Bull. 242, 63 p. sen's suggests that the only specific character dis- , 1904b, The geology of the north end of the tinguishable from the shell is the finer details of the Taconic range: Am. Jour. Sci., 4th ser., v. 17, surface markings. p. 185-190 Horizon and locality.—Lower Cambrian, Iocs. Y Flower, R. H., 1949, Structural history of the Hud- son Valley (Abstract): Geol. Soc. America Bull., Ha, 13, 16, 17, 11. v. 60, p. 1969 Figured specimens.—USNM 125749, 126750, Fowler, Phillip, 1950, Stratigraphy and structure of 126751 the Castleton area, Vermont: Vt. Geol. Survey Bull. 2, 83 p. Hadding, Assar, 1932, Glauconite and glauconitic PROBLEMATICA rocks: The Pre-Quaternary sedimentary rocks of Sweden, pt. 4, Medd. Lunds Geol. Min. Inst., Several fragments of apparent organic origin in no. 51, p. 1-175 Howell, B. F., et at., 1944, Correlation of the Cam- the etched material show marked wearing in their brian formations of North America: Geol. Soc. rounded or disc shape, and are of fluorapatite. Some America Bull., v. 55, p. 993-1003

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Howell, B. F., and Stubblefield, C. J., 1950, A revi- Rasetti, Franco, 1946, Cambrian and early Ordo- sion of the fauna of the north Welsh Cono- vician stratigraphy of the lower Saint Lawrence coryphe viola beds implying a Lower Cambrian valley: Geol. Soc. America Bull., v. 57, p. 687- age: Geol. Mag., v. 87, p. 1-16 706 Hupfi, Pierre, 1952, Contribution a 1'dtude du • , 1948, Lower Cambrian trilobites from the con- Cambrien Infgrieur et du Precambrien III de glomerates of Quebec: Jour. Paleontology, v. 1'anti-atlas Marocain: Protectorat de la R6- 22, p. 1-24 publique Francaise au Maroc, Direction de la ——, 1951, Middle Cambrian stratigraphy and production industrielle et des mines, Division faunas of the Canadian Rocky Mountains: des mines et de la Geologic, Service G6ol., Notes Smithson. Misc. Coll., v. 116, no. 5, 277 p. et M6m., no. 103, 383 p. , 1952, Revision of the North American trilo- , 1953, Classe des Trilobites: Trait6 de Paleon- bites of the family Eodiscidae: Jour. Paleon- tologie, v. Ill, p. 44-246 tology, v. 26, p. 434^51 Hutchinson, R. D., 1952, The stratigraphy and Resser, C. E., 1937, Third contribution to nomen- trilobite faunas of the Cambrian sedimentary clature of Cambrian trilobites: Smithson. Misc. rocks of Cape Breton Island, Nova Scotia: Coll., v. 95, no. 22, p. 1-29 Geol. Survey Canada Mem. 263, 124 p. Schuchert, Charles, and Dunbar, Carl 0., 1934, Kaiser, E. P., 1945, Northern end of the Taconic Stratigraphy of western Newfoundland: Geol. thrust sheet in western Vermont: Geol. Soc. Soc. America Mem. 1, 123 p. America Bull., v. 56, p. 1079-1098 Shaw, Alan B., 1954, Lower and lower Middle Keith, Arthur, 1923, Cambrian succession of north- Cambrian faunal succession in northwestern western Vermont: Am. Jour. Sci., 5th ser., v. Vermont: Geol. Soc. America Bull., v. 65, p. 5, p. 97-139 1033-1046 Kindle, Cecil H., and Tasch, Paul, 1948, Lower Walcott, C. D., 1886, Studies on the Cambrian Cambrian fauna of the Monkton formation of faunas of North America: U. S. Geol. Survey Vermont: Canadian Field-Naturalist, v. 62, Bull. 30, 369 p. p. 133-139 Laverdiere, J. W., 1949, Bedded limestones in the , 1887, Fauna of the "upper Taconic" of Em- LeVis formation: Royal Soc. Canada Trans., mons, in Washington County, New York: Am. 3d ser., sec. IV, v. 43, p. 71-83 Jour. Sci., 3d ser., v. 34, p. 187-199 Lochman, Christina, 1953, Corrections to trilobites , 1891, The fauna of the Lower Cambrian or in "Cambrian stratigraphy and paleontology Olenellus zone: U. S. Geol. Survey 10th Ann. near Caborca, northwestern Sonora, Mexico": Rept., p. 515-629 Jour. Paleontology, v. 27, p. 486-488 , 1910, Olenellus and other genera of the Meso- Okulitch, V. J., 1943, North American Pleospongia: nacidae: Smithson. Misc. Coll., v. 53, no. 6, p. Geol. Soc. America Special Paper 48, 112 p. 233-423 Osberg, Philip H., 1952, The Green Mountain Anti- . , 1912, Cambrian Brachiopoda: U. S. Geol. clinorium in the vicinity of Rochester and East Middlebury, Vermont: Vt. Geol. Survey Bull. Survey Mon. 51, pts. 1 and 2, 872 p., 363 p. 5, 127 p. Wilson, James L., 1954, Late Cambrian and early Poulsen, Christian, 1942, Some hitherto unknown Ordovician trilobites from the Marathon uplift, fossils from the Exsidans limestone of Born- Texas: Jour. Paleontology, v. 28, p. 249-285 holm: Medd. fra Dansk Geol. Forening. Koben- havn, Bd. 10, hefte 2, p. 212-235 Box 182, CAMPUS STATION, SOCORRO, NEW MEXICO Prindle, L. M., and Knopf, E. B., 1932, Geology of MANUSCRIPT RECEIVED BY THE SECRETARY OF THE the Taconic quadrangle: Am. Jour. Sci., 5th SOCIETY MARCH 3, 1955 ser., v. 24, p. 257-302 PROJECT GRANT 508-47