J ! RWPl 1^ F^c III / bv. --‘s ^ \ ■cb^ , \ ^ ' ' w r Mil rSl-T'''®'V fea 7« ■v 'w^<^^A?V'3lj^^ ^ IUl ^ o'i^tiHju >^,^t-AS?'>v* /wS'J^siii'i^ fU€«-«. VOLUME 4 Palaeontology 1961-2 PUBLISHED BY THE PALAEONTOLOGICAL ASSOCIATION LONDON Dates of publication of parts in Part 1, pp. 1-148, pis. 1-18 Part 2, pp. 149-312, pis. 19-38 Part 3, pp. 313-476, pis. 39-63 Part 4, pp. 477-662, pis. 64-80 Voiuine 4 30 April 1961 27 July 1961 28 October 1961 30 January 1962 THIS VOLUME EDITED BY W. H. C. RAMSBOTTOM, N. F. HUGHES, AND W. S. MCKERROW CONTENTS Part Page Barr, F. T. Upper Cretaceous planktonic foraminifera from the Isle of Wight, England 4 552 Bennison, G. M. Small Naiadites obesus from the Calciferous Sandstone Series (Lower Carboniferous) of Fife 2 300 Burnaby, T. P. The palaeoecology of the foraminifera of the Chalk Marl 4 599 Campbell, K. S. W. Carboniferous fossils from the Kuttung rocks of New South Wales 3 428 Casey, R. Stratigraphical palaeontology of the Lower Greensand : nomen- clatural corrections 2 312 Chaloner, W. G. and Clarke, R. F. A. A new British Permian spore 4 648 Clarke, R. F. A. See Chaloner, W. G. Collins, J. Eocene crabs in a London Clay nodule 1 85 CooKSON, Isabel C. and Dettmann, Mary E. Reappraisal of the Mesozoic microspore genus Aeqidtriradites 3 425 Cox, L. R. New genera and subgenera of Mesozoic Bivalvia 4 592 Dean, W. T, and Krummenacher, R. Cambrian trilobites from the Amanos Mountains, Turkey 1 71 Dettmann, Mary E. See Cookson, Isabel C. Dickins, J. M. Eurydesma and Peruvispira from the Dwyka Beds of South Africa 1 138 — The gastropod Platyteichiim in the Permian of Western Australia 1 131 — • Permian pelecypods newly recorded from Eastern Australia 1 119 Dunlop, Grace M. Shell development in Spirifer trigonalis from the Carboniferous of Scotland 4 477 Elliott, G. F. The sexual organization of Cretaceous Penuocalcuhis (Cal- careous Algae) 1 82 Gardiner, B. G. New Rhaetic and Liassic beetles 1 87 Gobbett, D. j. The Permian brachiopod genus Horridonia Chao 1 42 Gordon, W. A. Some foraminifera from the Ampthill Clay, Upper Jurassic, of Cambridgeshire 4 520 Hallam, a. Brachiopod life assemblages from the Marlstone Rock-bed of Leicestershire 4 653 Hamilton, D. Algal growths in the Rhaetic Cotham Marble of Southern England 3 324 Harris, T. M. The fossil cycads 3 313 Hudson, R. G. S. and Jefferies, R. P. S. Upper Triassic brachiopods and lamellibranchs from the Oman Peninsula, Arabia 1 1 CONTENTS Part Hughes, N. F. Further interpretation of Eucommiidites Erdtman 1948 2 Jefferies, R. P. S. The palaeoecology of the Actinocamax plenus Subzone (lowest Turonian) in the Anglo-Paris Basin 4 — See Hudson, R. G. S. Kato, M. and Mitchell, M. Slimoniphylliim, a new genus of Lower Car- boniferous coral from Britain 2 Krummenacher, R. See Dean, W. T, MacGregor, A. R. Upper Llandeilo brachiopods from the Berwyn Hills, North Wales 2 Maxwell, W. G. H. Lower Carboniferous gastropod faunas from Old Cannindah, Queensland 1 Melville, R. V. Dentition and relationships of the echinoid genus Pygaster J. L. R. Agassiz, 1836 2 Miller, T. G. Type specimens of the genus Fenestella from the Lower Car- boniferous of Great Britain 2 Mitchell, M. See Kato, M. Neale, J. W. Normanicythere Jeiodenna (Norman) in North America 3 Neves, R. Namurian plant spores from the southern Pennines, England 2 Rolfe, W. D. I. A syncarid crustacean from the Keele Beds (Stephanian) of Warwickshire 4 Rowell, A. J. The brachiopod genus Valdiviathyris Helmcke 4 Rudwick, M. j. S. The anchorage of articulate brachiopods on soft substrata 3 Sarjeant, W. a. S. Microplankton from the Kellaways Rock and Oxford Clay of Yorkshire 1 Smout, a. H. and Sugden, W. New information on the foraminiferal genus Pfenderina 4 Staplin, F. L. Reef-controlled distribution of Devonian microplankton in Alberta 3 Strusz, D. L. Lower Palaeozoic corals from New South Wales 3 Sugden, W. See Smout, A. H. Vella, P. Australasian Typhinae (Gastropoda) with notes on the subfamily 3 Watson, D. M. S. Some additions to our knowledge of antiarchs 2 Webby, B. D. A Middle Devonian inadunate crinoid from west Somerset, England 4 Williams, A. and Wright, A. D. The origin of the loop in articulate brachiopods ’ 2 Wilson, R. B. A review of the evidence for a ‘Nebraskan’ fauna in the Scottish Carboniferous 4 Wright, A. D. See Williams, A. Yates, Patricia J. New Namurian goniatites of the genus Eiimorphoceras 1 Page 292 609 280 177 59 243 221 424 247 546 542 475 90 581 392 334 362 210 538 149 507 54 VOLUME 4 • PART 1 5^40. S'4‘5L ? IS Ge<3 /. Palaeontology APRIL 1961 PUBLISHED BY THE PALAEONTOLOGICAL ASSOCIATION LONDON THE PALAEONTOLOGICAL ASSOCIATION The Association was founded in 1957 to further the study of palaeontology. It holds meetings and demonstrations, and publishes the quarterly journal Palaeontology. Membership is open to individuals, institutions, libraries, «&c., on payment of the appropriate annual subscription: Institutional membership £5. 5s. ($15.50) Ordinary membership . . . . . £3. 3if. ($ 9.50) Student membership £2. 2^. ($ 6.50) There is no admission fee. Student members will be regarded as persons receiving full-time instruction at educational institutions recognized by the Council. Subscrip- tions are due each January, and should be sent to the Treasurer, Professor P. C. Sylvester-Bradley, Department of Geology, The University, Leicester, England. Palaeontology is devoted to the publication of papers (preferably illustrated) on all aspects of palaeontology and stratigraphical palaeontology. Four parts are published each year and are sent free to all members of the Association. Members who join for 1961 will receive Volume 4, Parts 1 to 4. Back parts may be purchased separately at a cost of £2 ($6) post free for each part; orders should be sent to the approved agents, Messrs. B. H. Blackwell, Broad Street, Oxford, England. Manuscripts on all aspects of palaeontology and stratigraphical palaeontology are invited. They should conform in style to those already published in this journal, and should be sent to Mr. N. F. Hughes, Sedgwick Museum, Cambridge, England. A sheet of detailed instructions for authors will be supplied on request. UPPER TRIASSIC BRACHIOPODS AND LAMELLIBRANCHS FROM THE OMAN PENINSULA, ARABIA by R. G. s. HUDSON and r. p. s. Jefferies Abstract. Norian brachiopods (4 species) and lamellibranchs (25 species, 2 subspecies) from the Asfal and Sumra Formations (Elphinstone Beds) of the Jebel Hagab area, Oman, Arabia, are critically identified, new morphological features being described. The fauna shows considerable resemblances to those of the same age from Spiti, Central Himalayas, and Indonesia, notably Misol. Brachiopods described include Hagabirhyiichia arabica gen. et sp. nov., and Misolia lenticiilata sp. nov. New species and subspecies of lamellibranchs are Modiolus omanensis, ludopecteu amusiiformis, I. clignetti (Krumbeck) asperior, Palaeocardita trapezoidalis (Krumbeck) leesi, and Thiacia proavita. Structural colour-banding in ludopecteu is discussed. The Ruus al Jibal, the mountain range of the Oman Peninsula, is formed from a lower series of limestones and dolomites (Upper Permian to Middle Trias, 1,487 metres thick), a middle series of limestones, marls, and some sandstone (Upper Trias, 431 metres thick) and an upper series of limestone (Jurassic to Lower Cretaceous, 1,475 metres thick). The main exposure of the Upper Trias, the fauna of part of which is described in this paper, is on the east side of the peninsula where it outcrops on the western flank of the coastal anticline. It is also exposed in the northern part of the peninsula where it outcrops in the core of the Shumm Anticline on the sides of both the Elphinstone Inlet (Khor ash Shumm) and the Malcolm Inlet (Ghabbat al Ghazira). To the south on the western side of the peninsula and to the east of Ras al Khaima it outcrops on the flanks of the Hagab Monocline. There, on the southern flank, it is well exposed and accessible in Wadi Milaha and at the entrance to Wadi Bih, and it was there that the Upper Trias succession was measured and the fossils described in this paper collected. Triassic fossils from Oman were first collected by Blanford (1872) from the Elphin- stone Inlet and variously named by Stoliczka and Diener (19086) as of Triassic and Lower Cretaceous age. In 1924 and 1925 G. M. Lees and Washington Gray collected from the Upper Trias of the Elphinstone Inlet and from the mountain front of the Jebel Hagab area, about 5 miles east of Ras al Khaima. These fossils were named by Lees (1928) and considered to be of Upper Triassic age, probably Norian. The 500 feet of brown limestones, shales, and sandstones from which they were collected he named the Elphinstone Beds. In the spring of 1951 R. G. S. Hudson, R. V. Browne, and Z. R. Beydoun, geologists of the Iraq Petroleum Company, measured and sampled the Elphinstone Beds of Wadi Milaha. The fossils described in this paper were then col- lected by R. G. S. Hudson. From their colleagues, both in the field and in the laboratory, and from L. R. Cox of the British Museum (Natural History), the authors have received every help. To them and to the Directors and Chief Geologist of the Iraq Petroleum Company, who permitted the publication of this paper, the authors record their thanks. The fossils described in this paper have been presented to the Department of Palaeontology, British Museum (Natural History), and are referred to in this paper by their registra- tion numbers, those of the brachiopods being preceded by the letters BB and those of the lamelli- - branchs by LL. Numbers preceded by the letter L are of specimens collected by G. M. Lees (1928). [Palaeontology, Vol. 4, Part 1, 1961, pp. 1-41, pis. 1-2.] B 7879 B 2 PALAEONTOLOGY, VOLUME 4 FAUNAL STRATIGRAPHY The general succession (Permian to Lower Cretaceous) of the Ruus al Jibal was out- lined by Hudson, McGugan, and Morton (1954), its upper part (Musandam Limestone; Rhaetian to Aptian) being subsequently described by Hudson and Chatton (1959) and its lower part (Permian to Upper Trias) by Hudson (1960). In this last paper the Elphin- stone Beds were redefined as a group to include the following; metres Shuba Limestone and Sandstone; Upper Trias ......... 