SILURIAN and UPPER ORDOVICIAN ATRYPIDS of the GENERA Plectatrrpa and SPIRIGERINA

NORSK GEOLOGISK TIDSSKRIFT 47

SILURIAN AND UPPER ORDOVICIAN ATRYPIDS OF THE GENERA PLECTATRrPA AND SPIRIGERINA

A. J. BoucoT & J. G. JoHNSON (Division of Geological Sciences, California Institute of Technology, Pasadena, California, U.S.A.)

Abstract. The nomenclatural history of Plectatrypa and Spirigerina is traced and the basis for recognition of each taxon as a valid genus is developed. The earliest progenitors of Spirigerina marginalis, which range from the Upper Ordovician into the Lower Llandovery, are separated as a new subgenus Spirigerina (Eospirigerina), based on Atrypa praemarginalis Savage which is recognized in mid-North America and in Gaspe. The closely related S. (Eospi rigerina) gaspeensis is identified in Britain and Venezuela in the Lower Llan dovery. True Plectatrypa is unknown below the Lower Llandovery; previous citations from the Ordovician are of forms that the writers propose to include in Eospirigerina. A new species, Plectatrypa henningsmoeni, is proposed for a Lower Llandovery form from the Oslo region. Plectatrypa is regarded as an early offshoot of the Atrypinae, off the main line of evolution that resulted in Atrypa in a strict sense and then little differentiated from Eospirigerina, the earliest known member of the Carinatininae. The species and distribution of Plectatrypa and of Spirigerina are listed.

Introduction

In 1930, ScHUCHERT & CooPER proposed the genus Plectatrypa (1930 p. 278) for a group of sulcate Ordovician and Silurian atrypoids in cluding Atrypa imbricata Sowerby and Atrypa marginalis Dalman and their allies. Until about 1960, the name was commonly used for atrypoids related to imbricata and marginalis, with the exception of the work by PouLSEN (1943), who treated Plectatrypa as a synonym of Nalivkinia Bublitschenko. The work of ALEKSEEVA (1960) brought out the fact that the genus Spirigerina D'ORBIGNY (1849 p. 42), 80 A. J. BOUCOT & J. G. JOHNSON although long forgotten, had clear priority over Schuchert and Cooper's genus Plectatrypa, and, in her paper discussing Spirigerina, Alekseeva designat ed Terebratula marginalis Dalman, 1828 as the type species of the genus. This was the first valid designation of a type species for Spirigerina, because d'Orbigny originally included both marginalis and imbricata in his list of species assigned without designating one as type. Because Schuchert and Cooper chose Terebratula imbricata as a type for Plectatrypa and Alekseeva chose T. marginalis as the type of Spirigerina, there remained a subjective decision about possible synonymy of the two, and past usage alone would suggest that the genera are synonymous. According to Alekseeva, Spirigerina differs from Plectatrypa in having l) a straight or nearly straight ventral beak and visible delthyrium, 2) a clearly defined interarea, 3) numerous fine concentric growth lines opposed to lamellose growth lines in Plectatrypa, and 4) dental lamellae. At the time Alekseeva's work came to the writers' attention, work was far progressed on the atrypoids for the brachiopod volume of the Treatise on Invertebrate Paleontology (Moore 1965), and in an addendum to the writers' paper dealing with systematic revision of some of the atrypoids (BOUCOT, J OHNSON & STATON 1964 p. 820) the Plectatrypa-Spirigerina problem was noted, but the writers' ap praisal in the aforementioned addendum was based on an assumption (now found false) that finely ribbed specimens from the Silurian of North Greenland illustrated by PouLSEN (1943, Pl. 5, figs. 24--31) as marginalis truly belonged to that species. During the present study, the writers have had the opportunity to examine a number of well preserved specimens of Spirigerina marginalis from the type locality, Klinteham, Gotland, and find that we are in dose agreement with Alekseeva's appraisal of the points of distinction between Plectatrypa and Spirigerina. Some species that bear all the essential characteristics of Spirigerina lack dental lamellae; therefore, we would exclude Alekseeva's point 4 as a standard of comparison. Furthermore, a hetter insight into the nature of Ashgillian and early Llandovery age sulcate atrypoids convinces us that they rep resent a relatively tight-knit, phylogenetically homogeneous group not easily assignable to Plectatrypa or to Spirigerina when those two genera are diagnosed essentially on the characters of their type species. Plectatrypa has numerous, evenly spaced, frilly growth lamellae, a SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 81

FRASN AS H LLAN DOVE RY LUDLOW GEO. EMS . GIVET G ILL WENLOCK SKALA SIEGEN L l M l U EIFEL / l> l l l l l l l"" l l l PRO TRYPA ATRYPA l l l � l:f �-- l )li :.� lj 1 l ond o/liedgenera 1 l � LECTATRYPA )o / I._P l l l l [Tl l 11 l l ! l l l l l l l l l l l l ! �/ l l 1 11 � IEOSPIRIGERINA l SPIRIGERINA l z l\ l l l >� l : \� ___ l .. . f.�.0?!�_A_TI_N_A �,.I � l 1 on� o/lied genera � �·------�------�l � Fig. l. Relationship of Plectatrypa and Spirigerina to related atrypacean genera and their stratigraphic ranges in the Ordovician to Lower Devonian. strongly incurved ventral beak lacking a deltidium, and impressed track-like ventral diductor scars. Spirigerina lacks frilly growth lamel lae, and. instead, well-preserved specimens exhibit fine concentric filae; its ventral beak is straight and exhibits a delthyrium closed by conjunct deltidial plates. The ventral muscle impressions are faint, roughly trigonal, and neither flabellate nor track-like. Thus defined, on the basis of post-Lower Llandovery representatives, Plectatrypa and Spirigerina appear to exemplify the already fully differentiated subfamilies Atrypinae and Carinatininac, respectively. The frilly growth lamellae and strongly incurved ventral beak of Plectatrypa are important characters of true Atrypa of the Silurian and Devonian. Conversely, the straight ventral beak, the closed delthyrium, and the non-frilly growth lines of Spirigerina are important and characteristic features of most Devonian members of the Carinatininae. Late Ordovician and early Llandovery ribbed, sulcate atrypids are less easy to characterize in terms of the subfamilies Atrypinae or Carinatininae. The growth lines are not frilly as in Plectatrypa, nor 82 A. J. BOUCOT & J. G. JOHNSON

are they essentially absent as in Spirigerina. Instead, there are com monly a few irregularly spaced imbricate growth lines. The ventral beak is not straight, but is slightly incurved, and lacks deltidial plates. Internally, these early forms lack the track-like impressed diductors of Plectatrypa and instead have a non-impressed trigonal muscle field of Spirigerina type. We believe that this combination of features indi cates a close relation with Spirigerina, and we therefore propose Eospirigerina for those late Ordovician and early Llandovery forms. Eospirigerina is the earliest member of the Atrypidae and thus may be the ancestor of Protatrypa and Plectatrypa, which we assign to the Atrypinae-or the latter may have had a common ancestor with Eospirigerina so that Plectatrypa arose as a convergent homeomorph of Eospirigerina. Eospirigerina is thought to have given way to Spiri gerina sometime in the middle or early Late Llandovery, and Spiri gerina, in turn, is thought to have given rise to Carinatina sometime in the late Silurian (Fig. 1).

