Bulletin of the Geological Society of America Vol. 63, Pp

BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA VOL. 63, PP. 96-166, 15 FIGS., 11 PLS. FEBRUARY 1962

MOLLUSCAN FAUNA FROM THE PERMIAN KAIBAB FORMATION, WALNUT CANYON, ARIZONA

BY HALKA CHRONIC

ABSTRACT During the summer of 1946, field investigations of the Alpha member of the Permian Kaibab formation were undertaken in the region of Walnut Canyon, south of Flagstaff, Arizona. Excellence of exposures greatly facilitated the measuring of sections and tracing of rock units along the canyon. Specimens were collected for lithologic analyses, and representative fossils secured from several zonules. More extensive fossil collections were made at three exposures several miles north of Walnut Canyon, and at a fourth some 35 miles north. The fauna is analyzed and described, and an attempt is made to interpret the environment in which it developed and the conditions under which it was preserved. Environ- mental factors such as depth, salinity, temperature, and turbidity of the water, presence or absence of currents and other agitation, intensity of light, and the nature of the bottom are discussed. Conclusions reached indicate that the fauna, composed largely of mollusks, developed in a warm, shallow, epeiric sea not very far from land. A gradual retreat of the sea probably did not modify the depth of the sea very greatly. From low land to the northeast, fine sediments were brought into the sea, but it is believed that the water was not very brackish, except perhaps for short periods of time. The sea bottom was composed of a silty, clayey, calcareous mud containing abundant shells of dead organisms, and most of the smaller mollusks may well have lived attached to seaweeds and other marine growth, while larger and heavier forms crawled over or burrowed into the mud bottom. Periodic changes of conditions, probably due to oscillations in depth and a corresponding change in the nearness of the shore, brought about local extinction of the fauna and changes in the nature of the sediments.

CONTENTS TEXT Figure Page Page 3. Relation of width and pleural angle to Introduction 96 height in Ananias franciscanus 115 Review of literature 96 4. Relation of width and pleural angle to Statement of problem 96 height in Glabrocingulum laeviliratum 117 Acknowledgments 96 5. Position of carinae and selenizone in Stratigraphy 97 Platyworthenia, delicata 121 Physiography and structural geology 97 6. Position of carinae and selenizone in General description of stratigraphy 97 Worthenia corrugata 122 Stratigraphy in the Walnut Canyon region.. . 97 7. Relation of width and pleural angle to Descriptions of measured sections 100 height in Murchisonia. geminocarinata 124 Paleontology...... 104 8. Position of selenizone in Murchisonia a 106 geminocarinata, Murchisonia sp, and 9 S ' '' ' ' ' ' ' 111 ' ReTtbn of width;pleural angle,'and height "* Peewpoda136 of aPerture to height> and of heiSht of Scaphopoda 153 aperture to width of aperture, in Glypto- Echinodermata.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.'. 153 - ^acristulata .... 128 Selected bibliography 154 10n- Relation of width and height of aperture to height in Naticopsis kaibabensis 134 H. Relation of width and pleural angle to height in Orthonema f strialonodosum 135 Figure Page 12. Relation of height and convexity to length 1. Location of sections and fossil localities. ... 98 in Nwulana obesa 137 2. Relation of width and height of aperture 13. Relation of height and convexity to length to height in Bdlerophon deflectus 112 in Palaeonucula levatiformis 139 95

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INTRODUCTION tend to crumble and form soil-covered slopes. In the region around Bottomless Pits, however, Review of Literature there are outcrops of these beds where fossil molds are readily collected. The rocks are ex- A consideration of the fauna and ecology of posed here in an erosion gully and two old rail- the Kaibab formation of northern Arizona road cuts. Supplementary material was was presented by McKee in 1938. His study of obtained from a third locality, 35 miles north. the fossils of the Kaibab, though the most ex- Fossils from this locality are silicified and can tensive yet offered, was directed mainly toward be etched from the limestone in which they analysis and description of the brachiopods of occur. A number of limestone blocks collected the Kaibab and underlying Toroweap forma- and etched at the American Museum yielded tions. The molluscan elements were not de- abundant material for study, and this was sup- scribed. Other discussions of Kaibab fossils plemented by collections loaned by the Museum are scattered and varied. Early collections by of Northern Arizona and by the Grand Canyon Gilbert were described by White (1877; 1879); National Park museum. trilobites from this region were the subject of Localities and beds from which fossils were an article by Joseph Snow (1945); several collected are: pectinids and myalinids were described by Locality 1. Bottomless Pits. T 21 N, R 8 E, Newell (1937); and Nicol (1944) attempted a SW J sec. 17. brief environmental study of elements of the Bed 2—fossils preserved as molds in dolomitic facies discussed in this paper, but no systematic limestone. description of the molluscan fauna has been Bed 9—fossils preserved as molds in dolomitic published. limestone. Locality 2. Railroad cut. T 21 N, R 9 E, SW i Statement of Problem sec. 16. This paper attempts to interpret more ex- Bed 4—fossils preserved as molds in dolomitic actly than has heretofore been done the nature limestone. of the fauna and sediments of the Alpha mem- Locality 3. Rimmy Jim tank. T 27 N, R 9 E, ber of the Kaibab formation in the area of NW i sec. 17. Walnut Canyon, about 8 miles southeast of Fossils silicified in limestone. Flagstaff, Arizona. The area studied is bounded on the southwest by Lake Mary and extends A cknowledgments northeastward about 7 miles, following the stream course. The region around Bottomless The writer expresses her appreciation to Dr. Pits, 3 miles north of Walnut Canyon, is also Norman Newell of Columbia University, Dr. considered (Fig. 1). Siemon W. Muller of Stanford University, and The molluscan fauna of the Alpha member is Mr. Edwin McKee of the Museum of Northern described. In most of the natural exposures in Arizona for guidance and valued suggestions this region, fossil-bearing strata of the Alpha in the preparation of this paper. Thanks are member were not in evidence, apparently be- also due Dr. J. Brookes Knight for many sug- cause fossiliferous beds are very porous and gestions relating to study of the gastropods,

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Dr. Walter Bucher for aid in sedimentary Throughout the length of Walnut Canyon, aspects of the study, and the writer's husband, as well as at Lake Mary, strata are horizontal Dr. John Chronic, for advice and assistance or very nearly so. Near Bottomless Pits, north and for critical reading of this paper. The of Walnut Canyon, a few degrees of dip were privilege of using the Museum of Northern noted and taken into account when measuring Arizona laboratories during the summers of sections there. 1946 and 1947, and the laboratories of the American Museum of Natural History during General Description of Stratigraphy 1947-1949, is gratefully acknowledged. Per- The stratigraphic relationships of the Kaibab mission to carry on research within Walnut formation as a whole have been described by Canyon National Monument was granted by McKee (1938), who divided the formation the United States National Park Service, and into three members: collections of the Grand Canyon National The lowest, or Gamma, member was laid Park, the Museum of Northern Arizona, and down when the sea was gradually encroaching American Museum of Natural History were upon the land from the west. The dominant made available to the writer. rock type is a fine-grained limestone containing a molluscan fauna. It was deposited in water STRATIGRAPHY which was shallow and probably brackish, not very far from shore as the shore-line migrated Physiography and Structural Geology eastward. It overlies the Toroweap formation, The Kaibab formation forms the surface rock contact between the two being in most places of most of the Colorado plateau in the Grand level, though channelling and evidence of Canyon area. The plateau is cut by numerous slight deformation have been observed. canyons, among which is Walnut Canyon, a The Beta or middle member was deposited narrow gorge some 400 feet deep carved through at the time of the sea's maximum advance. In the entire thickness of the Kaibab formation most areas Beta sediments are pure marine and well into the underlying Toroweap. Al- limestones, but in the Walnut Canyon area the though the stream course is somewhat tortuous, rocks are fine-grained, silty to dolomitic lime- it runs in a general west-to-east direction. stones alternating with beds of chert. The Throughout most of the canyon, steep walls fauna here is dominantly molluscan in contrast and sparse vegetation combine with absence of to a brachiopod fauna farther west. This any structural complications to make excellent lithology and fauna are interpreted as repre- sequences of exposures. Beds are, for the most senting a near-shore environment. part, completely shown in section from top to Alpha member was formed as the seas re- bottom, and can be correlated if necessary by treated, so it also represents very near-shore tracing. In this study, however, where sections deposition. Evidence indicates that conditions were measured only a few miles apart, correla- were not as stable, however, as during deposition was usually possible by comparisons of tion of the Beta. Two rock types predominate: lithology, fossil content, and weathering char- (1) a porous, fossiliferous, dolomitic limestone acteristics of the beds. or dolomite which weathers rough and pitted, Except for a number of normal faults run- and (2) a nonfossiliferous, silty limestone ning in a roughly north-south direction so that weathering to smooth surfaces. they cross Walnut Canyon, the sequence of Over most of the Colorado plateau in the strata is not disturbed. In several places the Grand Canyon region, the Kaibab formation stream has followed zones of faulting for short forms the plateau surface, contact with the distances and in numerous places tributaries are overlying Lower Triassic Moenkopi formation subsequent to them. One of the largest of the being present only at the margin of the plateau. faults, along the eastern shore of Lake Mary, forms an escarpment several hundred feet high Stratigraphy in the Walnut Canyon Region and exposes the entire thickness of the Kaibab Along Walnut Canyon, several detailed sec- formation and the upper part of the Toroweap. tions of the Alpha member of the Kaibab were

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FIGURE 1.—LOCATION OF SECTIONS AND FOSSIL LOCALITIES

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measured, forming, together with a section from Beta fauna is dominated by Dictyoclostus bassi the Lake Mary escarpment, an irregularly and Plagioglypta canna; the Alpha fauna is east-west line of sections. In addition to these, typically composed of an abundance of small two incomplete sections near Bottomless Pits mollusks with Dictyoclostus bassi, pectinids, serve to locate fossiliferous beds in the lithologic and AUorisma terminate also present. sequence. The positions of measured sections The lowermost 80 feet of the Alpha member are indicated on the map (Fig. 1) and sections are more resistant than overlying strata so that are drafted (PL 11) and described. the beds form ledges and angular cliffs in the In examining the stratigraphy in the area, it walls of Walnut Canyon, or part of the steep has been possible to correlate the various sec- slope of the Lake Mary escarpment. At a tions by means of several well defined key beds. rather well-defined horizon, the nature of the One of these is a 3-foot bed which has been rocks changes and concealed slopes are formed. recognized at every section in Walnut Canyon Only at the East Walnut section are these upper and at Lake Mary. It is a fine-grained, pale- beds more completely exposed, and they are gray, silty limestone or calcareous siltstone, found to consist of alternating thin beds of weathering to a two-tone effect showing fairly pure, silty limestone and fossiliferous, laminations formed by ripples. In most places dolomitic limestone. The dolomitic limestone is it is exposed as a smooth slope, free from talus, porous and relatively non-resistant, and and so is easily identified. weathers in most areas to form a gentle slope Near the top of the section is a zone con- to the top of the plateau. Chemical analyses of taining one or more of three distinctive types of the fossiliferous dolomitic limestones from three rock. One of these is a limestone conglomerate localities at which fossils were collected are made up of irregularly shaped limestone frag- given below (analyses through the courtesy of ments. Another is a thick sandstone bed which F. G. Hawley): forms the surface of the plateau in many regions. It is cream-colored and very fine- Loc. 1 Loc. 1 Loc. 2 grained, but weathers to a red-brown color that bed 2 bed 9 bed 4 Loc. 3 is easily recognized. At its base, and also locally in another bed below, is the third type, a rather CaO . 29 8 31.2 30 7 24 2 curious very fine-grained sandstone containing MeO . 19 3 19 8 18 9 12 2 large, rounded, pitted sand grains in clusters SiOs . 4 8 2 5 4 7 29 2 or disseminated throughout. Because of the AUOs ... . 0.28 0.36 0 09 1 16 resemblance of the clustered grains to small FejOj 0.50 0.64 0 71 0 86 fish eggs, this bed is referred to as the "fish- egg sandstone." Analyses of silty limestone beds from approxi- Rocks comprising the Alpha member in the mately the same area are given by McKee area are primarily silty and dolomitic lime- (1938, p. 65, table 7a). stone, interbedded with calcareous siltstone and Above the series of limestones there is an sandstone. The lower boundary of the Alpha abrupt change to beds of sandstone, associated member is well marked by an abrupt change of locally with limestone conglomerate. The sand- lithology, thickness of the beds, and weathering stone, which is not calcareous, suggests a late characteristics of the rocks. Rounded, massive, stage in the cycle of the sea's advance and re- cliff-forming limestones of the Beta member treat, and may represent the time when the give way to more thinly bedded limestones and sea had nearly receded from the land and dolomites of the Alpha member, which weather deposits were being laid down in very shallow to a series of angular ledges with narrow slopes water close to shore. Locally the presence of between. Bedded cherts, common in the Beta large, rounded, pitted grains suggests that beach member, are lacking in the Alpha, though oc- or dune sand, derived from the shore, was casional chert nodules are present in the lower blown out to sea and deposited there with the part. An examination of the vertical distribu- water-transported material. Along new highway tion of fossils shows a change in fauna at the cuts a short distance to the east of Walnut same horizon as the lithologic change: the Canyon, thick redbeds are interbedded with

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light-colored sandstones and dolomitic lime- Feet From base glypta, Palaeonucula, pectinids, stones. These apparently represent the final other pelecypods) and at top stage of the cycle and fluvial deposition just (fenestellid bryozoans, mollusk fragments, Palaeonucula); forms previous to erosion of the pre-Moenkopi un- partly concealed slope with conformity in this area. weak ledges 13.0 76.0 Correlation of the Bottomless Pits and Rail- 9. Limestone: light gray grading road cut (Iocs. 1 and 2) fossil beds with the upward to white; magnesian near base grading to silty at top; more complete sections obtained along Walnut fossiliferous (abundant small, Canyon is possible, as the "fish-egg" sandstone fragmentary mollusks, small and conglomerate zone near the top of the cephalopod fragment, spines, bryozoan fragments); weathers Alpha is present in both localities. The two light gray to grayish brown; partial sections appear to represent approxi- forms series of weak ledges with mately the upper 85 feet of the Alpha, with occasional slopes 12.0 64.0 8. Limestone: pinkish white, silty, possible greater or lesser erosion of the few porous; like no. 10 but not fossilif- uppermost beds. This places the three main erous; weathers gray; forms fossil-bearing strata in the lower half of the ledge 2.5 61.5 7. Siltstone: white, slightly calcare- Alpha member, among those limestones and ous (7% soluble in HC1), friable; dolomites which in most areas form the upper beds thin (1-4 inches) and ir- part of the walls of Walnut Canyon. It is regular; shows ripple marks (marker bed); forms slope and probable that the fossiliferous beds at locality weak ledges; partly concealed.... 3.5 58.0 3 belong in the same approximate position. 6. Limestone: light gray to pink, silty, like no. 8; locally contains 1 manganese dendrites; beds 1^1 Descriptions of Measured Sections ft. thick; weathers light gray to LAKE MARY: Section on escarpment at north end of grayish brown; forms series of lake. T 20 N, R 8 E, NE i sec. 18. ledges; locally concealed 13.5 44.5 5. Limestone: light brownish gray, Top of plateau: Recent erosion surface. aphanitic, dolomitic, argillace- Kaibab formation (Permian), Alpha member: units ous, fossiliferous (mollusk frag- forming alternating series of silty limestones and ments); forms slope; mostly fossiliferous dolomites. concealed 2.0 42.5 Feei From baa 4. Limestone: pinkish white, silty; 13. Sandstone: very pale brown, like no. 8 4.0 38.5 very fine-grained with rounded, 3. Limestone: pinkish gray to light pitted, coarse grains scattered brownish gray, dolomitic, fos- throughout; weathers light red- siliferous; like no. 5; contains dish brown; serves as marker bed scattered rods of white calcite (red "fish-egg" sandstone); near top; forms partly concealed forms slope to top of plateau 5.5 117.0 ledges 19.5 19.0 12. Conglomerate: weathers very 2. Limestone: pinkish white, silty, pale brown; forms slopes; porous; like no. 8; forms receding Matrix: purplish red, silty lime- ledges 7.0 12.0 stone (locally siltstone); 1. Limestone: pinkish gray, apha- Pebbles: irregular fragments of nitic, dolomitic; like no. 5; pink dolomite | to 2 inches in fossiliferous (abundant Dictyo- diameter 6.0 111.0 closlus, Marginifera, Palaeo- 11. Concealed slope: contains: nucula, Bellerophon, pectinids, Limestone: very pale brown to Bryozoa); contains geodes and pinkish white, silty; fossilifer- chert nodules; weathers light ous at 5.5 feet (mollusk frag- gray; forms series of ledges 12.0 ments); ripple-laminated at 14 feet; forms weak ledges; Total... 22.0 89.0 Total 122.5 10. Limestone: very pale brown to Beta member: units forming massive cliffs and white, silty, porous; fossilif- slopes of silty limestone with chert nodules and erous at base (large Plagio- interbedded chert.

1 Grain sizes are according to the Wentworth WALNTJT BENB. Section at bend of Walnut Canyon scale. Color notations were obtained with soil 3 miles west of old ranger cabin. T 20 N, R 8 E, color charts issued by the U. S. Dept, of Agri- NE i sec. 5. culture, 1946. Top of plateau: Recent erosion surface.

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Kaibab formation (Permian), Alpha member: WALNUT RANGER CABIN. Section in Walnut Canyon Feet Prom bast below old ranger cabin. T 21 N, R 8 E, SW J 10. Sandstone: reddish yellow, very sec. 26. fine-grained; contains coarse, Top of plateau: Recent erosion surface. rounded grains; weathers yellowish red; serves as marker bed Kaibab formation (Permian), Alpha member: (red "fish-egg" sandstone); Peel From bast forms slope 8.5 139.0 15. Sandstone: white to red, very 9. Concealed: slope containing fine-grained; weathers reddish- series of weak ledges, mostly yellow to gray; serves as marker less than a foot thick, of: Lime- bed (red sandstone); forms stone: white to light gray, mag- much-concealed slope 12.0 118.0 nesian, silty; locally fossiliferous 14. Dolomite: reddish-yellow, apha- (Dictyodostus, Plagioglypta, nitic, argillaceous, hard; fragmentary moUusks) 48.0 91.0 weathers white to light brown, 8. Limestone: pinkish white to very rough, pitted; forms much-con- pale brown, magnesium, silty to cealed slope 2.0 116.0 argillaceous; very fossiliferous 13. Sandstone: very pale brown, (abundant mollusk fragments); very fine-grained, calcareous; beds 1-4 ft. thick; forms re- like no. 15; contains rounded treating ledges (rim of canyon).. 23.5 67.5 grains of coarse sand scattered 7. Siltstone: pinkish white to white, throughout; weathers reddish- calcareous; locally fossiliferous yellow to gray; serves as marker (mollusk fragments); locally con- bed (red "fish-egg" sandstone); tains geodes and small calcite forms slope, much concealed 3.0 113.0 rods; forms series of receding 12. Siltstone: very pale brown, cal- ledges with concealed slopes careous, friable; forms slope, between 12.5 55.0 mostly concealed 3.0 110.0 6. Limestone: very pale brown, 11. Concealed: slope: contains weak dolomitic; locally fossiliferous; ledges of fossiliferous magnesian contains partly concealed ledge limestone and dolomite 21.5 88.5 of pinkish-gray, silty limestone 10. Limestone: white, silty, porous; near base; forms angular ledge weathers light gray, silty, with lower 3 ft. concealed 5.0 50.0 smooth; forms thin ledges and 5. Limestone: light yellowish- concealed slope 8.5 80.0 brown, aphanitic, dolomitic, 9. Limestone: white to light gray, hard; beds J-2 ft. thick; parting dolomitic, silty; beds ^—3 ft. beds (1-6 in.) very pale brown, thick; locally fossiliferous (mol- shaly, calcareous siltstone; forms lusk fragments); forms cliff and cliff 8.5 41.5 retreating ledges (rim of canyon). 11.5 68.5 4. Limestone: very pale brown, 8. Siltstone: white, calcareous; like silty (11.8% insoluble in HC1), no. 10 but not porous; contains ripple-laminated; serves as geodes; forms ledge 2.0 66.5 marker bed; forms rounded 7. Limestone: pale yellow to light ledges or slopes 3.5 38.0 gray, dolomitic, silty; h'ke no. 9; locally fossiliferous (mollusk 3. Dolomite: pale brown, aphanitic; fragments); contains small (j-J forms 3-foot ledge with con- in.) calcite rods and irregular cealed slope above 8.5 29.5 masses; basal 1.5 ft. concealed; 2. Limestone: pale yellow, dolo- forms cliff 9.0 57.5 mitic; like no. 6; beds 1-2 ft. 6. Limestone: light gray, dolomitic, thick; locally less silty and fos- hard, brittle; slightly silty and siliferous (abundant mollusk white near top; weathers gray, fragments); contains band of pitted, irregular; forms cliff 3.0 54.5 large chert nodules at base; 5. Limestone: pale yellow to light forms steep angular ledge 8.5 21.0 gray, dolomitic, silty to argillace- 1. Limestone: white to light gray, ous, aphanitic, hard (especially aphanitic, very silty; like no. at top); like no. 9; weathers 7; beds 2-4 ft. thick; contains white to gray, pitted; forms abundant geodes in upper 2 ft.; ledges 5.5 49.0 forms ledges (6-8 ft.) with con- 4. Siltstone: white, calcareous cealed slopes (3^t ft.) between... 21.0 (19.1% soluble in HC1), friable; Total 147.5 like no. 8; weathers gray; forms slope, much concealed 2.5 46.5 Beta member: massive cliff-forming limestone 3. Limestone: light gray to light containing chert nodules, underlain by recess- brownish-gray, dolomitic, silty forming chert. (especially near base); beds

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/63/2/95/3441285/i0016-7606-63-2-95.pdf by guest on 30 September 2021 102 HALKA CHRONIC—MOLLUSCAN FAUNA FROM WALNUT CANYON, ARIZONA Feet From base Feet Prom base \—1 ft. thick; fossiliferous (mol- 9. Limestone: white, silty; like that lusk fragments); weathers white in no. 13; beds 1 ft. thick with to gray, rough, pitted, silty; irregular, wavy parting planes; forms receding ledges 16.0 30.5 formsrecess 3.0 63.0 2. Siltstone: white, calcareous 8. Limestone: very pale brown, (27% soluble in HQ); weathers mottled, very magnesian; beds white with wavy ripple laminae; 2-5 ft. thick; fossiliferous serves as marker bed; forms (Astartella, gastropods, small recess or steep slope usually pectinids, small pelecypods); freeof talus 3.0 27.5 contains small geodes, esp. near 1. Limestone: white, aphanitic, top; weathers gray, pitted; forms silty; beds 1-4 ft. thick; some massive cliff 9.0 54.0 beds magnesian and fossiliferous; 7. Dolomite: gray, aphanitic, contains vermilion geodes in brittle, shaly toward top; con- upper part; weathers light to tains much gray chert; fossilif- dark gray; forms retreating erous (abundant Schizodus ledges 27.5 locally); forms slope 4.0 50.0 Total 130.0 6. Limestone: white to light gray, silty, magnesian toward top of Beta member: ledge-forming and cliff-forming each bed; 2 beds 4 ft. thick; calcareous siltstone and limestone with nodular fossiliferous (Dictyoclostus, and interbedded chert. Wetterella, juvenile mollusks at top of lower bed, small mollusks EAST WALNUT. Section J mile E. of Walnut Canyon in upper bed); forms ledge with National Monument boundary. T 21 N, R 9 E, basal bed locally forming recess.. 7.5 42.5 NW i sec. 31. 5. Limestone: white, silty; grades up into tan magnesian lime- Top of plateau: Recent erosion surface. stone containing mollusk frag- Kaibab formation (Permian), Alpha member: ments; beds 1—3 ft. thick; bed- Feel Front base ding planes wavy and irregular 16. Sandstone: white to light red- with thin parting beds of silt- dish-brown, very fine-grained stone; weathers gray to black, with scattered coarse rounded angular; forms cliff 17.0 25.5 grains (red "fish-egg" sand- 4. Limestone: white, very silty stone); weathers red to grayish- (36% soluble in HC1); shows brown; forms weak ledges ex- ripple laminae (marker bed); posed in slope to top of plateau. . 22.0 120.5 forms bare slope or recess 3.0 22.5 15. Limestone: very pale brown to 3. Dolomite: light gray, silty, im- pink, silty to argillaceous; forms pure; contains 3-inch bed of cal- slope, much concealed 7.5 113.0 careous siltstone at base forming 14. Limestone: very pale brown, slight recess; fossiliferous dolomitic, argillaceous, porous; (Pleurophorus albequus very beds 2-6 ft. thick; weathers abundant, with both valves in- very pale brown and very pitted; tact) ; forms slope 1.0 21.5 forms ledge (rim of canyon) 6.5 306.5 2. Limestone: white to light olive gray, silty and argillaceous 13. Limestone: white to very pale (5.8% insoluble in HC1); very brown; alternates with: Lime- magnesian (progressively more stone: light gray, dolomitic, fos- so upward); beds 2 ft. thick; siliferous (mollusk fragments); fossiliferous near center of each weathers gray, pitted; Total bed (Palaeonucida, scaphopods, forms series of ledges and slopes.. 24.0 82.5 juvenile and fragmentary mol- 12. Sandstone: white, very fine- lusks); contains quartz geodes; grained, calcareous, silty; beds forms series of ledges 11.5 10.0 thin (1-6 in.) and irregular; 1. Siltstone: white, argillaceous, forms slope or recess 1.5 81.0 calcareous; like underlying Beta 11. Limestone: white, silty; weathers member but beds thin (1-3 ft.); buff to gray; alternates with: fossiliferous near center of each Dolomite: light gray, fossilif- bed (small mollusks, incl. erous; Total like no. 13; forms Schizodus, Astartella, Palaeonu- ledge and slope 4.0 77.0 cula, bellerophontids; large 10. Limestone: light gray; like that pelecypods); forms series of re- in no. 13; beds thick (2-6 ft.); treating ledges 10.0 fossiliferous (abundant pelecypod fragments, a few bel- Total 142.5 lerophontids); weathers gray, Beta member: thickly bedded, massive, cliff- pitted; forms massive cliff 11.0 66.0 forming, silty limestones and calcareous silt-

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stones with chert nodules, bedded chert, and Feet From base thin beds of brittle, cherty dolomite. 6. Limestone: very pale brown, silty, magnesian; contains mol- RAILROAD CUT (Fossil loc. 2). Partial section at lusk fragments; weathers same cut i mile S. of Bottomless Pits. T 21 N, R9 E, color to pink 1.5 15.5 SW i sec. 16. 5. Concealed: slope 3.0 12.5 Top of hill: Recent erosion surface. 4. Limestone: very pale brown, silty; very fossiliferous (see Kaibab formation (Permian), Alpha member: Tables 1, 2); weathers same Feet From base color; forms ledge 6.0 6.5 22. Conglomerate: forms slope. Matrix: yellow limestone; Peb- 3. Siltstone: white, calcareous, bles: limestone fragments, ir- weak, sugary; locally contains regular in shape, up to 8 in 2.0 82.5 quartzgeodes 1.5 5.0 2. Limestone: very pale brown, 21. Concealed: slope 2.0 80.5 silty; fossiliferous (fragments); 20. Sandstone: very pale brown to forms slope 1.0 .J{ 4.0 yellow, very fine-grained; con- 1. Limestone: white, magnesian, tains coarse, rounded grains in silty; locally fossiliferous clusters; serves as marker bed (mollusk fragments); forms ("fish-egg" sandstone) 1.0 79.5 ledge 4.0 19. Concealed: slope 15.5 64.0 Total exposed 84.5 18. Limestone: brownish-yellow, aphanitic, silty; fossiliferous Base concealed by slope and valley alluvium. (abundant small pelecypods incl. Dozierella, Promytilus?); weath- BOTTOMLESS PITS (Fossil loc. 1). Partial section ers very rough and pitted, locally from sink up west side of valley. T21 N, R 8 E pink, mostly yellowish-buff; SW i sec. 17. forms weak ledges 4.5 '' 59.5 Top of hill: Recent erosion surface. 17. Limestone: light gray, aphanitic, Kaibab formation (Permian); Alpha member: very argillaceous, hard and com- Feel From base pact; forms slope, much 23. Limestone: very pale brown, concealed 11.5 48.0 dolomitic; weathers light brown 16. Limestone: very pale brown, to gray, rough; forms slope to top silty, magnesian; fossiliferous of hill 5.5 92.0 (abundant very small mollusk 22. Sandstone: pink, very fine- fragments); weathers silty, grained, silty; weathers gray to pitted; forms weak ledge 1.0 47.0 pink; forms ledge 2.0 90.0 15. Limestone: light brownish-gray, 21. Sandstone: white, very fine- magnesian; weathers gray, lo- grained; contains coarse rounded cally pink; forms slope, much sand grains scattered through- concealed 2.5 44.5 out; weathers gray, pitted, ir- 14. Limestone: very pale brown, regular; forms marker bed ("fish- magnesian; weathers pitted, egg" sandstone); forms weak silty; forms ledge 1.5 43.0 ledge 2.5 87.5 13. Limestone: very pale brown, 20. Dolomite: yellow to pale brown; aphanitic, dolomitic, silty; lo- weathers pale gray; forms cally grades to yellow siltstone; slope 2.0 85.5 forms slope with weak rounded 19. Sandstone: white, very fine- ledges 4.0 39.0 grained, silty; contains coarse 12. Limestone: white; weathers rounded sand grains in clusters white; forms rounded ledge 1.5 37.5 ("fish-egg" sandstone); forms 11. Limestone: very pale brown, weakledge 5.0 80.5 silty; forms slope, much con- 18. Limestone: reddish-yellow, silty; cealed, with weak ledges 4.0 33.5 contains coarse rounded sand 10. Limestone: light gray, mag- grains locally; forms very weak nesian; forms series of ledges ledge or slope concealed at base.. 4.5 76.0 i-2 ft. thick 2.5 31.0 17. Sandstone: reddish-yellow to 9. Concealed: slope 1.0 30.0 very pale brown, calcareous; 8. Limestone: light gray, mag- very fine-grained; weathers same nesian; like no. 10; fossiliferous color; forms weak ledges much (mollusk fragments) 2.0 28.0 concealed 3.0 73.0 7. Limestone: very pale brown, 16. Sandstone: pink, very fine- silty; like no. 11; locally fos- grained, silty; weathers gray, siliferous (mollusk fragments); rounded; forms weak ledge 1.0 72.0 contains small silica rods up to 15. Siltstone: very pale brown, J in. long; weathers pale brown; argillaceous, calcareous; forms forms slope 11.0 17.0 slope 7.5 64.5