64 Sakhra Limestone; Upper Trias ........... 23 Sumra Limestone and Marl; Norian .......... 56 Asfal Limestone, Marl, and Sandstone; Norian . . . . . . . . .108 Milaha Limestone; Upper Trias (Carnian-Norian) . . . . . . . .180 The fossils described in this paper are from the Asfal and Sumra Formations only, mostly from the Sumra. All fossils from Oman discussed in this paper are from the Wadi Milaha, Jebel Hagab area, unless otherwise designated. Asfal Beds. In the lowest 42 metres of these beds there is as much sandstone as limestone and marly shale, both usually sandy: the remainder of the formation consists of lime- stone and shale, very much interbedded, some of the limestones being massive and fine- grained or even calcite-mudstones. There are occasional beds of shell debris and, more rarely, entire fossils. A common fossil is Spiriferina abichi Oppel occurring more par- ticularly in 4 metres of sandy marls and marly limestones, 42 metres from the base of the formation. Another common brachiopod, Misolia, usually M. lenticulata sp. nov., occurs in a nodular limestone 1-5 metres thick and 90 metres from the base. Elongate megalodontids, probably Dicerocardium, are abundant in the upper part of the formation notably in a feature-forming limestone, 2 metres thick and 73 metres from the base. Occasionally there are assemblages of small lamellibranchs comparable to those occur- ring in the Sumra Formation. Otherwise the only fossils are hydrozoans, mainly stromatoporoids, occurring in the more massive fine-grained limestones. Such a fauna occurs in the Lovcenipora Limestone, 3 metres thick, which forms a marked feature and is taken as the top bed of the formation. Sumra Beds. These are mainly thin-bedded, brown-weathering, shelly limestones, and reddish-purple, yellow or brown marly shales, closely interbedded. In the 15 metres at the top of the group, shales are more common than the limestones. There are also occasional massive fine-grained limestones. The fauna is essentially one of small lamellibranchs with occasional corals. The lower part (27 metres) is marked by an abundance of Lopha blanfordi and is distinguished as the Lopha Beds: the upper part (29 metres) has an abundance of Modiolus and Myophoria and is distinguished as the Modiolus Beds. Corals, mainly Thecosmilia and Thamnasteria, occur at various levels, notably in the uppermost 15 metres of shales with limestones. The brachiopod-lamellibranch fauna of the Sumra Beds is listed below (the number following the name is the number of specimens determined; * or ** indicates forms found respectively only in the Modiolus Beds or the Exogyra Beds). Numerous fossil fragments, mostly Lopha, were thrown away. brachiopoda: Hagabirhynehia arabica sp. nov., 10*; Misolia noetlingii (Bittner), 1*. LAMELLiBRANCHiA : Niicitla {? Niiculopsis) misoleusis Jaworski, 1*; Modiolus jaworskii Wanner and HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 3 Knipscheer, 20; M. speciosus Merla, 3*; M. omanemis sp. nov., 128*; Cassianella cf. subeuglypha Krumbeck, 1*; Aeqidpecten serraticosta (Bittner), 3**; Indopecten clignetti asperior subsp. nov., 16; Dimyodon cf. siibrichtofeni Krumbeck, 8; Loplui blaiifordi (Lees), 40**; Pseudolimea ?cianaunica ( Bittner), 36*; Plagiostoma nudum (Parona), 1 **; Costatoria onianica (Diener), 17*; C. ?vestitaeformis (Krumbeck), 4**; Myophoria verbeeki mansuyi Reed, 1**; Myoplioria sp. 3*; Palaeocardita biinica (Krumbeck), 3; P. trapezoidalis trapezoidalis (Krumbeck), S*; P. trapezoidalis leesi subsp. nov., 1; P. trapezoidalis subsp. indet., 1; Anodontopbora griesbachi Bittner, 26*; A. cf. lettica (Quenstedt), 2*; Megalodon ? hungaricum Kutassy, 1 ; ?M. rostratiforme Krumbeck, 5*; Pleuromya himaica Diener, 9*; Protocardia rhaetica (Merian), 4*; ? Homoinya sublariana Krumbeck, 2**; Tliracia proavita sp. nov., 3*. THE AGE AND GEOGRAPHICAL AFEINITIES OF THE SUMRA AND ASFAL FORMATIONS Most of the forms from Oman discussed in this paper occur in Tethyan Upper Triassic of other areas (Table 1). They range from Hungary and Lombardy in the west to the Misol Archipelago in the east, a distance of some 9,000 miles. Affinities, however, are much stronger with the Indo-Pacific region than with Europe. In the Himalayas, Sumra and Asfal forms are found from the Juvavites Beds to the Lower Kioto or Megalodon Limestone of Spiti (Diener 1908a, 1912), from the Proclydonaiitilns griesbachi Beds to the Sagenites Beds in Painkhanda (Bittner 1899; Diener 1912), and as isolated occurrences at Vihi (Kashmir), Depsang (Tibet), and Attock (West Pakistan). The Juvavites Beds and equivalent Proclydonautilus griesbachi and Halorites Beds are dated as Norian by their ammonites (Diener 1912, p. 94) and the Monotis Beds are also proved Norian by the presence of Monotis salinaria Bronn. There is, unfortunately, no satis- factory evidence for the age of the Quartzite Series or the overlying lower parts of the Kioto Limestone and it is at least possible that some of these horizons are Rhaetian. Subject to this qualification, however, comparison with the Himalayas suggests that the Sumra and Asfal Formations are of Norian age. The same comparison suggests that a Carnian age for the Asfal and Sumra can be excluded. The Carnian of the Himalayas, which immediately underlies the Juvavites and Proclydonautilus griesbachi Beds, is well dated by ammonites (Diener 1912, p. 87) and contains many brachiopods and lamellibranchs, but, so far as is known, is entirely without Elphinstone elements. In Indonesia, Sumra and Asfal forms mainly occur in the Nucula Marl and Athyris Limestone of Misol and the Fogi Beds of Burn. The Nucula Marl and Fogi Beds are dated as Norian by ammonites related to Hallstatt Limestone forms (Krumbeck 1913, p. 117; Jaworski 1915, p. 156) and also by elements related to those of the Himalayan Norian. Comparison with Indonesia, therefore, like the Himalayas, suggests a Norian age for the Sumra and Asfal Formations. Sumra and Asfal forms also occur in the Naiband Calciferous Sandstone of Persia, considered by Douglas (1929) to be Norian partly because the overlying Hauz-i-Khan Limestone contains European Rhaetian brachiopods. Thus by comparison with Indonesia, Persia, Spiti, and Painkhanda, the Sumra and Asfal Formations are Norian, and this conclusion is not contradicted by the other occurrences shown in Table 1 . The only possible reason for doubting this conclusion is the scarcity of well-described Rhaetian Indo-Pacific lamellibranch and brachiopod faunas. A Rhaetian lamellibranch fauna has, however, been fully described from the Napeng Beds of Burma (Healey 1908), and in it there are no Elphinstone forms. Geographically the Sumra and Asfal Formations belong to the Indo-Pacific Province TABLE IEJ3U30 ui adojng ( -l3onV . a 5:* r =^-- Si ^ ”5 "S O s S SUBSd3Q NJA ^g spsg sdjiudSos spsg npDqsduS 's spag sdiiAopH spsg iifDvqsDuS snji wvuopiIiub:m sp93 XXX : X : X X 9U01S31UIT SlAAlliy IJBpM vpionpi XXX : : : X S 5 ^ 5 v: ^ ^ ^ ■ -o S S *§ ' “Sll. ►-J ' .^•: i -2 ? ! o S ' i ? 5 ^ c 2i '! Q ^ 5 i s:§l -^2.^ O ^ i; 2 ^ .0^0-1 a, ^ ^ < a, a. 2 “O -2 c g ^"slf ;i| 3 £, « ' ^ -•■«.£ : 5 S C I 2 “O ;i; O S; <3 ^ < o e« o I ^■2*' cv,. a; CO * HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 5 with Indopeclen, Misolia and Spiriferina abichi, and, as Lees pointed out (1928, p. 596), a near absence of European species. The claim by Douglas (1929, p. 631) that Arabia and Persia in Norian times were connected with Indonesia not via the Himalayas but by newly opened seaways through Gondwanaland is probably not justified on faunal grounds. It is true that some forms are recorded in the Middle East and Indonesia but not in the Himalayas (as Niicula misolensis. Modiolus jaworskii, the Lopha blanfordi- parasitica group, Plagiostoma subvalouiense, Palaeocardita buruca, P. trapezoidalis, and Protocardia rhaeticd), but this may well be due to facies variation and the fact that Indonesian Norian faunas have been more extensively described than the Himalayan. The genus Indopecten, the distribution of which was thought by Douglas to support his views (1929, p. 631), does occur in the Himalayas as well as in Persia, Oman, and Indonesia (see later). BRACHIOPODA by R. P. S. JEFFERIES Family rhynchonellidae Gray 1848 Genus hagabirhynchia nov. Type species Hagabirhynchia arabica sp. nov. Diagnosis. Small multicostate rhynchonellids, inversely sulcate when very small. Del- tidial plates conjunct. Cardinal process present, no septalium, hinge-plate divided, even at umbo, crura radulifer, ending in broad, thin, vertically disposed plates. Weak median septum in brachial valve. In pedicle valve, strong dental plates, teeth non-denticulate, no pedicle collar. Comparison. Of the Liassic genera discussed by Ager (1956, 1958) Prionorhynchia, Cirpa, and Rudirhynchia are similar enough to Hagabirhynchia to merit