Systematic Paleontolo�y

Suborder ATRYPOIDEA Superfamily ATRYPACEA Family ATRYPIDAE Subfamily CARIN ATININAE

Emended diagnosis: Atrypidae with straight or nearly straight ventral beaks and conjunct deltidial plates enclosing the delthyrium. Shape typically subequally biconvex. Growth lines characteristically non frilly. Discussion: The genus Spinatrypina RZHONSNITSKAYA (1964 p. 101) may belong to the Carinatininae as it has a straight ventral beak and deltidial plates, but it is exceptional in the subfamily in ha ving frilly( ?) or at !east well-developed imbricate growth lamellae. In the brachiopod volume of the Treatise on Invertebrate Paleontology (MooRE 1965), the writers included the recently proposed genus Mi matrypa Struve, 1964, in the Carinatininae, although Struve had proposed the genus as a member of the Palaferellinae, i.e. a genus allied to Gruenewaldtia. COPPER (1964 p. 363), citing the presence of SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 83 ventral muscle platforms in both genera, amplified suggested relations of M imatrypa with the Palaferellinae by suggesting that M imatrypa was in fact derived from Gruenewaldtia in the Middle Devonian. The writers feel that the presence of a ventral platform in these atrypoids has been greatly overemphasized. Our survey of the atrypoids as a whole, in connection with the synoptical presentation in the Treatise, together with the present work convinces us that atrypoid ventral platforms occur in a number of genera that are otherwise unrelated. The structure is well known in certain smooth atrypoids such as Meifodia, Lissatrypa, Lissatrypoidea, and Glassia. It is strongly devel oped in some species of Plectatrypa as shown by the specimens illus trated in the present paper (Pl. 4, figs. 7, 11). That ventral platforms originated separately in several distinct groups of atrypoids appears undeniable and we therefore recommend reappraisal of the basis of including Mimatrypa and closely related shells in the Palaferellinae. The latter subfamily is exemplified by Gruenewaldtia in which there is developed a strongly convex pedicle valve with an extravagantly incurved ventral beak, and with plate-like platforms in both valves that are elevated on radial septa above the floor of the valve. In both of these features Gruenewaldtia stands alone and contrasts mark edly with the straight ventral beak and the sessile ventral platform formed by posterior thickening of the internal shell material in Mima trypa. The interested reader should compare the internal mold of Mimatrypa in the Treatise (MooRE 1965, p. H636, Fig. 521A) with internal molds of Gruenewaldtia ( = Palaferella) illustrated by SPRIE STERSBACH (1942, Pl. 7, figs. 2d, 3, 4). CoPPER (1964 Fig. l) showed no transitional forms between Gruene waldtia and Mimatrypa as regards either of the most characteristic features of Gruenewaldtia noted above, nor did he claim that such transitions existed; his analysis appears to have been based mainly on the argument that the presence of a ventral platform of any sort indicates same true homology involving the various forms studied. The writers believe that there is little likelihood that the thickened sessile ventral platform of the M imatrypa type is homologous with the elevated, plate-like, septa-supported platform of Gruenewaldtia. The systematic position of Mimatrypa was the subject of a recent analysis by ALEKSEEVA (1966). Reasoning on the basis of shell shape and internal shell thickening of posterior structures, Alekseeva pro- 84 A. J. BOUCOT & J. G. JOHNSON posed inclusion of Mimatrypa in the Karpinskiinae,although Karpinskia lacks a ventral platform such as that developed in Mimatrypa. Some specimens, as illustrated by Alekseeva in her Plate 13, do mimic the Katpinskia form in being elongate-suboval with a somewhat flat pedicle valve, although there is no question of M imatrypa flabellata conforming closely to the true Karpinskia form. ALEKSEEVA's dis covery of spiralia in a specimen of Mimatrypa flabellata (1966, Fig. 4, p. 158) di.>posesof COPPER's suggestion (1965 p. 360) that Mimatrypa lacks spiralia; his failure to discover them was evidently due to non preservation in the available specimens. Alekseeva's proposal of Mimatrypa as a karpinskiinid raises the question of what characters of Karpinskia rnay be regarded as diagnos tic to the discovery of subfamily relations based on an approxi mation of the true phylogeny of the genus and its allies. In an earlier paper, the writers (Boucor, joHNSON & STATON 1964 p. 811) proposed to include the unusual Australian genus Notoconchidium as a junior synonym of Karpinskia under the impression that Karpinskia bears very long, subparallel dental lamellae in the pedicle valve. With the acquisition of specimens of Karpinskia confugula from Dr. Alekseeva, the writers find themselves in a hetter position to evaluate the char acter of the internal structures of the genus and find that it does not in fact have long dental lamellae, but only long subparallel ridges that extend from posteriorly situated dental lamellae almost to the anterior margin of the valve. We thus abandon the proposed synonomy of Notoconchidium with Karpinskia in favor of the opinion that the Australian genus is rather a rhynchonellid, a view first proposed by TALENT (1964 p. 32). Concurrent studies of Vagrania and related brachiopods in western and Arctic North America by jOHNSON (1967) show that the ex ceedingly long subparallel ridges in the pedicle valve, already illus trated by the writers in V agrania (BOUCOT, JOHNSON & STATON 1964, Pl. 128, fig. 10), are like those developed in Karpinskia. Utili zation of the aforementioned ventral structures in the arrangement of a plausible phylogenetic scheme as discussed by Johnson would include in the subfamily Karpinskiinae only the genera Eokarpinskia RzHONSNITSKAYA 1964, Karpinskia TSCHERNYSCHEW, 1885, a new genus being proposed by Johnson, and Vagrania ALEKSEEVA, 1959. With this evaluation in mind, the writers believe that the vascular DOR SAL VENTRAL GROWTH VENTRAL CONVEXITY SULCATION SOCKETS DIDUCTOR BEAK LINES DIDUCTORS SITE

Subequally Fold ond lncurved, L..amellose lmpressed, Non- Smooth IJl biconvex sule us deltidial track-like crenulate - PLECTATRYPA plates t-< commonly Cl � lacking > z > Straight,wjth z Subequally Fold and Faint, with Faint, Non- Smooth tj SPIRIGERINA deltidial biconvex sulcus filae trigona l crenulate Cl plates "Ø ------r------r------f------lncurved, del· Subequally Fold and Sparce, Not Non- Smooth ;:g� tidial plates EOSPIR/GER/NA bi convex sulcus imbricate impressed crenulate o variable � tj

Subequally None lncurved, Lamellose Faint, Non- Smooth - biconvex deltidial trigonal crenulate ()� plates PROTATRYPA > commonly z locking � "Ø - Subequolly Commissure lncurved, Lamell ose, lmpressed, C renu late, Stria te t::l IJl biconvex deflected deltidial frilly flabellote with to convexo- dorsally plates orticulated ATRYPA pl ane loeking ridge

l 00 Fig. 2. Key to the diagnostic characters of Plectatyypa, Spi,-igeyina, PYotatyypa, and At,-ypa. (.It 86 A. J. BOUCOT & J. G. JOHNSON tracks that proceed anteriorly and bow laterally from the ventral platform of Mimatrypa, as illustrated in the TREATISE (MooRE 1965, Fig. 521A-1a) are similar to those seen in other atrypoids, including some that belong to Atrypa in the strict sense and which differ con siderably from the elongate subparallel ridges present in all of the Karpinskiinae. We recommend retention of Mimatrypa in the Carina tininae.

Genus Spirigerina d'Orbigny, 1849 Type species: Atrypa marginalis Dalman, 1828. DiscussiON: Spirigerina is typified externally by a slightly incurved to straight ventral beak, a short, flat interarea, and deltidial plates enclosing the foramen. Internally, the ventral musculature is trigonal and poorly impressed, the dorsal hinge plates are simple and discrete with the sockets uncorrugated and the site of diductor attachment nonstriate (Fig. 2). The ventral sulcus and dorsal fold distinguish Spirigerina from other carinatininids. A new genus Plectothyrella was recently proposed by TEMPLE (1965 p. 412) as a probable member of the Athyridacea. Plectothyrella bears a certain resemblance to Spirigerina and to Plectatrypa, and in the present writers' view is an atrypoid rather than an athyridacean. Examination of TEMPLE's illustrations (1965, Pls. 20, 21) and of specimens from the Hirnant beds from a small quarry, west of the road, about 4 miles SSE of the Railway Station at Bala, leads to the conclusion that Plectothyrella is an atrypoid best assigned to the Zygospirinae since its internal features are principally those of Catazyga and its allies (cf. BoucoT, joHNSON & STATON 1964, Pl. 126, figs. 21-24, and HALL & CLARKE 1895, Pl. 54, figs. 19, 20).