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Chemical analyses of rock from the four forms are not well enough preserved for specific zonules also reveal that, although at localities identification. 1 and 2 the nature of the rock is very similar, Correlation of the Alpha , member of the the limestone at locality 3 differs considerably Kaibab with lower Word is suggested by the in proportion of magnesium and silica. The strong resemblance of such pelecypods as silica is largely secondary, and occurs as cavity Kaibabella curvilenata, Astartella subquadrata, fillings. It is not indicative of increased and Grammatodon politus, and such gastropods sandiness. as Retispira undulata, Warthia sp., Worthenia Study of the collections has added to and corrugata, Stegocoelia quadricostata, Euomphalus made many changes in Nicol's list (1944, p. kaibabensis, Glyptospira cristulata, Orthonema 555), and new data have been obtained. striatonodosum, and Oncochilus insolitus. Molluscan species identified by the writer are Gastropods and pelecypods are, in general, listed in Tables 1 and 2, with approximations represented by small individuals, usually less of their relative frequencies in the four faunules than IS mm. in greatest dimension. In each under discussion. Frequency was determined faunule, however, one or more large forms oc- by a survey of the collections and by actual cur. At locality 1, bed 2, an occasional counts taken from random blocks of rock. Allorisma terminate or Aviculopecten kaibabensis The fauna of the four beds is dominantly stands out in contrast to many tiny forms. At molluscan, with gastropods and pelecypods locality 1, bed 9, the prominent large form is leading in both diversity and abundance. Allorisma terminate, and Aviculopecten Scaphopods, nautiloid cephalopods, and tri- kaibabensis, Aviculopinna sagitta, and Murchi- lobites vary in their distribution, and bryozoans sonia geminocarinata also reach considerable occur only as small fragments. Brachiopods are size. Bed 4 at locality 2 is dominated by the fairly abundant at localities 1 and 2, but are large brachiopod Dictyoclostus bassi. At locality limited in variety. They occur only excep- 3, large and perfectly preserved specimens of tionally at locality 3. A few crinoid arm plates Bellerophon deflectus are common. Fragments of occur at locality 3, but no other echinoderm nautiloid cephalopods at locality 1, bed 9, remains are known. and at locality 3, suggest that these forms were Because of poor preservation and scarcity of probably the largest hard-shelled animals in bryozoans and cephalopods, they are not de- the Kaibab Alpha sea. Large specimens must scribed here. Brachiopods from the western have had a body chamber diameter of several part of the Kaibab, including many forms inches. known from the present localities, are described In the lower faunule (bed 2) at locality 1, by McKee (1938). Trilobites from locality 1 the dominant forms are Astartella subquadrata, were discussed by Snow (1945). Pleurophorus albequus, and Palaeonucula levati- Thirty-seven gastropods are discussed in the formis. Gastropods, although varied, occur present paper, belonging to at least 24 genera. only in small numbers. Pelecypods abound, but Two forms could not be assigned generically. are more limited in variety. Three new genera and 22 new species are de- In bed 9, at locality 1, the fauna is markedly richer. Both pelecypods and gastropods are scribed; 13 forms are not assigned specifically. abundant and varied, and Plagioglypta canna None of the gastropods have previously been is also common. Individuals of almost all the described. The Kaibab gastropod fauna is species are larger and perhaps more mature than markedly unlike most other Permian faunas of at other localities. Fossils appear less frag- southwestern United States, being similar only mentary than in the other beds. Although to an as yet undescribed fauna from Word lime- almost or entirely absent in other faunules, stone no. 1 at the type locality in west Texas. high spired gastropods such as Murchisonia The pelecypods also bear a resemblance to geminocarinata are present at this locality and the fauna of Word limestone no. 1. Twenty-six sometimes reach considerable size. The large forms are recognized, representing 22 genera. pelecypod Allorisma terminate commonly oc- Only 8 of the forms are new species, however; curs in groups, as does Plagioglypta canna. 13 species have been described before and 5 Brachiopods are common, but do not dominate

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the fauna. A number of cephalopods have been measured, but for ancient seas, represented collected from this horizon, and trilobite pygidia today only by marine sediments and fossils, are fairly common. exact measurements are not available. A pic- Locality 2, bed 4 is exceptional in its almost ture of the ancient environment can be ob- complete lack of gastropods, as well as in the tained only by summation and interpretation abundance of the large brachiopod Dictyoclostus of information gleaned from the fossils and bassi. Many elements of the pelecypod fauna sediments. are obviously juveniles. The gastropod Retispira A comparison of fossil genera from the undulata may also be represented only by Kaibab with recent related animals of similar juveniles, as larger individuals, seemingly of form and structure supplies many clues to the the same species, are known from collections nature of the ancient environment in which from the Word limestone now at U. S. National the fossils lived, assuming that in most cases, Museum. Another unusual feature of this at least, an animal of today lives in an environ- faunule is the complete absence of Astartella ment more or less similar to that inhabited by subquadrata, which is exceptionally abundant its close relatives of the past. Accuracy is, of in the other three faunules, and has been recog- course, limited by the only distant relationship nized in quantity in many beds of the Alpha between Kaibab and modern forms. member. Paleoecological interpretations of this nature At locality 3 the fauna is diversified and are also limited by the amount of data available abundant, containing pelecypods and gastro- on living forms. Most studies of marine ecology pods in almost equal number. The absence of place emphasis on biologic factors, and although brachiopods is noteworthy, though Dictyo- these are also considered here, they are difficult clostus bassi has been found occasionally. of interpretation in fossil faunas. Biologic The gastropod Glyptospira cristulata is more factors do not seem less important to an under- common here than elsewhere. This is the only standing of the fauna than physical factors, locality at which echinoderm remains have been but data of marine biological researches are not found: numerous crinoid arm plates and a few available in a form convenient for the geologist, columnals were obtained from the siliceous and a synthesis of what is known of environ- residue. ments and their effects on animals is badly In summary: the four zonules all contain needed. molluscan assemblages, but the composition of Another limitation on inferences of past en- the faunas varies rather widely. This variation vironment from analogy with modern forms probably parallels a variation in environmental lies in the fact that transportation after death conditions, physical or biological, but may be is a common occurrence on any sea floor where partly due to a variation in time. Genera current or wave action is present. Within common to all three faunules are thought to the Kaibab Alpha, however, evidence of such represent hardy forms tolerant to a greater action is lacking, and shells are not believed to range of environment, while those present have been transported far from their original within only one or two faunules are absent else- habitat. The two valves in pelecypods are fre- where because conditions were not quite favor- quently not separated, and the presence of able. By an analysis of the physical environ- broken and fragmentary shells, though sugges- ment as recorded in the rocks and fossils we tive of agitation, may be attributed largely may hope to ascertain the nature of the Kaibab to the activities of predators, scavengers, and Alpha seas, and the similarities and differences other burrowing animals. of the environment of deposition of the four Certain features of the fauna as a whole indi- faunules under discussion. cate characteristics of the environment. The small size and delicate ornamentation of indi- Paleoecology viduals of several groups, for instance, is In any study of marine environments, many thought to indicate a mode of life contrasting ecological factors must be considered. In with that of large, thick-shelled, smooth-shelled modern seas most of these factors are easily individuals which occur in the same faunule.

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Thickness of shell, general size and shape, and spicules. There does not seem to be more sand characters of ornamentation might be useful in or silt present in residues from locality 3 than determining depth, temperature, and other in those from localities 1 and 2. factors, but here again lack of tabulation of It is obvious that the Plagioglypta faunule biologic knowledge for use in geological research at loc. 1, bed 9, existed in an environment is evident. containing less insoluble detrital material than Although geologists are not all agreed on did the other environments. the conditions of deposition of certain types of The evidence for a bottom composed of fine marine sediments, some aspects of sedimenta- muds is supported by a study of some of the tion serve as excellent guides to an understand- fossils. The abundance of fossils in itself may ing of paleoecology. Ecological factors inferred be significant, as a mud bottom supports a from the sediments are turbidity, agitation, larger number of individuals than does any nature of the bottom, temperature, and, to a other type. Nucula, modern relative of the limited extent, depth and distance from shore. Permian form Palaeonucida leoatiformis, bur- Using all available information, it has been rows in fine sand or silt, feeding below the possible to draw the following conclusions re- surface, and Nuculana, present in both Permian garding the environment of the Kaibab Alpha and modern seas, also prefers a mud substratum fauna, represented by the four faunules listed (Yonge, 1939, p. 82, 83). The presence of the above. long-spined Dictyodostus bassi, as well as other BOTTOM: The nature of the rock suggests that spine-bearing brachiopods, likewise suggests a the sea floor was covered by a calcareous mud. muddy bottom, as indicated by Cooper's ob- Examination of thin sections from the four servation (1937, p. 45) that productids were localities indicates that this mud was largely supported above a mud bottom by their spines, made up of broken and finely particulate shell in such a manner as to keep their margins above material, with perhaps a minor amount of the mud. Cooper also observed that genicula- chemically precipitated calcium carbonate. The tion of the shell, common in productids, in shell fragments were probably derived frem similar manner served to keep the margin of animals living on and in the mud, and include the shell above a mud surface. Modern fragments of foraminifera. The shells are scaphopods are known to burrow in mud, and thought to have become broken through the it is likely that Permian forms did also. The action of burrowers and scavengers rather than selenizone of Bdlerophon deflectus probably through wave action, as there is no evidence of supported a siphon, which was extended above sorting. the surface as the animal moved in the mud. Treatment of samples from the four zonules Cydic development of dolomitic, fossilif- with dilute HQ has yielded residues in the erous limestones alternating with silty, non- following proportions. fossiliferous limestones indicates a periodic variation in the composition of the bottom Loc. 1 Loc. 1 Loc. 2 Loc. 3 muds. The silty limestones probably represent bed 2 bed 9 bed4 changes in depth and nearness of the strand line. Occurrence of abundant similar silty lime- % insoluble (by 6.4 2.7 5.8 30.0 stones in the Beta member suggests that they weight) 6.6 1.6 5.1 32.6 represent deeper water than do the dolomitic limestones. Although their present silty texture The residues are composed largely of fine might suggest origin close to shore, shell mate- white silt with an admixture of day. The clay rial mduded in the dolomitic limestones formed at loc. 1, bed 2, and loc. 2, bed 4, is grayish a much coarser dastic. brown, and in bed 9 at loc. 1 it is orange-brown, DEPTH: A shallow-water environment (less appearing in all three cases to have caused than 100 fathoms, often less than 200 feet) is the color of the rock. The residue at loc. 3 is suggested by Cooper for Paleozoic epicon- made up almost entirely of silicified shell tinental seas in general (1937, p. 38). There is material, irregular particles of chert, and sponge considerable evidence supporting a shallow-

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water origin for the Kaibab Alpha member. evidence that the sea was shallow. Gastropods The sea in which the Kaibab formation was and pelecypods are known to be relatively rare laid down transgressed from the west, and the or absent in seas of today over 80 or 100 land over which it came was low and level fathoms in depth. Nomura and Hatai (1936) (McKee, 1938, p. 147-150). In the open sea, have listed depths of several forms which are pure, thick-bedded limestones were laid down; represented in the Kaibab Alpha by related nearer shore, the limestone became silty and forms. Pectens were observed to range from then dolomitic, and finally gave way to sand- about 50 to 225 meters, scaphopods from 50 to stone of eolian origin. Even during the maxi- 215 meters, and Nuculana from 160 to 220 mum advance of the sea, the strand line could meters. Nitcula and Natica, modern relatives not have been more than 70 miles east of the of Nuctdopsis and Naticopsis, were dredged Walnut Canyon region, though the sea may from 84 meters. Newell's examination of the have extended farther southeast. As the sea environments in which Mytilacea live today retreated, while the Alpha member was being led him to state that "Late Paleozoic Mytilacea deposited, the strand line migrated westward favored the shallow-water near-shore habitats so that the shore line progressively approached like those preferred by the majority of modern the Walnut Canyon area. With the approach Mytilacea" (Newell, 1942, p. 14). Modern of the shore, there must have been a corre- scaphopods usually live in fairly deep water, sponding decrease in depth, which could at no but their range is from two to more than 2400 time have been very great because of the flat- fathoms. Shimer and Shrock (1944, p. 521) ness of the land. believe that fossil species probably lived at Dolomitic limestones containing fossils sug- moderate depths. gest accumulation on the bottom of very Negative evidence may be found in Agassiz's shallow seas, and the low proportion of insolu- observation that calcareous and horny sponges ble elastics and lack of indication of agitation are replaced below 100 fathoms by siliceous suggest that the limestones may have been sponges. The presence in the Beta member of deposited in partially land-locked basins. Con- chert nodules often formed around sponges, ditions controlling the formation of dolomite and the absence of these cherts in the Alpha, are subject to much disagreement, but it is may be due to the difference in the depth at believed that dolomitic limestones of the which the two members were deposited. Sili- Kaibab formation definitely originated in ceous sponge spicules occur in the insoluble shallower water than did purer limestones residue from locality 3, but whether they farther west. This conception is supported by indicate a deeper water origin for the fossil- the relative position of dolomitic limestones in bearing rocks there is doubted, as other fossil the stratigraphic section: they cocur near the forms closely resemble those from the other base and top of the section, in members Gamma localities. and Alpha, which represent the incursion and Several authors have related thickness and withdrawal of the seas. Dolomitic limestones size of shells of mollusks and brachiopods to do not occur in the Beta member, which rep- depth. Thickness of shells of the Kaibab fossils resents the greatest advance of the sea and varies greatly, and lack of sufficient evidence therefore was deposited at the greatest depth. one way or the other makes any generalization There was undoubtedly much fluctuation of in this respect uncertain. It may be noted here depth during the time of deposition of the that Allorisma terminale and Aviculopecten Alpha member, and it brought about cyclic kaibabensis seem to have possessed thin shells development of alternating beds of fossiliferous relative to their size, while the shells of small dolomitic limestone and nonfossiliferous, silty, forms such as Astartella subquadraia, Palaeonu- nondolomitic limestone. The silty, nondolo- cvla leoatiformis, and ManzaneUa cryptodcntata, mitic limestones occur more abundantly sea- in contrast, appear to be thick. ward and seemingly represent somewhat On a basis of the evidence here presented, it deeper water than the dolomitic limestones. is thought that fades 3 and 4 of Kaibab The nature of the fauna supplies further Alpha, represented by the four zonules exam-

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ined, were deposited at a depth not greater tions of eolian sands landward from these than 500 feet. If, as suggested below, the formations. animals lived in a seaweed "forest," the depth AGITATION: There is no evidence in the four must have been less than 100 feet. fossil horizons of heavy wave or current action. BIOLOGICAL FACTORS: It is practically impos- The low proportion of land-derived clastic sible to learn anything certain about the part material in the limestones, particularly hi that played by biological factors in controlling a of bed 9 at Bottomless Pits, supports an past fauna without direct evidence such as the hypothesis of the absence of pronounced presence of symbionts and parasites in their agitation. The complete absence of ripple normal relationship, or the presence of scaven- marks or cross-lamination in these beds does gers and predators. Unfortunately, little such not serve as evidence, as finely particulate evidence is at hand in the Kaibab Alpha fauna. calcareous mud, particularly when held in The nature of the molluscan fauna, however, position by shell fragments, would not support suggests the presence of a biological factor such features. which may have been quite as important as The delicacy of the spines of productids, as depth and bottom conditions. Both pelecypods well as of the shells of many mollusks, is good and gastropods are divisible into two groups: evidence for moderately quiet waters. Many of smooth-shelled, thick-shelled, often rather large the fossils are fragmentary, but this may be forms; and light, finely ornamented, delicate explained by the action of predators and the shells. These two groups may have existed in movement of other animals, and, without sup- the complex environment of a seaweed "forest," porting evidence, should not be accredited to the finely ornamented, delicate forms clinging wave and current action. It has also been to seaweeds and the heavier, smooth-shelled observed that fossil shells show evidence of forms burrowing and crawling in the mud stacking as though some rearranging of shells beneath. had taken place. This may have been caused It is true that seaweeds grow on a hard by a slight amount of agitation on the bottom, bottom which facilitates anchorage of their by the action of burrowing animals pushing holdfasts, but it is not inconceivable that, in aside empty shells, or by disturbance of the quiet water, either algae or marine grasses may water and bottom materials by action of have been able to grow in the muddy bottom scavengers or other animals of larger size. If of epeiric Permian seas. There is no positive seaweed "forests" sheltered the area, little evidence of the existence of seaweeds, but the strong wave action, except during periods of dual nature of the fauna suggests that they storm, is likely to have reached the bottom. It may have been present in abundance. The is thought, however, that slight agitation was warm, shallow waters of the Kaibab seas must, present, at least periodically, and was strong of course, have offered an environment favor- enough to stir up the flocculent bottom muds. able to plant growth. There is present in the lower part of the TEMPERATURE: The Kaibab sea was prob- Alpha member, as exposed in Walnut Canyon, ably fairly shallow, as postulated above. Also one bed containing ripple marks. This bed the water was doubtless fairly quiet, as indi- extends over the entire area under discussion cated below. At this latitude, assuming the and represents a time of bottom conditions climate to be similar to or warmer than that of today (as has generally been thought to be the unlike those during the rest of Kaibab Alpha case in the Northern Hemisphere during time. Strong agitation was present, but whether Permian time), a shallow, quiet sea would in the form of waves or currents is not ascer- attain a temperature somewhat higher than tained. that of seas of the same latitude today. Evi- Intraformational conglomerates at the top dence that the climate was probably warm is of the section indicate considerable current or given by gypsum deposits and associated red wave action. This is as might be expected, for beds in both Toroweap and Kaibab forma- the increasing shallowness and nearness of the tions, and by the presence of vast accumula- shore line as the sea retreated would permit

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wave action more and more to reach the of the Kaibab has previously been interpreted bottom. as dwarfing due to low salinity, but on careful TURBIDITY: From the sediments themselves, study the fauna appears not to be dwarfed, turbidity can be inferred only as a function of but rather to consist of an abundance of small the rate of sedimentation. A study of insoluble forms, adapted to some special mode of life, residues is not sufficient to determine the with a high frequency of juveniles. amount of turbidity. The limestone appears to The presence of nautiloids in faunas lacking have been laid down as a fine calcareous mud, ammonoids is thought by Miller and Furnish with a certain proportion of insoluble material. (1937, p. 61) to indicate a difference in eco- The presence of burrowing animals indicates logical requirements of the two groups, but that it remained fairly soft, at least in the whether the difference is one of salinity has uppermost few inches, and it is likely that a not been demonstrated. Modern cephalopods certain amount of flocculent mud on the sur- are extremely sensitive to reduced salinity, and face of the bottom would cause considerable Paleozoic forms may well have been, also. turbidity with the slightest agitation. There is no paleogeographical evidence that Evidence favoring this condition is given by the Alpha member of Kaibab was laid down in the absence of corals and the almost entire a basin isolated from the rest of the sea by a absence of bryozoans. The lack of fusulinids physical barrier, but it is probable that, lack and echinoderms may also have been caused of currents and other agitation contributing, by turbidity. there was a gradation in salinity from open SALINITY: Salinity of water in epicontinental sea to near-shore sea. seas is basically a function of climate, though At several sections in the Alpha member, other factors, particularly currents or up well- some beds contain faunas predominantly or ings of water, may influence it. entirely composed of one species, either It has been suggested that salinity of the SMzodus texanus or Pleurophorus cf. P. Kaibab sea in the vicinity of Walnut Canyon mexicanus. These faunas bear resemblance to was not "normal," but whether the water was modern occurrences of single, widespread brackish or highly saline was not determined species in regions of reduced salinity. They are (McKee, 1938, p. 137-139). Gypsum and red euryhaline forms, able to withstand wide bed deposits in certain parts of the Alpha changes in salinity, and so exist in almost member suggest an arid climate that should limitless abundance under conditions where have caused at least a periodic increase in their natural enemies are unable to live be- salinity of the waters of the shallow seas. It is, cause of the rigors of the environment. It is however, within comprehension that the probable that the Pleurophorus and SMzodus gypsum deposits were laid down in more or beds observed in Walnut Canyon, as well as less isolated basins or lagoons while the seas those reported by McKee (1938, p. 143), repre- represented by the Kaibab Alpha in the Walnut sent periods of much reduced salinity, perhaps Canyon region and at locality 3 received abun- due to the shifting of the mouth of a river but dant fresh waters from rivers and streams more likely attributable to the development of draining the adjacent land and so were brackish off-shore bars preventing free circulation of in nature. The presence of quartz grains may the water. be due to introduction of material by streams, CONCLUSION: The fauna of facies 3 and 4 of but could also be due in part or in whole to the Alpha member of the Kaibab formation, removal of sand and silt from beaches by composed largely of mollusks but with brachio- waves or wind. pods, trilobites, and bryozoa also represented, The nature of the fauna in many ways indi- developed in a warm, shallow, epeiric sea of cates that salinity may have been slightly nearly normal or slightly reduced salinity, not below normal. The limited number of classes very far from land. A gradual retreat of the represented is in itself evidence that salinity sea was taking place, a fluctuating retreat was not normal, though turbidity may also be probably only slightly modifying the depth of important in controlling animal types. The the sea. Agitation was at a minimum, but prob- reduced size of the gastropods and pelecypods ably was sufficient to stir the flocculent muds

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of the bottom. The land to the east was of low TABLE 1. — GASTROPODS, OCCURRENCE AND relief and the climate warm and possibly arid. FREQUENCY CHART Fine sands from the land were washed or ^=^=^== Loc blown into the sea in limited quantity only. It Loc. 1 Loc. Loc. bed bed 9 bed 4 is likely that seaweeds grew in abundance, and 2 that many of the small mollusks lived upon ______^_^_- them, while others burrowed in the silty, Aclisinaf bisulcata sp. nov.. xx clayey, calcareous mud of the bottom, mud Ananias franciscanus sp. composed primarily of fragmentary shells of nov xx dead organisms. Ananias gibber sp. nov x Bellerophondeflectussp.nov.. x x xx Systematic Paleontology Eotrochusfliratussp.nov.... x GASTROPODA Euconospira? cryptolirata sp. nov x The gastropod fauna of the Kaibab Alpha Ew)nphalus kaibabensis sp. differs markedly from any previously described nov x x fauna of the United States. It bears a strong Euomphalusf sp. juvenile.... x similarity, however, to an as yet undescribed Euphemites aequisulcatus sp. fauna from the Word limestone no. 1, and the nov x xx two formations are thought to possess a number Euphemites sp x of species in common. Girtyspiraf sp x Of the 37 forms here discussed, 3 new genera Glabrocingulumt coronatum and 22 new species are described. A chart of _, SP' n?v" 1 ,'";,'. * ., ... , , , j-.ii. Glabrocmgulum laevmratum the„ relative abundance of gastropod. s in .th . e sp. nov xx xx xxx collections from four faunules is presented in Glyptospira cristula(a gen. Table 1. et sp. nov x ? xx Abbreviations used in tables of measure- Goniasmaf sp x ments are as follows: cf. Lepetopsis x x h = height Meekospiraf sp. 1 x w = width Meekospira? sp. 2 x ha = height of aperture Mourlonia? canceUata sp. wa = width of aperture wh = number of whorls nov x mbw = minimum width of outermost whorl Murchisonm gemmocannata (in bellerophontids) sp. nov x xxx x hbw = height of basal whorl Murchisonia sp x aa = anical an \e Naticopsis kaibabensis nov xx Superfamily BELLEROPHONTACEA Naticopsis sp xx Family BELLEROPHONTTOAE OncochUusinsolitus sp. nov.. x Genu/-• s BetterophonD n ii. Montfor-\r ±c t^ 180ior,o8 Orthonemal striatonodosum .. sp. nov ? xx BeUerophon deflectus sp. nov. Orthonema sp. 1 x PI. l, figs. 2a-5b Orthonema? sp. 2 x „ , . , ...... Platyworthenia delicata gen. DESCRIPTION: Subglobose, spirally coiled, involute gastropods with width and height about equal, and „ .. J.' Vj",' ' ..,,.,,, , , , ,,n_ , , Retispira undulata sp. nov... x xxx with finalwhor l somewhat expanded. Whorls gently 0. .. ,•. flattened on sides and top, strongly arched between, Ste^coeha quadrtcostata sp. givin,.,..g shell a subquadrate. ...., shouldere. d cross-section, ,; otrianemattna0. . '"".'. pulchrelirata,",",'•"," profile nsmg in median dorsal region to a rounded ridge bearing the selenizone; umbilici deen and „, ,'. narrow. Apertur..,,..e broadly remform, ; anteno. r lip „Warthw, . .sp x , , , ... - j i . . . .. Worthema corrugata sp. nov.. x x convex between umbilici and selenizone in luveniles m , . „ becomin, g gentl.iy sinuou• s in earl,y maturit.y and, „Worthentaf . sfp , . . x rathe., r stronglf iy so i• n adul, ,tt shells, „ , th, e sinu. s corre- Genus et sp. mdet. 1 x

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TABLE 1.—Continued DISCUSSION: A series of growth stages, represented by the measurements above and by Figure 2, indi- Loc. 1 Loc. 1 Loc. 2 T,or, cate that although great variation in size is shown, bed bed 9 bed* 3 there is no sudden change dividing the series into 2 two or more groups. The slow decrease in the Genus et sp. indet. 2 X XX x—rare xx—common -80mm xxx—abundant spending with dorso-lateral shoulder of shell; median slit fairly deep, sharply defined in uneroded -60 specimens; flare in lateral lip evident in early growth stages, well developed in adults and reflexed over umbilicus but not filling it; parietal inductura smooth but thick, nearly obscuring selenizonal ridge and forming a strong humped callus within the aperture of mature specimens. Ornamentation absent; growth lines uneven in strength and usually clear; marginal lineation sharply denning selenizone; lunules arcuate, distinct, irregular in strength. Shell thick, especially in adults, reaching about 1 cm. in thickness in region of umbilicus in large specimens. Width/height ratio gradually decreasing during 60mm. ontogeny, so that young shells are as broad or broader than high while shells over 20 mm. in FIGURE 2.—RELATION OF WIDTH AND HEIGHT height are higher than broad. Shell increasingly OF APERTURE TO HEIGHT IN Bdlerophon deflectus thick with growth, especially in umbilical portions; parietal inductura becoming increasingly thick width/height ratio, the gradual development of the after shell reaches about 20 mm. diameter, becom- shoulder and its corresponding sinus in the lip, and ing very prominent at about 60 mm. the steadily increasing prominence of the parietal MEASUREMENTS: 21 specimens were preserved inductura show this to be an uninterrupted series well enough for measuring. Dimensions in mm.: representing a single species. This form is not difficult to distinguish from h w ha wa mbw w/h ha/h other species of the genus Bdlerophon, its shoulder flexure being diagnostic. Although it never attains 1. 76. 5± 72.0 25.7 42.0 34± .94 .34 the large size of Walcott's B. majusculus, it closely 2. 71. 0± 67.0 26.5 42.0 34± .94 .37 resembles that species but has a more elevated 3. 67.6 59.1 30.0 .88 4. 58.0 40± selenizone, a dorso-lateral shoulder, and a lip more 5. 63± 55.5 27± .88 widely flaring in the umbilical region. The thick 6. 44.6 37.0 14.0 23.8 .83 parietal inductura diagnostic of B. majusculus is 7. 42.0 43± 18± 30.5 24 1.02 .43 8. 38.0 J36± 15.0 26.8 20.0 .95 .40 present here, but not so sharply delineated and 9. 29.2 28 + 11.0 21.0 17.5 .96 .38 seemingly thinner than in that form. In proportions 10. 21± 22± 7 14 11.8 1.05 .33 a Bellerophon called B. majusculus by Girty (1909b), 11. 18.7 16.0 9.0 15.0 10.1 .86 .48 from the Yeso and San Andres formations, is like 12. 17.5 19± 6.5 15.0 10 1.09 .37 13. 17.0 16.0 17± 9± .94 the Kaibab form. Although his figure shows a wider 14. 15.4 J18.0± 5.5 11.7 10.7 1.17 .36 selenizone and does not show a strong shoulder 15. 13± !l2.5 7.0 .96 angulation, it is possible that the two are con- 16. 13 113.5 5.5± 1.04 17. 11.6 10 3.5± 7± 5.3 .86 .30 specific. 18. 10.0 10.0 3.5 7.7 5.2 1.00 .35 B. blanfordianus Waagen, from the Productus 19. 9.0 7.0 3.8 .78 limestone of the Salt Range, has a shoulder and a 20. 9.0 8.0 3.0 5.8 4.9 .89 .33 21. j 6.8 7.0 2.0 4.7 4.1 1.03 .34 corresponding sinus, but appears not to have the thick parietal inductura developed in B. deflectus. TYPES: Holotype: Mus. Northern Ariz. G2.472. Paratypes: Mus. Northern Ariz., Grand Canyon OCCURRENCE: Loc. 3 (common, silicified); loc. 1, Nat. Park museum. beds 2, 9 (rare, fragmentary external molds).