further comparison. Prionorhynchia Buckman resembles Hagabirhynchia in the numerous ribs, the weak median septum in the brachial valve, the absence of a septalium, and the form of the crura. It differs from Hagabirhynchia in not being inversely sulcate when young, in having the hinge-plate entire for a short distance posteriorly, in having disjunct deltidial plates, and in being larger. Cirpa de Gregorio, though larger, resembles Hagabirhynchia exter- nally but differs (Ager 1958) in having the hinge-plate entire at the posterior margin and in having curious double deltidial plates. Rudirhynchia Buckman differs from Hagabi- rhynchia in having a septalium, and often a pedicle collar, and in lacking the plate-like crura. It is interesting that of these three genera Prionorhynchia and Cirpa are mainly Tethyan in distribution (Ager 1956, p. 47). Among Moiseev’s (1936) genera of rhynchonellids, RobinsoneUa is externally almost identical to Hagabirhynchia but differs internally in having the hinge-plate entire for a considerable distance posteriorly, and in the form of the crura. On external characters alone Hagabirhynchia would include some if not all of the small, multicostate rhynchonellids of liasischeni Habitus, placed in the Rhynchonella subrimosa and R. fissicostata group by Bittner (1890, p. 313). The internal structure of R. subrimosa, as far as known (Zugmayer 1882, p. 37, pi. 14, fig. 12), is also like that of Hagabirhynchia. 6 PALAEONTOLOGY, VOLUME 4 Hagabirhynchia arabica gen. et sp. nov. Plate 1, figs. 18-21; text-fig. 1 Holotype. BB20248 (PI. 1, figs. 18-21). Paratypes. BB20249 (text-fig. 1), BB20512-19. Modiolus Beds, Sumra Formation. Description. Length (BB20248, holotype) 10 mm., breadth 11 mm., thickness 6 mm. Apical angle about 95°. Anterior commissure with normal arched sulcus in adult but with weak inverted sulcus (norelliform stage) when very young and rectimarginate at 3-5 mm. from the brachial umbo. Ribs present even at the umbones, often forking once or twice during ontogeny, particularly near the median line. In adult about seven- teen ribs in the brachial valve, one less in the pedicle valve, three to four ribs present on -o -o ‘O ’ ’Q> TEXT-FIG. 1. Serial sections of Hagabirhynchia arabica gen. et sp. nov., x5. BB20249, Modiolus Beds, Sumra Formation. Numbers are distances in mm. from apex of pedicle valve. floor of sulcus in pedicle valve (four in holotype), one more on central fold in brachial valve. Beak suberect; beak ridges strong. Deltidial plates conjunct; foramen circular, hypothyrid. Internal structure as for genus (see text-fig. 1). Muscle scars unknown. Comparison. H. arabica is either identical to, or an external homeomorph of, Rhyn- chonella bainbanagensis Bittner (1899, p. 44, pi. 8, fig. 4, p. 56, pi. 9, fig. 18; Diener, 1908u, p. 128, pi. 23, fig. 8) from the Himalayan Norian. One particular point of resemb- lance is the distinct inverted sulcus in the very early growth-stages as shown by the specimen of R. bambanagensis figured by Diener (1908a, pi. 23, fig. 8). However, the internal structure of the Oman specimens justifies a new genus and since it would be unwise to make R. bambanagensis the genotype of this genus because its internal HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 7 Structure is unknown and its identity with the Oman material therefore uncertain, the Oman specimens are here allocated to a new species. H. arabica externally resembles Rhynchonella levantina Bittner (1891, p. 107, pi. 1, figs. 1-3) except that this latter species has a more acute apical angle. Externally it is also very similar to Robinsonella mastakanensis Moiseev (1936) but this species differs internally (see under genus above). H. arabica occurs in the Sumra Formation of Oman where it is fairly common. It has been considered to be possibly identical with Rhynchonella bambanagensis Bittner which occurs in the Coral Limestone, Monotis Beds and Quartzite Series of Spiti, and the Spiriferina griesbachi Beds of Painkhanda, all of which formations are Norian in age. Spiriferiua abichi Oppel 1865, p. 298, pi. 88, figs. 6a, b. Spirifera vihiana Davidson 1866 (Jan. or Feb.), p. 41, pi. 2, fig. 4. Spirifera kashmeriensis Davidson 1866 (Jan. or Feb.), p. 41, pi. 2, fig. 5. Spirifer Tibeticiis Stoliczka 1866 (Sept, or later), p. 28, pi. 3, figs. 1, 2. Spirifer altivagus Stoliczka 1866 (Sept, or later), p. 28, pi. 3, fig. 3. Spiriferina Griesbachi Bittner 1899, p. 51, pi. 9, figs. 1-13; Diener 1908a, p. 121, pi. 22, figs. 7-13. Material. BB20490(P1. l,figs. 13-17), BB20491 (PI. 1, fig. 23), BB20492-500, BB20501 (PI. 1, fig. 22), and BB20502-7. All from Spiriferina Bed, Asfal Formation. Description. Outline varying from slightly broader than long without cardinal extremities (PI. l,figs. 13-17, cf. Spirifera vihiana), through forms with produced cardinal extremities (PI. 1, fig. 23), to strongly transverse (PI. 1, fig. 22, cf. S. kashmeriensis). Delthyrium with narrow deltidial plates meeting only at the umbo. Brachial valve with low area and notothyrium. Sulcus of pedicle valve strong, with single, angular, median rib, correspond- ing to strong fold in brachial valve which is divided by single median furrow. Lateral slopes with about ten rather angular ribs separated from area of both valves by narrow ribless zone. Number of ribs increases in ontogeny by appearance of ribs at anterior edge of ribless zone. Pedicle valve with strong median septum touching deltidial plates where these are in contact at umbo. Dental lamellae strong, reaching to floor of pedicle valve, roughly parallel to median septum. Anterior margins of dental lamellae and median septum concave, the septum extending farther anteriorly than the lamellae. Cardinal process bifid, supported on hinge-plate which is clearly separated from floor of brachial valve and supported by weak, median septum. Spiralia of about fourteen whorls, connected by simple U-shaped jugum. Family spiriferinidae Davidson 1884 Genus spiriferina d’Orbigny 1847 Spiriferina abichi Oppel Plate 1, figs. 13-17, 22, 23; text-fig. 2 DIMENSIONS (in nnn.) Length Breadth Thickness BB20490 (without produced cardinal extremities) BB20503 (with produced extremities) . BB20501 (transverse form) .... 14-7 20-3 15-2 17-3 23-6 12-2 19-4 C.35 14-8 8 PALAEONTOLOGY, VOLUME 4 "id "w "® "® '■cro 7m 2m o o O ^ TEXT-FIG. 2. Serial sections of Spiriferina abichi Oppel, xl-5. Spiriferiita Bed, Asfal Formation. Where the external shell has been dissolved, a thin line represents the contact between the external matrix and the infilling. Numbers are distances in mm. from the apex of the pedicle valve. HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 9 Remarks. The nomenclature of this species is extremely confused but the name Spiriferina griesbachi Bittner, by which it is usually known, is certainly invalid. Bittner himself remarked (1899, p. 52) that his species S. griesbachi was probably identical with Spirifer tibeticus and S. altivagus Stoliczka 1866: the probability of their identity was strengthened by von Krafft (1900, p. 223) who showed that Stoliczka’s specimens were probably from the Coral Limestone (= Spiriferina griesbachi Bed) of Spiti. Bittner also noticed the resemblance between Spiriferina griesbachi and Spirifera vihiana Davidson 1866, which, though supposedly Carboniferous at the time of descrip- tion, came from an area (Vihi in Kashmir) where Upper Triassic rocks were later found (Middlemiss 1909). Spirifera kashrneriensis Davidson 1866, though much more trans- verse than S. vihiana, is nevertheless probably conspecific. This view is based firstly on the fact that Davidson’s figured specimens (here respectively designated holotypes) of S. kashrneriensis and S. vihiana occur on the same block, B82126, together with other fragments of Spiriferina and secondly on the existence of a transition between normal and transverse forms, noticed by Diener in Spiriferina griesbachi (1908n, pi. 22, figs. 7-12) and now confirmed from the Oman material. Davidson’s names (vihiana and kashrneriensis) have priority over Stoliczka’s names (altivagus and tibeticus) since they were published in the first part of Vol. 22, Quart. J. Geol. Soc. London, which appeared before 16 February 1866 (Council Report, Q.J.G.S. vol. 22, p. i), Stoliczka’s work being published in Memoir 5 of the Geological Survey of India with Oldham’s covering letter to the volume dated September 1 866. However, the valid foundation by Oppel (1865) of Spiriferina abichi seems to have escaped the notice of Bittner. Oppel based his description on a single pedicle valve whose age was unknown; its identity to tibeticus, altivagus, vihiana, kashrneriensis, and griesbachi is scarcely in doubt, however, since, besides the apparent identity of form and ribbing, there is also similarity of age, the village of Tingti where S. abichi was found being now known to be situated in the marine Triassic outcrop of Spiti. The internal structure of S. abichi from Oman is almost exactly like that of the type species of the genus, S. walcotti (Sowerby). The latter, however, because of the low con- vexity of the brachial valve, has a very much smaller space between the fioor of the valve and the hinge-plate, and the median septum of the brachial valve, which is weak in S. abichi, is sometimes absent in 5". walcotti. These differences are not of generic value and S. abichi is therefore confirmed as a Spiriferina (s'. 