Species assigned to Spirigerina Terebratula marginalis DALMAN (1828, p. 143, Pl. 5, figs. 6a�) Trematospira mathewsoni McCHESNEY (1868, p. 32, Pl. 7, fig. 3) Atrypa expansa LINDSTROM (1880, p. 22, Pl. 12, figs. 6-10, 17-19) Atrypa calvini NETTELROTH (1889, p. 89, Pl. 32, figs. 64-66) Atrypa marginalis var. multistriata FoERSTE (1890, p. 316, Pl. 6, fig. 8) Atrypa praemarginalis SAVAGE (1913, p. 84, Pl. 4, figs. 14-16) Atrypa parksi WILLIAMS (1919, p. 120, Pl. 7, figs. 19a, b, c) SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 87

Eatonia bicostata STAUFFER (1930, p. 109, Pl. 14, figs. 5-7) Plectatrypa gaspeensis CooPER (in ScHUCHERT & CooPER 1930, p. 279, Pl.2, figs. 13-15) Nalivkinia groenlandica PauLSEN (1943, p. 46, Pl. 5, figs. 17-23) Atrypa supramarginalis KHALFIN (1948, p. 159, Pl, 2, fig. 10; Pl. 4, figs. 4--7) Plectatrypa brownsportensis AMSDEN (1949, p. 64, Pl. 34, figs. 2, 3, 8-10) Plectatrypa sulvei jAANussoN (in ALIKHOVA 1954, p. 33, Pl. 20, figs. 3-7) Plectatrypa pennala RUKAVISCHNIKOVA (1956, p. 160, Pl. 5, figs. 12, 13) Spirigerina marginaliformis ALEKSEEVA (1960, 1962, p. 161, Pl. 9, fig. 10) Plectatrypa marginalis sibirica RZHONSNITSKAYA (1960, Pl. 53, fig. 24) Atrypa marginaloides NALIVKIN (lide ALEKSEEVA 1962, p. 158, Pl. 9, fig. 9) Plectatrypa australis PHILIP (1962, p. 218, Pl. 34, figs. 5-9)

Species questionably assigned to Spirigerina Atrypa canaliculata DALMAN (1828, p. 129, Pl. 4, figs. 4a-d) Spirigerina cordata LINDSTROM (1861, p. 363, Pl. 12, fig. 3) Atrypa altijugata LINDSTROM (1880, p. 23, Pl. 13, figs. 9-13) Plectatrypa carpulenta KHODALEVICH & BRIEVEL (1959, p. 65, Pl. 30, figs. 1-4) Atrypa ossa NALIVKIN (in KHODALEVICH 1951, p. 67, Pl. 10, fig. 7; NALIVKIN 1960, p. 381, Pl. 88, fig. l) Spirigerina(?) dauritschensis MENAKOVA (1964, p. 19, Pl. 4, fig. 5) Spirigerina cuboidea MENAKOVA (1964, p. 21, Pl. 4, figs. 6-8) Spirigerina dubia MENAKOVA (1964, p. 22, Pl. 5, figs. 1-5)

OCCURRENCE OF SPIRIGERINA

GREAT BRITAIN: Spirigerina marginalis, Wenloek Limestone, Dudley, England (DAVIDSON 1866-71, Pl. 15, figs. 1-2). Also in Boueot eoll., USNM loe. 10550, grid ref. 670/038. Old quarry on west side of Lineoln Hill. Iron-Bridge. Map sheet 118 (Shrewsbury). Spirigerina cf. marginalis, Upper Wenloek, grid reference 601/196. Old quarry about 1/3 mile southeast of Golden Grove, in Golden Grove Park; about 2 miles southwest of Llandilo. Map sheet 140 (Llandovery). USNM loe. 10497. Spirigerina cf. marginalis, grid reference 198/798, quarry at Penylan Hill, immediately E of Edward Nicholl home, Cyncoed, Cardiff (see SoLLAS 1879 for stratigraphic position). Map sheet 154 (Cardiff). USNM loe. 10464, January 1957. Age: Wenlock? S. (Eospirigerina) gaspeensis, Gasworks Mudstone, grid. ref. 956/155, road cut opposite NW end of gas works at Haverfordwest, about 240-260 paces SE of junction of Lower Cambrian Pla.ce with the New Road. Ma.p sheet 151 · (Pembroke), Boucot collection, 1957, USNM loe. 10509. BALTIC REGION: Spirigerina sp., Hamra Group, Gotland, Palaeont. Museum, Oslo eat. no. A28719. Age: Late Ludlow. 88 A. J. BOUCOT & J. G. JOHNSON

Spirigwina cf. marginalis, Hamra Limestone, shaley interbed on west slope of cliff at Hoburgen, Burgsvik quadrangle, Gotland. USNM loe. 10002. Age: Latest Ludlow or Early Skala. Spirigerina sp., Klinteberg Ls., Linde Klint, N-NW of Linde Church, Remse quadrangle, Gotland. USNM loe. 10024. Age: Ludlow. Spirigerina cf. marginalis, Shale of Hemse Group from canal banks l km N of church in Linde, Remse quad., Gotland. USNM loe. 10000. Age: Early Ludlow. Spirigerina cf. marginalis, Hemse Limestone, Sandarve Kulle, northeast slope, about 2 km W of Linde Church, Remse quadrangle, Gotland. USNM loe. 10085. Age: Early Ludlow. S. marginalis, Klinte berg Ls., Gotland, illustrated herein. Age: Late Wenlock or Early Ludlow. ?Spirigerina expansa, in beds of Ordovician age, Gotland; 'Calx Leptaer narum' of LINDSTROM (1880 p. 38). ?Spirigerina altijugata, in beds of Ashgill and early Llandovery age, Gotland; 'Calx Leptaenarum' and 'Calx Silurii superioris' of LINDSTROM (1880 p. 38). S. (Eospirigerina) cf. gaspeensis, Skålberget, north of Rattvik. Red and green marls above the black Tretaspis shales but below the Boda Reef Limestone, USNM loe. 12412; also in Boda Reef Limestone, Osmundsberget, USNM locs. 12414, 15, 16, 17. Coll. of U. Jux. Age: Late Ordovician. S. (Eospirigerina) sulvei, Pirgu-Stufe, Estland {JAANUSSON 1956, Pl. l, figs. 7, 8). Age: Late Ordovician. BoHEMIA: S. 'marginalis', Lower Koneprus beds (C HLUPAC 1953 p. 317). Age: Upper Gedinnian or Siegenian. ?S. marginalis, E2, Czechoslovakia (BARRANDE 1879, Pl. 31, figs. 1-3). Age: Wenlo«k according to HoRNY (1962 p. 903). Spirigerina cf. marginalis, Silurian, Kolednik, Bohemia. USNM 88453. Spirigerina marginalis, E8 Lodenice. USNM accession no. 195424. RussiA: ?S. carpulenta, Ivdel beds, Ural Mts. (KHODALEVICH & BRIEVEL 1959 p. 65, Fl. 30, figs. 1-4). Age: Emsian. ?S. ossa, Lower Devonian, Pai-Hoi (NALIVKIN 1960 p. 381). S. mar�?inaliformis, Petropavlovsk beds, north Urals (ALEKSEEVA 1962, Pl. 9, fig. 10; KHODALEVICH 1939, Pl. 25, figs. 1-3), also specimens under USNM 89670. Age: Gedinnian or Siegenian. ?S. marginaloides, Upper Krekova beds, Kuznetsk Basin (ALEKSEEVA 1962 p. 158, Pl. 9, fig. 9). Age: Siegenian. S. marginalis sibirica, Krekova beds, Kuznetsk Basin (RZHONSNITSKAYA, in SARYCHEVA 1960, Pl. 53, fig. 24). Age: Siegenian. S. supramarginalis, Solovien Limestone, Altai Mts. (KHALFIN 1948; KuLKOV 1963). Age: Siegenian. S. marginaliformis, Marginalis beds, Central Asia (NIKIFOROVA 1937, Pl. 8, fig3. 1-5). Age: Gedinnian or Siegenian. ?Spirigerina dauritschensis, S. cuboidea, and S. dubia in Llandovery to Wen lock age beds from the Zeravshano-Gissar Mountain Region, Central Asia (MENAKOVA 1964). SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 89