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Genus Euphemites Warthin 1930 Euphemites sp. Euphemites aequisulcatus sp. nov. PI. 2, fig. 2 PI. 1, figs, la-c A single crushed and somewhat fragmentary specimen of a large Euphemites differs from the DESCRIPTION: Involute, spirally coiled gastropods preceding form by its much greater size and by the of small to medium size, with whorls rapidly and fact that each revolving lira is flat-topped and regularly expanding. Whorls rounded rather evenly, bears a minute furrow along its crest. Interspaces though occasionally flattened along median line between lirae are shallow and flat-bottomed. toward the aperture; umbilicus closed on either MEASUREMENTS: Width 40 mm. ±; height 40 side by thickened corner of outer lip. Aperture mm. ±; height of aperture 14 mm. transverse and flatly reniform, about same height at sides as in center; outer lip not preserved except DISCUSSION: No Permian species of Euphemites at lateral margins, where it is thickened and pro- is known which shows flat-topped, furrowed lirae duced into a decided flare; evidence of selenizone such as are seen in this form. The specimen at not apparent; parietal inductura extending over hand, while well enough preserved to show thatfit most of body whorl, marked with lirae. is distinctive, is partly imbedded in insoluble Ornamentation 12-22 fine, irregular lirae on chertified limestone in such a manner that complete parietal inductura, closely and regularly spaced in description is not possible. center but not clearly marking position of selenizone; lirae fading out gradually so that last third of outer OCCURRENCE: Loc. 3 (rare, silicified); the single specimen is at Grand Canyon Nat. Park museum, whorl is smooth; growth lines not visible. FK 704. MEASUREMENTS: Only four specimens were preserved well enough to permit measurement. These Genus Retispira KNIGHT 1945 were broken around the outer lip. Dimensions in mm.: Retispira undulata sp. nov. PI. 2, figs, la, b h w mbw ha DESCRIPTION: Involute, spirally coiled, globose 1. 20± 20+ 12 (holotype) gastropods of medium size, with whorls regularly 2. 13.8 14.8 7 4 expanding and not flaring at the aperture; height 3. 13.6 13+ 7.2 3.5 4. 11.2 12 5 3 approximately equal to width. Whorls evenly rounded and without angulation at the selenizone; TYPES: Holotype: Mus. Northern Ariz. G2.1606. umbilical openings narrow and deep. Aperture Paratypes: Mus. Northern Ariz., Amer. Mus. Nat. reniform in cross-section; outer lip thin, with narrow Hist., Grand Canyon Nat. Park museum. sinus of moderate depth generating clearly defined DISCUSSION: This form bears a strong similarity selenizone flush with shell surface; posterior lip to shells which have long been recognized as E. with thin, unornamented parietal inductura extend- carbonarius (Cox), a species no longer considered ing slightly out of aperture and completely covering ornamentation of previous whorl; inductural margin valid (King, 1940, p. 151) as the type material is lost. Girty in describing "E. carbonarius" from the thin, concave and irregular; on the holotype, $ Wewoka formation suggests more variability and small, low nodes, arranged in a triangular pattern, intermittency in the lirae than is evident in the and an excentric ridgelike structure visible on one side of the inductura appear to be part of the specimens at hand, but it is likely that his forms are very similar to the Kaibab form. inductural structure, but, as their occurrence can only be noted on that single specimen, their nature The present form differs from Pennsylvanian is not known for certainty. species in its globose shape, the absence of an apertural callus or coinductural layer, and the Ornamentation of spiral lirae, spaced about 10 in absence of diagonal marginal lirae and nodes. 3 mm.; absent on selenizone; lirae varying in Several Permian forms have been described which strength, every second or third being somewhat lack nodes or median carination, most of them dif- stronger than those between, probably because of fering from the present form in number and nature increase in number of lirae by insertion; selenizone of lirae. E. subpapillosus (White), described from bounded by fine, sharp lirae, only locally visible the Kaibab formation, is distinguished by the pres- and seemingly mostly eroded; under magnification ence of papillae along the revolving carinae. 2 very obscure, fine lirae may be seen on selenizone, but these are usually obscured by erosion; trans- OCCURRENCE: Loc. 3 (common, silicified); loc. 1, verse lirae forming narrow, arcuate undulations bed 2 (rare, external molds). about 1 mm. apart, concave forward on each side

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of selenizone and forming somewhat less well de- Ornamentation lacking; growth lines cannot be nned, undulate lunules on selenizone. seen. MEASUREMENTS: Of the few specimens available, MEASUREMENTS: Only four specimens were col- all preserved as external molds, measurements lected, all of them incomplete. Dimensions in mm.: could be made of only two. As far as can be judged by fragmentary specimens, the shape appears to be h W ha fairly constant, though the two specimens measured are among the smallest in the collection. The size range is more fully represented by consideration of 1. 20+ 19.5 a large, fragmentary specimen having a width of 2. 18.1 16± 5.0 about 40 mm. The smallest shell identified with 3. 15.5 14± 4± this species has an estimated height of 9 mm. 4. 11.3 10.9 3.0 w h DISCUSSION: This form does not closely resemble any described American species of Warthia, although 1. 71. 5± 18.0 (holotype) it has approximately the proportions of W. breri- 2. 12. 5± 14 sinuata Waagen from the Salt Range. There is an undescribed form in the Word limestone no. 1 with TYPES: Holotype: Mus. Northern Ariz. G2.2959. similar proportions, but with a median ridge, absent Paratype: Mus. Northern Ariz. G2.2794. on the Kaibab form. Although these four specimens doubtless repre- DISCUSSION: Possession of a smooth parietal sent a new species, the fragmentary nature of the inductura and absence of a median internal carina material does not permit an adequate character- distinguish this form from Bucanopsis and place it ization. in the genus Retispira. The species is similar to R. modesta (Girty), being distinguished by its undulate OCCURRENCE: Loc. 3 (rare, silicified). transverse ornamentation and the selenizone flush with the shell surface. Also it is twice the size of Superfamily PLEUROTOMARIACEA Girty's shells. Still closer resemblance is shown with R. textilis (Hall). Family PLETJROTOMARITDAE The Kaibab shells have characters of juvenile Genus Ananias Knight 1945 Bellerophontids, in their globose shape and lack of the flaring hp typical of adults. Ananias franciscanus sp. nov. Undescribed collections at National Museum PI. 2, figs. 5a-6 include forms from Word limestone no. 1 which may be adults of this form. They are much larger, DESCRIPTION: Small, moderately high-spired, with undulations more fully developed as their size turreted pleurotomarians of 6-8 or more gradually increases. The larger fragments at hand from the expanding whorls, with a pleural angle usually be- Kaibab collections do not, however, show such tween 30° and 40°, lower in the most fully developed pronounced development of undulations. specimens. Suture slightly impressed, lying at or just below first basal costa; profile below suture OCCURRENCE: Loc. 2, bed 4 (common, external sloping outward only very slightly to form a steep molds). sigmoidal shoulder, convex above and concave below, to upper of 2 carinae; a strongly concave, Genus Warlhia Waagen 1880 fairly broad selenizone between 2 prominent Warthia sp. carinae, the lower of which is peripheral; below periphery, flank is strongly concave, slightly wider PI. 2, figs. 3a-l than selenizone, and sloping inward to a poorly DESCRIPTION: Involute, spirally coiled gastropods denned angulation limiting the base; base rounded, of small to medium size, having a somewhat globose anomphalous or narrowly phaneromphalous. Aper- shape, and showing no evidence of a flare at the ture obliquely oval, its widest point near the aperture. Whorls evenly rounded, most strongly middle; outer lip directed obliquely backward, with curved at or near mid-line and flattening slightly gentle sinuosity, from suture to selenizone, there on flanks; involution completely covering umbilicus. forming a slit of probably only moderate depth; lip Aperture reniform in cross-section, more than twice arching forward very slightly below selenizone, then as wide as high; outer lip with a median sinus of becoming vertical across flank, and seemingly moderate width and depth, not producing a sele- slightly concave between outermost few basal nizone; parietal inductura absent. costae, but in general directed radially with slight

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forward concavity across the base; columellar lip scribed and figured by White as Plewotomaria slightly flaring, reflexed; parietal inductura very grayvillensis Norwood and Pratten, was collected thin at aperture, though thick enough further by Gilbert from the Kaibab limestone south of within whorl to conceal ornamentation of preceding Pipe Springs, Arizona. It has a lower spire, and, to whorl. judge from White's figures, a somewhat differently Ornamentation of revolving costae and lirae; shoulder with many fine lirae, 2 or 3 above center being more prominent than the others; 1 or 2 very - lOrtim- fine lirae, often obscured, on selenizone; concave flank with 3 or 4 very fine lirae, often obscured, and with a single fine costa just above the regularly spaced basal costae; basal costae prominent, 7 or, more usually, 8 in number, becoming successively more closely spaced toward umbilicus, and separated by broad concave areas; growth lines fine but usually distinct; lunulae somewhat coarser than growth lines. Nucleus of about 2 smooth whorls; selenizonal carinae appearing as first spiral ornamentation, followed almost simultaneously by most prominent of the shoulder lirae, flank costa, and most of basal costae; basal costae all forming during early development and then apparently remaining constant in number. 30' MEASUREMENTS: Fourteen well preserved specimens offer fairly complete dimensions (in mm.) of this form: FIGURE 3.—RELATION OF WIDTH AND PLEURAL i ANGLE TO HEIGHT IN Ananiasfranciscanus h W ha I wa w/h * c wh placed selenizone than the present species, but 1. 10.6 5.4 3.7 3.0 .51 33° 8 8+ 2. 10.5 5.8 4.0 3.3 .55 34 8 7+ striking similarity in its ornamentation makes 3. 10.3 5.5 3.9 3.0 .53 35 7 5*+ relationship obvious. 4. 9.2 4.9 3.2 2.4 .53 33 7 7+ No other described forms resemble Ananias 5. 8.8 4.2 3.0 .48 26 8 6+ franciscanus. 6. 8.5 5.1 .60 30 6+ 7. 6.4 3.1 .48 34 8 5*+ 8. 6.0 3.4 2.4 1.9 .57 42 7 7+ OCCURRENCE: Loc. 3 (common, silicified). 9. 5.2 3.1| 2.0J 1.7 .60 43 j 8 6+ 10. 4.6 2.8l 1.8 1.4 .61 41 8 7+ Ananias gibber sp. nov. 11. 4.2 2.6i 1.7 1.5 .62 12. 4.2 2.2 1.7 .52 38 7 6 PI. 2, fig. 10 13. 4.0 2.5 .62 40 8 14. 2.2 1.4 .6 .64 42 7 5 DESCRIPTION: Shell of moderate size; whorls turbinate, turreted, regularly expanding. Suture c = number of basal costae strongly impressed; shoulder profile strongly sig- An increase in height relative to width, due to a moidal in younger whorls, sharply convex just below change in pleural angle during ontogeny, is shown suture and gently concave below this, flattening in Fig. 3. out as it approaches selenizone; convexity just below suture relatively reduced in last whorl; TYPES: Holotype: Mus. Northern Ariz. G2.1595. Paratypes: Mus. Northern Ariz., Amer. Mus. Nat. selenizone concave, bounded by fairly sharp Hist., Grand Canyon Nat. Park museum. carinae, tie lower of which protrudes strongly below the upper; whorl profile concave immediately DISCUSSION: Although much more highly spired below selenizone and then becoming convex again, than other reported species of Ananias, this form the convex portion protruding as far or farther bears such pronounced similarity with A. whitei than lower selenizonal carinae and forming periphery Knight, to which it is undoubtedly related, that it of shell; flank separated from base by an obscure cannot well be placed in any other genus. It possesses angulation on lower portion of peripheral convexity; all the characters of the genus. A. whitei, first de- base seemingly flattened or gently convex; umbilical

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region unknown. Outer lip directed backward with turreted than that of either A. wannensis or A. gentle sinuosity to selenizone; slit seemingly of gibber. moderate depth, with distinct lunules; lip directed forward immediately below selenizone, then almost OCCURRENCE: Loc. 1, bed 2 (one external mold). straight, with very slight backward obliquity and forward convexity to lower obscure angulation, at Genus Euconospira Ulrich 1897 which it arches backward and continues across base with forward concavity as far as visible; inner lip Euconospira ? cryptolirata sp. nov. unknown. PI. 2, figs. 11, 12 Ornamentation fine, somewhat irregular revolving lirae on shoulder and sides, spaced about 0.1 mm. DESCRIPTION: Shell of moderate size, trochiform, apart; every second or third lira stronger on convex of about 6 gradually enlarging volutions. Sutures portion of sides; liration much finer on base than shallow, impressed, lying at lower edge of selenizone elsewhere, and difficult to follow although the in apical whorls, slightly below selenizone in adult directional pattern is visible; growth lines distinct whorls; profile of shoulder convex just below upper and often fasciculated, the bundles or crenulations suture and concave from half way down shoulder thus produced tending to form radially elongated to peripheral margin; periphery with a narrow nodes below suture, especially in younger whorls; selenizone bounded by lirae, the lower of which on the last whorl the crenulations become quite marks shell periphery; whorl profile below selenizone distinct on the shoulder and especially on sides and turning inward strongly, with an obscure angulation base, and form slight beads at intersections with occurring some distance below periphery; base only revolving lirae. slightly flattened, strongly convex toward umbilical Nucleus unknown; convexity below suture be- region; umbilicus probably present, though nature coming less pronounced in last whorl, with corre- of umbilical region is not fully known. Aperture sponding reduction in radial nodes; crenulations incomplete; outer lip, as indicated by growth lines, resultant from reticulation of growth lines becoming leaving suture with a backward obliquity of about more pronounced in last half of final whorl, espe- 50°, then curving with a still greater backward cially on sides and base. obliquity to a narrow slit which forms a selenizone in which growth lines are lunulate; lip projecting MEASUREMENTS: Only one specimen is known, below selenizone with strong forward obliquity for an incomplete external mold. Measurements of it are in part estimated: height 11.5 mm. + ; width a short distance, then arching backward, with 13.5 mm. ±; pleural angle about 90°. strong forward convexity, toward umbilical region; inner lip unknown. TYPES: Holotype, an external mold of the final Ornamentation, low and somewhat obscure 3i whorls: Mus. Northern Ariz. G2.2968. revolving carinae bordering selenizone; many faint DISCUSSION: In general shape, the presence of revolving lirae on upper surface of whorl, spaced carinae bounding the selenizone, and the fasciculate about 12 per mm.; revolving lirae of lower surface growth lines which form beading at intersections of same magnitude but less distinct; selenizone with revolving ornamentation, this form appears to ornamented with finer spiral lirae, numbering belong to the genus Ananias. The lower carina about 15 where selenizone is 1 mm. in width; growth bounding the selenizone protrudes well beyond the lines fine. upper, however, so that the selenizone is more or Ontogenetic variation is seen in position of less continuous in profile with the shoulder, while suture, which lies in the first 3 whorls just on in the genotype of Ananias it protrudes only "very periphery of whorl above, and in later whorls slightly." The pronounced bulging on the lower slightly below periphery. part of the whorl is not characteristic of other MEASUREMENTS: Only two specimens are known, examples of the genus, nor is the strong sigmoidal both about the same size, and both incomplete. curvature of the upper surface on all but the last Measurements are approximations drawn from a whorl. study of both specimens (in mm.). In shape and size this form is most nearly com- height 24± parable to A. wetteri (Newell) and ^4. wannensis width 19.5± (Newell), differing from both of these primarily in height of last whorl 12.7 the sigmoidal profile of the shoulder and side. In height last whorl above periphery 6 ornamentation it is rather similar to A. wannensis, not possessing the pronounced beading shown by A. TYPES: Syntypes: Mus. Northern Ariz. G2.545 welleri. The spire of A. welleri is more strongly and G2.547.

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DISCUSSION: On the basis of its trochiform shape Glabrocingulum laeviliratum sp. nov. and the presence of a narrow selenizone just above PI. 2, figs. 7-9b the lower suture, this form is placed in the genus Euconospira. The base is considerably more convex DESCRIPTION: Shell small, turbinate, composed of than is usual for the genus, however, the measure- 4-6 whorls, usually somewhat wider than high but ment of the final whorl below the selenizone being quite variable in this respect; spire moderately low;

-8 mm

% <:

-4

2 8mm. FIGURE 4.—RELATION OF WIDTH AND PLEURAL ANGLE TO HEIGHT IN Glabrocingulum laeviliratum

about equal to that above. In this regard the form pleural angle generally of QO^lOO" but varying appears to be intermediate between Euconospira widely. Whorl profile gently convex immediately and Mourlonia. Astonishing similarity is shown to below suture, then gently concave to periphery so the Ordovician genus Palaeoschisma Donald. that profile above periphery is sigmoidal; profile The present species differs from Euconospira turning sharply vertical at periphery and having a obsolete Girty in its weaker growth h'nes, of equal broad, concave median band just below shoulder; strength on the upper and lower portions, in the strongly rounded below; base with moderately wide faintness of its spiral ornamentation, and in the umbilicus; sutures well defined and lying usually sigmoidal curve of its shoulder profile. It is similar just below median band of preceding whorl. Aper- to E. turbiniformis (Meek and Worthen), but has ture almost circular, usually very slightly higher than wide, and slightly concave on upper, inner many more and finer revolving striae and a convex side; outer lip thin, with a slit generating a concave base. selenizone just above periphery of whorl; upper OCCURRENCE: Loc. 1, bed 9 (two external molds). margin of lip directed backward as far as slit; below slit, lip curves gently backward to lowest part of whorl, where it is continuous with inner lip; Genus Glabrocingulum Thomas 1940 inner lip narrow in young specimens, thickened and apparently reflexed slightly over umbilicus in more The genus Glabrocingulum differs little if at all adult individuals. from Raphistomella Kittl 1891, a Triassic form, and Ornamentation fine revolving lirae, often indis- may be either identical with or ancestral to it. A tinct above selenizone, usually quite distinct and complete analysis of the genotypes would be neces- fairly widely spaced below median band but more sary to reveal relationships of the two genera. closely crowded toward base of whorl; lirae on base

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tending to form a cancellate pattern with growth that genus, and nuclear characters of the genus are lines, but not forming nodes; growth lines fine, present. In details of ornamentation, however, this directed sharply backward from suture to selenizone, species does not agree with the original definition gently concave forward across slit, then directed of Glabrocingidum, which includes nodose orna- forward for a short distance below selenizone before mentation on the basal portion, the spiral lirae continuing slightly backward to base of shell. forming tiny beads where they cross growth lines. Protoconch about 0.1 mm. in diameter; first 2 As such fine details of ornamentation have usually whorls lacking ornamentation, next whorl bearing been considered specific characters in gastropods, it fine revolving lirae; angulation and selenizone ap- is thought advisable here to consider the genus as pearing in fourth whorl; no perceptible change in including forms of similar shape which do not bear proportion during growth (Fig. 4), although pleural such nodose ornamentation. angle tends to become smaller as shell increases in G. lamliratum may be related to Girty's species size. "Baylea" euglyphea, from which it differs primarily in its smaller size. It also has a sharper angulation MEASUREMENTS: An abundance of good speci- at the shoulder than is shown in Girty's figure, and mens, with individuals of all stages of develop- many specimens show the presence above the ment, was on hand for measuring. Dimensions in mm.: shoulder of very fine striae not mentioned by Girty. h w ha wa h/w * wh OCCURRENCE: Loc. 1, bed 2 (rare, external molds), bed 9 (rare, external molds); loc. 3 (abun- 1. 9.9 11.1 dant, silicified). 2. 9.7 5.3 4.8 72° 3. 8.8 8.9 5.1 4.6 .99 88 si 4. 7.1 7.7 4.6 4.2 .92 90 5 Glabrocingulum? coronatum sp. nov. 5. 7.0 6.6 4.1 3.5 1.06 84 6. 6.9 7.7 4.7 3.8 .90 93 PI. 3, figs, la-3 7. 6.5 5.7± 1.14 5 8. 6.2 6.7 3.9 3.1 .93 92 5 + DESCRIPTION: Low-spired, conical gastropods of 9. 5.9 6.5 3.9 3.7 .91 90 about 5 gradually enlarging and rather deeply em- 10. 5.8 5.9 3.5 3.1 .98 80 4i bracing whorls. Suture very slightly impressed; 11. 5.7 6.4 4.0 3.4 .89 91 4| 12. 5.7 6.2 3.7 3.2 .92 93 6 whorl profile below suture slightly sinuate, convex 13. 5.7 6.2 3.8 3.8 .92 100 4J close to suture and concave toward marginal seleni- 14. 5.4 5.7 3.9 3.2 .95 102 4* zone; selenizone located between 2 distinct carinae 15. 5.3 5.6 3.1 2.7 .95 87 4i on shoulder angle; whorl somewhat concave, almost 16. 5.2 6.5 3.8 3.2 .80 95 51 17. 5.0 5.9 3.5 3.0 .85 109 4i vertical but sloping gently outward below shoulder 18. 4.9 5.4 3.1 .91 92 4J carina to a basal carina, at which it turns inward at 19. 4.7 5.1 3.0 2.8 .92 92 41 an abrupt angle to form a gently convex, narrowly 20. 4.6 5.0 3.1 .92 phaneromphalous base; umbilicus partly filled with 21. 4.6 4.9 2.9 2.6 .94 98 5 22. 4.5 4.9 3.0 2.2 .92 86 4J a crescent-shaped callus, especially apparent in 23. 4.5 4.7 .96 91 large specimens. Aperture roundly rectangular in 24. 4.4 4.9 3.0 2.4 .90 91 4i cross-section, usually very slightly broader than 25. 4.3 4.9 2.9 2.9 .88 102 4i high; outer lip thin above, slightly thickened near 26. 4.2 5.1 2.9 2.7 .82 95 4 27. 4.1 4.7 2.5 2.3 .87 92 basal angulation; lip leaving suture at right angles, 28. 4.0 4.2 2.5 2.4 .95 100 5 convex forward and directed backward with gentle 29. 3.9 4.3 2.6 2.1 .91 96 4i obliquity to selenizone; shoulder angle with a nar- 30. 3.8 4.0 2.2 2.1 .95 99 4 row slit of, seemingly, considerable depth, generat- 31. 3.4 4.5 2.5 2.5 .76 116 4* 32. 3.2 3.7 2.0 2.0 .86 109 4 ing a selenizone; below selenizone, outer lip slightly 33. 2.9 3.6 1.9 1.8 .81 102 4 convex forward but directed almost vertically to 34. 2.7 3.0 1.8 1.5 .90 95 4 lower angulation, whence it continues with a 35. 2.5 2.8 1.8 1.6 .89 4 slightly arcuate pattern radially to umbilicus; 36. 2.4 3.0 2.0 1.8 .80 114 4 columellar lip much thickened, presumably in formation of umbilical callus. TYPES: Holotype: Mus. Northern Ariz. G2.567. Ornamentation both radial and spiral; shoulder Paratypes: Mus. Northern Ariz., Amer. Mus. Nat. Hist., Grand Canyon Nat. Park museum. with fine arcuate growth lines developing near suture into radial undulations or elongate nodes DISCUSSION: In general shape this species is giving surface a crown-like sculpture; shoulder sur- closely similar to other species of Glabrocingidum; face with only very faint and fine spiral ornamenta- the lip and selenizone correspond with features of tion, not evident on most specimens; selenizone

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bounded by 2 sharp, angular spiral carinae; a less vittense (Norwood and Pratten), a species very acute but no less distinct carina lying at the lower similar to G. sarrauti. angulation; area between selenizone and lower Another form with similar ornamentation is a carina with spiral ornamentation consisting of 4 or fragmentary specimen figured by Mansuy (1914, 5 rather unevenly spaced and somewhat irregular p. 39, pi. 7, fig. 5) as Mourlonia?. It bears orna- spiral lirae, crossed by fine arcuate growth lines; mentation identical with that of G.? coronatum and base with one very fine revolving lira immediately may be closely related to or even conspecific with it. below lower carina, and with obscure growth lines. An undescribed form from the Hueco formation Nucleus of 2 smooth, rounded whorls arising of west Texas, now at the U. S. National Museum, from a minute protoconch, projecting somewhat appears to be exceedingly similar to this species. above the plane formed by flattened shoulders of OCCURRENCE: Loc. 1, bed 9 (rare, external molds); later whorls; selenizone appearing at third whorl, loc. 3 (rare, silicified). followed quickly by appearance of coronal radial ornamentation. The suture often varies slightly in position during growth. Genus Mourlonia Koninck 1883 Mourlonia? cancettata sp. nov. MEASUREMENTS: Five specimens were meas- urable, but two are external molds and did not PI. 3, figs. 4a-c permit complete measurement. Dimensions in mm.: DESCRIPTION: Trochiform, somewhat globular gastropods of medium size with 6 or more rounded h w ha wa * wh whorls increasing fairly rapidly in size. Sutures distinct, falling a short distance below selenizone; 1. 9.6 11.0 94= 6f whorl gently rounded below suture as far as flat- 2. 4.5 5.6 2.4 2.5 108 5 3. 4.1 5.3 2.4 2.6 107 4| tened peripheral selenizone, strongly arched at 4. 112 5J+ (mold) periphery; selenizone not quite vertical, sloping ?). 6.7 114 5+ (mold) outward slightly toward its lower margin; base unknown. Apertural section unknown; upper lip TYPES: Holotype: Mus. Northern Ariz. G2.554. convex forward and directed obliquely backward Paratypes: Mus. Northern Ariz., Grand Canyon from suture to selenizone, forming a broad sinus Nat. Park museum. culminating in a moderately wide slit which gen- erates a selenizone on periphery of whorl; lip below DISCUSSION: This form resembles representatives selenizone convex forward and directed obliquely of the genus Glabrocingitlum except for an angula- forward; basal portion of lip and inner lip unknown. tion separating the base from the flank; typical Ornamentation strong growth lines which become specimens of Glabrocingulum are smoothly convex costa-like near upper suture, particularly in later below the selenizone. In the angular whorl profile, whorls, the costae being rather sharply crested; specimens of G.I coronatum resemble Worthenia, radial ornamentation crossed by spiral lirae of about but lack the diagnostic convex selenizone of that equal strength varying in number from 6 to 10, genus. No genus is known in which the lower which in mature whorls occupy only lower part of angulation typically forms the shell periphery. A shoulder, and which become less strong in final shell similar in general shape to G.f coronatum has whorl; spiral lirae and radial ornamentation to- been figured by Branson (1930, p. 56, pi. 99, figs. gether forming a reticulate pattern but without 14-16) under the name Worthenopsis bicarinata. It well defined nodes; selenizone bounded by a pair of has the 2 carinae of this species, but the upper of fine, high revolving lirae and sometimes bearing the 2 forms the periphery of the shell. In addition, upon its surface an indistinct liration; lunulae indis- the shell is higher than wide while the Kaibab form tinct, only slightly curved, sloping somewhat ob- is wider than high. liquely forward; ornamentation below selenizone The sculpture and ornamentation of the upper seemingly similar to that above. surface seems nearly identical with that of Gla- Nucleus of about 2J smooth whorls; third whorl brocingulum sarrauti (Mansuy), but Mansuy's with both transverse and revolving ornamentation figures do not show a lower carina, and his descrip- appearing at once, so that third and fourth whorls tion, as far as can be ascertained from a somewhat have entire surface covered by reticulate ornamen- different terminology, does not include it. Spiral tation; the following 1 or 2 whorls with only lower ornamentation of the upper surface is much fainter portion of shoulder thus ornamented, upper part in the Kaibab specimens than in Mansuy's figures, covered by radial costae only; transverse orna- the same being true in comparison with G. gray- mentation much reduced in last part of final whorl.