5'.). Three other Triassic spiriferinids closely resemble S. abichi, particularly in the pre- sence of a rib in the median sulcus. These are S. rnoscai Bittner (1892, p. 80) from the Upper Trias of Anatolia, S. lipoldi Bittner (1890, p. 139) from the Ladinian and Carnian of the Alps, and S. subgriesbachi Krumbeck 1924 from the Upper Trias of Timor. Of these S. subgriesbachi differs from S. abichi in being smaller, having coarser growth-lines and fewer but coarser ribs. Its internal structure is unknown but Krumbeck, as the name implies, closely related it to S. abichi. S. lipoldi resembles S. abichi externally but has no dental lamellae and so cannot be closely related. S. rnoscai, on the other hand, has strong dental lamellae and must be close to S. abichi, particularly to the more transverse variants. It differs from these latter, however, in its more rounded lateral extremities and in having fewer (about five) more rounded ribs on the lateral slopes. The Oman specimens of S. abichi are smaller than typical specimens from the gries- 10 PALAEONTOLOGY, VOLUME 4 bachi Bed of the Himalayas, but the Indian populations of the species vary in size (Diener 1908u, p. 121). S. abichi thus occurs in the Asfal and Sumra Beds of Oman, the Triassic of the Vihi district, Kashmir, the S. griesbachi Beds of Painkhanda, and the Coral Limestone, Monotis Beds, and Quartzite series of Spiti. Family athyridae Davidson 1884 Genus misolia von Seidlitz 1913 Misolia noetUngii (Bittner) Plate 1, figs. 5-8 Spirigera? NoetUngii 1899, p. 68, pi. 11, figs. 2, 3; Diener 1908a, p. 135, pi. 24, figs. 1, 2; ?Merla 1933, p. Ill, pi. 5, fig. 4. Misolia noetUngi (Bittner). Seidlitz 1913, p. 191. Material. BB20240 (PI. 1, figs. 5-8), BB20242, BB20520, Misolia Bed, Asfal Formation; BB20241, Modiolus Beds, Sumra Formation. The Oman specimens agree very well externally with those figured by Bittner and Diener though the umbones cannot be compared since they have been damaged in the Oman specimens. Apart from the fact that spiralia are definitely present the complicated internal structures described by Seidlitz (1913) in M. misolica from the Alhyris Lime- stone of Misol could not be proved in the Oman material. M. noetUngii is thus referred to its genus mainly on external features. EXPLANATION OF PLATE 1 All figured specimens are from the Elphinstone Beds, Upper Trias, of Wadi Milaha, Jebel Hagab area, near Ras al Khaima, Trucial Oman, Arabia. All, except those of figs. were coated with ammonium chloride before photography. Figs. 1, 2, 3. Indopecten clignetti asperior subsp. nov. Modiolus Beds, Sumra Formation. 1, Right valve, LL314, X L5, holotype. 2, Left valve, LL315, X 1-5, paratype, showing Indopecten structure and the introduction of a radial geniculation just anterior to the posterior row of tubercles. 3, LL321, X 10, Showing Indopecten structure in part of shell where the calcitic layer has mostly been removed but persists in the zigzag thickenings. Fig. 4. Pseudoliinea ?cumaunica (Bittner). LL375, X 10. Right valve showing secondary ribs in the troughs between slightly abraded radial folds, and raised growth-lines considerably stronger than the radial striae. Modiolus Beds, Sumra Formation. Figs. 5-8. Misolia noetUngii (Bittner). BB20240, Xl-5. Shell missing from near umbo of brachial valve. Misolia Bed, Asfal Formation. Figs. 9-12. Misolia lenticulata sp. nov. Holotype, BB20243, X 1-5, slightly crushed. Misolia Bed, Asfal Formation. Figs. 13-17. Spiriferina abichi Oppel, form without produced cardinal extremities, cf. S. vihiana (Davidson). BB20490, X 2-5, decorticated near brachial valve umbo. Spiriferina Bed, Asfal Forma- tion. Figs. 18-21. Hagahirhynchia arabica gen. et sp. nov., holotype, BB20248, x2-5. Modiolus Beds, Sumra Formation. Fig. 22. Spiriferina abichi Oppel, transverse form, cf. S. kashmeriensis (Davidson), BB20501, x2-5. Spiriferina Bed, Asfal Formation. Fig. 23. Spiriferina abichi Oppel, rather narrow form with produced cardinal extremities. BB20491, X 2-5. Decorticated near brachial umbo. Note Dimyodon on area. Spiriferina Bed, Asfal Formation. Palaeontology, Vol. 4. PLATE I HUDSON AND JEFFERIES, Noric brachiopods and lamellibraiichs HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 11 M. noetlingii is more tumid, narrower, and more strongly sulcate than M. lenticiilata sp. nov., M. maniensis (Diener), or M. maniensifonnis (Diener), and its ribs are coarser than even the coarsest ribbed specimens of M. misoHca Seidlitz. The Misolia which Krumbeck (1913, p. 30) compared with M. noetlingii has more ribs which fork more often and is less tumid and less deeply sulcate. M. noetlingii lacks the characteristic asymmetry of M. asymmetrica Wanner, Knipscheer, and Schenk (1952, p. 72) which is also present in the various species of Misolia described by Kutassy (1934). M. noetlingii is longer and more tumid than M. pinajae Krumbeck (1923, p. 327) and lacks the crenulations on the ribs of M. aspera Krumbeck (1924). Spirigera trieupii Bittner 1892 is like M. noetlingii in general shape but has no ribs in the sulcus. The specimen which Merla (1933, p. Ill) identified as M. noetlingii is not typical since it has three ribs instead of two in the median sulcus. Apart from Oman, M. noetlingii is thus only known from the Megalodon Limestone of Spiti. Misolia lenticiilata sp. nov. Plate 1, figs. 9-12 Holotype. BB20243 (PI. 1, figs. 9-12). Paratypes. BB20244-7, BB2052I-48. All from Misolia Bed, Asfal Formation. Description. Shell terebratuliform, both valves of low but about equal convexity. Dimensions (BB20243, holotype): length 28 mm., breadth 26 mm., thickness 12 mm. Sulcus of pedicle valve shallow; linguiform process not prominent. Median fold of brachial valve weak. Two ribs in sulcus of pedicle valve correspond to two furrows separating three ribs on median ridge. Lateral slopes with five or six ribs on each valve on each side, the number of ribs increasing in ontogeny by addition of ribs near the umbo. On material seen the ribs do not branch. Concentric growth-lines weak. Beak erect to sub-erect without beak ridges. Pedicle opening large, permesothyrid. Strong subparallel dental lamellae and distinct hinge-plate present : fragments of spiralia also observed. Other features not ascertainable in specimens examined. Remarks. This species is less tumid than M. noetlingii Bittner. Probably the most closely related species is M. maniensifonnis Diener (1908o, p. 126). The latter, which was based on one specimen from the Quartzite Series of Spiti, is similar to M. lenticiilata in having two ribs in the sulcus and in its low convexity. It differs by being more strongly sulcate and perhaps by having fewer ribs on the lateral slopes (three instead of about five). M. aspera Krumbeck 1924 resembles M. lenticiilata in its low tumidity but has more numerous ribs which branch fairly often : it also has coarse growth-lines. More numerous, more often branching ribs also distinguish M. pinajae Krumbeck 1923 and M. cf. noetlingii Krumbeck 1913 from M. lenticiilata. M. asymmetrica Wanner, Knipscheer, and Schenk 1952 and species such as M. loczyi described by Kutassy (1934) are distinctly asymmetrical in rib-arrangement. It may be of phylogenetic significance that Arabian and Indian species of Misolia (M. noetlingii, M. maniensis, M. maniensiformis, M. lenti- ciilata) have fewer, simpler ribs than Indonesian species. 12 PALAEONTOLOGY, VOLUME 4 TEXT-FIG. 3. A, Aeqiiipecten serraticosta (Bittner), LL306, X 10. B, Lopha blanfordi (Lees), LL363, x3-5. C, Costatoria omanica (Diener), LL409, X 10. D, Pseiiclolimea ?cwnaunica x4. E, Costatoria ?vestitaeformis (Krumbeck), LL426, x3-5. F, Aiiodontopliora griesbachi Bittner, LL474, X 3-5. LAMELLIBRANCHIA by R. G. s. HUDSON and r. p. s. Jefferies Family nuculidae d’Orbigny 1846 Genus nucula Lamarck 1799 Subgenus nuculopsis Girty 1911 ?Nuculopsis misolensis (Jaworski) Plate 2, figs. 15, 19, 20 Nucula sp. nov. Krumbeck 1913, p. 53, pi. 3, figs. I80, b. Nucula misolensis Jaworski 1915, p. 106, pi. 44, figs. 7-13; Wanner and Knipscheer 1951, p. 58, pi. 5, fig. 5. ?Nucula cf. misolensis Jaworski. Reed 1927, p. 205. ?Nucula cf. strigillata Goldfuss. Lees 1928, p. 634. HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 13 Material. LL120, internal cast with tooth lamellae preserved (PI. 2, figs. 15, 19, 20). Modiolus Beds, Sumra Formation. This specimen agrees very well in shape with Type B of Niiciila misolensis Jaworski (1915, pi. 44, fig. 13, not fig. 12). However, it is much smaller than most of the speci- mens of this species figured by Jaworski and also smaller than that figured by Wanner and Knipscheer (1951, pi. 5, fig. 5). It is, therefore, probably juvenile, which would explain why it lacks the internal ribs recorded by Wanner and Knipscheer and also, since the number of teeth in a taxodont increases with the age of the shell ( Bernard 1896), why the anterior tooth-row has thirteen teeth instead of about twenty. In his synonymy of N. misolensis, Jaworski quoted N. frit schi Boettger 1880. Though there is fairly good agreement between N. misolensis and the specimen figured by Boettger (1880, pi. 1, figs. 19, 20), later figures of N.fritschi (Krumbeck 1914, pi. 16, figs, \6a-d, 17) show a strong keel. There is also a strong external resemblance between N. misolensis and N. strigillata Goldfuss from the Ladinian of the Alps (see, for example, Bittner, 1895, pi. 17, figs. 1-17). The latter species, however, has a keel running forward from the umbo and its anterior dorsal sides are less steeply inclined to the median plane and are clearly visible in lateral view. Wanner and Knipscheer stated that the hinge of N. misolensis