AusTRALIA: Spirigerina australis, Boola beds, Tyers area, Victoria, Australia (PHILIP 1962 p. 219). Age: Early Siegenian. Spirigerina marginalis, Lower Trilobite beds of the Bowning Series on the east and west sides of the Bowning syncline, New South Wales (MITCHELL & DuN 1920 p. 269, Pl. 15, figs. 14-16; Pl. 16, figs.l-5). Age: Wenloek or Ludlow. NEVADA and CALIFORNIA: S. supramarginalis (as S. cf. sibirica), Windmill Limestone, north Simpson Park Range, central Nevada (USNM locs. 10757, 58) (JoHNSON 1965 p. 371). Age: Siegenian. S. cf. marginalis, Roberts Mountains Formation, Roberts Mts., central Nevada (USNM locs. 12325, 36) (Johnson, Boucot & Murphy, in prep.). Age: Beds of Ludlow age. Spirigerina cf. marginalis, 'Lone Mountain Dolomite', short distance N of Cunningham Prospect, Tybo District, Hot Creek Range, Nye County, Nevada. Collection of A. J. Boucot, 1964, USNM loeality 11081. Age: Ludlow. Spirigerina cf. marginalis, basal Sevy Dolomite, Pahranagat Range loeality 6 of JoHNSON & REso (1964), Nevada. Age: Probable Ludlow. S. bicostata, Vaughn Gulch Limestone, Inyo Mts., southeastern California (STAUFFER 1930 p. 109, Pl. 14, figs .. 5-7). Age: Probable Gedinnian. S. cf. marginalis, Hidden Valley Dolomite, Funeral Range, southeastern California. Age: Beds of Wenlock Ls. age, USNM loe. 12878. VENEZUELA: S. (Eospirigerina) gaspeensis, Caparo Formation, Merida Andes, Venezuela, Lower Llandovery beds, loe. 80748 of Smith, USNM loe. 12305, and SMe 1583 of R. Shagam, USNM loe. 12658. EASTERN AND CENTRAL UNITED STATES: Spirigerina sp., Liston Creek bio herm, 3 miles southeast of Sweetser, Indiana. North %. section 16, T24N., R7E., 2,000 yards either side of a bridge over Pipe Creek, Carnes Collection, 1961, USNM loe. 11923. Age: Ludlow. S. brownsporlensis, Brownsport Formation, Tennessee (AMSDEN 1949, Pl. 34, figs. 2, 3, 8-10). Also in Boucot coll., USNM loe. 11922, glade 150 yards S of Mt. Lebanon Community Center, Perry Co., Tenn. Age: Late Wenlock. Spirigerina calvini, 'Niagara Group' east of Louisville, Kentucky (NET TLEROTH 1889 p. 89, Pl. 32, figs. 64-66). Age: Probably Louisville Ls. ofWenloek Ls. or Ludlow age. Spirigerina cf. S. (E.) praemarginalis, Brassfield Formation, Centerville, Ohio, from Wards, January 1935, USNM 155871. Spirigerina sp. (with very fine ribs), Brassfield Formation southwest of New ]asper, Ohio, collection of A. F. Foerste, USNM no. 85172. Spirigerina (Eospirigerina) gaspeensis, Silurian, (Brassfield?) , l mile S of Bridgeport, Alabama, USNM no. 90665. Spirigerina cf. S. (E.) praemarginalis, Noix Formation, Henderson Farm, 3 miles W of Louisiana, Missouri. Collection of F. R. Long, USNM 155872. S. (Eospirigerina) praemarginalis, Edgewood Limestone, below Bowling Green Member, vicinity of Edgewood and Watson Station, Pike Co., Missouri, and near Thebes, Illinois (SAVAGE 1913 pp. 84-85, Pl. 4, figs. 14-16). Age : Early Llan dovery. 90 A. J. BOUCOT & J. G. JOHNSON

Spirigerina multistriata, Clinton Group, Hanover, Indiana (FoERSTE 1890 p. 316, Pl. 6, fig. 8). Spirigerina mathewsoni, in Niagara Limestone, Bridgeport, Illinois (Mc CHESNEY 1868 p. 32, Pl. 7, fig. 3). CANADA: Spirigerina (Eospirigerina) parksi, Manitoulin Dolomite, Manitoulin Island, Ontario (WILLIAMS 1919 p. 120). Spirigerina aff. marginaliformis, in a limestone eonglomerate in St. Leon Siltstone, Beland eolleetion, no. BB-18-0, 1959, west half of Ste. Blandine sheet, lot 17, Range I, Maepes twp., on a NE ridge, immediately NW of Ste. Blandine eemetery, on NE side of main village road, Rimouski Co., Quebee. USNM loe. 10982. Spirigerina aff. marginaliformis, Bouleaux Formation, east Port-Daniel township, east side of Pointe Bouleaux, Gaspe, Quebee. Skidmore loeality 61-F-4, July 1961, USNM loe. 11449. Age: Ludlow. · Spirigerina sp., sayabee Formation, 430 ft below top, 1.25 miles ENE of the village of La Redemption, Awantjish twp., Matapedia Co., Quebee. Coll. of W. M. J. Linekens, 1966. USNM loe. 12779. Spirigerina aff. marginaliformis, Sayabec Limestone, west half of Lae Humque sheet, near boundary of lots 4 and 5, on the SE side of road separating Ranges Il and Ill, Awantjish twp., 0.6 mile NE of village of La Redemption, Matapedia Valley, Quebee, Beland locality BB-24, 1959; USNM loe. 10981. Age: Wenloek or Ludlow. S. (Eospirigerina) gaspeensis, Grande Coupe beds (F1 and F2} at Peree, Quebec (ScHUCHERT & CoOPER 1930 p. 279). Age: Late Ordovician. Aeeording to Dr. P. J. Lesperanee, the F1 (Friest Road) loeality is Middle Ashgill, dated by Warburgella. The F2 (Grande Coupe) loeality is in beds that probably span part of the Caradoc and Lower Ashgill. Sehuehert (in ScHUCHERT & CooPER 1930 p. 169) listed P. gaspeensis from F, (Silurian, pre-Monograptus turriculatus zone) and F5 (of uneertain age). S. (Eospirigerina) praemarginalis, Ellis Bay Formation, locs. 52b, 49, 47, 36, 35 (TWENHOFEL 1928 p. 218). Age: Lower Llandovery. GREENLAND: S. groenlandica, Offley Island Fm., N Greenland (PouLSEN 1943 p. 46, Pl. 5, figs. 17-23). Age: Late Llandovery. Spirigerina sp. (as Nalivkinia marginalis}, Offley Island Fm., N Greenland (PoULSEN 1943, Pl. 5, figs. 24-31). Age: Late Llandovery.

Subgenus Eospirigerina nov. Type species: Atrypa praemarginalis Savage, 1913. DISCUSSION; The new subgenus differs from Spirigerina (Spirigerina) in having a more strongly incurved ventral beak and less prominent ventral interarea and deltidial plates. In addition, there is an irregular development of growth lamellae at distant intervals on some species SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 91

of Eospirigerina, but well-developed growth lamellae are not present in Spirigerina (Spirigerina). Eospirigerina first appears in the middle Ashgillian with E. gaspeensis (Cooper), a species that continues up into the Lower Silurian and is illustrated in the present paper by specimens from Venezuela and from Britain. Eospirigerina praemargi nalis is present only in the Lower and probable Middle Llandovery and is at present recognized in the mid-continent of the United States in the Edgewood Formation and on Anticosti Island, represented by numerous specimens from the Ellis Bay Formation originally assigned to Atrypa marginalis Dalman. Eospirigerina is thus known in the Ashgill and Lower Llandovery beds, but still unknown in beds cer tainly assigned to the Middle Llandovery. It probably gave rise to true Spirigerina some time in the late Llandovery and continued as a prominent element of Wenlock, Ludlow, and Lower Devonian faunas, although no Lower Devonian Spirigerina is known in the Appalachian Province of North America.

Spirigerina (Eospirigerina) praemarginalis (Savage) Pl. l, figs. 1-16 1913 Atrypa praemarginalis SA VAGE, p. 84, Pl. 9, figs. 14-16.