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MEASUREMENTS: The three specimens at hand DISCUSSION: The establishment of a new genus are external molds. Although squeezes were made from them they do not lend themselves well to on two external molds, one of the base and one of measuring, as their bases are not preserved. Di- the spire, is undertaken with an appreciation of the mensions in mm.: assumptions made and of the risks involved. The very excellent preservation of the specimens, which w height of spire enables clear and distinct rubber squeezes to be made, allows no doubt that the form is new, and 1. 12.5 7.5 the close similarity of ornamentation on both 2. 11.0 6.0 3. 9.5 5.2 specimens indicates that they represent the same species. A steinkern that was attached to the external mold of the spire shows configuration of the TYPES: Holotype: Mus. Northern Ariz. G2.577. Paratype: Mus. Northern Ariz. G2.2985. base similar to that of the external mold of the base. Observations on the peripheral angulation, DISCUSSION: This form has the conical shape, part of which was preserved in both specimens, rounded whorl profile, and peripheral selenizone of and on the general size and shape of the specimens the genus Mourlonia, as well as spiral and radial likewise indicates their relationship. The two speci- ornamentation characteristic of many species of mens occur close to each other, almost touching in that genus. The basal and apertural characters fact, both on a single sample of rock. cannot be seen, however. In size it is somewhat The exact relationships of this genus are difficult larger than many other species of Mourlonia. to determine since the absence of a selenizone in Similarity is noted between this form and the genus the first several whorls is unusual. Assuming a Shansidla Yin, characterized likewise by rounded selenizone to be present in late stages, however, the whorls but with the selenizone located just below genus shows relationship to Euconospira in its the periphery and without pronounced radial flattened upper whorl surface and in the angulation ornamentation. bounding the umbilicus, but has neither the sharp Some resemblance may be seen between this peripheral carinae nor the very flat base character- form and Girty's Mourlonia idahoensis, from the istic of that genus. Phosphoria formation of Idaho. The two differ, Distinct changes in the location of the suture and however, in the shape of the upper surface of the in the calibre of the ornamentation during growth whorl, the profile in Girty's specimen appearing are noted in the genotype, but may be characters of more strongly arched. The base is not preserved in no more than specific rank. Only by discovery of the Kaibab forms so comparison in that respect is more specimens and species may it be ascertained not possible. Spiral ornamentation is more marked whether these changes are a consistent feature of in the present form, though revolving grooves the genus. defining the selenizone in Girty's specimens are not present here. RANGE: Permian, Kaibab formation. The shape is similar to that of M. nana Yin, from Permian beds in China, but that species has Pernotrochus arizonensis sp. nov. cancellate ornamentation of fine growth lines upon PI. 3, figs. Sa-7 more fully developed lirae. OCCURRENCE: Loc. 1, beds 2 and 9 (rare, ex- DESCRIPTION: Trochiform gastropods of moderate ternal molds). size, consisting of 6 or more whorls regularly increasing in size. Suture distinct, impressed, lying Genus Pernotrochus gen. nov. slightly below peripheral angulation on first 4 whorls, then coming to lie on peripheral angle so DEFINITION: Turbinate gastropods of moderate that shell is cone-shaped; upper surface of whorl size having a more or less flattened shoulder and a very gently convex in upper half and concave in flat base becoming convex near periphery and lower half, producing a slightly sigmoidal profile meeting shoulder at a well denned angulation; inclined at an angle of about 40° to the axis; in outer lip with a v-shaped sinus seemingly terminat- final whorl, a broad flat area lies between upper ing on final whorl in a shallow slit which forms a convex and lower concave portions, the concave poorly denned selenizone with indistinct lunulae; part becoming a well defined, narrow band seem- ornamentation fine revolving lirae; base with a ingly representing a selenizone; periphery angular funnel-like umbilicus bounded by an obtuse angu- and abrupt, with a slight carina formed by con- lation. cavity of upper surface; base very gently rounded, GENOTYPE: Pernotrochus arizonensis sp. nov. flat toward umbilicus, with an obtuse angulation

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marking the limits of a funnel-like umbilicus. whereas the selenizone of the present form is, like Aperture quadrate in cross-section (by reconstruc- that of Worthenia, convex and straddling the upper tion), its margin directed obliquely backward, with carina. forward convexity, from suture across most of whorl face, and then arching, in last 2 whorls at least, to RANGE: Permian, Kaibab formation. cross periphery in a forwardly direction, forming a poorly denned concave sinus or slit; this slit in the Platyworthenia delicata sp. nov. last whorl forming a selenizone; lip continuing to PI. 3, figs. 8a-9 be directed forward for a short distance on the base, then arching abruptly to a radial direction DESCRIPTION: Very small, turreted pleuroto- continuous to umbilicus; columellar lip reflexed marians of about 4 or 5 regularly enlarging volu- sharply toward umbilicus, parietal lip unknown. tions. Suture located on basal angulation of preced- Ornamentation fine spiral lirae, spaced about 16-20 per mm. on base, distributed over entire surface including selenizone; spiral lirae on more youthful whorls fewer in number, more widely spaced (10 per mm.), and not continuing quite to selenizone periphery; new lirae introduced by intercalation; growth lines fine, and usually obscure near peripheral portion of upper surface. Nucleus of 2 smooth whorls, followed by 2J whorls in which spiral lirae are coarsely spaced and periphery of shell projects slightly over lower suture; later whorls with finer liration and with periphery covered by succeeding whorl. In first 5 whorls there is no trace of a selenizone, though in FIGURE 5.—POSITION OF CARINAE AND SELENIZONE the last whorl there is one, poorly defined possibly IN Platyworthenia delicata. because of the shallowness of the slit and indis- tinctness of the lunulae. ing whorl; shoulder profile flat except for a slight rise near center, sloping outward below suture at an MEASUREMENTS: Only two specimens are known, one of the base and the other of the spire. Measure- angle of about 40° to axis of shell; profile becoming ments are approximations drawn from a study of abruptly vertical at prominent upper carina and both specimens: height of spire above periphery of forming a flank of about the same breadth as the last whorl 8.0 mm.; depth of base below periphery shoulder; base flattened, anomphalous, delineated of last whorl 2.0 mm.; estimated total height 10.0 mm.; width 11.0 mm. from flank by a sharp carina ted angulation. Aper- ture almost circular; outer lip directed obliquely TYPES: Syntypes: Mus. Northern Ariz. G2.130S. backward from suture to a shallow notch which straddles upper angulation, giving rise to an OCCURRENCE: Loc. 1, bed? (very rare, external angularly convex selenizone; lip directed gently molds). forward below selenizone to second flank lira, below which it becomes directed almost vertically or with Genus Platyworthenia gen. nov. gentle backward obliquity to lower carina; lip almost radial on base; columellar lip thickened and DEFINITION: Small, turreted pleurotomarians reflexed; parietal inductura probably present. having a flat shotilder, flat, vertical flank, and a Ornamentation prominent spiral lirae and carinae flattened anomphalous base separated from each of varying strength; shoulder without visible lira- other by sharp carinae; outer lip with a sinus tion except for the sharp but fine upper boundary terminating at upper carina in a convex selenizone; of selenizone; lower selenizonal lira, on flank, sharp ornamentation revolving lirae and carinae; nucleus and fine; flank with 3 equally prominent carinae, of several smooth whorls planospirally coiled. the upper one bearing the selenizone, not noded GENOTYPE: Platyworthenia delicata sp. nov. but showing distinct lunulae, the second one at about the middle of the flank, and the third at DISCUSSION: This genus shows striking resem- basal angulation; between selenizone and second blance to the genus Platypleurotomaria Wanner, carina is a fine liration at which outer lip turns which, like it, has a planospirally coiled nucleus. downward; base with 4 or 5 regular, evenly spaced, But Wanner's form has a concave selenizone, strong lirae.

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Nucleus of about 2 smooth whorls planospirally of whorl; between second and third carinae, and coiled; the 3 flank carinae appear simultaneously also between third and fourth, there are small on the third whorl. sharp lirae denning selenizone margins, the third or MEASUREMENTS : Two specimens are known from shoulder carina thus running through selenizone loc. 3 which are well enough preserved for complete measuring. A third doubtful specimen, from loc. 2, bed 4, is somewhat larger. Dimensions in mm.:

h W ha wa hbw •t> 1. 5.5+ 4.8 52° 2. 4.5 3.2 2.0 1.8 3.2 51 3. 3.9 3.0 1.8 1.6 2.8 50 (holotype) TYPES: Holotype: Mus. Northern Ariz. G2.571. Paratype: Amer. Mus. Nat. Hist. DISCUSSION: The two specimens from loc. 3 differ from the dubious specimen from loc. 2, bed 4, in that they are smaller in size and have much more prominent ornamentation. The third specimen, however, shows the convex selenizone and flattened nucleus characteristic of the genus, and is weakly lirated to correspond with the carination of specimens from loc. 1. The difference in ornamentation and size may be an ecological one, or the ornamentation may have been reduced by erosion. OCCURRENCE: Loc. 3 (rare, silicified); loc. 2, bed 4 (very rare, external mold). FIGURE 6.—POSITION or CARINAE AND SELENIZONE IN Worthenia corrugata Genus Worthenia de Koninck 1883 Worthenia corrugata sp. nov. slightly above its center; lower bounding lira of selenizone with another equally fine or finer lira PI. 4, figs, la-c immediately below it. Growth lines usually distinct; DESCRIPTION: Small turbinate gastropods of about lunules in selenizone very evenly spaced and 5 whorls, with spire medium in height; suture im- regular, but not forming the strong nodes usually pressed, lying just at base of vertical side of whorl; characteristic of the genus. whorl profile slightly flattened above, sloping out- Nucleus small, the first 1J whorls without orna- ward at 55° to axis, turning abruptly vertical at mentation; third carina appears first, then fourth, shoulder angle, and inward below a vertical face at fifth, second, and first, in that order. an obscure angulation; base rounded; umbilicus MEASUREMENTS: Only two specimens were narrow. Aperture not quite circular; outer lip thin, preserved well enough for measuring. Dimensions directed backward in a sigmoidal curve on the shoulder to a slit above the center generating a convex selenizone on shoulder angle; lip below h w I ha wa w/h <#> selenizone directed obliquely forward at first, then arching to a backward obliquity on the base; outer 1. 7.0 5.8 3.7 3.4 .83 65.5° lip continuous with columellar lip, which is reflexed 2. 4.1 3.9 2.5 2.1 .95 80 slightly over umbilicus; parietal inductura seemingly absent. TYPES: Holotype: Amer. Mus. Nat. Hist. 27109:1. Paratypes: Amer. Mus. Nat. Hist, and Ornamentation consisting of 13 strong revolving Mus. Northern Ariz. carinae, 2 located on shoulder, a third forming shoulder angle, fourth and fifth on vertical side of DISCUSSION: The position of the selenizone strad- shell, and next 8, more closely spaced than the dling the shoulder angle, and the enlargement of preceding and becoming slightly more crowded the lunules in the selenizone, place this form in the toward umbilicus, occupying lower rounded portion genus Worthenia. In shape, ornamentation, and

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turning inward to a second angulation, below which Girty (1909) are too poorly described and illus- it is concave and curves downward into a rudi- trated to identify with either species. mentary anterior canal. Aperture irregularly tri- Knight observed (1940) that in Murchisonia angular in cross section; outer lip directed backward gouldii the position of the selenizone on the whorl below suture, continuing with slight forward con- varies considerably not only between specimens but vexity to a peripheral slit of unknown depth, form- between the whorls of a single specimen. This is ing a selenizone in peripheral carina; below slit, lip also true of M. geminocarinata. Measurements of directed obliquely forward, convex, running in an arc to anterior canal; columellar lip seemingly rotated inward to form a border to the canal; parietal portion of inner lip unknown. -25mm. Ornamentation consisting of a row of nodes along selenizone, apparent only in ephebic whorls; -20 revolving lirae on shoulder and between peripheral carina and sub-sutural angulation very fine and often obliterated; base with several very low rounded lirae, the uppermost of which lies at the subsutural angulation; growth lines very fine. Nucleus of about 6 whorls with selenizone bor- 15mm. 35° 40° dered by a pair of sharp carinae, and without evidence of nodes; at about the sixth whorl, carinae FIGURE 7.—RELATION or WIDTH AND PLEURAL become slightly and separately noded, the nodes ANGLE TO HEIGHT IN Murchisonia geminocarinata merging gradually until there is but a single row of them and the carina appears single and rounded. the height of the whorls between sutures and of the distance between the upper suture and the center MEASUREMENTS: Since the tip of the spire is of the selenizone were made on 63 whorls on 13 nearly always broken, measurements of height us- specimens. The ratio between height of whorl and ually must be approximated. Dimensions in mm.: distance from suture to selenizone was calculated, h W h/w wh giving a numerical figure for position of the selenizone ranging from .50 to .76, with an average of .63. 1. 27.0 10.5 .40 24° 11+ The ratios show a curve of normal distribution. 2. 25 11.8 .47 25 9 Figure 8 shows that although the range in some 3. 25+ 9.0 .36 26 10+ individuals is very large, in others it is rather small 4. 23 8+ 5. 16+ 7 .43 24 6+ and there is only slight variation in the regularity of 6. 15+ 6.6 .44 28 the whorls. 7. 15+ 6.5 .43 23 7 + The nature of the selenizone on early whorls and 8. 15 6.2 .41 7+ 9. 12.5 5.0 .40 24 6+ its development during the ontogeny of the shell is 10. 11 + 3.9+ .35 24 10+ readily observed and is of special interest since, in 11. 10+ 4.7 .47 20 7+ different stages, there is resemblance to the seleni- 12. 9.2+ 3.7 .40 26 8+ 13. 7.6 3.3 .43 23i 8 zone of other species. In the juvenile whorls, the sharply carinated selenizone is reminiscent of There is no apparent regular change in pleural Murchisonia goiMii. From about the sixth whorl angle or proportions during growth (Fig. 7). from the apex, the 2 carinae, each with gradually TYPES: Holotype: Mus. Northern Ariz. G2.353. developing elongate nodes, bear strong resemblance Paratypes: Mus. Northern Ariz, and Grand Can- yon Nat. Park museum. to the doubly nodular carina of Helicospira buttersi (Girty) from the Lykins formation of Colorado, DISCUSSION: This form bears a strong resemblance although the shell lacks the pronounced transverse to Murchisonia lerebra, described and illustrated by ornamentation of Helicospira. This stage may be White from south of Pipe Springs, probably from termed the neanic stage of the shell. The ephebic the Kaibab formation. That form, however, bears or adult stage is arrived at slowly by a merging of strong revolving ornamentation and has nodes the nodes of the 2 carinae and a consequent obscur- only very weakly developed; examination of the ing of the exact boundaries of the selenizone. type shows that it is not the same as this form. In OCCURRENCE: Loc. 1, bed 2 (rare, external general it may be said that specimens recorded as molds), bed 9 (common, external molds); loc. 3 M. terebra by White (1883), Keyes (1894), and (rare, silicified).

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Goniasma sp. 2.

Murchisonia sp.

position of selenizone .70 .80 .90

FIGURE 8.—POSITION OF SELENIZONE IN Murchisonia geminocarinata, Murchisonia sp., and Goniasma sp.

Murchisonia sp. MEASUREMENTS: A squeeze from a poorly preserved external mold shows the following dimen- PI. 4, fig. 11 sions: height 30 mm. +; width 14.5 mm.; number of whorls 7. DESCRIPTION: Medium-sized, high-spired, many A second fragment, probably of the same species, whorled gastropods. Suture slightly impressed, reaches a diameter of about 43 mm., and the entire shell must originally have measured at least 12 or clearly defined, lying just below peripheral angula- 15 cm. in height. tion; shoulder profile sigmoidal, sloping vertically or even a little inward below the suture, then DISCUSSION: The material at hand is too poor to curving outward to periphery of whorl; profile be identified accurately or described completely, turning abruptly inward below the narrowly rounded periphery, and curving inward and down- but examination of the fragmentary specimens ward for a short distance to an obscure angulation shows them to have the selenizone lower than in limiting the flattened base; umbilical portion of Knight's specimens of M. gouldii or in specimens of base unknown. Aperture unknown; upper lip seem- M. geminocarinata sp. nov. (Fig. 8), and to have a ingly straight and oblique backwards from suture sigmoidal shoulder pattern not characteristic of to periphery, which may be occupied by a selenizone; those species. In addition, the pleural angle is lip below periphery apparently directed sharply and greater, resulting in a greater width/height ratio. obliquely forward, at least to the obscure basal This form lacks the spiral ornamentation character- angulation, beyond which its course is unknown; istic of M. terebra but may be an eroded specimen inner lip unknown. of that species. Ornamentation, except for indistinct nodes along selenizone, absent or not in evidence; very OCCURRENCE: Loc. 1, bed 9 (rare, external faint growth lines have been observed. molds).

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Genus Stegocoelia Donald. 1889 micula, and UM." turritella, Hall, forms which are not mutually distinguishable and which are prob- Stegocoelia quadricostata sp. nov. ably conspecific. PI. 4, fig. 10 Superficial resemblance is seen to 5. cincta (Donald), and to the type of the genus, 5. compacta DESCRIPTION: Minute, high-spired, somewhat Donald, the primary difference being in the number, turreted shells with a very low pleural angle so that position, and relative strength of the revolving the sides are almost parallel in adult whorls; number of whorls unknown but more than 6; whorls costae and in the position of the selenizone. There is also strong resemblance to a number of species of only very slowly expanding. Whorl profile sloping sharply outward from the rather deep suture to Orthonema, especially O. marvinwelleri Knight, first of 4 carinae, then almost vertically downward which has however a different spacing of the lirae and is thought to lack a selenizone, although growth to third carina, below third, sloping inward to lines and lip are not preserved. fourth; base defined by a sharp angulation at lowest No other forms have been described which bear carina, and incompletely known but probably flat- close resemblance to the new species, although a tened; suture lying just below fourth carina. Aper- ture unknown; outer lip almost vertical below form almost identical with it has been observed in suture to first carina, then oblique backward to the U. S. National Museum collections from the second carina and forming a slit of unknown depth Word limestone no. 1 at its type locality. giving rise to a selenizone between second and OCCURRENCE: Loc. 1, bed 2 (very rare, external third; lunulae very gently concave; lip directed mold). obliquely forward below selenizone; columellar and parietal lips unknown. Superfamily ETJOMPHALACEA Ornamentation consisting of 4 revolving carinae, the distance between suture and first carina and Family EUOMPHALIDAE between first and second carinae about half that Genus Euomphalus Sowerby 1814 between second and third, and that between third and fourth about two-thirds that between second Euomphalus kaibabensis sp. nov. and third; first and third carinae the most prom- PI. 4, figs. 15-16C inent, forming respectively the upper and lower limits of the vertical side of the whorl; growth lines DESCRIPTION: Discoidal, planospirally coiled very fine. gastropods of about 4 volutions, the whorls increasing fairly rapidly in size but without covering upper MEASUREMENTS: Only one specimen, the holo- and lower surfaces of preceding whorls. Whorl pro- type, is known. It reveals neither the base nor the tip of the spire. Measurements of a rubber squeeze file angular, with upper and lower carinae giving are as follows: length 5.9 mm.; width 1.8 mm.; shell a trapezoidal cross-section; upper suture sharp pleural angle 11°. and in an angulation formed by upper surface of TYPES: Holotype: Mus. Northern Ariz. G2.2983. whorl with side of previous whorl, which projects somewhat above suture; upper surface gently convex DISCUSSION: Although not all of the characters of near suture, flat or very gently concave in remaining the genus are revealed in this specimen, the nature part; upper carina sharp and nodose; outer surface of the outer lip, known from the growth lines, shows fairly convex and sometimes tending to have a it to be a Murchisonid. It bears close resemblance faint angulation midway between upper and lower to members of the genus Stegocoelia, although the carinae; lower carina more rounded than upper and position of the selenizone is considerably lower on bearing a row of prominent rounded nodes; base of the whorl face than in other species. The general whorls rounded so that lower sutures are fairly shape, with very slowly expanding whorls showing deep; umbilicus broad, its sides forming an angle of a low pleural angle, and the nature of the spiral about 90°. Upper lip directed perpendicularly out- ornamentation, is in agreement with that genus. ward from suture, seemingly curving backward to The predominance of the first and third lirae cause form a shallow sinus on upper carina, and then a flattening of the side of the whorl which contrasts curving forward and vertically downward on outside with the more rounded whorls of other members of of whorl, more or less radially but with slight for- the genus. The nature of the columellar lip, im- ward concavity on basal surface; aperture sub- portant in the diagnosis of the genus, cannot be trapezoidal to subpentagonal in shape. Ornamenta- seen on the specimen. tion consisting of elongate nodes on both upper and This species bears strong resemblance to the lower carinae, these numbering 10 in the last volu- Mississippian "Murchisonia" attenuata, "M." ver- tion of a specimen 31 mm. in diameter; growth lines

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fine and much eroded from specimens at hand; posses,? angular upper and lower carinae in youthful spiral ornamentation lacking. stages. Apparently subquadrate in cross-section, it cannot however be assigned to the genus Am- MEASUREMENTS : Of the 4 specimens at hand phiscapha as the lower carina projects downward only 1 is complete. Partial measurements of the others give an idea of the size range. Dimensions rather than outward as in that genus. in mm.: OCCURRENCE: Loc. 1, bed 9 (very rare, external d wa h ha mold). 1. 30.8 12.2 12.2 12.0 (holotype) Superfamily PATELLACEA 2. 22.8 9± 3. 14.5 14.5 14.0 Family PATEIXIDAE 4. 7.3 8.4 Genus Lepetopsis Whitfield 1882 TYPES: Holotype: Mus. Northern Ariz. G2.557. cf. Lepetopsis Paratype: Mus. Northern Ariz. G2.547. PI. 4, figs. 3a, b DISCUSSION: The presence of an upper sharp External and internal molds of a small, low-coned carina and a lower more rounded one, both project- patellid, and an internal mold of a somewhat larger ing about equally, places this form in the genus specimen, do not show enough characters to be Euomphalus rather than in Amphiscapha, although accurately classified. Their measurements are re- the nodose character of the carinae at first suggests corded here, however, and the form is figured. They assignment to the latter. probably represent a new species. A strong resemblance may be seen between E. kaibabensis and the Pennsylvanian E. pernodosus MEASUREMENTS: (in mm): Meek and Worthen. The form differs, however, in its smaller size and in the possession of well-defined l w h nodes on the upper carina. Illustrations of E. pernodosus by Meek and Worthen show the upper 1. 12 0 9 5 3.8 (internal mold) 2 carina as relatively smooth and the texts of their 2. 5 3 3 8 .0 (external mold) papers describe it as rugose or somewhat cor- rugated. The nodes on E. kaibabensis are as distinct OCCURRENCE: Loc. 1, beds 2 and 9 (very rare, even on somewhat eroded specimens on the upper external and internal molds). as on the lower carinae, and are about equal in number, often occupying alternating positions. Superfamily TROCHONEMATACEA Another markedly similar form is E. nodocarinatus Wanner, which differs in its less rapidly expanding Family TROCHONEMATIDAE whorls, which give it a wider umbilicus and a lesser Genus Glyptospira gen. nov. height in proportion to its diameter. It also has a more convex outer surface than the Kaibab form, DEFINITION: Small, moderately high-spired, with resultant lesser angularity in the whorl profile. turbinate gastropods with rounded aperture, gently This appears to be a long-ranging species, and oblique outer lip, and no slit or selenizone; whorls has been observed by the author in collections of rounded or slightly angular, sutures deep; anom- the U. S. National Museum from the Word lime- phalous or minutely phaneromphalous. Ornamenta- stone no. 1 and from the S an Andres, as well as in tion prominent revolving carinae, varying in collections from the Fort Apache limestone of number and strength, on sides and base; growth Arizona, now at the American Museum of Natural lines usually distinct. Nuclear whorls smooth. History. GENOTYPE: Glyptospira cristulata sp. nov. OCCURRENCE: Loc. 1, bed 2 (very rare, external molds); loc. 3 (rare, silicified). DISCUSSION: This genus bears little resemblance to any other Paleozoic genus except Microdoma Euomphahts? sp., juvenile Meek and Worthen, from which it may be de- PI. 4, fig. 2 scended. It may be in line of descent through Microdoma from the genus Pagodea Perner. Species An external mold of the base of a small spiral of the genus have been observed in the Wolf- gastropod reveals characteristics seen in the juve- campian (Hueco limestone), Leonardian (Bone niles of the genus Euomphalus, many of which Springs formation), and Guadalupian (Word lime-

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stone no. 1) of Texas, in the collections of the U. S. lira; umbilicus very minute or not apparent. Aper- National Museum, but have not been described. ture almost circular, very slightly flattened at base They were discussed by J. B. Knight at the Novem- and somewhat pointed at suture; outer lip thin,

-12mm

-4

-2

6mm. 30° 4,0° FIGURE 9.—RELATION or WIDTH, PLEURAL ANGLE, AND HEIGHT OF APERTURE TO HEIGHT, AND OF HEIGHT OF APERTURE TO WIDTH or APERTURE, IN Glyptospira cristulata

ber 1948 Geological Society of America meetings in locally thickened as it meets spiral ornamentation, New York. Variation in proportion, number of and directed with gentle backward obliquity and carinae or lirae, and degree of prominence of orna- forward convexity from suture to umbilical region; mentation may be considered specific and subspecific no slit, notch, or selenizone is present. characters. Ornamentation 3 strong, rounded, revolving carinae on flanks and 5 or 6 less prominent lirae on RANGE: Permian. base; the first of the carinae lying a short distance below suture, second and third forming periphery Glyptospira cristulata sp. nov. of whorl; first lira lies at or immediately above lower PI. 4, figs. 4a-6b suture; lirae becoming successively broader and less pronounced toward base, until the last is barely DESCRIPTION: Small gastropods with moderately visible; growth lines fine and very sharply raised. high spire and 5-8 whorls, with a pleural angle Nucleus of 2| smooth whorls, with ornamenta- ranging from about 50° in juveniles to about 25° in tion appearing on third whorl; second and third largest specimens. Whorl profile rounded, most carinae appear first and for several whorls remain convex just below periphery of shell and becoming the most prominent. There is a distinct change in less convex toward base; sutures moderately deep, proportions during growth, the smallest individuals impressed, and lying just below fourth revolving having a width/height ratio of about 0.90, and the

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largest having a ratio of about 0.45. The change in Family PALAEONUSTIDAE proportions is accompanied by a decrease in pleural Genus Eotrochus Whitfield 1882 angle from about 50° to about 25°, and possibly by a slight change in shape of aperture. Eotrochus? liratus sp. nov. PI. 4, figs. 7a-8 MEASUREMENTS : An abundance of specimens was available for measuring, representing all growth DESCRIPTION: Shell conical, twice as wide as stages. Dimensions in mm.: high, with a pleural angle of about about 100°; h w ha wa w/h ' 0 wh 4-5 volutions enlarging regularly; suture appressed, each whorl overlapping preceding one slightly, 1. 12± is. 4 3.4 3.1 .45 25° 6± forming a narrow step at suture. Whorl profile very 2. 10.8 5.3 .49 28 slightly convex below this for about \ distance 3. 10.1±4.5 .45 7J 4. 10. 0±4.8± .48 26 down whorl, then very slightly concave to shoulder 5. 8.0+ 4.4 .55 angle, but in general appearing almost flat and slop- 6. 7.9 4.6 .58 41 ing strongly outward; lamellar extension of shoulder 7. 7.8 4.1 3.0 2.4 .53 8 slope extending downward and outward about 8. 7.8 4.3 2.8 2.4 .55 61 9. 7.5 4.2 2.7 2.2 .56 .3 mm. below base, forming a flange; base, sur- 10. 7.5 4.0 .53 34 rounded by flange, flat near outer margin, then 11. 7.3 4.5 3.0 2.6 .62 6 rounded regularly into umbilicus. Aperture lens- 12. 6.8 3.8 2.7 2.0 .56 41 71 shaped in cross-section, somewhat less convex on 13. 6.7 4.1 2.4 2.1 .61 6 14. 6.5 3.8 2.4 2.1 .58 Si upper side than below, and rounded at outer margin 15. 5.9 4.2 .71 44 by a thickening of calcareous material. Upper lip 16. 5.8 3.9 .67 6 leaving suture almost at right angles, then curving 17. 5.8 3.4 2.4 2.0 .59 39 6 obliquely posteriorly in a broad arc until at periph- 18. 5.7 3.5 2.4 1.8 .61 6 19. 5.7 3.8 2.4 2.1 .67 ery of shell it is almost parallel to margin; lower 20. 5.6 3.5 2.4 2.0 .62 Si lip, as indicated by faint growth lines, very slightly 21. 5.5 3.8 .69 oblique forward on outer flat portion of base, then 22. 5.5 3.2 2.0 1.7 .58 39 6 becoming almost radial as it crosses third, or largest, 23. 5.4 3.4 2.3 1.8 .63 74 24. 5.3 3.2 .60 42 of basal lirae; growth lines cannot be traced on 25. 5.1 3.2 .63 44 lower surface of flange; parietal inductura lacking. 26. 5.1 3.4 2.1 1.7 .67 Ornamentation 6 or 7 fine, evenly spaced, re- 27. 4.8 3.1 2.0 1.5 .66 St volving lirae of equal magnitude on shoulder slope; 28. 4.7 3.1 2.0 1.5 .66 Si 29. 4.5 2.4 1.6 1.5 .53 40 Si 5 stronger revolving lirae on base of shell, the first 30. 4.4 3.1 2.0 1.5 .70 41 5+ lying close to flange, the second in center of flat 31. 4.4 2.7 .61 41 area of base, the third and strongest forming bound- 32. 4.3 2.6 1.6 .65 42 ary between outer flat area and that part of shell 33. 4.3 3.0 .70 37 34. 4.2 2.5 1.6 1.3 .62 6 which arches into umbilicus, the fourth and fifth, 35. 4.1 2.6 1.6 1.3 .63 44 61 which are successively less strong, lying on umbili- 36. 4.0 2.8 .70 49 cal portion; a sixth lira sometimes present, but 37. 3.8 2.5 .66 41 usually only vaguely suggested; growth lines faint. 38. 3.8 2.4 1.6 1.4 .63 45 Si 39. 3.5 2.7 .77 49 Nuclear whorls seemingly no different in shape 40. 3.5 2.4 .66 44 Si than later whorls, lacking visible ornamentation; 41. 3.4 2.2 .65 50 first certain appearance of h'rae on third whorl 42. 3.1 2.0 .65 54 below apex. 43. 2.9 1.9 .66 44. 2.7 1.9 1.2 1.1 .70 41 MEASUREMENTS: (in mm.): 45. 2.6 1.9 .73 60 ; 46. 1.4 1.3 0.8 0.7 .93 51 4 h W ha wa hbw h/w Changes in proportion and in pleural angle with 1. 3.8 7.6 1.6 2.6 2.0 92° .50 (holo- growth are represented in Figure 9. 2. 3.3 6.0 2.5 1.9 96 .55 type) 3. 3.0 5.4 1.3 3.0 1.6 107 .55 TYPES: Holotype: Amer. Mus. Nat. Hist. 27108:1. Paratypes: Amer. Mus. Nat. Hist., Mus. TYPES: Holotype: Amer. Mus. Nat. Hist. Northern Ariz., Grand Canyon Nat. Park museum. 27111:1. Paratypes: Amer. Mus. Nat. Hist., Mus. Northern Ariz. OCCURRENCE: Loc. 1, bed 9 (very rare, external molds); loc. 2, bed 4 (very rare, external molds); DISCUSSION: This form has been assigned to the loc. 3 (abundant, silicified). genus Eotrochus on the basis of its shape and size,