was not like that of N. strigillata since, in the former, the chondrophore slanted forward from the umbo and the anterior tooth row slightly overlapped the posterior, features which were both noticed by Quenstedt (1930) in the Jurassic species N. hammer i Defrance. The resemblance to N. hammeri suggests the allocation of N. misolensis to Paleo- nucula Quenstedt 1930, of which N. hammeri is the type. According to Schenck (1934, p. 36), however, Paleonucula is probably only a subgenus of Nuculopsis Girty 1911 to which, therefore, the present species is tentatively ascribed. N. misolensis is the name-fossil of the Niicida Marl of the Misol Archipelago and is also known from the Fogi Beds of the west Burn and possibly from the Upper Triassic of Yunnan. Family mytilidae Fleming Genus modiolus Lamarck 1799 Modiolus jaworskii Wanner and Knipscheer Text-fig. 4a Modiola spec, indet. Jaworski 1915, p. 105, pi. 45, fig. 4. Modiola jaworskii Wanner and Knipscheer 1951, p. 57, pi. 5, figs. 2-4. Material. LL126, LL127, LL139-45 (LL140, text-fig. 4a), Lopha Beds, Sumra Formation. LL128-38, Modiolus Beds, Sumra Formation. The Oman specimens agree very well with published figures of M. jaworskii from Indonesia though it is true that the shading in Jaworski’s figure (1915, pi. 45, fig. 4) seems to indicate that the sulcus connecting the umbo with the middle of the ventral margin is deeper than in the Oman material. But the sulcus does not show in the growth- lines of the same figure and Jaworski says that the ventral margin is ‘ganz geradlinig, vielleicht ganz schwach konkav eingebuchtet’. This would exactly describe the ventral margin of an Oman specimen. Some specimens of M. jaworskii figured by Wanner and 14 PALAEONTOLOGY, VOLUME 4 Knipscheer show strong concentric sulci. These, however, do not appear to be present in all Indonesian specimens and are occasionally found in specimens from Oman. Con- sequently they do not justify specific separation. M. jaworskii grows to a greater size than M. omanensis while young specimens can be distinguished from the latter by having a weaker sulcus, straighter ventral margin, longer hinge margin, and greater obliquity. From most other Triassic Modiolus, M. jaworskii can be separated by its great height in relation to its length. M. diibius Healey (1908, p. 55, pi. 8, fig. 11) is very small but probably close to M. jaworskii, as also is Bittner’s Myoconcha sp. (1899, pi. 7, fig. 21). Modiola sp. (Krumbeck 1913, p. 49, pi. 3, figs. 9-10) is longer and slimmer than M. jaworskii and has a much more concave ventral margin and deeper sulcus. M. jaworskii is recorded from the Nucula Marl of the Misol Archipelago. TEXT-FIG. 4fl. Modiolus jaworskii Wanner and Knipscheer, left valve, LL140, X 2-5. 4b and c. Modiolus speciosus Merla, left valve, LL146, xl-5. c. Dorsal view looking down commissural plane of left valve. Both from Lopha Beds. Specimens of text-figs. 4-12 (except 10()) are from Sumra Formation, Wadi Milaha, Oman. All, except text-fig. 7, were coated with ammonium chloride before photography. Modiolus speciosus Merla Text-figs. 4b, 4c Mytilus sp. ind. Diener 1908a, p. 139, pi. 24, fig. 6. Modiola speciosa Merla 1933, p. 117, pi. 6, fig. 17. Material. LL146 (text-figs, lb, 7c), LL147-8. Lopha and Modiolus Beds, Sumra Formation. Merla rightly compared his new species with M. paronai Bittner (1895, p. 48, pi. 5, fig. 19) from the Carnian of Lombardy and with M. frugi Healey (1908, p. 54, pi. 8, figs. 8-10) from the Burmese Rhaetian. M. speciosus, however, differs from Af. /it/rtwc// and most other described Triassic Modiolus in its strong carina. It differs from M. frugi in having no sharp angle between the hinge-line and posterior margin. Mytilus sp. ind. (Diener 1908t7) is clearly a specimen of Modiolus speciosus. In con- HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 15 sidering its generic position it is noteworthy that Diener compared his specimen with Modiolus minutus (Goldfuss) from the German Muschelkalk. The type specimens of M. speciosus Merla came from the Upper Norian of Depsang, Tibet, and the specimen figured by Diener (1908a) from the Megalodon Limestone of Spiti. Modiolus omanensis sp. nov. Text-fig. 5a-c Holotype, LLl 54 (text-figs. 5b, c). Paratype, LL150-3, LL200 (text-fig. 5a). Other specimens, LL155- 99, LL201-303, LL305, all from Modiolus Beds, Sumra Formation. Description. Dimensions (LLl 86): Length 18 mm., height 14 mm., width 8 mm. Outline rounded trigonal or oblong with height only slightly less than length. Hinge-line some- what convex, grading into anterior and posterior margins. Slightly convex posterior TEXT-FIG. 5. Modiolus omanensis sp. nov. from Modiolus Beds, a. Left valve of trigonal form, LL200, x2-5. b and c, Holotype, oblong form, LL154, x2-5. b. Right valve; c, dorsal view. margin grades into slightly concave ventral margin with which it makes an angle of about 10° (in oblong forms) or 20° (in trigonal forms). A weak sulcus runs from the umbo to the slight concavity of the ventral margin. Umbones projecting above hinge, subterminal, somewhat prosogyrous, without an umbonal septum. Shell thin, brownish as preserved, ornamented with weak concentric growth-lines and revealing characteristic radial mytilid structure when slightly weathered. Comparison. The forms which Healey described (1908) from the Rhaetian of Burma as Modiola spp. 1, 2, 3, and 4 are almost certainly conspecific and closely resemble M. omanensis. The latter, however, has a less pronounced antero-ventral angle. M. omanensis is also superficially like Datta oscillaris Healey (1908) but lacks the well-developed posterior wing and the very strange hinge-structure of that species. M. frugi Healey (1908) from the Burmese Rhaetian, and M. salzsteltensis Hohenstein (1913) from the Trochitenkalk of the Black Forest are small, rather trigonal forms like M. omanensis but their umbones are more nearly terminal. M. sodburiensis Vaughan (1904) from the Rhaetian of South Wales is more orbicular in outline than M. omanensis and its height still more nearly equal to its length. Krumbeck’s Modiola sp. (1914, p. 49, pi. 3, figs. 9, 10) from the Fogi Beds of west Burn is more elongate than M. omanensis but similar in general outline. Diener, however (1923, p. 202), thought this species was a Myoconcha, a matter which could only be decided by examining its shell structure. 16 PALAEONTOLOGY, VOLUME 4 Family pteridae Meek Genus cassianella Beyrieh 1861 CassianeUa cf. subeuglypha Krumbeck COMPARE CassianeUa subeuglypha Krumbeck 1913, p. 143, pi. 1, figs, \6a-d. CassianeUa cf. subeuglypha Krumbeck. Jaworski 1915, p. 94, pi. 43, figs. 18, 19. Material. LL149t7, a single left valve with ventral parts missing. Modiolus Beds, Sumra Formation. L52751, coll. Lees, poor internal cast of left valve. Five miles east of Ras al Khaima, Oman. The Oman specimens are very like C. subeuglypha as figured by Krumbeck (1913, pi. 1 , figs. 16 a-d). His figured specimen, however, seems to have a concave anterior ear and more deeply concave sulci between the radial keels or ribs; it is also somewhat less oblique than the Oman specimens. These differences suggest that the Oman form is possibly a new species. Other species dilfer from the Oman specimens as follows : C. katialotica Krumbeck from the Norian of Sumatra (Krumbeck, 1914, p. 226, figs. 2-4) has a greater length/ height ratio and a posterior keel only weakly developed. C. verbeeki Krumbeck 1914 lacks the anterior keel but has a general resemblance in shape. C. cf. subeuglypha Jaworski (1915, p. 96, pi. 43, figs. 18-19) differs by having a better developed central keel; otherwise it is very close indeed. C. nov. sp. alf. subeuglypha Krumbeck (1924, p. 248, pi. 186, figs, \6a-b) differs in the shape of the anterior ear and by its strong radial ornament. C. subeuglypha Krumbeck and C. cf. subeuglypha Jaworski come respectively from the Athyris Limestone of Jillu (Misol Archipelago) and from the Nucula Marl of Misol. EXPLANATION OF PLATE 2 All figured specimens are from the Elphinstone Beds, Upper Trias of Wadi Milaha, Jebel Flagab area, near Ras al Khaima, Trucial Oman, Arabia. All were coated with ammonium chloride before photography. Figs. 1-14, 16-18, 21, 23-26, xl. Figs. 15, 19, 20, 22, x2. Figs. 1-4, 8, 9. Indopecten cUgnetti asperior subsp. nov. 1-3, LL321; 4, 8, LL310; 9, LL313. Modiolus Beds, Sumra Formation. 1, 4, Left valve; 2, 8, 9, posterior view; 3, right valve. Figs. 1-4 are abraded specimens which, in consequence, resemble "Pecte/d inargariticostatus Diener. Figs. 5-7. Indopecten ainusiiformis sp. nov., holotype, LL309. 5, Right valve; 6, posterior view; 7, left valve. Dicerocardium Limestone, Asfal Formation. Figs. 10, 11, 14. ?Honwmya sublariana Krumbeck, LL452. 10, Right valve; 11, anterior view; 14, dorsal view. Lopha Beds, Sumra Formation. Figs. 12, 16, 21. Protocardia rhaetica (Merian), LL430. 12, Left valve; 16, dorsal view; 21, anterior view. Modiolus Beds, Sumra Formation. Figs. 13, 17. Megalodon ?hungariciim Kutassy, 'LLAllb. 13, Dorsal view; 17, right valve. Elphinstone Beds (exact horizon not known). Figs. 15, 19, 20. Nucula misolensis Jaworski, LL120. 15, Left valve; 19, dorsal view; 20, posterior view. Modiolus Beds, Sumra Formation. Figs. 18, 23, 24. Aequipecten seiraticosta (Bittner), LL306. 