DiscussiON: This species is a relatively finely costate one with a well-developed fold and sulcus, and generally the beak is slightly incurved and the development of the deltidial plates is somewhat variable, but examination of over 100 very well preserved specimens from Anticosti Island, which were originally assigned to Atrypa marginalis by TwENHOFEL (1928 p. 218), shows that some have a relatively well-defined interarea and prominent deltidial plates even though there is beak curvature. E. praemarginalis can be distinguished from the closely allied species E. gaspeensis by the well-developed furrows that bound the dorsal fold and by the complimentary promi nent margins of the ventral sulcus in E. gaspeensis. Numerous sped mens of E. praemarginalis from Illinois and from Anticosti Island bear out the fact that the absence of dorsal bounding furrows in that species is a consistent feature and is probably the only way the two species can be differentiatedwith any certainty, although E. gaspeensis tends to have a slightly straighter hingeline. 92 A. J. BOUCOT & J. G. JOHNSON

LUDLOW

1------11------S. marginalis WENLOCK (S)

----- Ll --�- �-----�1------

c3-cs------1 ---·-- -- LLANOOVERY t prr.�arginalis - ) -- S. (E. ____ -·- - -A 1 -_c_2 - l 1- -1 ···. . · S. gas eensis UPPER .. . (E.) p l ORDOVICIAN l l . . Fig. 3. Phylogeny of species of Spirigerina illustrated in the present paper.

The specimens described below under the name Spi:rigerina (Eo spirigerina) gaspeensis from Britain therefore indicate some strati graphic range for the species spanning the Upper Ordovician and Lower Silurian, and it appears likely that E. praemarginalis arose from E. gaspeensis. Furthennore, because of a tendency for the anterolateral portions of the pedicle valve of E. gaspeensis to be reflexed and because of the bounding furrows, the species appears doser to Spirigerina marginalis and is probably the stock from which the latter arose (Fig. 3).

Spirigerina (Eospirigerina) gaspeensis (Cooper) Pl. 1, figs. 17-20; Pl. 2, figs. 1-15 1930 Plectatrypa gaspeensis Cooper (in ScHUCHERT & CooPER p. 279, Pl. 2, figs. 13-15) ExTERIOR: The valves are subequally biconvex to unequally biconvex with the brachial valve the deeper. Pedicle valves are subpentagonal in outline and brachial valves are rounded subtrigonal The hinge line is relatively long and nearly straight on large specimens. The place SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 93 of maximum width is in the posterior half. Pedicle valves are nearly evenly convex posteriorly, but the flanks flatten out anterolaterally, adjoining what is commonly a well-developed median sulcus. The sulcus is accentuated by elevated margins forming three distinct scctors on most specimens. The brachial valves have a corresponding fold delimited by fairly well-defined bounding furrows. The external ornament consists of numerous raised rounded costae that increase in number anteriorly by bifurcation and by implantation. Bifurcating costae may produce pairs of subequal size, but commonly intercalated costellae are considerably smaller in width than adjoining costae. The interspaces are relatively deep and U-shaped. The best preserved specimen shows very numerous but poorly defined con centric growth lines and a few larger shells show relatively well marked growth lines anteriorly. The ventral beak is short and narrow and relatively strongly incurved. INTERIOR OF PEDICLE VALVE: On the inner edges of the delthyrium, there is a pair of broad longitudinal grooves that become shallow and disappear on the posterior faces of the binge teeth. Ringe teeth are triangular in cross-section and supported by very short dental lamellae that join the side of the valve. The ventral musculature is not im pressed. The interior is crenulated over most of its area by the im press of the costae. INTERIOR OF BRACHIAL VALVE: The binge plates define shallow rounded sockets that partly overhang the posterior portion of the dorsal interior. The sockets are not crenulated and do not bear longi tudinal articulating ridges. The inner edges of the socket plates diverge at a moderate angle anterolaterally and descend below the plane of commissure where they are thickened to form triangular crural bases with flat ventral faces paralleling the plane of commissure. Crural lobes appear not to be differentiated and the crural bases are discrete, defining an anteriorly widening notothyrial cavity. The site of diductor attachment is apparently not striated. The adductor impressions are indistinct, being defined essentially by a few poorly defined radial ridges in the posterior part of the valve which is crenulated from posterior to anterior by the impress of the costae. FIGURED SPECIMENS: USNM 155062, 155063 (from Venezuela), 155064, 155064A-155069 (from England). 94 A. J. BOUCOT & J. G. JOHNSON

Subfamily ATRYPINAE

EMENDED DIAGNOSIS: Atrypidae with incurved ventral beak lacking deltidial plates. Shape subequally biconvex to convexo-plane. Exterior typically with frilly growth lamellae. Intemally, early genera have a poorly impressed non-flabellate muscle field, or if impressed the di ductors are track-like and may be divided by an adductor platform. Yo unger forms have flabellate ventral muscle scars.

Genus Plectatrypa ScHUCHERT & CooPER, 1930

Type species: Terebratula imbricata SowERBY, 1839, p. 624.

Species assigned to Plectatrypa

Terebratula imbricata SowERBY (1839 p. 624, PL 12, fig. 12) Atrypa flexuosa MARR & NICHOLSON. (1888 p. 725, PL 16, fig. 20) Atrypa tubulistriata SAVAGE (1913 p. 86, PL 5, figs. 23, 24) Plectatrypa henningsmoeni BoucoT & J OHNSON, herein

Species questionably assigned to Plectatrypa

Atrypa rugosa HALL (1852 p. 271, PL 56, fig. l) 'Plectawypa' conci'nna Lamarck (lide ScHUCHERT & CooPER 1930)

Species rejected from Plectatrypa

Atrypa nodostriata HALL (1852 p. 271, PL 56, fig. 2). Specimens examined in the USNM collections show that this species does not possess the impressed track-like diductor scars of Plectatrypa. Its coarse lamellose growth lines distinguish it from Spirigerina. Although sulcate, 'Atrypa' nodostriata some what resembles Spinatrypa and I nvertrypa; it differs from those two genera in the absence of crenulated sockets. Atrypa, in the strict sense, differs in having finer costae and crenulated sockets.

OCCURRENCE OF PLECTATRYPA

GREAT BRITAIN: Plectatrypa imbricata, Wenlock shale equivalent, top 1/1, grid reference 383/742. Stream section 200 yards E of Eastnor Park Lodge on the ridge way. Map sheet 143, Gloucester and Malvem, USNM loe. 10447. Age: Wenlock. Plectatrypa imbricata, Wenlock Limestone, Dudley, England (DAvmsoN 1866-71, PL 15, figs. 3--6). SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 95