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the shape of the aperture, the presence of a periph- Strianematina pulchrelirata sp. nov. eral flange, and the shape and sculpture of the PI. 5, fig. 3 base, as well as on the presence of spiral lirae and lack of radial ornamentation. The upward exten- DESCRIPTION: Moderately high-spired, sub-tur- sion of the columellar lip seen by Knight (1932) in binate gastropods with at least 6 whorls and with sectioning a paratype of the genus, is not present a pleural angle of approximately 39°; final whorl in these specimens, however. If the extension of the measuring about two-thirds entire height of spire. lip is to be considered a generic character, this form Suture slightly impressed; whorl profile gently rounded, somewhat more strongly rounded below represents a new genus. suture and between flank and base, the whole There is also resemblance to Flemingella Knight, blending into a smooth curve; base rounded, prob- but that genus lacks the basal flange and is very ably minutely phaneromphalous. Aperture seem- narrowly phaneromphalous. In addition, its spire ingly oval, rounded below and somewhat pointed is not usually as low as in Eotrochus. above; outer lip thin, nearly straight, and gently The course of the lower lip, which could not be oblique backwards, rounding below and seemingly seen on the genotype, can be seen on E.f liratus. continuous with inner lip; inner lip unknown, In its smaller size, presence of revolving lirae on parietal inductura apparently absent, thin, or not the shoulder slope, and ornamentation of the base, extensive. this shell differs from E. tenuimarginatus (Miller). Ornamentation fine revolving striae, spaced about The latter has a smooth upper surface and a large 9 or 10 per mm. on base; on last whorl, about 5 number of fine revolving lirae on the lower surface, revolving striae similar to those on base may be and appears to have a smaller pleural angle than seen just below suture; growth lines fine. Nucleus E.? liratus. unknown. OCCURRENCE: Loc. 3 (rare, silicified). MEASUREMENTS: The spire of the single specimen is not complete so that shell height is estimated. Height 17 mm. ±; width 8 mm.; height of Superfamily TROCHACEA aperture 7.5 mm.; width of aperture 4.9 mm. Family TROCHOTTJRBINIDAE TYPES: Holotype: Mus. Northern Ariz. G2.273S. DISCUSSION: The species is based on only one Genus Strianematina gen. nov. specimen, an external mold revealing clearly the DEFINITION: Moderately high-spired, sub-turbi- characteristic ornamentation. nate gastropods having a thin, nearly straight outer OCCURRENCE: Loc. 1, bed 2 (very rare, external lip directed with slight backward obliquity and mold). probably having a simple inner lip and a thin parietal inductura. The genus is characterized by Superfamily SUBULITACEA fine revolving striae on the base, and, in some species, near the upper suture. Family PSEUDOMELANUDAE GENOTYPE: Strianematina pulchrelirata sp. nov. Genus Girtyspira Knight 1936

DISCUSSION: Strianematina shows close relation- GirtyspiraT sp. ship to the genus Strophostylus Hall, and, more PI. 5, fig. 1 particularly, to Anematina Knight, differing from both of these in the presence of revolving ornamen- Two small external molds revealing some of the tation. In his definition of Anematina, Knight characteristics of the genus Girtyspira are tenta- (1933, p. 36) parenthetically broadened the defini- tively placed with that genus. Their rounded whorl tion to include the occasional presence of revolving profile with narrow angular shoulder just below ornamentation on the base, as in A. marshalli the suture, their sub-conical base, and reflexed (Roundy), a species which now is embraced by inductura, as well as the absence of ornamentation, Strianematina. Thus the genus Anematina may be tend to place them in this genus, although the specimens are too poorly preserved to make assignment restricted to forms completely lacking ornamenta- certain. tion. OCCURRENCE: Loc. 1, bed 9 (rare, external RANGE: Mississippian to Permian. molds).

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Genus Meekospira Ulrich 1897 upper margin arching back into aperture and dis- appearing long before reaching suture. Meekospiraf sp. 1 Spiral ornamentation absent; growth lines fine PI. 5, fig. 2 but distinct. Nucleus unknown. DESCRIPTION: High-spired, many whorled gastro- MEASUREMENTS: Several external molds were pods with a low apical angle and a somewhat higher collected, most of them too fragmentary for measuring. One specimen was fairly complete except pleural angle; whorls gradually expanding, with for the tip of the spire. Height 18.2 mm. +; width height of final whorl measuring slightly more than S.7 mm.; height of aperture 5.7 mm.; width of half the height of entire shell. Suture impressed, aperture 2.4 mm.; pleural angle 19°+; width/ fairly deep; whorl rounded below suture, somewhat height ratio .32. natter on sides; base with a rudimentary anterior canal. Apertural section somewhat pointed below, DISCUSSION: On a basis of the character of the more sharply pointed above, and widest below parietal inductura this form is tentatively grouped middle, showing in young specimens an increase in with Meekospira. The shape of the whorls and their convexity between side and base of shell; outer lip proportions are not, however, completely typical thin and probably almost straight or gently convex of that genus and this form may well belong in some forward; columellar lip unknown; parietal inductura other genus, possibly Pseudozygopleura Knight, passing out of sight into the aperture. although without the diagnostic nuclear whorls that Ornamentation 4 fine, regularly spaced striae on assignment cannot be made, or in Acteonina, which outer basal portion of whorl; growth lines barely typically has a well developed, narrow shoulder visible. Nucleus unknown. below the suture. The change in shape of the whorl in this species, MEASUREMENTS : Only one specimen, an ex- marking the end of the neanic and the beginning of ternal mold of which rubber squeezes were made, the adult stage, is quite distinctive, accompanied was collected. Its dimensions are: height 16.2 mm.; width 5.0 mm.; height of aperture 5.5 mm.; as it is by a change in the shape of the outer lip. width of aperture 2.8 mm.; pleural angle 15°; The change in profile causes a sudden difference in width/height ratio .31. the pleural angle, which may be as much as 23° if measured from a rounded whorl to a flatter one, DISCUSSION: The whorl shape and the nature of or as low as 15° if measured on 2 succeeding flat- the parietal inductura are the only bases for placing tened whorls of a young specimen. this form in the genus Meekospira, a genus which Several Pennsylvanian species of Meekospira normally shows no spiral ornamentation of any show superficial similarity to the Kaibab form, kind. Though this form may represent a new genus, among them M. peracuta (Meek and Worthen), material at hand is not adequate for complete which, however, does not show the rounding and description and definition. expansion of the final whorl so characteristic of the present species. OCCURRENCE: Loc. 1, bed 9 (rare, external molds). OCCURRENCE: Loc. 1, bed 9 (rare, external Meekospiraf sp. 2 molds). PI. 5, fig. 4 Family SUBUUTIDAE DESCRIPTION: High-spired, many whorled gastro- Genus Onchochilus Petho 1882 pods with a high pleural angle and with height of final whorl less than a third the height of the shell. The Permian genus Cylindritopsis, named by Suture impressed; whorl profile rounded below Gemmellaro in 1890 to include forms having a suture, somewhat flatter on sides, especially in early double fold on the callus-like parietal lip, seems to whorls, so that an obscure shoulder is formed; be synonymous with the Triassic genus Oncochilus another strongly rounded region below flank divides Petho. The genus Naticodon Ryckholt is also in flank from base; final whorl evenly rounded and many ways like members of the genera Cylindritop- somewhat more bulbous in shape; base with, pos- sis and Oncochilus. That genus, however, was never sibly, an anterior canal. Outer lip thin, straight on adequately described, and cannot be recognized. neanic whorls, concave forward on later whorls and Oncochilus has priority and is here used as the becoming convex forward very near columella, name of a Permian species which, though higher- suggesting an anterior canal; columellar lip almost spired than many previously described species, vertical; parietal inductura smooth and with its shows the double fold clearly.

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Oncochilus insolitus sp. nov. insolitus. Closely related forms are also in collections PI. 5, fig. 7 from the Texas Hueco and Leonard formations. DESCRIPTION: Minute, roundly fusiform gastro- OCCURRENCE: Loc. 3 (very rare, silicified). pods with about 5 rapidly expanding volutions, each deeply embracing preceding one so that the Superfamily SUBULITACEA? spire projects above body whorl a distance equal to Family STREPTACIDIDAE? only about a fourth the length of body whorl. Suture only slightly depressed; whorl profile Genus Adisina de Koninck 1882 smoothly rounded below suture, straightening Aclisinaf bisulcata sp. nov. slightly near pointed base; anomphalous. Aperture PI. 5, figs. 5a-6 semicircular, measuring more than half the height of shell, slightly rounded at base, coming to a point DESCRIPTION: Small, moderately high-spired at upper end; outer lip thin, slightly convex forward, gastropods of approximately 6 regularly expanding describing an arc downward and backward and volutions and with a pleural angle generally between straightening as it approaches siphonal notch; 30° and 40°. Suture slightly impressed, located on siphonal notch rounded and bounded above by a or just below the lowermost of 3 low but distinct well developed siphonal fold; parietal inductura lirae on flank; profile below suture only very slightly thickened, extending as a callus beyond aperture, convex, becoming flat almost immediately to form and developed into a siphonal fold at lower end and a steep flank rounding gradually below into a into a parietal fold of approximately the same size, slightly flattened base; base very minutely phaner- located half the distance up parietal side of aperture. omphalous. Aperture somewhat rectangular, pointed Shell smooth; growth lines not visible. at suture; outer lip thin, gently oblique backwards Nuclear whorls apparently of same shape as later with slight forward convexity to periphery, and whorls; parietal fold seemingly not strongly de- with slight forward concavity on base; columellar veloped in youthful whorls but forming a low angu- lip thin, vertical, reflexed; parietal inductura lation that lends strong resemblance to the genus lacking. Strobeus; parietal fold attaining a size almost equal Ornamentation 3 low, rounded revolving lirae to that of siphonal fold by fifth whorl. dividing flank from base, separated by 2 broad, shallow depressions; the lowermost of the 3 lirae MEASUREMENTS : Two specimens were excellently is actually the first of 12-16 fine basal lirae, which preserved and permitted complete measurements become finer and more closely spaced toward um- to be made. Dimensions in mm.: bilicus; flank with a suggestion of very fine liration; h w ha wa hbw w/h growth lines obscure. Nucleus of 2 or 3 smooth whorls, the first of which 1. 5.1 3.4 2.8 1.6 4.0 .67 (holo- is coiled almost in a plane; spiral grooves between type) peripheral lirae appear first, followed by lirae. 2. 4.0 2.6 2.4 1.3 3.1 .65 MEASUREMENTS: Of 12 measureable specimens, several were partially broken around aperture or TYPES: Holotype: Amer. Mus. Nat. Hist. tip of spire. Dimensions in mm.: 27113:1. Paratype: Mus. Northern Ariz. h W ha wa w/h S wh DISCUSSION: This form differs from Triassic species of Oncochilus in its higher spire and more 1. 9.4 4.2 3.4 2.3 .45 32 12 6* fusiform shape. It is smaller in size and somewhat 2. 9.0 4.0 3.2+ .43 29 7 3. 18. 6 4.1 .48 32 16 7+ more globose than Gemmellaro's species "Cylindri- 4. 6.1 3.2 .53 31 14+ 6 topsis" ovalis and "C." inflatus. "C." minimus, 5. 5.9 3.1 1.7 1.5 .53 33 15 6+ "C." cheilodonfus, and "C." conicus, Gemmellaro's 6. 5.8 3.3 2.1 1.7 .57 29 13 6 other species, are probably conspecific and differ 7. 5.6 3.2 2.3 1.7 .57 36 15 6 8. 5.3 + 2.9 1.8+ 1.5 .55 37 6+ from the present form in their more elongate shape, 9. 5.0 2.9 1.6 .58 33 5+ greater proportionate height of final whorl, and 10. 4.1 2.4 1.6 1.3 .59 40 14 5 nature of lip. Except for "C." minimus, which was 11. 2.4 1.7 1.2 14 probably a juvenile, they are larger than the Kai- 12. 3.5 2.0 1.3 1.1 .57 28 13+ 5 bab form. s = number of basal striae. Undescribed specimens in the U. S. National TYPES: Holotype: Amer. Mus. Nat. Hist. Museum, collected from Word Limestone no. 1 of 27116:1. Paratypes: Amer. Mus. Nat. Hist., Mus. the Glass Mountains, Texas, are very like Oncochilus Northern Ariz., Grand Canyon Nat. Park museum.

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DISCUSSION: Because of poorness of preservation, Surfaced marked by fine growth lines, without of growth lines in particular, this form cannot be other ornamentation. well assigned generically. In nature of ornamenta- Nucleus similar to later whorls, there being no tion it seems to be closest to the genus Aclisina, evidence of any regular change in proportions during although it does not show the sinuate lip nor the ontogeny (Fig. 10). inductural characters of that genus. In addition, MEASUREMENTS: A fairly large number of speci- the nucleus appears planospiral and not, as is fre- mens were available, covering a good range in size quent in Aclisina, detached, and the spire is lower and representing all ontogenetic stages. Dimensions and the whorls more flattened than in that genus. in mm.: No closely similar species is known. h W ha wa w/h ha/h wh OCCURRENCE : Loc. 3 (common, silicified). 1. 11.0 10.2 9.0 6.3 .93 .82 4 2. 10/6 10.2 9.6 6.7 .83 .91 31 Family PSEUDOMELANHDAE? 3. 9.9 10.3 8.9 5.4 1.04 .90 3i 4. 9.1 8.5 7.8 4.9 .94 .86 31+ Genius et species indet. 1 5. 9.0 9.2 6.9 5.9 1.02 .77 31 6. 7.4 7.0 5.9 5.2 .95 .78 4 PI. 5, fig. 8 7. 7.1 6.5 5.4 4.0 .92 .76 31+ 8. 6.1 5.9 5.8 3.5 .97 .95 A fragmentary external mold of 2 whorls of a 9. 6.1 5.6 5.6 3.4 .92 .92 4 small gastropod could not be identified. It is finely 10. 6.0 5.0 5.0 3.1 .82 .83 and delicately ornamented with alternating strong 11. 5.7 5.5 5.0 3.1 .97 .88 3i and weak spiral lirae, and shows straight growth 12. 5.0 4.9 4.5 2.7 .98 .90 3 lines only very gently oblique backwards, suggest- 13. 5.0 4.1 4.1 2.7 .82 .82 3i 14. 4.9 5.6 4.1 3.1 1.14 .84 34 ing that it may belong to the family Pseudome- 15. 4.6 4.4 4.0 2.5 .96 .87 3i laniidae. It shows resemblance to the Triassic 16. 4.6 5.0 4.3 2.9 1.09 .94 3* genus Rhabdoconcha, but is not completely enough 17. 4.3 4.0 4.0 3.1 .93 .93 preserved to assign generically. 18. 3.5 3.2 3.9 1.8 .91 .83 19. 3.4 3.1 2.6 1.9 .91 .76 2J 20. 3.2 2.9 2.1 1.5 .91. .66 OCCURRENCE: Loc. 1, bed 2 (very rare, external 21. 3.1 2.9 2.3 1.7 .94 .74 mold). 22. 2.5 2.6 2.1 1.5 1.04 .84 3 Superfamily NERITACEA TYPES: Holotype: Amer. Mus. Nat. Hist. Family NERITOPSIDAE 27112:1. Paratypes: Amer. Mus. Nat. Hist., Mus. Northern Ariz., Grand Canyon Nat. Park museum. Genus Naticopsis McCoy 1844 DISCUSSION: The ultimate diagnosis of species of Naticopsis appears to depend on color patterns. In Naticopsis kaibabensis sp. nov. the absence of preserved coloration, however, PI. 5, figs. lOa-llb species must be established on the slight differences in shape shown by the fossils. For this reason, DESCRIPTION: Small, globose, very low-spired measurement of as many characters as possible on gastropods varying in proportion from slightly as many specimens as practical is offered. higher than wide to slightly wider than high; 3-4 This form bears closest resemblance to N. de- rapidly enlarging volutions, each embracing almost formis Girty, but comparison with Girty's type the whole of preceding whorl; spire projecting less specimens reveals that they are not the same. than 1 mm. above final whorl. Whorl profile in- Girty's form is more transverse and more rotund flated, with broad, gently convex upper and lateral than most of the Kaibab specimens, and has a lower surfaces sometimes showing a slight development of spire. Superficial examination reveals other differ- a shoulder, and becoming straight on base; anom- ences which, due to the rounded shape of both phalous. Aperture tear-drop shaped, widest at or shells, cannot be measured. very slightly below center; length of aperture about Strong resemblance to a form identified by Girty 0.8 or 0.9 that of shell; outer lip directed backward (1909a, p. 463, pi. 10, figs. 3, 3a) as Strophostylus from suture at an angle of about 80°, and running subovatus is evident, although identity of either obliquely backward with forward convexity to basal Girty's specimen or the Kaibab forms with .S. portion of shell, then almost radially; parietal lip subovatus Worthen seems extremely doubtful. thickened, with a callus-like inductura extending Girty in his later papers did not appear to recognize outside of aperture and sharply flattened near this similarity nor to discuss it under affinities of columella. N. deformis.

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This species also resembles N. transverse (Beede) shoulder, as well as a less oblique outer lip, than is in general shape. Although Knight (Newell, 1940) evident in N. kaibabensis, and are to be considered describes some specimens of N. transversa as having a different species. Because of the preservation as little or no transverse ornamentation, complete external molds, the aperture and parietal lip cannot

FIGURE 10.—RELATION OP WIDTH AND HEIGHT or APERTURE TO HEIGHT IN Naticopsis kaibabensis

absence of any such ornamentation in the Kaibab be studied with the material at hand, so these specimens is considered sufficient evidence that they specimens are not classified specifically. The dis- are separate species. covery of more specimens may enable identification In shape, this form, especially certain of the or show that these are a more mature form of juveniles, also resembles N. nana Meek and N. kaibabensis. Worthen, but is more globose and has a less pro- OCCURRENCE: Loc. 1, bed 2 (common, external nounced spire, while the shape of the aperture molds). differs markedly. N. remex White has a more evenly rounded whorl, without any development of a Superfamily CERITHIACEA shoulder. There is strong resemblance to the Mon- golian form, N. khurensis Waagen, from which it Family TTJRRITELLIDAE differs in the more rounded base and the less oblique Genus Orthonema Meek and Worthen 1861 character of the aperture. Orthonema? striatonodosum sp. nov. OCCURRENCE : Loc. 3 (abundant, silicified). PI. 5, figs. 13a-H Naticopsis sp. DESCRIPTION: Small, high-spired, many whorled PI. 5, fig. 12 gastropods of somewhat fusiform shape, the apical angle being always greater than the pleural angle; A few specimens of Naticopsis from locality 1 whorls numbering about 10; basal whorl nearly show a larger size and a much more pronounced half entire height of shell. Suture shallow, appressed;

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whorl profile very gently arching below suture; final sp. 1 is possibly a mature specimen of O.I striato- whorl more strongly rounded at lower side of flank, nodosum. forming an almost indiscernible angulation; base The straight outer lip seen in specimens of O.f extended very slightly into an anterior canal. Aper- striatonodosum is not characteristic of the genus, ture lozenge-shaped in cross-section; outer lip though in its other characters this form resembles straight and almost vertical, extending below base members of the genus. It is placed tentatively to form a short anterior canal; inner lip thickened at canal, and with edge of rather thick parietal induc- •|2mm tura forming an arc upward to suture. Ornamentation consisting of a row of indistinct, low, vertically elongated nodes below line of suture, bounded above and below by poorly developed, striae-like furrows which are often obscured or erased by erosion; growth lines rarely evident, straight and almost vertically directed. Nucleus seemingly smooth, with spiral furrows appearing before development of nodes. MEASUREMENTS: The spires of most specimens are broken at the tip, and often the anterior canal is broken away, so measurements of height and number of whorls were estimated by comparison FIGURE 11.—RELATION or WIDTH AND PLEURAL with a few more complete specimens. Dimensions in ANGLE TO HEIGHT IN Ortkonema? mm.: striatonodosum h W ha bw w/h aa wh * within the genus until further collections, possibly 1. 11.9 4.1 3.3 5.5 .34 8° 32° 8+ of specimens with well preserved apertures, can 2. 11.3 3.8 3.3 4.9 .34 15 40 9 be made. 3. 11.0+ 4.1 5.0 .37 18 32 8* A form very like this occurs in the Word lime- 4. 10.8 4.2 3.7 14.4 .39 6 40 9+ stone no. 1 of the type locality, but has not yet been 5. 10.2 4.0 3.0+ 4.5 6. 10.1 3.9 5.0 .39 12 41 10* described. 7. 9.0 3.5 .39 14 9* Although in general shape this form strongly 8. 9.0+ 3.5 .39 13 35 9+ resembles O. conicum Meek and Worthen, from the 9. 9.0+ 3.3 .37 9 47 7+ Pennsylvanian of the Mississippi valley, it does not 10. 8.9+ 3.7 2.8 4.5+ .42 19 33 8+ 11. 8.7 3.6 have the sinuosity of the outer lip or a distinct 12. 8.4 3.3 2.6 4.0 .39 9 J43 7+ angulation at the base. In ornamentation there is also some resemblance TYPES: Holotype: Amer. Mus. Nat. Hist. no. to 0. cerithioides Mansuy. That Indochinese species 27117:1. Paratypes: Am. Mus. Nat. Hist., Mus. differs from O.f striatonodosum in its more regularly Northern Ariz. conical shape, for it has little tendency toward fusiformity, and in its lack of striae above and DISCUSSION: The specimens at hand show con- below the row of nodes. siderable variety in form. Although the majority OCCURRENCE: Loc. 1, bed 9 (rare, external tend to be quite high-spired and to have a very low molds); loc. 3 (common, silicified). pleural angle and an apical angle considerably greater, others give an impression of being rounded, Orthonema sp. 1 with the apical angle close to 40°, while the pleural angle is very low, perhaps below 10°, so that con- PI. S, fig. 18 siderable gibbosity is apparent. DESCRIPTION: A high-spired, many whorled There is much resemblance between this form and gastropod of medium size, having about 10 whorls Orthonema sp. 1, described below. The latter, a and a pleural angle of 12j°; whorls regularly en- single specimen, is two or three times as large and larging and overlapping so that basal whorl is shows a definitely orthonematid bend in the upper about two-fifths the height of entire shell. Suture part of the outer lip (as indicated in growth lines) shallow, appressed, located just above a rounded and quite a strong angulation between the base and but pronounced angulation dividing the base and flanks. These characters may become pronounced sides of shell; shell profile sloping gently outward only in advanced stages of ontogeny, so that O. below suture for a short distance, forming a narrow,

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steeply inclined shoulder, then turning abruptly low on the whorl, as on some of the extreme variants vertical to form flanks, and rounding at basal of M. gouldii Beede described by Knight (Newell, angulation into an inclined, anomphalous base with 1940, p. 308). a short anterior canal. Aperture oval, pointed above OCCURRENCE: Loc. 1, bed 9 (rare, external and leading below to anterior canal; outer lip molds). directed gently and obliquely backward below suture to shoulder angle, where it becomes vertical and continues so, being radial on base. Superfamily et family indet. Ornamentation includes some very obscure nodes Genus et species indet. 2 along shoulder angle and a faint suggestion of spiral liration, especially on flanks; growth lines fine and PI. 5, figs. 16, 17 often indistinct. A number of small, high-spired gastropods 4-12 Nucleus unknown. mm. in height, having 8-10 gradually expanding MEASUREMENTS: The single silicified specimen volutions, are not well enough preserved to be has the following dimensions. As the spire is broken assigned either generically or specifically. Growth at the tip, height is estimated. Height 25 mm. + ; lines and ornamentation are usually not distinguish- width 9.0 mm.; height of aperture 6.0 mm.; height of basal whorl 10.0 mm.; width/height ratio .36; able, though one specimen shows growth lines which pleural angle 12J°. indicate the outer lip is vertical below the suture, curving to backward obliquity about half way down DISCUSSION: The specimen is similar in general the shell and forming a shallow sinus above the shape and in its faint nodular ornamentation to the periphery, then directed forward across the periph- associated, more abundant small species 0.1 striato- ery and base of the shell. One specimen shows a nodosum. Its growth lines, however, very distinctly suggestion of vertical ribbing (which may however bend forward above the shoulder angulation in be an irregularity of preservation) and several true orthonematid fashion, and the basal angulation others show spiral striation on the base and a single is considerably stronger than in the smaller forms. fine stria just above the periphery. It is possible that these are characters which develop It is highly probable that more than one form is fully only in advanced stages of ontogeny, but the included here. Specimens bear a superficial resem- fact that they are evident in the smallest preserved blance to Orthonema socorroense Girty, but they may whorls of the spire suggests that this is not merely not be orthonematid in nature. a more mature O.f striatonodosum, but a different species, definitely one of the orthonematid group. OCCURRENCE: Loc. 1, bed 9 (rare, external No other species of Orthonema is known to which molds); loc. 3 (common, silicified). this specimen can be assigned. It resembles in shape but not in ornamentation the Pennsylvanian species PELECYPODA O. salteri (Meek and Worthen), and differs from O. socorroense Girty in the presence of a shoulder Twenty-six pelecypods are here described, be- angulation and in the more rounded character of longing to 22 genera. Two new genera and 8 new the basal angulation. It is twice as large as that species are described. The pelecypods bear a re- form. semblance to those of the Word limestone no. 1, but the similarity is not so pronounced as in the OCCURRENCE: Loc. 3 (very rare, silicified). gastropods. A chart of occurrence and relative abundance of Orthonema? sp. 2 pelecypods from the four faunules is presented PI. 5, fig. 15 below. Measurements of various forms are recorded in full. Where a large number of specimens made it A small, high-spired, trochiform gastropod of un- practical, ratios of width to length and convexity certain affinities shows strong superficial resem- to length have been presented graphically. blance to 0. socorroense Girty, from which it differs, Abbreviations used in tables of measurements are however, in the faint sinuosity of the whorl profile. as follows: It also resembles Taosia dozierensis (Beede), but 1 = length has none of the faint transverse undulations de- h = height scribed by Knight (Newell, 1940, p. 310) in that g = length of hinge genus, nor is there any sign of a median slit band. att = number of anterior teeth That it is a member of the genus Orthonema is not ptt = number of posterior teeth certain; growth lines revealing the shape of the c = convexity, both valves together Jc = convexity of one valve outer lip can not be seen. It may possibly be a a = length of shell anterior to beak Murchisonia with the selenizone located extremely b = height at beak, perpendicular to hinge

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TABLE 2.—PELECYPODS, OCCURRENCE AND Nuculana obesa, WHITE, U. S. Geol. and Geog. FREQUENCY CHART Survey Terr. Wyo. and Idaho, Ann. Repts., vol. 12, pt. 1 (1883), p. 136, pi. 34, figs. 2a-c. Loc. 1 Loc. 1 Loc. 2 Loc. Leda obesa, GIRTY, U. S. Geol. Survey, Bull. 389 bed 2 bed 9 bed 4 3 (1909), p. 76. Leda obesa, GIRTY, U. S. Geol. Survey, Bull. 436 (1910), p. 40, pi. 4, figs. 7, 8. Acanthopecten coloradoensis Leda obesa, BRANSON, Missouri Univ. Studies, (Newberry). X vol. 5, no. 2 (1930), p. 43, pi. 10, figs. 21, 22. Allorismaterminale'Ra.]\... . X X Allorisma? juveniles.. x DESCRIPTION: Nuculoid pelecypods of moderate Alula gtiberti (White) X size, with posterior margin extended. Cardinal Astartella subquadrata margin strongly arched anteriorly and continuous Girty xxx xxx Amculopecten kaibabensis Newell X X X Aviculopinna sagitta sp. nov X -15 mm Bakevettiaprorasp. nov XX X Bakevellia cf. B. sulcata (Geinitz) x Dozierellasp. 1 ... x Dozierellaf sp. 2 X Hdmondia- sp X Goniophora cristata sp. nov. . X X X Grammatodon politus (Girty) . . XX XX x x Kaibabella curmlenata gen. et sp. nov XX x x FIGURE 12.—RELATION OF HEIGHT AND CONVEXITY Manzanella cryptodentata TO LENGTH IN Nuculana obesa x x Myalindla? adunca sp. with anterior margin, which arches below smoothly nov X into gently arcuate ventral margin; cardinal Nuculana obesa White XX XX margin concave posteriorly and continuous with Palaeonucula levatiformis much extended, upward-curving posterior margin, (Walcott) xxx xxx xxx xxx which gapes at its truncated termination. Beaks Pleuroplwrus albequus Beede xxx XX xxx X small, posteriorly directed; posterior umbonal Pleurophorus cf. P. mexi- ridge sharp, concave upward. canus Girty X Ornamentation fine and somewhat irregular Promytilus retusus sp. nov... X X XX concentric lirae, spaced 3-5 per mm., becoming Rimmyjimina. arcula gen. more crowded toward umbo; lirae broad and flat, et sp. nov XX separated by narrow furrows, and independent of XX x growth lines except near margin of adults; growth Schizodus texanus Clifton. . . X lines obscure. Solemya parattda Beede Escutcheon elongate and pointed; dentition and Rogers x x taxodont, with about 10-16 closely spaced, vertically elongated, sharp teeth anterior to beak and x —rar e usually 9-14 posterior to beak; distally the poste- xx — common rior teeth become distinctly chevron-shaped; xxx — abundant pallial line sinuate and commonly deep in adult shells; anterior muscle scar circular, only slightly Superfamily NUCULACEA depressed, generally indistinct; a rounded internal Family NUCULANIDAE ridge bearing irregular scars of pedal muscles near Genus Nuculana Linck 1807 umbo and bordered by depressions, extending vertically downward from umbonal region to about Nuculana obesa White 1879 middle of shell. Posterior adductor impression not PI. 6, figs, la-3 observed. Nuculana obesa WHITE, U. S. Geol. and Geog. Constrictions in shell during growth are occa- Survey Terr., Bull. 5 (1879), p. 216. sional, most shells over 10 mm. long showing at