18, Dorsal view; 23, left valve; 24, right valve. Lopha Beds, Sumra Formation. Fig. 22. ?Megalodon rostratifonne Krumbeck, LL429, left valve. Modiolus Beds, Sumra Formation. Fig. 25. Pleuromya himaica Diener, LL462, left valve. Modiolus Beds, Sumra Formation. Fig. 26. Myophoria verbeeki mansuyi Reed, LL422, left valve. Lopha Beds, Sumra Formation. Palaeontology, Vol. 4 PLATE HUDSON AND JEFFERIES, Noric Uimellibranchs HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 17 Family pectinidae Fleming Genus aequipecten Fischer 1886 Aequipecten serraticosta (Bittner) Plate 2, figs. 18, 23, 24; text-fig. 3a Lima serraticosta Bittner 1899, p. 50, pi. 8, figs. 12, 13; ?p. 51, pi. 10, fig. 26. Lima cf. serraticosta Bittner. Diener 1908a, pp. 99, 132, pi. 17, fig. 6. ?Indopecteu sp. Cox 1935, p. 3, pi. 1, figs, la, b. Material. LL306 (PI. 2, figs. 18, 23, 24), LL307-8. Lopha Beds, Sumra Formation. Morphology. Right valve more convex than left. Left valve with eight radial folds, the anterior and posterior pairs being much weaker than those between. All folds, except the most anterior and the most posterior, distinctly angular in section and separated by furrows of same shape and amplitude. Crest of each fold carries a row of tubercles. Whole surface ornamented by close-set, fine, concentric growth-lines, every fourth or fifth growth-line being raised and the free edge characteristically crimped (text-fig. 3a). These crimped growth-lines do not show on a weathered specimen since the crimping affects only the free edge of a raised growth- line and the base is not involved. Shell consists of an outer, transparent, thin, dark-brown layer and an inner, opaque, thick, light-brown layer, the former being thickest over the tubercles. No trace of Indopecten structure (see later). Ornament of right valve like that of left but nine radial folds instead of eight. This is due to additional coarse median fold. One valve (?right) much thicker- shelled than the other and provided with strong radial ribs before and behind each radial fold. Internal radial ribs on the thinner valve lie opposite those on the thicker and are less well developed. Ears not seen. Divided from flank in both valves by slightly concave areas perpendicular to the commissure. Comparison. In specimen LL306 the two most anterior ribs are farther apart than in the first figured specimen of Lima serraticosta (Bittner 1899, pi. 8, fig. 12): otherwise there is very good agreement. The Oman specimen also resembles the other specimen figured by Bittner (1899, pi. 8, fig. 13): this, however, is an internal cast so that com- parison is difficult. The Oman specimens are less like the specimen figured by Bittner on pi. 10, fig. 26: this has non-tuberculate ribs and comes from a higher horizon than the other two specimens. Indopecten sp. from the Triassic of the Attock district (Cox 1935) is probably A. serraticosta. Since it did not show Indopecten structure it was thought to be a right valve. Generic allocation. Bittner (1899) and Diener (]908n) allocated "serraticosta' to Lima’. this is clearly incorrect since Lima is never inequivalve. Subsequently Krumbeck (1924, p. 343) placed it near his new species Pecten (Aequipecten) subserraticosta. The latter has rather sparse Indopecten structure on the left valve and for this reason Krumbeck placed it in the "verbeekV group. Consequently, when this group was made the basis for the new genus Indopecten, both serraticosta and subserraticosta Bittner were allocated to that genus (Douglas 1929, p. 633). It seems very likely that the present species is indeed related to Indopecten subserraticosta Krumbeck for there is a strong resemblance in the ribbing and the internal ribs are also Indopecten-Vikc. There is, however, no true Indo- pecten structure though the outer brown layer is especially thick over the tubercles of the B 7879 c 18 PALAEONTOLOGY, VOLUME 4 left valve which suggests that these tubercles looked like dark spots when the animal was alive, that is, it had a colour pattern produced in fundamentally the same way as in Indopeclen. Since ‘‘serraticosta’ is neither a Lima nor an Indopecten and since it has an inequivalve shell and because of the nature of its ribbing it is here placed in Aequipecten. Distribution. Known from the 'Tropites Beds’ (= Halorites a.nd Proclydonautihis gries- bachi Beds) and possibly from the 'Spiriferina griesbachC Beds and Sagenites Beds of Painkhanda, the Juvavites and Monotis Beds and Quartzite Series of Spiti, and from beds referred to Triassic in the Attock district. Genus indopecten Douglas 1929 Structural colour-banding. The genus Indopecten Douglas (type species : Pecten clignetti Krumbeck 1913) is based on Krumbeck’s 'verbeekr group (1924, p. 343). It includes a number of Upper Triassic Indo-Pacific Pectens which have the left valve somewhat less convex than the right and in which both valves carry five or more weak or strong radial folds and have internal ribs arranged in pairs near the ventral border: the shell structure is also characteristic for both valves consist of an outer translucent dark-brown layer covering an inner opaque light-brown layer, and in the left valve zigzag thickenings of the outer layer let into the outer surface of the inner layer show from outside as a pattern of dark-brown lines within the shell. This structure of zigzag brown lines is in the paper referred to as Indopecten structure (PI. 1, figs. 3, 4). The genus includes the following species: Pecten verbeeki Boettger 1880, P. niicro- glyptus Boettger 1880, P. {Variamussiuin) margariticostatus Diener 1908a, P. {Aequi- pecten) clignetti Krumbeck 1913, P. misolensis Jaworski 1915, P. krwnbecki Jaworski 1915 (= P. clignetti glabra Krumbeck 1913), P. iranicus Krumbeck 1922 {noni. nud.), P. subserraticosta Krumbeck 1924, P. (Aequipecten) seinaarnensis Krumbeck 1924, Indopecten palfyi Kutassy 1935, ?I. transylvanicus Kutassy 1935, /. giganteus Wanner and Knipscheer 1951, I. clignetti (Krumbeck) asperior subsp. nov., and I. amusiiformis sp. nov. ?Lima serraticosta Bittner 1899, though probably related to I. subserraticosta, does not seem to be strictly an Indopecten and the same is probably true of Indopecten sp. Cox 1935: in neither is Indopecten structure known. Krumbeck (1913, p. 39) hesitantly suggested that Indopecten structure served to strengthen the left valve. It seems more likely to have been an expression of colour- banding. This would explain its restriction to the left valve since Pectens always swim or lie with the left valve uppermost so that this valve is usually more brightly coloured than the right. Structures superficially comparable to Indopecten structure also occur in recent molluscs, such as the gastropod Neritina communis from the Philippines. If this interpretation is correct the presence of Indopecten confirms that the Sumra Formation was deposited in photic conditions. Indopecten structure is by no means confined to Indopecten', it also occurs in the ; following Triassic species of Entolium: Pecten discites Schlotheim 1820, P. filosus Hauer 1857, P. azzarolae Stoppani 1861, P. schldsseri Wohrmann 1889, P. cf. subdemissus Bittner 1895, P. (Syncyelonema) cpwtidianus Healey 1908, and P. (Entolium) decorat i- formis Krumbeck 1924. It does not seem to be known whether Indopecten structure is : restricted to the left valve in these forms. They are most likely closely related to each i other and probably to Indopecten, and Jaworski (1915, p. 147) included them in his f HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 19 clignetti group together with Indopecten. It should be noted that Bittner (1895, p. 165) described Indopecten structure as colour-banding in Entoliiim cf. subdemissum (Muenster). Fischer (1925) described three colour varieties of Pleiironectites kievigatus from the Muschelkalk near Toulon. One of these varieties, P. laevigatus derognati (Fischer), shows what is essentially Indopecten structure on the left valve only. Pre- sumably this variety is not phylogenetically connected either with Indopecten or with the species of Entoliimi listed above: its Indopecten structure must be an independent development. The distribution of Indopecten. Douglas (1929, p. 631) based far-reaching palaeogeo- graphical conclusions on the distribution of many forms supposedly absent from the Himalayas but present in Indonesia and the Middle East. Among such forms he wrongly included Indopecten which had already been found in Spiti (Diener 1908n) and recorded as Pecten aff. monilifero (= /. clignetti) and as Pecten sp. ind. aff. massalongi Stoppani {= I. amusiifonnis sp. nov.). Pecten (Varianmssiuni) margariticostatus is also probably an Indopecten, possibly /. clignetti. Arkell (1956, p. 401) has already refuted Douglas’s views on the basis of the Indo- pecten sp. recorded by Cox (1935, p. 3, pi. 1, fig. 1) from the Attock district of the Himalayas. As pointed out above, however, Cox’s specimen is probably Aequipecten serraticosta (Bittner) and hence cannot be used as evidence against the views of Douglas. Indopecten anmsiifonnis sp. nov. Plate 2, figs. 5-7 Pecten sp. ind. alT. Massalongi Stoppani. Diener 1908n, p. 131, pi. 23, fig. 10. Holotype, LL309 (PI. 2, figs. 5-7). Dicerocantiinn Limestone, Asfal Formation. Description. Shell thin-shelled, right valve slightly more convex than left. Length 32 mm., height 36 mm., thickness 11 mm. Umbones median, projecting slightly above hinge- line; apical angle about 100°. Outline of flank of shell (apart from ears) an almost regular pentagon but angles rounded (except umbo). Left valve with six weak folds separated by five weak furrows. Near the umbo these folds are stronger than farther away and somewhat angular. The two median folds coincide with rounded obtuse angles in ventral margin. Three median folds near umbo have weak secondary ribs which quickly die out ventrally. Indopecten structure present over whole valve. Ears separated from flank by elongate, concave areas, roughly per- pendicular to commissural plane. Anterior margin of anterior ear arcuate with distinct byssal sinus. Posterior margin of posterior ear probably sinuous. Near ventral margin internal ribs present before and behind second to fifth radial folds. Internal ribs anterior and posterior to this possibly present but not seen. Right valve with five radial folds, very weak except near umbo. Folds separated by four furrows that are distinctly angular in section near umbo but much weaker ventrally. Internal ribs present near ventral margin in pairs before and behind each furrow with the addition of a single rib before the anterior radial fold. Ears separated from flank by sharp flexure. Anterior margin of anterior ear with distinct byssal notch. Posterior margin of posterior ear sinuous. 