?Plectatrypa sp., Canaston beds, grid reference 059/144. Small quarry on southeast side of Blackpool road, southwest side of Pen Glyn, about 1/8 mile SW of Blackpool (about 7 miles east of Haverfordwest). Map sheet 151 (Pem broke), USNM loe. 10514. Age: Late Llandovery. Plectatrypa flexuosa, Lower Skelgill beds (Aal) at Skelgill, Lake District in the north of England (MARR & NicHOLSON 1888 p. 725). Age: Earliest early Llandovery. GoTLAND: ?Plectatrypa sp., Slite Group, Visby quad., 450 m northwest of Martebo station, Martebo Parish, Gotland. USNM loe. 10083. Age: Late Wenlock. Plectatrypa sp., Slite Group, Canal in Slite group about 500 yards S of church in Eskelhem Klintehamn quad., Gotland. Age: Wenlock. ?Plectatrypa sp., basal beds of Hogklint Group, east side of Kopparsviksgatan and Gutervagen, Visby, where these streets intersect. USNM loe. 10050. Age: Wenlock. Plectatrypa cf. imbricata, Upper Visby Mari, shore just north of harbor at Gnisvards flge., Tofta Parish, Klintehamn quad. USNM loe. 10047. Age: C8, Upper Llandovery or early Wenlock. RussiA: Plectatrypa imbricata, Kitaigorod Formation, Podolia (NIKIFOROVA 1954, Pl. 14, figs. 1-4). Age: Late Llandovery. Plectatrypa imbricata, Llandovery age beds, Siberian Platform (NIKIFOROVA & ANDREEVA 1961, Pl. 47, figs. 9-14). BoHEMIA: Plectatrypa imbricata, Silurian, Lodenice, Bohemia. USNM nos. 88459 and 100034. EASTERN AND CENTRAL UNITED STATES: Plectatrypa imbricata, Clinton (Rochester), Lockport, N.Y. USNM accession no. 226024. ?Plectatrypa rugosa, Roehester Shale at Lockport, N.Y. (HALL 1852 p. 271, Pl. 56, fig. 1; GILLETTE 1947 p. 105). Age: Wenlock. ?Plectatrypa sp., Cordell Dolomite, Baileys Harbor, Wisconsin, opposite County Park in cut behind church. USNM loe. 11639. Age: C5 to Wenlock. Plectatrypa tubulistriata, Noix Oolite Member of the Edgewood Formation at Louisiana, and near the mouth of Buffalo Creek, in Pike Co., Mo. South of Hamburg in Calhoun Co., Ill. (SAVAGE 1913 p. 87). Age: Early Llandovery. ?Plectatrypa sp., Lilley Formation, Crooked Creek, Adams County, Ohio. USNM 87717; accession no. 120245. Age: Wenlock. Plectatrypa cf. imbricata, Edmunds Formation, Machias quad., southeastern Maine, collection of Olcott Gates, 1960, no. F-38, along U.S. Rt. l, about 2.5 miles E of Gardner Lake on strike with Edmunds Formation projected SE from SW corner of Eastport quad. USNM loe. 11851. Age: Wenlock. Plectatrypa sp., 50 ft above the base of the exposed section at Limestone Hill, N of Flagstaff Lake, NE corner of Stratton quad., northwesternMaine; collection of K. Pankiwskyj, 1959. USNM loe. 11918. Age: Late Llandovery. CANADA: ?Plectatrypa sp., un-named beds on north side of southeast Upsal quitch River, approx. 1,500 ft SW of the mouth of Little Popologan Brook, New Brunswick. R. R. Potter coll. 1962. USNM loe. 11980. Age: C3 to Wenlock. Plectatrypa imbricata, un-named beds, Back Bay, New Brunswick, USNM 96 A. J. BOUCOT & J. G. JOHNSON

loe. 11917, G.S.C. loe. 55050 (BOUCOT, jOHNSON, HARPER & WALMSLEY, 1966, Pl. 13, figs. 3-16). Age: C,-C6, Late Llandovery. ?Plectatrypa sp., Anantjvik Fm. below Val Brilliant, Beland, 1960, collection no. JB-44, east half Lac Prime sheet, Club Richard road branching off from the road along and W of Lac des Eaux Mortes, in green slates 1.5 miles west of road junction, Rimouski-Matapedia, Quebec, USNM loe. 11194. Age: Late Llandovery C1 or higher. ?Plectatrypa sp., Lac Castor Member of Lac Raymond Formation, Lat. 48°05', Long. 68°15', La Prime West, l mile N45E from Castor Lake, Lajoie, 1960 collection, Rimouski, Matapedia, Quebec. USNM loe. 11490. Age: Late Llandovery, C1. Plectatrypa henningsmoeni, 'Clemville' Formation, probably Weir Formation of Ayrton Mts. 7'4 mile up little Port Daniel River from bridge, 2 miles W of Port Daniel, Quebec, collection of G. A. Cooper, 1932, USNM 155873. Plectatrypa sp., Becsie Formation, Becsie River, Bear Cliff, Anticosti Is., Peabody Museum, Yale Univ. no. 3063/64. These specimens were reported as Atrypa marginalis by TWENHOFEL (1928 p. 218).

Plectatrypa henningsmoeni n. sp.

Pl. 4, figs. 1-12

DIAGNOSIS: Large transverse Plectatrypa with a long hinge line. EXTERIOR: Shells attain large size and are strongly inflated, sub equally biconvex in profile. The valves are rounded, subpentagonal in outline, with a relatively long hinge line, and a maximum width posterior to midlength. The ventral umbo is low, and the ventral beak is minute and strongly incurved over the beak of the brachial valve. No interarea is present externally. The pedicle valve bears a moderately well-developed sulcus set off laterally by a very faintly developed pair of bounding plications. The brachial valve bears a narrow rounded fold. Neither fold nor sulcus flare anteriorly, but widen by increasing divergence of straight lateral margins. The anterior commissure is moderately to strongly sulcate, even geniculate on some large specimens that develop a tongue-like ventral projection that is accommodated anteriorly by the fold on the brachial valve. The ornament consists of numerous rounded bifurcating costae crossed by well defined imbricating concentric growth lamellae more or less over the whole of each valve. INTERIOR OF PEDICLE VALVE: Hinge teeth are blunt and triangular, attached to the inner posterior surface of the valve and unsupported SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 97

by dental lamellae. The delthyrial cavity is trigonal in outline, re stricted at its anterior by a pair of knob-like protuberances of shell. The diductor scars are prominent and track-like anterior to the delthyrial cavity and diverge broadly anterolaterally. The adductors are situated centrally in the muscle scar and are elongate-cordate and moderately well impressed. The anterior edge of the media! area between the divergent diductor tracks is elevated forming a plat form. Irregularly disposed vascular tracks are impressed on large specimens in the media! area corresponding to the sulcus. The interior is creriulated peripherally by the impress of the costae. lNTERIOR OF BRACHIAL VALVE: The sockets are broadly divergent; their medial edges defined by thickened triangular socket plates that are divided medially by a narrowly triangular notothyrial cavity. Sockets are uncrenula:ted. The site of diductor attachment appears to be an elongate medial ridge on the floor of the notothyrial cavity and is unstriated. The dorsal adductor muscle impressions consist of two elongate pairs faintly impressed. The posterior adductors are langer and enclose a medially situated short pair of anterior adductors at the midline. The interior is crenulated peripherally by the impress of the costae. CoMPARISON: Plectatrypa henningsmoeni has a langer straighter hingeline than P. imbricata and is considerably more flattened at the posterolateral extremities. It is a much larger and more robust species than Atrypa rugosa which is provisionally assigned to the genus here. Atrypa tubulistriata, which is assigned here to Plectatrypa, may be closely related, but it has an inverted pyriform outline that tapers considerably toward the midline anteriorly, and differs from the transversely suboval outline of P. henningsmoeni. Plectatrypa flexuosa (Marr and Nicholson) is more deeply sulcate than the new species. FIGURED SPECIMENS: Paleont. Mus. Oslo nos. 21212 (holotype), 41247, and 51944a.

Acknowledgements

For the loan of fossils studied during preparation of the present paper, we thank Dr. T. Bolton, Geological Survey of Canada, for 'Atrypa' parksi; Mr. A. G. Brighton, Sedgwick Museum, for plaster replicas of 'Atrypa' flexuosa; Dr. G. A. Cooper of the Department of Paleo- 98 A. J. BOUCOT & J. G. JOHNSON biology, U. S. National Museum for numerous specimens; Creole Pe troleum Corporation for collections made by W. R. Smith; Dr. G. Henningsmoen of the Paleontologisk Museum, Oslo; Dr. Lois Kent of the Illinois Geological Survey for the loan of specimens made by R. R. Parizek; Dr. Copeland MacClintock of the Peabody Museum, Yale University, for 'Plectatrypa' gaspeensis and of specimens from Anticosti Island collected by W. H. Twenhofel; Ministerio de Minas e Hidrocarburos, Caracas, Venezuela for collections made by Dr. R, Shagam; and to Dr. Tor Orvig and Dr. H. Mutvei of the Riksmuseum, Stockholm, for specimens of Spirigerina marginalis. Mr. J. Peck of the University of California, Berkeley, lent the type specimens of 'Eatonia' bicostata. Professor H. W. Scott, University of Illinois lent the types of 'Atrypa' tubulistriata Savage. Preparation of this paper was supported by funds from a grant to the California Institute of Technology from the National Science Foundation, no. 54034.