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least a slight constriction near ventral margin, at a DESCRIPTION: Very small, subtriangular nuculids, position corresponding externally to pallial line. a little longer than high, with biconvexity of the 2 At this constriction, the lirae are truncated by suc- valves somewhat more than half the length. Ante- ceeding lirae. There is a slight change in length rior margin irregularly convex, forming a rounded during growth, youthful stages being relatively bulge below beak; posterior margin almost per- shorter than adult. Posterior siphonal part of shell pendicular to anterior, gently and regularly convex; appears proportionately more slender in adults ventral margin quite convex and rounding abruptly than in juveniles. into anterior margin, less abruptly into posterior margin. Beak pointed, prosogyre, not strongly in- MEASUREMENTS : Ten silicified specimens have the curved; shell evenly convex, without umbonal ridge. following dimensions (in mm.): Ornamentation of fine, low, evenly spaced con- l h : c h/1 | c/l centric lirae, spaced about 10 per mm.; one or more concentric growth constrictions near ventral margin 1. 26+ 15.2 .58 of some shells. 2. 24.0 13.7 9.6 .57 .40 Dentition taxodont, with about 10-13 anterior 3. 22+ 13.3 9.1 .60 .41 4. 20.5+ 12.6 9.4 .61 .46 teeth and 6-9 posterior teeth in large individuals; 5. 18.7 11.4 7.1 .61 .38 teeth increasing in size and spacing away from beak, 6. 18.0 11.0 8.4 .61 .47 the outermost few often being considerably enlarged; 7. 10.9 6.8 4.6 .62 .42 a triangular resilium lies under beak. Pallial line 8. 10.6 6.6 4.0 .62 .38 and anterior muscle scar usually not visible; poste- 9. 10.2 6.2 4.4 .61 .43 10. 7.5 4.8 3.6 .64 .48 rior scar strongly impressed along its anterodorsal margin. Three internal molds are intermediate in size, Although proportion of height to length of the though measurements are not directly comparable shell shows no regular change with growth, relative with those above because the thickness of the shell is lacking. convexity tends to increase during ontogeny. Occa- sional strong growth constrictions are seen in a 11. 18+ 8.2 number of large shells, often more than one in a 12. 15+ 8.7 single shell. 13. 12.5+ 6.6 Figure 12 shows the slight change in height- MEASUREMENTS: Sixty specimens were selected length ratio during growth. There is seemingly no for measurement. Dimensions in mm.: change in convexity. 1 h c c/l h/l 1 h c c/l h/l DISCUSSION: In shape, size, and ornamentation, 1. 7.3 6.0 4.5 .61 .82 31. 5.64.7 3.6 .64 .84 this form agrees closely with White's original 2. 7.1 6 4 4 6 64 90 3^ 5.64.7 1 4 61 81 definition of Nuculana obesa, from specimens col- 3. 7.15.94.2 .59 .83 33. 5.64.6 3.4 .61 .82 lected from the Kaibab formation north of Grand 4. 7.05.9:5.3 .76 .84 34. 5.65.0 3.6 .64 .89 5. 6.85.714.3 63 84 3S 5.514.7 3 0 67 86 Canyon. 6. 6.75.7|4.6 .69 .85 36. 5.4 4.6 2.9 .54 .85 Increase in the ratio of height to length during 7. 6.75.64.0 .60 .84 37. 5.4 4.6 3.4 .63 .85 successive growth stages, as described by Girty 8 6.65.54.2 64 81 38 S 4 4 6 3 4 63 86 (1910), is evident but not pronounced in these 9. 6.65.5:4.6 .70 .83 39. 5.3 4.73.6 .68 .89 10. 6.6J5.3J4.6 .70 .80 40. 5.3 4.63.8 .72 .87 specimens. A change in convexity, also noted by 11. 6.65.44.8 .73 .82 41. 5.1 4.513.2 .63 .88 Girty, is not so evident, as the convexity varies 12. 6.55.4:3 8 .58 83 1"> S 0 4 Oi3 0 60 80 considerably at all growth stages. 13. 6. S|5. 54. 2 .65 .85 43 4 7 4030 64 85 14. 6.5i5.23. 7 57 80 44. 4.6 4.02.6 S7 87 OCCURRENCE: Loc. 2, bed 4 (common, external 15 6.5'5.4i4 4 68 83 45 463077 so SS and internal molds); loc. 3 (common, silicified). 16. 6.4 5.4 3.6 .56 .85 46. 4.5 3.712.8 .62 .82 17. 6.4 5.5 4.5 .70 .86 47. 4.4 3.62.5 .56 .82 18 6.3 S ^ 4 4 .70 83 48 4 4 3725 57 8<1 Genus Palaeonucula Quenstedt 1930 19 6.35 340 64 84 49 4 3 3 4^2 4 56 70 20. 6.35.4 4.7 .75 .86 50. 4.3 3.62.5 .58 .84 21. 6.05.2 3.7 .62 .87 51. 4.1 3.52.5 .58 .84 Palaeonucvla levatiformis (Walcott) 1884 22. 6.05.1 4.2 .70 .85 52. 3.9 3.312.8 .72 .85 23. 6.05.4 4.4 .73 .90 53. 3.7 3.412.3 .62 .92 PI. 6, figs. 4-9 24 5.9LS.2 4 1 .70 88 S4 3 6 .3020 66 83 25. 5.85.0 1 8 .66 .86 ss 3.6!3.1 7 7 61 86 Nucula levatiforme WALCOTT, U. S. Geol. Survey, 26. 5.7 4 8 3 6 63 84 56 3.32.6 1 8 S4 81 Mon. 8 (1884), p. 241, pi. 22, figs. 1, la. 27. 15. 75.014.0 .70 .88 57. 3.32.6 2.0 .61 .79 Nucula levatiformis, GIRTY, U. S. Geol. Survey, 28. 5.74.83.4 .60 .84 58. 2.7(2.1 1.5 .56 .78 Bull. 389 (1909), p. 74, pi. 10, figs. 7, 8. 29. 15.74.63.4 .60 81 S9 2.2-1.7 1 3 59 77 Nucula levatiformis, CLIFTON, Jour. Paleont., ! 5.03.8 vol. 16 (1942), p. 693. 30. 5.7 .67 .88 60. 2. 01. 61. ,3 .65 .80

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-6mm.

7mm. FIGURE 13.—RELATION OF HEIGHT AND CONVEXITY TO LENGTH IN Palaeonucula levatiformis

DISCUSSION: The similarity of size, shape, and in the possession of an enlarged anterior lamellar surface sculpture of Kaibab material to those of cardinal tooth, associated with reduced posterior Walcott's specimens of P. levatiformis is pronounced, cardinal teeth. There is some resemblance to the and agreement with forms identified as "Nucula family Nuculinidae, but in that family as in the levatiformis" by Girty confirm the assignment to genus Nuculina, the large lamellar tooth appears to that species. There is some similarity to P. mont- be posterior, and the taxodont teeth anterior. pelierensis Girty, a form much the same in proportions of length and height, but slightly less convex Manzanella cryptodentata sp. nov. than P. levatiformis, and bearing finer concentric PI. 6, figs, lla-14 striae. It seems likely, as Girty suggests, that the 2 forms are members of a single long-ranging and DESCRIPTION: Small, thick-shelled, transversely locally abundant species. ovate, strongly convex pelecypods having height OCCURRENCE: Loc. 1, beds 1, 9 (abundant, ex- equal to 0.8-0.9 the length, and biconvexity equal ternal and internal molds); loc. 2, bed 4 (abundant, to about 0.6-0.7 the length. Margins rounded and external and internal molds); loc. 3 (abundant, without angulations, usually sh'ghtly truncate silitified). posteriorly, but in general oval in plan, somewhat Superfamily? expanded anteriorly; cardinal margin slightly flattened anterior to beak; beak thick, short, proso- Family MANZANELLIDAE gyre, located slightly posterior to middle; umbonal Genus Manzmetta Girty 1909 or siphonal ridge lacking. The taxonomic position of the genus Manzanella Ornamentation lacking; growth lines fine, irregu- is very uncertain. It differs from other pelecypods lar, with occasional weak growth constrictions.

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Lunule very small, subtriangular, lying just identical. Examination of the type specimens of under beak; escutcheon well defined, with a narrow, M. elliptica shows that Girty's figure is accurate. arcuate ligament groove; dentition actinodont, In spite of difference in dentition, there is close with one or more strong but short, oblique, rounded, similarity in other characters of the two forms. Of posteriorly directed cardinal teeth in left valve and the Kaibab specimens, only one small left valve corresponding sockets in right valve; a low, verti- shows the posterior teeth well. In it there are 3 cally directed cardinal tooth in right valve with a almost straight, oblique, posterior cardinals. On triangular socket just in front of cardinal tooth of larger specimens the teeth appear to become longer, left valve; a strong, very prominent lamellar anterior and lamellar, and to lie almost parallel to each other, cardinal tooth in each valve, that of left valve below the escutcheon. The teeth are clearly not fitting into a socket between anterior tooth and taxodont, as Girty described them. thickened cardinal margin of right valve, and bear- The reason for differences in dentition between ing on its lower side a lamellar socket to receive two shells otherwise so similar is not apparent. For tooth of right valve; anterior tooth buttressed by lack of intermediate or transitional forms, the Kai- a strong, rounded, thick ridge extending down into bab specimens are here treated as a new species, shell. Ligament external, opisthodetic, lying in a but such differences may be induced, in part at narrow arcuate groove above posterior teeth. Ante- least, by variations in ecologic conditions. Further rior and posterior adductor muscles almost equal, study of the influence of environment on the de- anterior perhaps the larger and more deeply im- velopment of dentition is necessary, and may lead pressed, lying just anterior to thickened buttress; to the conclusion that the two forms of Manzanella a depressed area bounds the buttress posteriorly are conspecific. In such a case, the thicker shell and ventrally; anterior and posterior accessory substance of Girty's larger specimen and the higher muscle pits well marked, lying at extremities of beak and more strongly arched valves of both his hinge plate, just above adductor scars; pallial line types may also be interpreted as ecologic differences apparently simple. or may be attributed to geographic differentiation, Little change in proportion during growth is since the two forms are of about the same age. evident although young specimens are slightly OCCURRENCE: Loc. 1, bed 9 (rare, external thinner proportionately than older ones; the small molds); loc. 3 (rare, silicified). oblique posterior teeth apparently increase in length, but not in number, with growth. Superfamily ARCACEA MEASUREMENTS: (in mm.) Family GRAMMATODONTIDAE l h C h/1 c/l Genus Grammatodon Meek and Hayden 1860 1. 11.4 9.5 7.0 .83 .62 2. 11.0 9.8 7.6 .89 .69 Grammatodon politus (Girty) 1909 3. 10.2 9.0 6.6 .88 .65 4. 10.0 8.5 6.6 .83 .64 PI. 7, figs. la-2b 5. 9.7+ 8.0 5.8 .84 .60 6. 9.6 8.0 6.0 .83 .63 Parallelodon politus GIRTY, U. S. Geol. Survey 7. 9.1 8.0 6.4 .88 .70 Prof. Paper 58 (1909), p. 424, pi. 9, fig. 25. 8. 8.5 6.4 4.6 .75 .54 9. 8.2 6.5+ 5.2 .79 .63 DESCRIPTION: Transverse shells of medium size, 10. 5.7+ 4.3 3.0 .75 .53 11. 5.6 4.5 3.2 .80 .57 with height usually a little over half the length, and 12. 5.4 4.2 2.6 .78 .48 convexity about 0.4 the length. Cardinal margin almost straight; anterior margin obliquely rounded, Girty's specimens of M. elliptica: forming an acute angle with cardinal margin, and 1 h C h/i c/l rounding gradually into ventral margin; ventral margin almost straight, though sometimes with a 1. 12.1 10.0+ 9.8 .83 .81 slight sinus about two-fifths the distance toward 2. 10.1 9.1 7.1 .91 .73 posterior margin, diverging from hingeline toward posterior; posterior margin rounded below, obliquely TYPES: Holotype: Amer. Mus. Nat. Hist. truncated above, forming an angle of about 120° to 27101:1. Paratypes: Amer. Mus. Nat. Hist., and 140° with cardinal margin; beak low, anteriorly Mus. Northern Ariz. directed; umbo flattened, or, sometimes, with a DISCUSSION: The posterior elements of the denti- shallow sulcus obscure except in very young tion of these specimens differs from Girty's Man- individuals. zanella elliptica from the Yeso (Leonardian), al- Radial ornamentation lacking; growth lines though other characters of the shells are almost irregular and locally lamellose.

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Dentition consisting of 2-5 oblique anterior directed backward from cardinal margin at an angle teeth, the anterior 2 or 3 in large specimens being of 120°, and rounding below into ventral margin, the most prominent, with corresponding sockets which is almost straight; anterior margin sharply in each valve, and of 2 or 3 diverging lamellar rounded. Beak not well preserved, probably low and teeth with corresponding sockets; number of teeth lying near anterior end; convexity of shell apparently increasing with growth; ligament external, amphi- greatest at point two-thirds the distance below detic; pallial line simple; muscle scars not well cardinal margin. shown. Ornamentation lacking; growth lines irregular There appears to be no appreciable change in except near ventral margin, where they are very proportions during growth. closely spaced. MEASUREMENTS : Four silicified specimens and seven internal molds have the following dimensions (in mm.): 1 h c h/I c/1 g a b 1. 25.7 12.7 9.4 .49 .37 21.0 5.2+ 10.3 (mold) 2. 20.0 11.0 .55 15.8 3.9 10.0 (mold) 3. 17.7 9.0 8+ .51 .45 14.1 3.3 8.0 (mold) 4. 15.2 7.8 6.4 .51 .42 11.0 3.0 6.9 5. 13.3 7.0 .53 10.8 (mold) 6. 12.3 5.8 6.0 .47 .49 9.9 2.0 5. 8 (mold) 7. 10.5 6.0 .57 (mold) 8. 7.8 4.3 .55 9. 6.8 4.0 2.8 .59 .41 5.3 1.5 3.3 (mold) 10. 6.7+ 3.3+ 2.8 .50+ .42 5.3 1.1 3.1 11. 4.8 2.9 2.0 .60 .42 1.0 2.7

DISCUSSION: This form strongly resembles G. Internal structures unknown. politus (Girty) in its lack of radial ornamentation. Some specimens reveal a gentle sinuosity of the MEASUREMENTS: The holotype has the follow- ventral border not reported by Girty, but his speci- ing dimensions: length 100 mm.; height 20 mm.; mens were exceedingly fragmentary and not very thickness 8 mm. +. abundant. TYPES: Holotype: Mus. Northern Ariz. G2.1300. There is close affinity also with the Pennsyl- vanian form G. obsoletus Meek, which has a distinct DISCUSSION: The external mold showing the ventral sinus but is somewhat more elongate than above characters is unlike any previously described this form and bears obscure radial ornamentation Pennsylvanian or Permian species of Aviculopinna. near the hingeline behind the umbo. It is much more acute than A. nebraskensis Beede Most other forms of this genus bear distinct and not so large. It differs from A. peracuta (Shu- radial ornamentation and so differ markedly from mard) in its obtuse posterior angulation, and from the present form. A. ittinoisensis Worthen in its straight cardinal OCCURRENCE: Loc. 1, beds 2, 9 (common, ex- margin. A. americana Meek is not as thick and ternal and internal molds); loc. 2, bed 4 (rare, shows besides a sinuosity in the posterior margin juvenile internal and external molds); loc. 3 (rare, and a few radiating ridges. A. pinnaeformis (Gei- silicified). nitz) is apparently much smaller and also shows Superfamily PTERIACEA radiating striae. A. knightii Beede, a much larger species, has the cardinal and ventral margins almost Family PINNIDAE parallel. Genus Aviculopinna Meek 1867 Although the material is not complete and but a single specimen is available, that specimen is so Aviculopinna sagitta sp. nov. obviously distinct from previously described forms PI. 6, fig. 10 that it warrants being named the holotype of a new species. DESCRIPTION: Highly oblique, elongate pelecypods with straight hinge and subterminal beak, and with cardinal and ventral margins diverging OCCURRENCE: Loc. 1, bed 9 (one external mold). Fragmentary external molds were observed in at about 9°. Cardinal margin straight, somewhat various parts of the Kaibab section, and often thickened into a narrow, thread-like ridge which reached a much greater size than the present speci- becomes stronger posteriorly; posterior margin men. They may not, however, be conspecific.

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Family LEIOPTERIIDAE thinner, more delicate, and less often preserved Genus Dozieretta Newell 1940 than left. Hingeline long and straight, about 0.9 the length of shell; anterior margin protruding, rounded, Dozierella sp. 1 merging at a gentle sinus into gently convex ventral PI. 7, figs. 4a-5 margin; posterior margin strongly concave below hinge, forming a concave emargination in posterior A single, somewhat fragmentary left valve, and a auricle, then turning with sharp convexity to meet tiny juvenile right valve of a small pterioid are dis- ventral margin. Valve strongly convex transversely tinguished from specimens of Bakevellia prora sp. except for flattened posterior auricle and a shallow nov. by their ornamentation and dentition. The left sulcus extending from anterior side of umbo almost valve is marked by fine, wavy, but rather regularly vertically to ventral margin, delimiting anterior spaced concentric lirae, following the growth lines, auricle; anterior sulcus bounded posteriorly by a and by fairly widely spaced, stronger growth con- sharp though slight change in convexity of shell. strictions. The posterior sinus is only feebly de- Growth lines irregular over most of shell, often veloped, and no anterior sinus is discernible in the lamellose anteriorly and near ventral margin, fairly broken shell. The left valve bears a single long, regular only on posterior auricle. ^ posterior tooth almost parallel to the cardinal Hinge of left valve with a long posterior groove margin. Anterior dentition is not visible. bounded above and below by narrow ridges and The right valve bears 3 small cardinal teeth, the bearing 3 or more irregularly spaced, oval multi- anterior one almost parallel to the anterior margin, vincular ligament pits, one just below beak and two the second parallel to the cardinal margin, and the about a third the distance behind it; anteriorly a third oblique to the cardinal margin, an arrange- fairly strong lamellar tooth, with a small linear ment similar to that described for Dozierella. At socket above it, extends forward f the distance least one posterior tooth is present, diverging gently to anterior margin. Dentition of right valve not well from the cardinal margin. The arcoid ligamental known, apparently consisting of an anterior oblique area typical of Dozierella is not observable in these tooth and a posterior groove similar to that of left specimens. valve. MEASUREMENTS: (in mm.) MEASUREMENTS: Eleven molds of left valves h valve were collected, and only one of a right valve. 1 . c L_s gp i Dimensions in mm.: 1. 7.5 4.7 5.0 left 2. 3.4 2.1 0.7 i 2.6 2.2 right h l ic hi gp = hinge posterior to beak. 1. 7.0 10.5 2.1 OCCURRENCE: Loc. 3 (very rare, silicified). 2. 6.1 3. 5.9 9.0 2.2 8.0 Dozierella? sp. 2 4. 5.6 8.9 1.6 1 7.3 5. 5.5 9.0 1.8 8.3 PI. 7, fig. 3 6. 5.4 10.4 1.9 9.5 (holotype) 7. 5.4 8.2 1.7 7.3 The internal mold of a right valve of a small 8. 5.3 '•• 10+ 2+ 8+ pterioid is very oblique in shape, has a posterior 9. 4.7 ; 7.6 2.1 6.5 auricle, and several subparallel posterior lamellar 10. 4.4 ! 6.5 2.0+ 5.2+ 11. 4.2 ; 7.3+ 1.8+ 6.9+ teeth. The single specimen is inadequate, however, 12. 4.7 8.3 1.2 6.5 (rt. valve) for substantial description or comparison. It may belong to Dozierella, though the dentition does not TYPES: Holotype: Mus. Northern Ariz. G2.1307. appear closely similar to that of the genotype. Paratypes: Mus. Northern Ariz. MEASUREMENTS: Length 9.3 mm.; height 4.7 mm.; convexity 1.0 mm.; length of hinge 5.2 mm.; DISCUSSION: These specimens differ from pre- maximum diameter 10.0 mm. viously described members of Bakevellia in shape OCCURRENCE: Loc. 1, bed 9 (one internal mold). and convexity, and in length of posterior auricle. They are further distinguished by a sharp change in Family ISOGNOMONTIDAE convexity of the shell along the anterior sulcus. Genus Bakevellia King 1848 B. prora resembles Pteriat guadalupensis Girty but the posterior sinus is not so deep nor is the shell Bakevellia prora sp. nov. as long and slender as in Girty's species. PI. 7, fig. 10 OCCURRENCE: Loc. 1, bed 9 (common, external DESCRIPTION: Small, strongly oblique isognomon- and internal molds); loc. 2, bed 4 (rare, external tids, probably inequivalved and with right valve and internal molds).

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Bakevellia cf. B. sulcata (Geinitz) 1877 SMzodus texanus CLIFTON, Jour. Paleont., vol. 16 (1942), p. 691, pi. 101, figs. 20-28; pi. 102, PI. 7, figs. 6-9 figs. 10-13. DESCRIPTION: Very small, strongly oblique isog- DESCRIPTION: Trigonal shells of medium size and nomontids, slightly inequivalved, with right valve moderate convexity, having a short, arcuate somewhat less convex than left. Hingeline straight, cardinal margin, a circular anterior margin curving extended posteriorly along auricle; posterior mar- continuously into arcuate ventral margin, and an gins seemingly strongly extended, but posterior obliquely truncated, slightly convex posterior auricle partly broken away in all specimens at hand; margin. Umbones high, with beaks pointed, strongly anterior margin protruding, rounded, the anterior incurved, slightly opisthogyre; umbonal ridge auricle being defined by a broad sulcus directed almost perpendicular to hinge; ventral margin prominent on exterior of shell, slightly less so on gently convex except for shallow anterior sinus, and internal molds, dividing shell into an anterior, more rounding into posterior margin rather sharply. or less strongly convex region and a posterior, Left valve ornamented by a prominent ridge on flattened region. each side of anterior sulcus, increasing in prominence Ornamentation of fine, regularly spaced (about and diverging toward ventral margin; right valve 7 in 5 mm.), concentric lirae, separated by flat unornamented; growth lines fine, commonly in- interspaces; lirae rarely impressed on internal distinct. molds. Oblique ligament pits are present along liga- Dentition not readily described from interior mental area posterior to beaks; anterior to beak in molds, but similar to that described by Clifton for left valve there is a large oblique tooth; other this species. Anterior muscle scar of moderate size, characters of hinge not observed. bounded by a slight ridge posteriorly; posterior muscle scar of similar size, with a slight ridge around MEASUREMENTS: In all specimens the posterior auricle is broken, so total length can only be esti- its dorsal and anterior margins. Pallial line simple. mated. Specimens 1-3 are doubtless quite immature; specimen 4, though much larger, is very in- MEASUREMENTS: (in mm.) complete. Dimensions in mm.: 1 h c valve 1 h ic valve 1. 5.0+ 2.6+ right 1. 31 23 6 right 2. 4.5+ 2.7 right 2. 30 23 7 left 3. 5.2 3.3 2.0 both 3. 27 27 7 left 4. 5.4 left 4. 27 22 8 right 5. 26 21 6 right 6. 25 20 6 right DISCUSSION: This form resembles a group of 7. 25 20 6 right species, placed by different authors in several 8. 25 20 5.5 right 9. 23 18 5 left genera, characterized by two or more ridges de- 10. 23 19 6 left fining an anterior sulcus. To this group belong 11. 22.5 17 4.5 right Bakevellia sulcata (Geinitz) and Pteria richardsoni 12. 19 16.5 5 right Girty, both somewhat similar in shape to the 13. 16 13 4 right 14. 6.9 2.0 right present form. IS. 6.5 5.2 1.5 right OCCURRENCE: Loc. 3 (rare, silicified). DISCUSSION: This species was proposed by Clif- Superfamily TRIGONIACEA ton to include specimens identified by White and Girty as 5. wheeleri Swallow, a Pennsylvanian Family TRIGONHDAE species. Clifton reports it from the Elaine and Dog Genus SMzodus King 1844 Creek formations, as well as from the San Andres of New Mexico. Kaibab individuals correspond well ScJuzodvs texanus Clifton 1942 with Clifton's examples and with those of White and Girty. PI. 7, figs, lla, b ^Mzodus wheeleri, WHITE, U. S. Geog. Survey, OCCURRENCE: Loc. 1, bed 9 (rare, external and W. 100th Merid. Rept., vol. 4 (1877), p. 154, internal molds); molds are also very abundant in pi. 11, figs. 6a, b. debris from excavations at loc. 1, and are believed SMzodus wheeleri, GIRTY, U. S. Geol. Survey, to have come from horizons lower than the section Bull. 389 (1909), p. 82, pi. 10, fig. 6. measured.