20 PALAEONTOLOGY, VOLUME 4 Remarks. The holotype of /. amiisiiformis clearly belongs to the same species as the specimen from the Monotis beds of Spiti described by Diener (1908a) as Pecten sp. ind. aff. Massalongi. This specimen, contrary to Diener’s opinion, is a left valve for his figure shows excellent Indopecten structure. I. amusiiformis is not very similar to P. massalongi Stoppani in which the internal ribs are much more numerous. The new species differs from I. cUgnetti asperior (subsp. nov.) and /. clignetti clignetti (Krumbeck) in being more nearly equivalve, in having weaker secondary ribs, a thinner shell, and no crenulations on the radial folds of either valve. It differs from /. krumbecki (Jaworski) in having much weaker radial folds and from /. verbeeki (Boettger), I. micro- glyptus (Boettger), and I. misolensis (Jaworski) in lacking crenulations on both valves. /. glabra Douglas (not Krumbeck 1913) is a much bigger species, very inequivalve and with strong secondary ribs. EntoUiim cf. subdemissum Muenst. (Diener 1908a, p. 138, pi. 24, fig. 12) at first sight closely resembles the present species but shows no sign of radial folds or Indopecten structure. Of the species just mentioned the one closest to I. annisii- formis is probably I. microglyptus (Boettger). Indopecten cUgnetti asperior subsp. nov. Plate I, figs. 1-3; Plate 2, figs. 1-4, 8, 9 ?Pecten (Variamussiiim) rucirgariticostatiis Diener 1908a, pp. 97, 131, pi. 18, figs. 1-3. ?Pecten aff. monUifero Muenst. Diener 1908a, pp. 98, 131, pi. 13, fig. 4, pi. 23, figs. 11-13. Pecten (Aeqiiipecten) cUgnetti Krumbeck (;7a/^) 1913, p. 41; Krumbeck (/7ari) 1923, p. 345, pi. 193, fig. 9. Chlaniys {Aeqiiipecten) cUgnetti G. Boehm emend. Krumbeck. Lees 1928, p. 636, pi. 44, fig. 3. Holotvpe, LL314, right valve (PI. 1, fig. 1). Paratvpe, LL315, both valves (PI. 1, fig. 2). Other speci- mens,'LL310 (PI. 2, fig. 9), LL311, 312, LL313 (PI. 2, figs. 4, 8), LL316-20, LL321 (PI. 1, fig. 3; PI. 2, figs. 1-3), LL322-4. LL310-17, LL319-21 from Modiolus Beds; LL3 1 8, LL322-4 from Lopha Beds. All from Sumra Formation. Description. Shell thick-shelled, inequivalve; both valves convex but right more convex than left. Shell nearly equilateral but umbones slightly anterior. Umbones not pro- minent, apical angle about 90°. Left valve with six narrow radial folds separated by five broad furrows. Anterior and posterior folds much weaker than the others. The three median furrows each carry two radial secondary ribs. No secondary ribs in the anterior furrow. The posterior furrow bears two secondary ribs near the umbo of which the more posterior is much the stronger and changes ventrally into a sharp radial genicula- tion. All six folds carry a single row of crenulations which tend to die out ventrally but persist longer on the median four folds than on the anterior or posterior folds. The secondary ribs and the posterior geniculation also often die out ventrally. The left valve has Indopecten structure. Before and behind the four median folds the brown lines are curved divaricate. Between these two areas the lines are zigzag with the bi- sectors of the angles of the zigzag radiating from the umbo. Right valve with five primary radial folds separated by four radial furrows narrower than the folds. The anterior and posterior folds are much weaker than the others. Each fold carries rows of tubercles; there are one to two rows on the anterior and posterior folds and usually three on the others, and the tubercles are concentrically paired or tripled on each fold. Furrows without secondary ribs. In both valves concentric growth-lines are convex distally in the furrows, convex HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 21 proximally over the primary folds. Inside both valves, except near the umbo, there are radial internal ribs. In the left valve, one internal rib lies beneath the posterior radial fold, and internal ribs lie just before and behind the second to fourth radial folds. There is no internal rib beneath the anterior radial fold. In the right valve there is an internal rib opposite every internal rib of the left valve. Ears like portion of cylinder with horizontal axis (compare those of Pecten inaxinms (L.) ). Ears of left valve concave, separated from flank by areas roughly perpendicular to plane of commissure; ears of right valve convex, separated from flank by sharp flexures. Left anterior ear with arcuate anterior margin; right anterior ear with strong byssal notch. Posterior border of pos- terior ear sinuous. Remarks. I. clignetti asperior differs from /. cUgnetti cUgnetti (Krumbeck 1913, p. 36, pi. 2, figs. 1-8, pi. 4, fig. 29) by having three rows of tubercles on the third rib of the right valve (and sometimes on second and fourth ribs also) instead of only two. This difference, however, does not demand full specific separation since the form with three rows of tubercles is known in Indonesia (Krumbeck 1913, p. 41; 1923, pi. 193, fig. 9) within the I. clignetti clignetti plexus. The Oman form is therefore considered to be a geographical variant of the Indonesian species. The name asperior { = rougher) indi- cates that the tubercles are more abundant than in I. clignetti cUgnetti. The form which Diener (1908u) figured and described as Pecten aff. monilifero is clearly specifically identical with /. clignetti. Which subspecies it belongs to, however, cannot be decided until the right valve is known. It is also possible that Pecten margaritU costatus Diener 1 908a is based on abraded specimens of I. clignetti. Certainly abraded specimens of /. clignetti asperior (PI. 2, figs. 1-4) from Oman have a strong resemblance to one of the figures of P. margariticostatiis (Diener 1908u, pi. 18, fig. 1). If P. niargariti- costatus is identical with I. clignetti the latter is a junior synonym. The matter, however, can only be decided by examination of the type specimens of the former. Pending such examination it is better to retain the specific name clignetti. I. seinaamensis (Krumbeck 1923, p. 344, pi. 193, figs. 10-12) differs from /. clignetti asperior by having more than five tuberculate folds on the right valve, by having up to five rows of tubercles on the median fold of the right valve, and by the absence of distal weakening in the ornament. I. clignetti asperior probably spent most of its life with the commissure about level with the sea-bed and the right valve buried. The radial folds of the right valve would help to hold the shell in place; a suggested explanation for why they are so much stronger than those of the left valve. Distribution. I. clignetti asperior is known from the Fogi Beds and Athyris Limestone of the Misol Archipelago. I. margariticostatus (Diener) and ‘‘Pecten aff. monilifero', which may be identical with I. clignetti asperior, are known from the Juvavites Beds, Monotis Beds, and Quartzite Series of Spiti. DIMYIDAE Dali Genus Dimyodon Munier-Chalmas 1886 Dimyodon cf. subrichtofeni Krumbeck COMPARE Dimyodon subrichtofeni Krumbeck 1924, p. 347, pi. 193, fig. 18; ?Reed 1927, p. 221. Dimyopsis sp. Lees 1928, p. 637. 22 PALAEONTOLOGY, VOLUME 4 Material. LL325, LL326 (attached to Spiriferina abichi (Dav.) s.l.), BB20491, BB20502, BB20503 from Spiriferina Limestone, Asfal Formation. LL327 (attached to shell fragment), Lopha Bed, Sumra Formation. LL427a attached to Megalocion himgaricum LL427Zj; exact horizon in Elphinstone Beds not known. LL51449, thirteen specimens attached to holotype of Myophoria gigantea Lees (= M. verbeeki mansuyi Reed). The genus Dimyopsis (Bittner 1895, p. 219), in which Lees placed his specimens of this species, differs from Dimyodon in having no teeth. This distinction, however, is very difficult in practice since the umbo region of these forms is thin and has usually been damaged. Thus of the seventeen specimens examined in the present investigation only two show the two small diverging teeth of the right valve characteristic of Dimyodon : the differences between these specimens and the others are certainly preservational and have no taxonomic value whatever. None of the specimens seen are well enough preserved to prove that they belong to Dimyodon subrichtofeni Krumbeck rather than to D. richtofeni Bittner (1895, p. 217). They have been compared with the former species only because an Indonesian relation- ship seems more likely than a European one. The specimens described as Dimyopsis cf. intusstriata Emmrich from the Fogi Beds and Athyris Eimestone of the Misol Archi- pelago (Krumbeck 1913, p. 44) and as Dimyodon richtofeni Bittner from the