REFERENCES

ALEKSEEVA, R. E. 1959. A new genus of the family Atrypidae Gill (Brachiopoda). Dok. Akad. Nauk. SSSR, 126 (2), 389-391. ALEKSEEVA, R. E. 1960. On the genus Spirigerina Orbigny. Paleont. Zhurn. 4, 63-68. ALEKSEEVA, R. E. 1962. Devonian Atrypidae of the Kuznetsk and Minusinsk Bassins and the eastern slope of the north Urals. A kad. nauk. SSSR, Siberian Div. Inst. Geol., Geophy., 192 pp., 12 Pls., Moscow. ALEKSEEVA, R. E. 1966. On the systematic position of the genus Mimatrypa. Paleont. Zhurn. 1, 153-159, Pl. 13. ALIKHOVA, T. N. (ed.) 1954. Field Atlas of Characteristic Fauna! Deposits of the Ordovician and Gotlandian of Southern Part of Lithuainian SSR. Trudy VSEGEI, 98 pp., 26 Pls. AMSDEN, T. W. 1949. Stratigraphy and Paleontology of the Brownsport for mation (Silurian) of western Tennessee. Peabody Mus. Nat. Hist. Bull. 5, 134 pp., 34 Pls. BARRANDE, J. 1879. Systeme Silurian du centre de la BoMme, v. 5, Brachio podes. 226 pp., 153 pls., Prague, Paris. BoucoT, A. J., JoHNSON, J. G., HARPER, C. W. & WALMSLEY, V. G. 1966. Silurian brachiopods and gastropods of southern New Brunswick. Canada Geol. Surv. Bull. 140, 45 pp., 18 Pls. SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 99

BoucoT, A. J., JoHNSON, J. G. & STATON, R. D. 1964. On some atrypoid, retzi oid, and athyridoid Brachiopoda. Jour. Paleontology 38, 805-822, Pls. 125-128. CHLUPÅC, I. 1953. Stratigraphical investigation of the border strata of the

Silurian and the Devonian in central Bohemia. Sobornic Uslred. Ustaver Geol. 20, 277-380, 4 Pls. Praha. CoPPER, P. 1964. European mid-Devonian correlations. Nature, 204 (no. 4956), 363-364. CoPPER, P. 1965. Unusual structures in Devonian Atrypidae from England. Palaeontology 8 (2), 358-373, Pls. 46, 47. DALMAN, J. W. 1828. Uppstii.llning och Beskrifning af de i Sverige funne Tere bratuliter. K. svenska Vetenskaps-Akad. Hand/. (1827), 85-155, Pls. 1-6. DAVIDSON, T. 1866-71. British fossil Brachiopoda, pt. 7, The Silurian Brachi opoda. v. 3, pp. 1-397, Pls. 1-50, Palaeontographical Soc. Mon. FoERSTE, A. F. 1890. Notes on Clinton Group fossils, with special reference to collections from Indiana, Tennessee and Georgia. Proc. Boston Soc. N at. Hist. 24, parts 3 & 4, pp. 263-355, Pls. 5-9. GILLETTE, T. 1947. The Clinton of Western and Central New York, New York St. Mus. Bull. 341, 191 pp. HALL, J. 1852. Containing descriptions of the organic remains of the lower middle division of the New York System. Nat. Hist. N. Y. Pal., v. 2, 362 pp., 85 Pls. HALL, J. & CLARKE, J. M. 1893, 1895 (1894). An introduction to the study of the genera of Palaeozoic Brachiopoda. Palaeontology of New York, v. 8, pt. 2, pp. 1-317 (1893): pp. 319-394, Pls. 21-84 (1895). HoRNY, R. 1962. Das InittelbOhmische Silur. Geologie 11 (8), 873-916. JAANUSSON, V. 1956. Untersuchungen iiber den oberordovizischen Lyckholm Stufenkomplex in Estland. Bull. Geol. Inst. Uppsala 36, 369-400, Pl. l. JoHNSON, J. G. 1965. Lower Devonian stratigraphy and correlation, northem Simpson Park Range, Nevada. Bull. Canadian Petrol. Geol. 13 (3), 365-381. JoHNSON, J. G. (in press). Toquimaella, a new genus of karpinskiinid brachi opod. Jour. Paleontology 41 (4). JoHNSON, J. G. & REso, A. 1964. Probable Ludlovian brachiopods from the Sevy Doloinite of Nevada. Jour. Paleontology 38, 74-84, Pls. 19-20. JoHNSON, J. G., BoucoT, A. J. & MuRPHY, M. A. (in press). Lower Devonian faunal succession in central Nevada. Symposium on the Devonian System, Calgary, Canada, 1967. KHALFIN, L. L. 1948. Fauna i Stratigrafiya Devonskikh Otlozhenii Gornogo Altaia. Izvestiya Tomskogo Ordena Trudovogo Krasnogo Znameni Politek. Inst. imeni S. M. Kirova, v. 65, no. 1, 464 pp., 36 Pls. KHODALEVICH, A. N. 1939. Upper Silurian Brachiopoda of eastem slope of the Ural. Geol. Serv. USSR, Trans. Ural Geol. Service, 135 pp., 28 Pls. KHODALEVICH, A. N. 1951. Lower Devonian and Eifelian brachiopods of the Ivdel and Serov districts of the Sverdlovsk region. Trudy, Sverdlovsk Mining Inst. v. 18, 169 pp., 30 Pls. 100 A. J. BOUCOT & J. G. JOHNSON

KHODALEVICH, A. N. & BREIVEL, M. G. 1959. Brachiopods and corals of the Eifelian bauxite deposits of the eastem slop of the middle and north Urals. Urals Geol. Uprav. 282 pp., 61 Pls. KULKOV, N. P. 1963. Brachiopodi Solovikhinskikh Sloev Nizhnego Devona gomogo Altaia. Akad. nauk SSSR, 132 pp., 9 Pls. LINDSTROM, G. 1861. Bidrag till kannedomen om Gotlands Brachiopoder. K. svenska Vetenskaps-Akad. FiWhandlinger, Ofversigt, 17 (1860), pp. 337-82, Pls. 12-14. LINDSTRoM, G. 1880. Fragmenta Silurica. 62 pp. 20 Pls., Holmiae. McCHESNEY, J. H. 1868. Descriptions of fossils from the Palaeozoic rocks of the western states, with illustrations. Trans. Chicago Acad. Sei., v. 1, pt. 1, pp. 1-57, Pls. 1-9. MARR, J. E. & NrcHOLSEN, H. A. 1888. The Stockdale Shales. Geol. Soc. London, Quart. jour. 44, 654-732, PI. 16. MENAKOVA, G. N. 1964. Brachiopods from Lower Silurian deposits of the Zeravshano-Gissar Mountain Region. Paleont. & Strat. (NEDRA), v. 1, pp. 1-51, Pls. 1-10. MITCHELL, J. & DuN, W. S. 1920. The Atrypidae of New South Wales, with references to those recorded from other states of Australia. Proc. Linnean Soc. New South Wales 45, pt. 2 (no. 178), 266-276, Pls. 14-16. MooRE, R. C. (ed.) 1965. Treatise on Invertebrate Paleontology, Part H, Brachi opoda. xxxii + 927 pp., 5,198 Figs., Lawrence, Kansas. NALIVKIN, D. V. 1960. New species of Devonian Atrypidae and Spiriferidae of the arctic. In Markovsky, B. P. (ed.) New species of fossil plants and invertebrates of the USSR, patt 1. VSEGEI, pp. 380-386, Pls. 87-90. NETTLEROTH, H. 1889. Kentucky fossil shells; a monograph of the fossil shells of the Silurian and Devonian rocks of Kentucky. Kentucky Geol. Survey, 1-245. NIKIFOROVA, O. I. 1937. Upper Silurian Brachiopoda of the central Asiatic part of the USSR. Central Geo/. Prospect. Inst., Mon. Pal. USSR, v. 35, 93 pp., 14 Pls. NIKIFOROVA, O. I. 1954. Stratigraphy and brachiopods of the Silurian deposits of Podolia. Trudy VSEGEI, 218 pp., pt. l, 19 Pls.; pt. 2, 18 Pls. NIKIFOROVA, O. I. & ANDREEVA, O. N. 1961. Ordovician and Silurian stratig raphy of the Siberian platform and its paleontological basis (Brachiopoda). Trudy VSEGEI, n. s., v. 56, 412 pp., 56 Pls. 0RBIGNY, A. D' 1849. Prodrome de paleontologie stratigraphique universelle. v. l, Paris, 394 pp. PoULSEN, C. 1943. The fauna of the Offley Island formation, pt. 2, Brachiopoda. Medd. om Gronland, v. 72, no. 3, 60 pp., 6 Pls. PHILIP, G.M. 1962. The Palaeontology and Stratigraphy of the Siluro-Devonian sediments of the Tyers area, Gippsland, Victoria. Proc. Roy. Soc. Victoria 75 (2), 123-246, Pls. 11-36. RuKAVISCHNIKOVA, T. B. 1956. Ordovician brachiopods of the Chu-ilisk Moun tains. Akad. nauk SSSR, Trudy Geol. Inst. 1, 105-168, 5 Pls. SILURIAN AND UPPER ORDOVICIAN ATRYPIDS 101