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Superfamily PECTINACEA 1 h ic valve Family AVICULOPECTINIDAE 12. 8.0 7.2 1.4 left Genus Aviculopecten McCoy 1851 13. 49 36 5 right 14. 40+ 35 3 right Avicidopecten kaibabensis Newell 1937 15. 26+ 22 2 right 16. 25+ 20+ 2 right PI. 8, figs. 1-7 17. 9 8 0.2 right Aviculopecten kaibabensis NEWELL, Kansas State 18. 6.3 6.5 0.4 right Geol. Survey, vol. 10 (1937), p. 60, pi. 4, figs. 17, 18. DISCUSSION: This species was first described from DESCRIPTION: Large, circular pectinoids with three specimens collected from the Kaibab forma- strongly convex left valve and somewhat flatter tion at Padre Canyon, about 12 miles east of right valve. Hingeline straight, seemingly not as locality 1. Left valves in the present collection show long as body of shell; anterior auricle of left valve a wide range in size and hence illustrate the species not strongly extended, separated from remainder much better than the original material. One com- of valve by an abrupt vertical flexure; byssal sinus plete internal mold shows that the right valve was shallow; posterior auricle of left valve not strongly somewhat natter than the left, and lacked the strong differentiated; umbonal ridge lacking. Right valve ornamentation of that valve. Numerous internal probably smaller than left, gently convex and with molds of right valves found in association with the a deeply impressed byssal notch and extended left valves of the species also show less convexity anterior auricle; posterior auricle pointed, gently and a smoother surface than do the left valves, and concave below hinge, divided from body of shell although none of them are as large as some of the by a low ridge. left valves in the collection they are believed to Ornamentation of left valve consisting of many represent the same species. closely spaced costae; about 10 primary costae OCCURRENCE: Loc. 1, bed 2 (rare, external and remaining slightly more prominent than secondary internal molds); bed 9 (rare, external and internal and later costae throughout height of valve; later molds); loc. 2, bed 4 (rare, external and internal molds of juveniles). Abundant specimens occur costae added by intercalation so that entire valve in debris from excavations at loc. 1, and seem to appears about evenly costate; on interior of left represent horizons lower than the measured section. valve, the impression of external ornamentation can be observed, but primary and later costae Genus Acanthopecten Girty 1903 cannot be differentiated, and all costae appear sharply and finely striated longitudinally; anterior Acanthopecten coloradoensis (Newberry) 1861 auricle of left valve with about 4 primary costae and PI. 8, fig. 8 2-4 costae intercalated between each primary pair; posterior auricle with 12-15 widely spaced costae; Pecten (Monotis?) coloradoensis NEWBERRY, Ives Colo. Explor. Exped. (1861), p. 121, pi. 1, growth lines fine, evenly spaced, distinct only at figs. 6, 6a. margins and on auricles. Right valve shown only Acanthopecten coloradoensis, STOYANOW, Geol. Soc. by internal molds, apparently smooth or with sub- Am., Bull., vol. 47 (1936), p. 532. dued radial ornamentation; anterior auricle of right Acanthopecten coloradoensis, NEWELL, Kans. State Geol. Survey, Bull., vol. 10 (1937), p. 75, valve probably with radial ornamentation. pi. 12, figs. 7a, b, 13-15b. MEASUREMENTS: A number of almost complete shells are available; measurements of others are A small fragment having the characteristic in part estimated. Dimensions in mm.: ornamentation of this species is in the present collection. It is, however, inadequate for description. 1 h ic valve OCCURRENCE: Loc. 1, bed 9 (very rare, external mold). 1. 65+ 60+ 17 left 1. 65+ 60+ 9 right 2. 73+ 75+ 12 left Superfamily MYTILACEA 3. 49+ left Family MYTILIDAE 4. 43+ 45 11 left 5. 27 31 j 8 left Genus Promytilus Newell 1942 6. 22 18 3.5 left 7. 12.1 13.7 3.2 left Promt/tilus retusus sp. nov. 8. 11 11 2.5 left PI. 7, figs. 12-15 9. 10+ 11 left 10. 9.5 10 2 left DESCRIPTION: Elongate, oblique, inflated myt- 11. o. 9.5 1.2 left ilids with terminal beaks. Cardinal line very gently

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arcuate, about half to three-fourths the length of OCCURRENCE: Loc. 1, bed 2 (very rare, internal and external molds), bed 9 (rare, internal molds); shell; posterior margin curved, meeting cardinal loc. 2, bed 4 (common, internal and external margin at an angle of 130° or more, and rounding molds). regularly into ventral margin; ventral margin oblique, slightly concave, continuing with slightly Superfamily MYHLACEA? increasing convexity near anterior margin, which Family MODIOLOPSIDAE? is very slightly expanded into an anterior lobe. Genus Goniophora Phillips 1848 Beak bluntly pointed; umbonal ridge prominent, forming an angle of about 45°-50° with cardinal Goniophora cristate sp. nov. margin near beak, up to 60° near ventral margin PI. 8, figs. 9a-llb in larger shells. DESCRIPTION: Small, elongate, angular pelecy- Shell without ornamentation. pods having an exceedingly high and prominent Hinge not well preserved in specimens at hand, umbonal ridge. Cardinal margin almost straight, but apparently edentulous, with a linear nymph about half maximum length of shell; posterior for support of ligament; ligament groove wide and margin oblique and arcuate, making an angle of concave. Muscle scars and pallial line not visible. about 50° with cardinal margin; anterior margin MEASUREMENTS: Specimens are internal molds, strongly concave for a short distance just below hence measurements necessarily represent slightly beak, then bulging forward strongly so that maxi- less than external shell dimensions. Dimensions mum forward projection lies about half way be- in mm.: tween cardinal and ventral margins; ventral margin sinuate, rounding with regular convexity into anterior margin, forming a very acute angle with 1 h ic md valve posterior margin; beak incurved and anteriorly 1. 26.5 22.1 4.2 29.9 right directed; shell strongly convex in front, flattened 2. 17.4 14.0 3.9 19.8 left (holo- over most of its surface to the high, acute, flange- type) like umbonal ridge, behind which is a flattened 3. 17. 4± 12.5 3.6 18. 1± left area almost perpendicular to plane of shell; um- 4. 15.0 12.7 3.2 18.5 right 5. 13.0 10.0 3.7 15.2 left bonal flange extending to ventral margin. Lunule 6. 12. 6± 12.0 2.4 15.4 right deep, semicircular on each valve, its widest point 7. 12.3 10.6 3.5 14.7 right anterior to its center; escutcheon long and very 8. 11.3 8.8 2.0 11.9 left narrow, depressed only slightly below posterior 9. 10.3 7.4 1.9 10.4 right 10. 9.7 5.5 1.8 10.5 left area. 11. 8.7 6.9 1.6 9.7 left Ornamentation, other than umbonal crest, about 12. 8.6 7.0 1.8 9.0 right 6 or 7 concentric lamellose ridges on and near umbo, 13. 8.0 7.0 1.9 8.8 left following growth lines; remainder of shell without 14. 6.8 5.8 1.5 8.8 left 15. 6.6 5.8 1.5 8.8 left concentric lamellae, but with faint growth lines and even fainter and usually obscured radial liration. md = maximum dimension, measured obliquely Hinge and dentition dysodont; a triangular from beak posteroventrally. cardinal tooth in left valve, surrounded above and! TYPES: Holotype: Mus. Northern Ariz. G2.347. in front by an arc-shaped socket; right valve with a Paratypes: Mus. Northern Ariz. thin, sharp-edged, arcuate projection, having a shallow depression on lower surface which serves DISCUSSION: The only species of Promytilus as a socket for cardinal tooth of left valve, but resembling this in size is a form identified by White which does not completely embrace that tooth; a (1877) as "Myalina swollen McChesney," from the strong, rounded ridge on left valve fits into a broad Fort Apache limestone, Camp Apache, Arizona. furrow immediately overlying projection of right White's illustration shows his form to be more valve; a narrow crest above this furrow meets a strongly curved and to have the anterior lobe more fine groove on left valve. fully developed so that the beaks are not quite MEASUREMENTS: Three excellently preserved terminal. The two forms, though slightly dissimilar specimens give the following dimensions (in mm.): in age, may be members of the same species. Since 1 h lc Jcfl White's form obviously is not Promytilus swattovi, gp the present form is described as new. 1. 9.9 4.6 2.1 3.0 5.2 The Kaibab species is deceptively similar to 2. 6.8 3.6 1.7 1.7 3.3 small specimens of Myalina wyomingensis, but 3. 6.8 3.5 1.6 1.7 3.4 appears to be equivalved, and therefore not a i cfl = convexity at flange Myalina. gp hinge length posterior to beak

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TYPES: Holotype: Amer. Mus. Nat. Hist. Though strongly resembling Promytilus retusus 27096:1. Paratypes: Amer. Mus. Nat. Hist., Mus. Northern Ariz. sp. nov., Myalinella adunca differs from that form in a number of characters. The shell is propor- DISCUSSION: This form agrees with the generic tionately shorter and less oblique than in P. retusus characters of Goniophora in its dentition, shape of and the umbonal ridge shows a marked curvature. shell, and prominent angular umbonal ridge. Al- The hinge is short, the beaks are more pointed, and though smaller than most older representatives of there is no pronounced anterior lobation. In addi- the genus, it resembles in size the Pennsylvanian tion, the posterior margin meets the hinge at an form G. plicata Hall, which, however, is distin- angle of 125°-130°; in P. retusus the angle is much guished by its two posterior ridges. No other forms more obtuse. are known to range as late as Permian. OCCURRENCE: Loc. 1, bed 9 (rare, internal molds). OCCURRENCE: Loc. 1, bed 9 (rare, external molds); loc. 2, bed 4 (very rare, external molds); loc. 3 (rare, silicified). Superfamily ANATINACEA Family PHOLADELLIDAE Family MYALINIDAE Genus Allorisma KING 1844 Genus Myalinella Newell 1942 Allorisma terminate HALL 1852 Myalinella? adunca sp. nov. PI. 9, figs. 4a-c PI. 9, figs. 1, 2 Allorisma terminalis HALL, Stansbury's expedition DESCRIPTION: Elongate, oblique, convex mytilids to the Great Salt Lake (1852), p. 413, pi. 2, with terminal beaks. Cardinal line straight or very figs. 4a, b. gently arcuate, two-thirds to three-fourths the Allorisma subcuneata MEEK AND HAYDEN, Acad. Nat. Sci. Philadelphia, Pr. (1858), p. 263. length of shell; posterior margin curved, meeting Allerisma terminate, GIRTY, U. S. Geol. Survey, posterior part of hinge at an angle of 125°-130°, Bull. 389 (1909), p. 90 (see for synonymy). and rounding rather sharply into antero-ventral margin; antero-ventral margin gently concave along DESCRIPTION: Large, thin-shelled, transversely its entire length, strongly so in some specimens, oval pelecypods with hinge equal to slightly more and without anterior lobation. Umbonal ridge than half the total length. Cardinal margin straight prominent but, because of absence of anterior behind beak; anterior margin rounded, projecting lobation, not well denned; beaks sharp and curved in front of beak less than a seventh the length of the forward. shell; posterior margin regularly rounded, meeting Shell seemingly smooth; faint concentric ruga- cardinal margin without angulation, and curving tions very indistinctly visible on interior of shell. somewhat less sharply ventrally to merge with Hinge seemingly edentulous, bearing an elongate ventral margin; ventral margin almost straight, with nymph below a shallow furrow for support of liga- a gentle sinuosity about a third the distance back ment. Muscle scars and pallial line not visible. from anterior end of shell. Beaks low, anterior, orthogyrate; umbonal ridge lacking; shell strongly MEASUREMENTS: Five well preserved internal molds have the following dimensions (in mm.) -. convex anteriorly, flattened posteriorly. Ornamentation of low, irregular concentric rugae I 1 i h ic md ' valve and many minute papillae, the latter arranged in 1. 18.8 19.2 4.3 22.0 right irregular radial rows; shell thin, so that rugae are 2. 14.5 12.6 2.5 15.3 left reflected on interior. 3. 13.4 13.1 2.5 15.6 right (holotype) Dentition and other internal features unknown. 4. 12.6 ! 12.3 : 2.8 15.1 right md = maximum diameter, measured from beak MEASUREMENTS: Three internal molds have the to posterior ventral margin. following dimensions (in mm.): TYPES: Holotype: Mus. Northern Ariz. G2.542. l h c a h/l a/1 Paratypes: Mus. Northern Ariz. 1. 10.0 S.5± 3.8 1.3 .55 .13 DISCUSSION: This species is referred to the genus 2. 9.3 4.8 3.7 1.3 .52 .14 Myalinella- because of lack of anterior lobation. It 3. 6.0 3.1 2.2 .8 .52 .13 differs from known species of Myalinella in the pronounced curvature of its umbonal ridge and the DISCUSSION: From a study of the type specimens concavity of its antero-ventral margin. of Allorisma terminale Hall and A. subcuneata

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Meek and Hayden, Girty (1903, p. 438) was able Pleurophorus albequus, CLIFTON, Jour. Paleont., to conclude that the two forms, described from the vol. 16 (1942), p. 693, pi. 101, figs. 8-12. same horizon at the same locality, are conspecific. DESCRDPTION: Equivalved, very inequilateral, The type specimen of A. terminate is, according to elongate pelecypods of medium size; valves moder- Girty, elongated by compression, and the beaks are ately convex, sometimes with a broad, poorly de- thrust far forward. fined sulcus extending postero-ventrally from um- Apparently there is considerable variation among bones. Cardinal margin very gently arcuate,, members of this species, some showing a concave rounding into sharply curved posterior margin; hingeline, others a straight or convex one. The beaks ventral margin parallel to cardinal margin, straight vary in position, lying behind the anterior margin or gently arcuate, sometimes slightly sinuate at between .14 and .20 of the total length in examples described and figured by Girty, White, and others. about mid-length, rounding gently into posterior In Kaibab specimens they lie rather uniformly .13- margin and somewhat more strongly into anterior .14 of the total length behind the anterior margin, margin; anterior margin projecting only slightly and thus are slightly more anterior than in most anterior to beaks, arcuate. Beaks small, anterior, other examples. This discrepancy may be due to almost terminal, prosogyre; umbonal ridge faintly the fact that the present material consists of in- defined. ternal molds. Ornamentation commonly so faint as to be almost In view of the infraspetific variation evident in indiscernible, consisting of low radial ridges on this species, the constancy of proportions of the posterior portion of valves, and closely spaced rows three Kaibab specimens is quite remarkable. of fine papillae covering entire shell; anteriorly, OCCURRENCE: Loc. 1, bed 2 (very rare, internal the papillae are less definitely aligned and take on and external molds), bed 9 (generally rare, occur- appearance of lamellose, wavy corrugations, but on ring in groups; internal and external molds). posterior half or f of shell there are distinct tiny sharp papillae arranged in a quincunxial pattern; Allorisma? juvenile growth lines irregular, prominent, often rugose, PI. 9, figs. 3a, b frequently with stronger growth constrictions. Lunule small, very deep, clearly defined; es- A single small but perfect specimen cannot be cutcheon long and very narrow, set off from rest of placed in any of the preceding groups and appears shell by low angular ridge; deep, narrow ligament to be a juvenile Allorisma. It is completely smooth groove extending from beak half the length of on the exterior, and lacks dentition. escutcheon; dentition 1 cardinal tooth in each MEASUREMENTS : Length 5.8 mm., height 3.6 mm. valve, and 1 lateral tooth in left valve; cardinal tooth of right valve triangular, lying above socket; OCCURRENCE: Loc. 3, (one silicified specimen). cardinal tooth of left valve transverse, with triangular base, lying below triangular socket, and Superfamily PLEUROPHORACEA bearing on its dorsal surface a tiny secondary socket, presumably to receive an irregularity of Family PLEUROPHOREDAE cardinal tooth of right valve; lateral tooth of left Genus Pleurophorus King 1844 valve originating at about mid-length and extending Pleurophorus albequus Beede 1902 posteriorly with slight obliquity, forming with cardinal margin a long, narrow, triangular socket PI. 9, figs. 5a-6b which receives extended margin of right valve. Pleurophorus sp. BEEDE, Okla. Geol. Survey, 1st. Anterior muscle scar very deep, bounded posteriorly Bien. Rept., Advance Bull. (1902), p. 9, pi. 1, by thick, prominent buttress; posterior muscle scar fig. 4. usually not well defined; a rather large pedal muscle Pleurophorust albequus BEEDE, Kans. Univ., Sci. Bull., vol. 4 (1907), p. 160, pi. 6, figs. 8-8e. scar forms an arcuate pit on ventral surface of Pleurophorust albequus longus BEEDE, Kans. cardinal tooth of left valve, and corresponding pit Univ., Sci. Bull., vol. 4 (1907), p. 162, pi. 6, on right valve is located just below cardinal socket. fig-9. Pleurophorus albequus, NEWELL, Geol. Soc. Am., Relatively few immature specimens are avail- Bull., vol. 51 (1940), p. 298, pi. 3, figs. 1, 4-8, able, the majority of the specimens being of ap- 14, 16-18. proximately the same size and apparently mature. Pleurophorus albequus longus, NEWELL, Geol. Soc. Am., Bull., vol. 51 (1940), p. 300, pi. 3, No pronounced change in shape, ornamentation, or figs. 2, 3, 15, 19-23. rate of growth can be observed.

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MEASUREMENTS : (in mm.) Genus Rimmynmina gen. nov. 1 h C h/1 Pleurophorus, BITTNER (pars), Abh. der K. K. Geol. Reichsanstalt, Wien, Bd. 18, Heft 2 1. 11.5 7.0 (1907), p. 156. 2. 27.6 11.2 7.0 .41 3. 25 10.2 .41 (mold) 4. 20+ 9.4 .47 (mold) DIAGNOSIS: Equivalved, inequilateral, quad- 5. 19.7 8.5 6.6 .43 rangular to oblong pelecypods with beak anterior 6. 17.2 7.0 .41 (mold) but not terminal. Hinge with elongate, narrow 7. 14.8 6.2 .42 (mold) escutcheon bearing a fine ligament groove, and small 8. 13.7 5.8 .42 (mold) 9. 11.0 5.2 .47 (mold) but well defined lunule. Dentition actinodont, with 10. 9.5 4.7 4.0 .49 (mold) an obtuse, elongate, obliquely oriented cardinal 11. 8.1 3.6 .44 (mold) tooth in right valve, and a shallow socket, formed by shelf-like extension of anterior margin, in left valve; left valve with well developed posterior DISCUSSION: In size, shape, ornamentation, and lamellar tooth; right valve with obscure posterior characters of dentition, this form seems to be identi- lamellar ridge on interior of shell, possibly repre- cal with forms from the Whitehorse sandstone and senting a tooth. Dozier dolomite described by Beede as P. albequus and P. albequus longus. The latter subspecies, oc- GENOTYPE: Rimmyjimina arcula sp. nov. curring as it does in association with P. albequus, seems to be not a true subspecies, but to consist of DISCUSSION: The shells representing this genus more fully mature individuals or slightly more show definite affinity with the genus Pleurophorus, elongate variants of the same species. The species but differ too markedly in dentition to be assigned has also been recognized from the Elaine and Dog to that genus. Pleurophorus, as redefined by J. Creek formations of Texas. Bohm (1914), bears a well defined cardinal tooth in each valve, and has in each valve also a deep, clearly OCCURRENCE: Loc. 1, bed 2 (common, external and internal molds), bed 9 (common, external and defined socket. Triassic forms identified by Bittner internal molds); loc. 2, bed 4 (abundant, internal as Pleurophorus curionii Hauer and P. curionii var. and external molds); loc. 3 (very rare, silicified). meriani Parona, appear to have dentition similar to the specimens at hand, and are interpreted as Pleurophonis cf. P. mexicanus GIRTY belonging within the new genus. Licharew defined the Upper Permian genus Internal molds of an elongate, posteriorly con- Pleurophorina as having no tooth in the left valve, tracted pleurophorid are extremely abundant at but his photographs of a squeeze do not convincingly an unidentified horizon in the Kaibab limestone corroborate his definition: the specimen appears to (Alpha member). They most closely resemble, in be a true Pleurophorus and is not easily confused both size and shape, Girty's form from the Manzano with the present form. group (Permian), a species which has also been RANGE: Permian, Kaibab formation; Upper identified by Clifton from the Permian Elaine and Triassic. Dog Creek formations of Oklahoma. MEASUREMENTS: (in mm.) Rimmynmina arcula sp. nov. 1 h Jc valve PI. 9, figs. 7-1 lb 1. 30 14 4.5 left DESCRIPTION: Small, subquadrate, closed, mod- 2. 27 14 5.5 both erately convex pleurophorids, somewhat expanded 3. 27 13.5 4 left posteriorly, with height 0.6-0.7 the length. Cardinal 4. 26 13 5 right margin gently convex; hinge equal to about f total 5. 25 12 3.5 left 6. 24 11.5 5 right length in juveniles, somewhat more in larger shells; 7. 23 11 3 right anterior margin somewhat lobate, straight but 8. 21 11 3 right steeply inclined below beak and rounding rather 9. 20 10 3 left sharply into ventral margin, sometimes forming a 10. 17 8 left point. Ventral margin very gently convex in most individuals, but in many juveniles showing a slight OCCURRENCE: Loc. 1, bed 9 (rare, external and internal molds). This form occurs abundantly in sinus in anterior third; ventral margin curving more debris from the excavations at loc. 1, and is thought strongly posteriorly to meet posterior margin at an to have come from beds lower than those measured. obscure angulation; posterior margin regularly

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convex, almost vertical, meeting cardinal margin at tooth below beak, and left valve with a shelf-like an obtuse angle. Beak low, anterior but not termi- extension of anterior margin to serve as a socket nal, prosogyrate; umbonal ridge very obscure, for it; an elongate posterior lamellar tooth diverges extending from beak to posterior ventral angulation; from posterior cardinal margin of left valve, forming valves fairly convex, convexity being greatest along with it an elongate triangular socket for reception of umbonal ridge, and shell below umbonal ridge extended margin of right valve; in right valve, almost flat or, in many juveniles, gently depressed. there is a very slight prominence immediately Ornamentation lacking; growth lines fine, slightly beneath posterior end of cardinal margin which has lamellose, often very distinct, especially on ventral the appearance of an undeveloped lateral tooth. slope; occasional more strongly marked constric- Anterior muscle scar pronounced, deeply imbedded tions are evident on some shells. beneath a strut-like ridge which extends from an- Hinge arcuate, with a long, narrow escutcheon, finely pointed anteriorly, separated from rest of tero-lateral surface obliquely upward to inner valve by a rounded ridge; ligament groove thin, surface of lunule; posterior muscle impression extending from beak half to f the length of cardinal seemingly somewhat larger than anterior, located margin; lunule small, oval, depressed, lying almost close under posterior part of hinge, not strongly under beak; dentition actinodont, right valve bear- impressed; pallial line simple, not strongly im- ing an obtuse, broadly triangular, low cardinal pressed.

MEASUREMENTS: (in mm.) 1 h 5c g h/1 c/l g/i vent. mgn. valve 1. 10.2 6.9 2.75 8.5 .68 .54 .83 straight (holotype) 2. 6.8 4.6 1.95 5.6 .68 .57 .82 straight right 3. 6.7 4.2 1.7 + 5.3 .63 .51 .81 straight right 4. 5.7 3.9 1.55 4.4 .68 .54 .77 sinuate right 5. 5.4 3.8 1.4 4.3 .70 .52 .80 straight right 6. 5.4 3.7 1.4 3.7 .69 .52 .69 sinuate left 7. 5.3 3.7 1.2 4.1 .70 .45 .77 straight left 8. 5.1 3.4 1.3 3.6 .67 .51 .71 straight left 9. 4.9 3.3 1.3 3.6+ .67 .53 .73 sinuate left 10. 4.9 3.1 1.3 3,3 .63 .53 .73 straight right 11. 4.8 3.1 1.25 3.3 .65 .52 .69 sinuate left 12. 4.7 3.1 1.3 3.5 .66 .55 .74 straight left 13. 4.7 3.0 1.2 3.2 .64 .50 .68 sinuate right 14. 4.6 3.0 1.3 3.7 .65 .57 .80 straight right 15. 4.6 2.8 1.15 3.2 .61 .50 .70 straight right 16. 4.5+ 3.1 1.1 3.4 .69 .49 .76 straight left 17. 4.4 2.8 1.1 3.3 .64 .50 .75 straight left 18. 3.6 2.4 2.7 .67 .75 sinuate? right 19. 3.5 2.1 .95 2.4 .60 .54 .69 sinuate? left 20. 2.7 1.7 .7 1.9 .63 .52 .70 straight left 21. 2.5 1.6 .6 1.7 .64 .48 .68 straight right TYPES: Holotype: Mus. Northern Ariz. G2.541. Paratypes: Mus. Northern Ariz., Amer. Mus. Nat. His t

DISCUSSION: Although in proportions of length, width, arid thickness this form appears to remain • 6 about the same during ontogeny, several changes in shell form may be noted. In the very smallest shells -5 the ventral margin is straight for much of its length. In shells about 4.5-5.5 mm. long there is commonly a gentle sulcus developed anterior to the umbonal ridge, forming a sinus in the margin. With further -3 growth the sinuosity disappears, so that when the -Z shell is about 6.5 mm. long, the ventral margin is gently convex. A slight trend is seen toward relative elongation FIGURE 14.—RELATION or HEIGHT AND CONVEXITY of the cardinal margin with growth, the posterior TO LENGTH IN Rimmyjimina. arcula margin becoming straightened simultaneously. Ad-

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ditional material is needed to show this, however, Lunule short and not strongly denned except as the present collection has few shells between 6 near beak; escutcheon long, narrow, very poorly and 10 mm. long. The single shell over 10 mm. long denned, with a short, arcuate ligamental furrow is decidedly flattened posteriorly. starting at beak and extending posteriorly less than OCCURRENCE: Loc. 3 (juveniles common, adults half the length of escutcheon. Dentition prehetero- rare, silicified). dont (?) with 2 large, triangular cardinal teeth in each valve, those in left valve lying anterior to 2 Superfamily ASTARTACEA triangular, vertically walled sockets and those in right valve lying posterior to sockets; in left valve, Family ASTARTIDAE? posterior tooth is the more prominent; in right valve, Genus Kaibabetta gen. nov. anterior one is larger; anterior tooth of left valve continuous with anterior margin of shell; in both DIAGNOSIS: Equivalved, almost equilateral, oval valves the ligamental Surrow limiting a very rudi- pelecypods having an arcuate hinge with a small, mentary third tooth; dentition supported by a poorly denned lunule and a long, narrow escutcheon. strong, thick, rounded shelf. Anterior and posterior Dentitionpreheterodont (?), with 2 large, triangular adductor scars about equal, each slightly impressed, cardinal teeth in each valve, those in left valve both located fairly near beak. Pallial line simple, anterior to those in right valve; without lateral but not distinct. Anterior pedal muscle scar fairly teeth. A rudimentary third tooth may be present deep, lying close under lunule, above anterior ad- below the ligamental furrow. ductor impression, on rounded shelf which supports teeth; posterior pedal impression very deep, lying GENOTYPE: Kaibabetta curvilenata sp. nov. far under shelf. DISCUSSION: This genus does not show the lateral No change in proportions of length or width dur- teeth evident on the genotype of Astarte, and ing ontogeny can be seen, but there is a slight in- present in Astartella. Astartila, as now understood, crease in convexity as shell becomes larger. lacks teeth altogether and has a much longer ex- MEASUREMENTS: (in mm.) ternal ligament than does the present form. The genus Pachydomus from the Permian of Australia 1 h c h/l c/1 is probably also related. It is defined as having 1. 13.9 11.5 7.2 .83 .52 (holotype) "one or two (?) large teeth in each valve," the one 2. 12.7 10.6 6.0 .83 .47 in the left valve being the largest, but no illustra- 3. 10.2 8.0 4.0 .78 .39 tions have been presented of its dentition. Australian 4. 10.0 8.3 5.0 .83 .50 5. 7.9 6.4 3.5 .81 .44 species are all many times larger than the Kaibab 6. 7.4 5.9 3.2 .80 .43 form, and much more convex. 7. 7.2 6.4 3.4 .89 .47 8. 6.7 5.8 2.5 .86 .37 RANGE: Permian, Kaibab formation. 9. 6.1 5.2 2.2 .85 .36 10. 5.4 4.5 2.0 .83 .37 Kaibabella curvilenata sp. nov. 11. 4.4 3.8 1.5 .86 .34 12. 4.0 3.6 1.6 .90 .40 PI. 10, figs. la-4c 13. 3.7 3.2 1.4 .86 .38 DESCRIPTION: Small, roundly triangular or ovate TYPES: Holotype: Mus. Northern Ariz. G2.1748. pelecypods, slightly longer than wide, with con- Paratypes: Mus. Northern Ariz., Amer. Mus. vexity about half the length in adults, somewhat Nat. Hist., Grand Canyon Nat. Park museum. less in juveniles. Anterior margin almost smoothly OCCURRENCE: Loc. 1, bed 9 (common, external curved, but forming a slight angle about halfway and internal molds); loc. 2, bed 4 (very rare, ex- down and rounding smoothly into ventral margin; ternal and internal molds); loc. 3 (rare, silicified). posterior margin very slightly curved, often with a slight angulation % of the distance to posterior Family ASTARTIDAE extremity, rounding sharply into ventral margin at Genus Astartetta Hall 1858 posterior extremity; ventral margin smoothly curving; beaks small, pointed, probably almost in con- Astartella subquadrata Girty tact when shell is closed; shell regularly and PI. 10, figs. 5-15 smoothly arched except for a low, obscure umbonal Astartella subquadrata GIRTY, U. S. Geol. Survey, ridge limiting a slightly flattened posterior area. Bull. 389 (1909), p. 94, pi. 10, figs. 10-13. Ornamentation fairly strong, rounded concentric Astartdla subquadrata, CLIFTON, Jour. Paleont., undulations, 9 in 5 mm. near ventral margin of vol. 16 (1942), p. 693. largest specimen, but much more closely spaced and DESCRIPTION: Small, thick-shelled, subquadrate often obscure near umbo and on small specimens. pelecypods, slightly longer than high, with thickness

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somewhat more than half the length. Cardinal 1 h lc g h/1 c/1 g/i margin and ventral margin gently curved, more or less distinctly contracting posteriorly; posterior 20. 6.1 5.4 2.0 4.3 .89 .66 .70 outline nearly perpendicular to cardinal and ventral 21. 6.0 5.1 1.9 .85 .64 22. 6.0 5.1 2.0 .85 .67 margins, and gently convex, rounding into ventral 23. 6.0 5.0 1.8 3.8 .84 .60 .65 margin but meeting cardinal one in an obscure 24. 5.8 5.2 1.9 4.1 .90 .66 .71 angle; anterior outline concave below beak, ex- 25. 5.8 5.2 1.8 4.0 .90 .62 .69 tending downward and somewhat forward for about 26. 5.8 5.0 1.8 4.0 .86 .62 .69 27. 5.8 5.0 1.7 4.0 .86 .59 .69 two-thirds or three-fourths length of shell, meeting 28. 5.6 4.7 1.7 .84 .61 upward-curving anterior end of ventral outline 29. 5.3 4.9 1.8 .93 .68 usually in a rather distinct angle; beak flattened; 30. 5.3 4.6 1.7 .87 .64 no appreciable umbonal ridge. 31. 5.3 4.3 1.6 3.4 .81 .61 .64 32. 5.2 4.3 1.6 .83 .62 Ornamentation of regular concentric lamellae, 33. 5.1 4.5 1.7 .89 .67 varying in number according to size of shell, the 34. 5.0 4.4 1.6 .88 .64 distance between lamellae increasing regularly 35. 5.0 4.4 1.7 3.5 .88 .68 .70 from beak to margin; lamellae about 5 per mm. next 36. 5.0 4.1 1.4 3.2 .82 .56 .64 37. 4.8 4.4 1.4 3.5 .92 .58 .73 to umbo, 2 per mm. near ventral margin of large 38. 4.8 4.0 1.6 .83 .67 specimens; lamellae thus about 9 in number in 39. 4.8 3.8 1.4 3.4 .79 .58 .71 specimens under 3 mm. in length, at least 15 in 40. 4.7 4.0 1.5 .85 .64 number in those of 16 mm. 41. 4.7 4.0 1.5 2.9 .85 .64 .58 42. 4.6 4.2 1.6 .91 .69 Hinge structure and dentition typically astar- 43. 4.5 4.0 1.4 .89 .62 tellid; concave lunule anterior to beak; cardinal 44. 4.4 4.0 1.4 .91 .64 margin bearing a well-marked escutcheon; each 45. 4.4 4.0 1.2 3.0 .91 .55 .68 valve with a strong cardinal tooth, that of left 46. 4.3 3.6 1.3 2.9 .84 .60 .67 valve being posterior to a deep triangular socket, 47. 4.2 3.4 1.2 .81 .57 48. 4.2 3.1 1.2 .74 .57 that in right valve being anterior to socket; along 49. 4.0 3.6 1.4 .90 .70 cardinal margin of left valve a trench-like depres- 50. 4.0 3.5 1.2 .87 .60 sion receives the sharply angular edge of right valve, 51. 4.0 3.4 1.1 2.8 .85 .55 .70 and a similar groove anterior to beak of right valve 52. 3.9 3.5 1.3 2.7 .90 .67 .69 53. 3.8 3.2 1.0 .84 .53 corresponds with angular and somewhat extended 54. 3.8 3.2 1.2 .84 .63 edge of left valve. Anterior muscle scar impressed, 55. 3.8 3.5 1.1 2.6 .92 .58 .68 especially at its posterior margin; other muscle 56. 3.8 3.4 1.3 2.6 .89 .68 .68 scars not evident. 57. 3.6 3.0 1.0 .83 .55 58. 3.2 2.8 0.9 2.2 .86 .56 .69 No change in proportions during ontogeny is 59. 3.0 2.8 1.0 1.9 .93 .67 .63 evident. 60. 2.9 2.6 0.8 2.1 .90 .55 .72 MEASUREMENTS: An abundance of excellently preserved specimens permitted a large number of measurements to be made. Variability in measurement of angles is unavoidable because of difficulty in making measurements in these shells. Dimen- sions in mm.: -6 mm. l h Jc g h/1 c/1 g/l 1. 7.4 6.2 2.4 .84 .65 2. 7.3 6.4 2.4 5.4 .88 .66 .74 3. 7.0 6.0 2.6 .86 .66 4. 6.9 6.2 2.2 5.0 .90 .64 .73 5. 6.9 5.7 2.2 .83 .64 6. 6.9 5.6 2.0 i .81 .58 7. 6.7 5.9 2.1 .88 .63 8. | 6.7 5.9 2.2 4.8 .88 .66 .72 9. 6.7 5.8 2.1 .87 .64 10. 6.6 5.9 2.0 4.6 .90 .70 .61 11. 6.5 5.6 2.4 .86 .74 12. 6.5 5.3 2.2 .82 .68 13. 6.5 5.0 2.0 4.0 .77 .62 .62 14. 6.5 5.3 1.8 .82 .55 15. 6.4 5.5 1.9 4.4 .86 .59 .69 16. 6.3 5.4 2.0 4.1 .86 .63 .65 17. 6.3 5.2 2.1 4.4 .83 .67 .70 18. 6.2 5.4 2.2 .87 .71 FIGURE 15.—RELATION OP HEIGHT AND CONVEXITY 19. 6.2 5.3 2.0 4.4 .86 .64 .71 TO LENGTH IN Astartetta subquadrata