RzHONSNITSKAYA, M. A. 1960. Order Atrypida. In SARYCHEVA, T. G., (ed), Osnovi Paleontologii, pp. 257-264, Pls. 53-56. RzHONSNITSKAYA, M. A. 1964. Stratigraphy and Brachiopoda of the Devonian of the maYgins of the Kuznetsk Basin. VSEGEI, Leningrad, 48 pp. SAVAGE, T. E. 1913. Stratigraphy and paleontology of the Alexandrian Series in Illinois and Missouri, Part l. Illinois Geol. Survey, extract from Bull. 23, 124 pp., 7 Pls. ScHUCHERT, C. & CooPER, G. A. 1930. Upper Ordovician and Lower Devonian Stratigraphy and Paleontology of Perce, Quebec; Part 2, New species from the Upper Ordovician of Perce. Am. Jour. Sei. 5th ser. v. 20, 265-288, Pls. 1-3. SoLLAS, W. 1. 1879. On the Silurian district of Rhymney and Pen-y-lan, Cardiff. Geol. Soc. London, Quart. Jour. 35, 475-507, Pl. 24. SowERBY, 1. DE C. 1839. Part Il, Organic remains. In MuRCHISON, R., The Silurian System, pp. 579-768, Pls. 1-37. SPRIESTERSBACH, 1· 1942. Lenneschiefer (Stratigraphie, Fazies und Fauna). Abh. Reich, f. BodenfOYs., N. F., V. 203, 219 pp., 10 Pls. STAUFFER, C. R. 1930. The Devonian of California. Calif. Univ. Pubs. in Geol. Sei. v. 19, no. 4, pp. 81-118, Pls. 10-14. STRUVE, W. 1964. Mimatrypa n. g. (AtrypidaefPalaferellinae). Senck. leth. 45 (5), 433-40. TALENT, 1. A. 1964. The Silurian and Early Devonian faunas of the Heathcote District, Victoria. VictOYia Geol. Surv. Mem. 26, 55 pp., 27 Pls. TEMPLE, 1. T. 1965. Upper Ordovician brachiopods from Poland and Britain. Acta Palaeont. Polonica 10 (3) , 379-450, Pls. 1-21. TscHERNYSCHEW, T. 1885. Die Fauna des unteren Devon am West-Abhange des Urals. Mem. Com. Geol. 3 (1), 107 pp., 9 Pls. TWENHOFEL, W. H. 1928. Geology of Anticosti Island. Canada Geol. Survey Mem. 154, 481 pp., 60 Pls. WILLIAMS, M. Y. 1919. The Silurian geology and faunas of Ontario Peninsula, and Manitoulin and adjacent islands. Canada Geol. Survey Mem. 111, 195 pp., 34 Pls. PLATE l

Figs. 1-16. Spirigerina (Eospirigerina) praemarginalis (Savage). Figs. 1-5. Edge wood Formation, SWY4, SWY4, SE Y., sec. 10, T. 25N., R. SE., in ditch along road, Forreston quad., Ogle Co., Ill. Coll. of R. R. Parizek. Figs. 6-16. Edge wood Formation, SE Y., SEY4, swy., sec. 11, T. 25N., R. SE., Forreston quad., Ogle Co., Ill. Coll. 3a of R. R. Parizek. Specimens at Illinois State Geological Survey. (Figs. 1-5. Ventral, posterior, side, dorsal, and anterior views X 1.5, ISGS 47P-1. Figs. 6, 7. Ventral and dorsal views X 2, ISGS 47P-2. Figs. S-12. Ventral, posterior, dorsal, anterior, and side views X 3, ISGS 47P-3. Figs. 13-15. Anterior, ventral, and dorsal views x 2, ISGS 47P-4. Fig. 16. Dorsal view x 2, ISGS 47P-5.) Figs. 17-20. Spirigerina (Eospirigerina) gaspeensis (Cooper) Lower Llandovery age beds of Caparo Formation. Merida Andes, Venezuela; coll. of R. Shagam, USNM loe. 121S4. (Figs. 17, lS. Dorsal and posterior views of intemal mold of brachial valve x 2, USNM 155062. Figs. 19, 20. Posterior and dorsal views of intemal mold x 3, USNM 155063.) PLATE l

8 lO

9 li

15 14

20 17 ' l

PLATE 2

Figs. 1-15. Spirigerina gaspeensis (Cooper). Gasworks Mudstone, grid. ref. 956/155, road cut opposite NW end of gas works at Haverfordwest, about 240-260 paces SE of junction of Lower Cambrian Place with the New Road, Map Sheet 151 (Pembroke), Boucot Coll., 1957, USNM loe. 10509. (Figs. l, 2. Internal mold of pedicle valve and rubber impression of internal mold x 2, USNM 155064. Figs. 3, 4. Rubber impression of dorsal internal mold X 3 and internal mold X 1.5, USNM 155065. Fig. 5. Internal mold of brachial valve x 2, USNM 155066. Figs. 6, 7. Rubber impression of external mold of pedicle val ve and external mold x 2, USNM 155064A. Figs. 8, 9. Internal mold of pedicle valve and rubber impression of counterpart external mold x 2, USNM 155068 and 155067, respectively. Fig. 10. Rubber impression of external mold of brachial valve X 2, USNM 155067. Figs. 11-15. Ventral, dorsal, side, anterior, and posterior views of internal mold X 1.5, USNM 155069.) PLATE 2

3 1 2

. •' ,,/,·r J '> ·r

5 6 4

7 8 9

'fO

13 -14 PLATE 3

Figs. 1-10. Spirigerina marginalis (Dalman), Klinteberg, Gotland. Fig. l. Dorsal view x 5, specimen B42054. Figs. 2-6. Posterior, side, anterior, dorsal, and ventral views of internal mold X 2, specimen B42051. Figs. 7, 8. Ventral and dorsal views X 2, specimen B42052. Figs. 9, 10. Dorsal and ventral views X 2, specimen B42053. Specimens in Riksm. Pal. zool. Avd. Stockholm.) Figs. 11-14. Protatrypa malmoeyensis Boucot, Johnson, and Staton, Lower Llandovery beds (6c of Kiaer), Malmoya (west side), Inner Oslofjord, Norway. Dorsal, ventral, posterior, and anterior views X 2, specimen 41948A, Pale ontologisk Museum, Universitetet i Oslo. PLATE 3

4 PLATE 4

Figs. 1-12. Plectatrypa henningsmoeni Boucot and Johnson n. sp. (Figs. 1-5. Ventral, dorsal, side, posterior, and anterior views X 1.25. Specimen 21212, holotype. Lower Llandovery, (6a), Malmoya, near Oslo. Figs. 6-10. Side, ventral, dorsal, anterior, and posterior view of internal mold X 1.25, specimen 51944a. Lower Llandovery, (6a), Leangbukta, Asker. Figs. 11-12. Ventral and dorsal views of an internal mold X 2, specimen 41247. Lower Llandovery, probably Malmoya near Oslo. Specimens in Paleont. Mus., Oslo.) Figs. 13-16. Protatrypa malmoeyensis Boucot, Johnson, and Staton, Lower Llandovery beds (6b of Kiær), Malmoya, near Oslo, Norway. USNM loe. 10106. (Figs. 13, 14. Ventral and dorsal views of internal mold X 2, specimen USNM 155070. Figs. 15, 16. Ventral and side views of the holotype X 1.5, specimen 2389b, Paleontologisk Museum, Universitetet i Oslo). PLATE 4