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DISCUSSION: This species may be far more wide- DISCUSSION: This form most closely resembles spread than recorded observations indicate. De- members of the genus Sanguinolites, but cannot scribed by Girty from the Manzano group (Per- definitely be assigned to that or any related genus mian), and recorded by Clifton from the Elaine until the confusion surrounding definition of the and Dog Creek formations, it also occurs in the Word genera has been clarified. The posterior triangular limestone no. 1 of the Texas Permian section. area, set off by the umbonal ridge, recalls such forms Several European and Asiatic forms appear to be as Allorisma? geinitzi (Meek), A.f costatum Meek similar to Girty's species but are too poorly figured and Worthen, and Pleurophorus subcostatus Meek to make synonymy certain. and Worthen. In none of those species is the dentition well known, and it is likely that they are all more OCCURRENCE: Loc. 1, beds 2 and 9 (abundant; closely related generically than has heretofore been external and internal molds); loc. 3 (abundant, silicified). indicated. OCCURRENCE: Loc. 1, bed 9 (common, external Superfamily GRAMMYSIACEA and internal molds); loc. 2, bed 4 (very rare, external molds of immature individuals). Family SOLENOPSIDAE Genus Alula Girty 1912 Genus Sanguinolites McCoy 1844 Alula gilberti (White) Sanguinolites? sp. PI. 10, fig. 18 PI. 10, figs. 16, 17 Allerisma gilberti WHITE, U. S. Geol. and Geog. DESCRIPTION: Elongate, equivalved, inequilateral p. 137, Survey Terr., Rept, for 1878, pt. 1 (1883), pi. 33, figs. 9a, b. pelecypods of flattened cylindrical form, slightly Alula gilberti?, GIRTY, N. Y. Acad. Sci., Ann., vol. 22 (1912), p. 5, pi. 1, fig. 6. gaping posteriorly. Hingeline straight or slightly A single small but complete internal mold of a concave upward; anterior margin gently concave in right valve shows the characteristic shape, as well front of beaks, then curving sharply down and as the impression of the chondrophore (identified rounding into gently curving, slightly sinuate ven- by Girty as a cardinal tooth) and elongate posterior tral margin; posterior margin arcuate but appearing lateral teeth (possibly an elongate nymph) of the slightly truncate, as it rounds suddenly into ventral genus Alula. margin. Beaks low, rather flat, located about a The mold is elongate, with the hingeline long and third of distance from anterior margin; umbonal gently arcuate upward and extending almost the ridge low but distinct, dividing posterior portion of entire length of the valve. The anterior margin is shell into an elongate triangular area which is bi- convex and rounds smoothly into the long, arcuate sected longitudinally by a second low ridge. ventral margin. Posteriorly the rostrum is appar- Ornamentation coarse, irregular growth lines ently truncate and open. The beak is moderately giving shell the appearance of being concentrically well developed. wrinkled. The impression shows that high, platelike poste- Hinge characters not known; shells appear rior lateral ridges, the edges of a linear nymph, ex- edentulous. tend along the anterior two-thirds of the cardinal margin. An impression below the beaks suggests a MEASUREMENTS: (in mm.) triangular chondrophore. 1 h ic valve MEASUREMENTS: Length 10.6 mm.; height 4.2 mm.; convexity of one valve 1.0 mm. 1. 40 16.5 5 right 2. 36 12 2.5 left DISCUSSION: This specimen is easily identified as 3. 35 13.5 3.5 right 4. 34. 15 5 left A. gilberti, first described by White from the Kaibab S. 32 13 3 right formation south of Pipe Springs, Arizona, and also 6. 31 14 3.5 right recognized by Girty in the Lykins formation (Per- 7. 25+ 11 3.5 left mian) of Colorado. It is distinguished from Alula 8. 22 8 2 right 9. 20 7 1.5 right squamulifera Girty, also from the Lykins formation, 10. 17 6.5 1.5 left by its shorter length and lack of a strong umbonal 11. 15 7.5 1.5 right ridge. 12. 14 5 1 left 13. 10 4 1 left OCCURRENCE: Loc. 1, bed 9? (very rare, internal mold).

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Family CARDIOMORPHIDAE DISCUSSION: These specimens differ from most species of Solemya in their unusual radial ornamen- Genus Edmondia Koninck 1841 tation, and seem to be conspecific with S. parallella, Edmondia sp. described by Beede and Rogers from the Middle Pennsylvanian of Kansas. PI. 7, fig. 16 OCCURRENCE: Loc. 1, bed 9 (rare, external and Internal molds of edentulous pelecypods of internal molds); loc. 3 (rare, silicified). medium size and somewhat ovate outline show evidence of the concentric ornamentation which Class SCAPHOPODA characterizes the genus Edmondia. The form is rather less elongate and more quadrangular than Family DENTALIIDAE Girty's species E.I belMa and E.? phosphatica, Genus Plagioglypta Pilsbry 1898 though it most closely resembles the latter. Speci- mens are much larger than E. minuta Stauffer and Plagioglypta canna (White) 1874 Schroyer, and smaller and more quadrate than Dentalium canna WHITE, U. S. Geog. Geol. Survey E. gibbosa Swallow. From all these Permian forms W. 100th Mer. (1874), p. 23. they can easily be distinguished, and probably Plagioglypta canna, GIRTY, U. S. Geol. Survey, a new species is represented. More complete mate- Prof. Paper 16 (1903), p. 452. rial is necessary for complete description, however. Plagioglypta canna, BRANSON, Univ. Missouri Studies, vol. 5 (1930), p. 58 (see for synonymy), MEASUREMENTS: (in mm.) pi. 15, fig. 6. 1 j h ic DESCRIPTION: Subcylindrical, gradually tapering, very gently curved scaphopods, with thick shells 1. 16+ I 12 4 lacking ornamentation but showing irregular trans- 2. 15.5 i 11.5 4.5 verse growth striae. OCCURRENCE: Loc. 1, bed 9? (rare, internal MEASUREMENTS: No complete specimens were molds). collected, but several fragments show the following dimensions (in mm.): Superfamily SOLEMYACEA 1 ds dl Family SOLEMYACIDAE 1. 87 2.0 8.3 2. 52 2.0 6.0 Genus Soletnya Lamarck 1818 3. 50 4.0 8.0 4. 25 1.8 3.6 Solemya paraUella (Beede and Rogers) 1899 5. 2 1.8 4.0 Solenomya parallella BEEDE AND ROGERS, Kans. ds = diameter at small end Univ. Quart., vol. 8 (1899), p. 131, pi. 34, dl = diameter at large end fig. 1. The shell is about 1 mm. thick at the large end of broken fragments, but thins rapidly toward the DESCRIPTION: Elongate-cylindrical shells, seem- aperture of unbroken specimens. ingly gaping at both ends, with straight, parallel cardinal and ventral margins and rounded anterior OCCURRENCE: Loc. 1, bed 9 (common, internal and posterior margins. Beaks not elevated, located and external molds); loc. 2, bed 4 (abundant, internal and external molds); loc. 3 (abundant, a fourth or fifth the length of shell from anterior end. silicified). Ornamentation low, wide, flat radiating costae separated by narrow concave striae; costae some- ECHINODERMATA times marked with very shallow striations. Hinge and dentition not known. Class CRINOIDEA MEASUREMENTS: Three fragmentary specimens Crinoid plates of about the same size show the following recon- structed dimensions (in mm.): PI. S, figs. 19a-29 Numerous crinoid brachial plates and a few tiny columnals were collected from locality 3. The arm 1. 47+ 16 10.5 plates range in diameter from 2 to 12 mm., large 2. 45+ 15+ 13 3. 43+ 11 ones being about 3 mm. in maximum thickness but usually thinner on one side than the other. They

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are almost circular in plan and bear an ambulacral Comm. Paleoecol., Nat. Res. Council, Div. Geol. and Geog., p. 54-58. notch on one side; occasional plates are doubly Newell, N. D. (1937) Late Paleozoic pelecypods notched. The muscle pattern is distinctive, con- Pectinacea, Kans. State Geol. Survey, vol. 10, sisting of 3 tiny central ridges, the center one the p. 10-123. longest, and a marginal depression on one surface (1940) Invertebrate fauna of the Late Permian Whitehorse sandstone, Geol. Soc. Am., Bull., of the plate, and a transverse or obliquely trans- vol. 51, p. 261-325. verse ridge on the other side. The ambulacral notch (1942) Late Paleozoic pelecypods: Mytilacea, is bounded on one side by strong ridges, on the Kans. State Geol. Survey, vol. 10, pt. 2, p. 1- other by depressions. 115. Nicol, David (1944) Paleoecology of three faunules of the Permian Kaibab formation at Flagstaif, OCCURRENCE: Loc. 3 (common, silicified). Arizona, Jour. Paleont., vol. 18, p. 553-557. Nomura, S., and Hatai, K. (1936) A short note on SELECTED BIBLIOGRAPHY the shells of certain invertebrates, Saito Ho-on Kai Mus. Res. Bull. no. 10, p. 212-217. Agassiz, Alexander (1888) Three cruises of the U. S. (1936) A note concerning data on the bathymetric Coast and Geodetic Survey steamer Blake, range of certain marine animals, etc., Saito London, vol. 2, p. 1-220. Ho-on Kai Mus. Res. Bull. no. 10, p. 231-334. Beede, J. W. (1907) Invertebrate paleontology of the Payne, Thomas G. (1942) Stratigraphical analysis Upper Permian Red-Beds of Oklahoma and the and environmental reconstruction, Am. Assoc. Panhandle of Texas, Kansas Univ. Sci., Bull., Petrol. Geol., Bull., vol. 26, p. 1697-1770. vol. 4, p. 115-171. Pia, Julian (1930) Grundbegri/e der Stratigraphie, Branson, C. C. (1930) Paleontology and stratigraphy Leipzig und Wien, p. 1-252. of the Phosphoria formation, Missouri Univ. Scott, Gayle (1940) Paleoecological factors controll- Stud., vol. 5, no. 2, p. 1-99. ing distribution and mode of life of Cretaceous • (1948) Bibliographic index of Permian inverte- ammonoids in the Texas area, Am. Assoc. brates, Geol. Soc. Am., Mem. 26, p. 1-1049. Petrol. Geol., Bull., vol. 24, p. 1164-1203. Clarke, F. W., and Wheeler, W. C. (1922) The in- Shimer, H. W., and Shrock, R. R. (1944) Index organic constituents of marine invertebrates, fossils of North America, New York, p. 1-837. U. S. Geol. Survey, Prof. Paper 124, p. 1-62. Snow, Joseph I. (1945) Trilobites of the Middle Clifton, R. L. (1942) Invertebrate faunas from the Permian Kaibab formation of northern Arizona, Elaine and the Dog Creek formations of the Plateau, vol. 18, p. 17-24. Permian Leonard series, Jour. Paleont., vol. Stoyanow, A. A. (1936) Correlation of Arizona 16, p. 685-699. Paleozoic formations, Geol. Soc. Am., Bull., Cooper, G. A. (1937) Brachiopod ecology and paleo- vol. 47, p. 459-540. ecology, Comm. Paleoecol., Nat. Res. Council, White, C. A. (1877) Report upon invertebrate fossils Div. Geol. and Geog., rept, p. 26-53. collected in portions of Nevada, Utah, Colorado, Diener, Carl (1925) Grundzuge der Biostratigraphie, New Mexico, and Arizona, etc., U. S. Geog. Leipzig und Wien, p. 1-304. and Geol. Survey W. 100th Merid., vol. 4, Girty, G. H. (1909a) The Guadalupian fauna, U. S. pt. 1, p. 1-219. Geol. Survey, Prof. Paper 58, p. 1-651. (1879) Paleontological papers, no. 11: Remarks (1909b) Paleontology of the Manzano group of upon certain Carboniferous fossils from Colo- the Rio Grande valley, New Mexico, U. S. Geol. rado, Arizona, Idaho, Utah, and Wyoming, etc., Survey, Bull. 389, p. 41-136. U. S. Geol. and Geog. Survey Terr., Bull. 5, (1910) Fauna of the Phosphate beds of the Park p. 209-221. City formation in Idaho, Wyoming, and Utah, Williams, H. S. (1895) Geological Biology, New U. S. Geol. Survey, Bull. 436, p. 1-82. York, p. 1-395. Knight, J. B. (1941) Paleozoic gastropod genotypes, Yonge, C. M. (1939) The protobranchiate mol- Geol. Soc. Am., Spec. Paper 32, p. 1-510. lusca: a functional interpretation of their struc- McKee, Edwin D. (1938) The environment and ture and evolution, Royal Soc. London, Philos. history of the Toroweap and Kaibab formations Tr., vol. 230B, p. 79-147. of northern Arizona and southern Utah, Car- negie Inst. Washington, Pub. 492, p. 1-268. UNIVERSITY or COLORADO, BOULDER, COLO. Miller, A. K., and Furnish, W. M. (1937) Paleo- MANUSCRIPT RECEIVED BY THE SECRETARY ecology of the Paleozoic cephalopods, Rept. OF THE SOCIETY, MAY 25, 1949.

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PLATES 1-10

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PLATE 1.—GASTROPODS Page Euphemites aequisulcatus sp. nov 113 la-c. Holotype, a specimen from loc. 3; apertural, lateral, and adapertural views, X 2. Bellerophon deflectus sp. nov Ill 2a-c. Topotype, a juvenile specimen from loc. 3; apertural, adapertural, and lateral views, X 1. 3a, b. Holotype, a specimen from loc. 3; adapertural and lateral views, X 1. 4. Topotype, a very young specimen showing juvenile shape; apertural view, X 4. 5a, b. Topotype, a large specimen; oblique-lateral view to show shape of callus, apertural view, X 1.

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GASTROPODS

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PLATE 2.—GASTROPODS Page Reiispira undulata sp. nov 113 la, b. Rubber squeeze of holotype, an external mold from loc. 2, bed 4; apertural and lateral views, X 2. Euphemites sp 113 2. Specimen from loc. 3; apertural view, X 1. Warthia sp 114 3a, b. Specimen from loc. 3; apertural and lateral views, X 3. 4. Larger specimen from loc. 3, showing sinus in broken outer lip; oblique-apertural view, X 2. Ananias franciscanus sp. nov 114 Sa-c. Holotype, a specimen from loc. 3; apertural, basal, and adapertural views, X 4. 6. Topotype, an eroded specimen; apertural view, X 4. Glabrocingulumlaemliratumsp.n.ov 117 7. Topotype, a very small specimen from loc. 3, showing nucleus; top view, X 10. 8a, b. Topotype, showing outer lip and selenizonal notch; lateral and apertural views X 4. 9a, b. Holotype, a specimen from loc. 3; apertural and basal views, X 4. Ananias gibber sp. nov 115 10. Rubber squeeze of holotype, an external mold from loc. 1, bed 2; lateral view, X 2. Euconospiraf cryptolirata sp. nov 116 11. Rubber squeeze of cotype, an external mold from loc. 1, bed 9; spire, X 2. 12. Rubber squeeze of cotype, an external mold from loc. 1, bed 9; basal portion, X 2.

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PLATE 3.—GASTROPODS Page Glabfocingulum? coronation sp. nov 118 la-c. Large specimen from loc. 3, showing external shape but almost without ornamentation; top, basal, and lateral views, X 3. 2a, b. Rubber squeeze of holotype, an external mold from loc. 1, bed 9; top and lateral views, showing ornamentation; X 6. 3. Small complete specimen from loc. 3, showing radial ornamentation faintly developed; oblique lateral view, X 5. Mourloniaf cancellata sp. nov 119 4a-c. Rubber squeeze of holotype, an external mold from loc. 1, bed 9; top, lateral, and oblique lateral views, X 3. Pernotrochus arizonensis gen. et sp. nov 120 5a, b. Rubber squeeze of syntype, an external mold from loc. 1; oblique lateral view and top view, X 3. 6. Rubber squeeze of syntype; basal view showing funnel-like umbilicus; X 3. 7. Steinkern of syntype; apertural view, X 3. Platyworthenia delicata gen. et sp. nov 121 8a-c. Holotype, a silicified specimen from loc. 3; apertural, basal, and oblique top views, X 10. 9. Rubber squeeze of external mold from loc. 2, bed 4; lateral view, X 6.

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GASTROPODS

PLATE 4.—GASTROPODS Page Worthenia comtgata sp. nov 122 la-c. Holotype, a silicified specimen from loc. 3; apertural, basal, and lateral views, X 5. Euomphalusf sp., juvenile 127 2. Rubber squeeze of an external mold from loc, 1, bed 9; basal view, X 3. cf. Lepetopsis 127 3a, b. Internal mold from loc. 1, bed 9; lateral and top views, X 3. Glyptospira cristulata gen. et sp. nov 128 4a, b. Holotype, a silicified specimen from loc. 3; basal and apertural views, X 5. Sa, b. Topotype; apertural and basal views, X 5. 6a, b. Topotype; apertural and basal views, X 5. Eotrochasf liratus sp. nov 129 7a, b. Holotype, a silicified specimen from loc. 3; apertural and basal views, X 5. 8. Topotype, a smaller specimen; basal view showing liration, X 6. Goniasma? sp 123 9. Rubber squeeze of an external mold from loc. 1, bed 9; lateral view, X 1. Stegocoelia quadricostata sp. nov 126 10. Rubber squeeze of holotype, an external mold from loc. 1, bed 2; lateral view, X 8. Murchisonia sp 125 11. Rubber squeeze of an external mold from loc. 1, bed 9; lateral view, X 1. Murchisonia geminocarinata sp. nov 123 12. Rubber squeeze of an external mold from loc. 1, bed 9; lateral view showing development of carina and nodes, X 3. 13. Rubber squeeze of an external mold from loc. 1, bed 9; lateral view, X 1J. 14. Holotype, a silicified specimen from loc. 3; apertural view, X lj. Euomphalus kaibabensis sp. nov 126 15. Rubber squeeze of external mold from loc. 1, bed 2; top view, X 1. 16a-c. Holotype, a silicified specimen from loc. 3; top, apertural, and basal views, X 1.

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PLATE 5—GASTROPODS AND CRINOIDS Page Girtyspira? sp 130 1. Rubber squeeze of an external mold from loc. 1, bed 9; apertural view, X 3. Meekospiraf sp. 1 131 2. Rubber squeeze of an external mold from loc. 1, bed 9; apertural view, X 3. Strianematina pulchrdirata gen. et sp. nov 130 3. Rubber squeeze of holotype, an external mold from loc. 1, bed 2; apertural view, X 3. Meekospiraf sp. 2 131 4. Rubber squeeze of external mold from loc. 1, bed 9; lateral view, X 3. Aclisinaf bisulcata sp. nov 132 5a, b. Holotype, a silicified specimen from loc. 3; apertural and basal views, X 5. 6. Topotype, a smaller specimen; apertural view, X 5. Oncochilus insolitus sp. nov 132 7. Holotype, a silicified specimen from loc. 3; apertural view, X 5. Genus et sp. indet. 1 133 8. Rubber squeeze of specimen from loc. 1, bed 2; lateral view, X 3. Worthenia? sp 123 9. Rubber squeeze of a poorly preserved external mold from loc. 1, bed 9; top view, X 5. Naticopsis kaibabensis sp. nov 133 lOa, b. Holotype, a silicified specimen from loc. 3; apertural and top views, X 3. lla, b. Topotype, a smaller specimen; apertural and top views, X 3. Naticopsis sp 134 12. Rubber squeeze of external mold from loc. 1, bed 2; adapertural view, X 2. Orthonemaf slriatonodosum sp. nov 134 13a, b. Holotype, a silicified specimen from loc. 3; apertural and adapertural views, X 4. 14. Topotype, a smaller specimen showing parietal inductura; apertural view, X 4. Orthonemaf sp. 2 136 15. Rubber squeeze of external mold from loc. 1, bed 9; apertural view, X 3. Genus et sp. indet. 2 136 16. Rubber squeeze of specimen from loc. 1, bed 9; apertural view, X 3. 17. Small silicified specimen from loc. 3; adapertural view, X 4. Orthonema sp. 1 135 18. Silicified specimen from loc. 1; apertural view, X 2. Crinoid arm plates 153 19a-25. Specimens from loc. 3, showing muscle scars and variation in size; X 2. 26, 27. Specimens from loc. 3, showing double ambulacral notch; X 2. Crinoid colwnnals 153 28, 29. Silicified columnals from loc. 3; X 5.

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GASTROPODS AND CRINOIDS

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PELECYPODS

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PLATE 6—PELECYPODS Page Nactilana obesa White 137 la, b. Silicified specimen from loc. 3; left valve, exterior and interior views, X 2. 2a, b. Silicified specimen from loc. 3; both valves, dorsal view and view of right valve, X 2. 3. Small silicified specimen from loc. 3; right valve, exterior view, X 3. Falaeonucula levatiformis (Walcott) 138 4. Silicified specimen from loc. 3; left valve, interior view, X 4. Sa, b. Silicified specimen from loc. 3; right valve, interior and exterior views, X 4. 6a, b. Silicified specimen from loc. 3; both valves, view of right valve and anterior view, X 4. 7-9. Silicified specimens from loc. 3; right valves, exterior views showing size and shape variations, X 4. Aviculopinna sagitta sp. nov 141 10. Rubber squeeze of the holotype, an external mold from loc. 1, bed 9; left valve, X 1. Manzandla cryptodentata sp. nov 139 lla. Holotype, a silicified specimen from loc. 3; right valve, exterior view, X 3. lib. Same, interior view, X 4. 12. Topotype; right valve, interior view, X 4. 13. Topotype; small left valve, showing oblique posterior teeth; interior view, X 4. 14. Topotype; left valve, interior view, X 4.

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PLATE 7.—PELECYPODS Page Grammatodon politus (Girty) 140 la, b. Silicified left valve from loc. 3; interior and exterior views, X 3. 2a. Rubber squeeze of internal mold of a left valve, from loc. 1, bed 9; X 2. 2b. Internal mold from which squeeze was taken; X 2. Dozierellaf sp. 2 142 3. Internal mold of a right valve, from loc. 1, bed 9; X S. Dozierella sp. 1 142 4a, b. Silicified left valve from loc. 3; interior and exterior views, X S. 5. Silicified right valve from loc. 3; interior view, X S. Bakevdlia cf. B. sulcata (Geinitz) 143 6, 7. Silicified right valves from loc. 3; exterior views, X 5. 8, 9. Silicified left valves from loc. 3; exterior views, X S. Bakevdlia prora sp. nov 142 10. Rubber squeeze of holotype, an external mold from loc. 1, bed 9; left valve, X 4. SMzoaus texanus Clifton 143 lla, b. Internal mold from loc. 9, bed unknown; right valve, anterior and lateral views, X 1J- Promytilus retusus sp. nov 144 12. Specimen from loc. 2, bed 9; internal mold of left valve, X 3. 13. Holotype, internal mold of left valve, from loc. 1, bed 9; X 3. 14. Internal mold of a left valve from loc. 2, bed 4; X 3. 15. Internal mold of a left valve from loc. 1, bed 2; X 3. Edmondia sp 153 16. Internal mold of a right valve from loc. 1, bed 9?; X 2.

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PELECYPODS

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PELECYPODS

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PLATE 8.—PELECYPODS Page A viculopeclen kaibabensis Newell 144 1. Rubber squeeze of external mold of left valve, from loc. 1, bed?; X 1. 2. Rubber squeeze of external mold of portion of a left valve, from loc. 1, bed 9; X 2. 3. Internal mold of a right valve, from loc. 1, bed 9; X 1. 4. Rubber squeeze of external mold of a left valve, from loc. 1, bed 2; X 1. 5. Rubber squeeze of external mold of an immature right valve from loc. 2, bed 9; X 3. 6a. Internal mold of a small left valve, from near loc. 1; X 2. 6b. Rubber squeeze of external mold of same specimen; X 2. 7. Internal mold of a large left valve, from loc. 1, bed 9; note fine striation of costae on interior; X 1. Acanthopecien coloradoensis (Newberry) 144 8. Rubber squeeze of fragmentary external mold, from loc. 1, bed 9; X 3. Goniopkora cristata sp. nov 145 9a, b. Topotype, a silicified right valve from loc. 3; interior and exterior views, X 5. lOa, b. Topotype, a silicified left valve; interior and exterior views, X 5. lla, b. Holotype, a silicified right valve from loc. 3; exterior and interior views, X 5.

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PLATE 9.—PELECYPODS Page Myalinella? adunca sp. nov 146 1. Topotype, an internal mold of a right valve from loc. 1, bed 9; X 3. 2. Holotype, an internal mold of a right valve, from loc. 1, bed 9; X 3. Allorismal juvenile 147 3a, b. Silicified left valve from loc. 3; interior and exterior views, X 5. Attorisma terminate Hall 146 4a. Rubber squeeze of external mold of specimen from loc. 1, bed 9, showing papillate surface; X 2. 4b. Same, entire squeeze of external mold, X 1. 4c. Internal mold of same specimen, X 1. Pleurophorus albequus Beede 147 5a, b. Silicified left valve from loc. 3; exterior and interior views, X 2. 6a, b. Silicified specimen from loc. 3; view of left valve showing fine papillation of anterior surface, and dorsal view, X 2. Rimmyjimina arcula gen. et sp. nov 148 7. Topotype, a silicified left valve from loc. 3; juvenile specimen having convex ventral margin; X 4. 8. Topotype, a silicified left valve; juvenile specimen having a sinuate ventral margin; X 4. 9a, b. Topotype, a slightly larger left valve, with slightly sinuate ventral margin; X 4. lOa, b. Topotype, a silicified right valve; X 4. lla, b. Holotype, a silicified left valve from loc. 3; X 4.

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PELECYPODS

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PELECYPODS

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PLATE 10.—PELECYPODS Page Kaibabella cumlenala gen. et sp. nov 150 la, b. Holotype, a silicified left valve from loc. 3; exterior and interior views, X 2. Ic. Same, enlarged to show dentition; X 4. 2a, b. Topotype, a silicified left valve; X 2. 3a, b. Topotype, a silicified right valve; X 2. 4a, b. Topotype, a silicified right valve; X 2. 4c. Same, enlarged to show dentition; X 4. Astartella subquadrata Girty 150 5. Silicified specimen from loc. 3; dorsal view of both valves, X 5. 6a, b. Silicified right valve from loc. 3; exterior and interior views, X 5. 7a, b. Silicified left valve from loc. 3; exterior and interior views, X 5. 8-11. Silicified right valves from loc. 3, showing variation in shape; X 2. 12-15. Silicified left valves from loc. 3, showing variation in shape; X 2. Sanguinolilesf sp 152 16. Rubber squeeze of an external mold from loc. 1, bed 2?; X 1. 17. Rubber squeeze of an external mold of a left valve from loc. 2, bed 4; X 3. Alula gilberti (White) 152 18. Internal mold of a right valve, from loc. 1, bed 9? X 5.

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Vertical Scale WALNUT BEND BOTTOMLESS PITS (T-IOOft. ( LOG. I ) EAST WALNUT RAILROAD CUT WALNUT RANGER { LOG. 2 ) CABIN I— 80 LAKE MARY

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STRATIGRAPIIIC SECTIONS OF THE ALPHA MEMBER OF THE KAIBAB FORMATION, IN THE WALNUT CANYON REGION

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