Nucula Marl of Misol (Jaworski 1915, p. 103) are probably specifically identical with the Oman specimens. The left valve of D. subrichtofeni has not previously been described. It is thin, moderately convex, and with faint radial striae. Some of the specimens of ^Myophoria gigantea' show both valves in apposition. The type of D. subrichtofeni is from the Carnian of Timor. Comparable forms are known from the Norian of the Misol Archipelago and the Upper Triassic of Yunnan. Family ostreidae Fleming Genus lopha Bolten 1798 Lopha blanfordi (Lees) Text-figs. 3b, Set, e Exogyra Stoliezka in Blanford 1872, p. 76. Exogyra sp. ind. aff. conica Diener 19086, p. 159, pi. 36, fig. 4 (not CItama conica J. Sowerby 1813). Ostrea {? Exogyra) Blanfordi Lees 1928, p. 634, pi. 44, figs. 2a-b. Alectryonia parasitica Saurin 1941, p. 7, pi. 1, fig. 38, pi. 2, figs. 2-5 (not Krumbeck 1913). Probably Alectryonia aff. montis caprilis Saurin 1941, p. 7, pi. 1, figs. 39-41, pi. 2, fig. 1 (not Klipstein 1843). Material. LL328-42 (LL335, fig. 8d, e),LL344-61, LL365, LL366. Lopha Beds, Sumra Formation. LL343, LL362^. Modiolus Beds, Sumra Formation. Morphology. Internal features seen in specimen LL363. Anterior external ligament trace reduced or absent. Internal ligament trace not a distinct groove but marked by series of growth-lines slightly convex distally. Adductor scar just ventral to umbo. No pseudo-taxodont dentition, no internal marginal crenulations ; left valve not thicker shelled than right. External folds only reflected internally near the shell margins. Remarks. The present species has the strong radial ribs and serrated commissure of Lopha (= Alectryonia) and the involute mnbones of Exogyra. In fact it could almost HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 23 equally well be placed in either genus. It is here referred to Lopha because the nature of the ribbing is somewhat easier to see than the nature of the umbo. Krumbeck would probably have approved this ascription since he called the most nearly related form Alectryonia parasitica (1913, p. 47, pi. 3, figs. 4-8). L. blanfordi differs from A. parasitica Krumbeck in having somewhat stronger ribs which begin at the attachment area instead of more distally. The weaker ribbing of A. parasitica is probably not due to the nature of the attachment since the attachment area varies greatly in size in the published figures (Krumbeck, 1913, pi. 3, figs. 4-8) and the ribbing is not affected. Ostrea {Alectryonia) cf. parasitica Krumbeck (1923, p. 206, pi. 13, figs. 2-4) is still more like L. blanfordi but the ribs seem wider and do not always start at the attachment area. The form which Saurin (1941, p. 7) called A. parasitica is more like L. blanfordi since it is ribbed over the whole free surface. It also seems likely that A. aff. montiscaprilis of Saurin is of the same species as his A. para- sitica and should also be united with L. blanfordi. Saurin described the form of his specimens as not recourbee without describing the curvature of the umbones which in true montiscaprilis are non-involute (Bittner 1912, pi. 6, fig. 17). In his synonymy of L. blanfordi Lees (1928, p. 634) rather doubtfully quoted A. cf. haidingeriana of Healey (1908, p. 37, pi. 5, figs. 18-19). This seems to have been a mistake, however, for Healey stated of her specimens that though the umbo was twisted in certain examples, in most it remained straight (p. 37). The umbo is also straight in the form identified by Fleming (1953, p. 276) as L. cf. haidingeriana (Emmrich) from the Rhaetian of New Zealand. Krumbeck (1913, p. 48) mentioned the occurrence of oysters with involute umbones in the Rhaetian of Hungary. These forms must be closely related to L. parasitica and L. blanfordi. L. blanfordi is recorded from the Elphinstone Beds of the Elphinstone Inlet and of the area 5 miles east of Ras al Khaima, and from the Upper Triassic of Hoa Huynh, south Annam. Family limidae d’Orbigny Genus pseudolimea Douglas and Arkell 1932 Pseudolimea ?cumaunica (Bittner) Plate 1, fig. 4; text-figs. 3d, 6a, b Lima ciimaimica Bittner 1899, p. 59, pi. 10, fig. 25. 1908a ?Lima ciimaimica Bittner, p. 137, pi. 24, figs. 10, 11. Lima subciimaunica Lees 1928, p. 636; not Jaworski 1915, p. 96, pi. 43, figs. 20, 21 ; not Lima (Radula) siibcumaimica Krumbeck 1913, p. 34, pi. 1, figs. 19, 20. Material. LL368, LL369 (text-fig. 6a, b), LL370-4, LL375 (PI. 1, fig. 4), LL376-98. Modiolus Beds, Sumra Formation. LL401-3, Sumra Formation (exact horizon not known). LL406 Spiriferina Bed, Asfal Formation. Morphology. Flank with about fifteen strong primary ribs having flat sides and rounded apices. Anterior flank ribs sometimes strongly crenulate distally. Primary flank ribs separated by furrows which are rounded and equal to the ribs in width near umbo (up to a shell length of about 10 mm.) but wider than the ribs and flat-bottomed away from umbo. The rounded parts of the furrows near the umbo carry a distinct secondary rib. Surface covered with numerous regularly spaced growth-lines which are weak on lunule 24 PALAEONTOLOGY, VOLUME 4 and escutcheon but strong and raised on the flank, not only in the furrows but also over the main ribs when the specimen has not been abraded. The raised growth-lines are interrupted by the secondary ribs and crossed by numerous radial striae weaker than the growth-lines. The growth-lines are convex away from the umbo over the flank ribs and in general convex towards the umbo in the furrows. Where they touch the secondary ribs, however, they form an obtuse angle pointing away from the umbo. This obtuse angle is also present in the parts of the shell farther from the umbo where secondary ribs have disappeared. Radial ribs usually absent on lunule and escutcheon except on the parts nearest the flank. Ears subequal. Hinge-line with distinct triangular internal ligament-trace and about two small pseudo-taxodont teeth on each side near the cardinal extremities (see text-fig. 3d). Remarks. Lima cumaimica Bittner is referred to Pseudo- limea Douglas and Arkell 1932 because of its small size and the presence of strong flat-sided ribs and secondary ribs. There is some disagreement about the hinge of Pseudolimea. Arkell (1932, text-figs. 20, 21) figured two Pseudolimea hinges, both of them edentulous, but Cox (1944) has pointed out that pseudo-taxodont teeth do sometimes occur in the genus. The nature of the hinge, TEXT-FIG. 6. Pseudolimea ?cumau- therefore, does not exclude L. cumaimica from Pseudo- iiica (Bittner), LL369, x5-5, from Jimea. Modiolus Beds, o. Dorsal view of Oman specimens tentatively referred to P. cwnaii- left valve , Z), left valve. agree with Bittner’s and Diener’s figures of this species in size, outline, number of flank ribs, the presence of secondary ribs (see Diener 1908a, pi. 24, fig. 8), and, with a few exceptions, the general lack of radial ribs on most of the lunule and escutcheon (Bittner 1899, p. 59). The horizon is also similar since the species is known in the Himalayas from the Megalodon Limestone and the Spiriferina griesbachi Bed. The Oman material, however, has very prominent growth-lines, whereas Bittner described the growth-lines of his specimens as scarcely perceptible. He had, however, only two valves and these may have been abraded. For this reason it seems better tentatively to identify the Oman material with Bittner’s species than to create a new one. Lees identified the shells in his collection as Lima subcumaimica Krumbeck. The latter is certainly closely related to L. cumaimica and has been much better described (Krumbeck 1913, p. 34; Jaworski 1915, p. 96). It differs from the Oman specimens by being more oblique (the angle between the hinge-line and the greatest diameter being about 55° instead of 65°), by normally having abundant radial ribs on lunule and escutcheon, and by having the fine radial lines as strong as the growth-lines instead of being much weaker (Krumbeck 1913, pi. 1, fig. 19Z?; Jaworski 1915, pi. 43, fig. 21a). With the possible exception of the last, all these features also distinguish L. subcumaimica from the Himalayan L. cumaimica. A number of other Pseudolimea from the Himalayas deserve mention. Lima sp. (Bittner 1899, p. 50, pi. 7, fig. 20) from the Halobia comata Beds is more orbicular in HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 25 outline than L. cumaunica. Lima sp. (Bittner 1899, p. 50, pi. 8, fig. 1 1) is rather close to L. cumaunica but too badly preserved for detailed comparison: Lima sp. ind. alT. cumaunica (Diener 1908n, p. 132, pi. 23, fig. 14) may possibly be identical with L. cumaunica. Five of the specimens of P. ?cumaunica from Oman are double-\alved. Two of these, LL395 and LL397, give the impression, from the way they are crushed, that they were buried with the commissure roughly vertical. This suggests that in life P. ?cumaunica adopted the same position as modern Lima with the antero-dorsal margin resting on the sea-bed. This is the more likely in view of the somewhat excavated lunule of the species which would make a very firm base. A similar mode of preservation with the animal resting on the lunule also occurs in L. Uneata Schlotheim from the German Wellenkalk. The other double valved specimens, which from their mode of crushing were probably buried with commissure horizontal, were probably rolled over by current action after death. P. cumaunica is known from the Spiriferina griesbachi Beds of the Painkhanda and the Megalodon Limestone of Spiti. The closely related P. subcumaunica is from the Fogi Beds of Bum and the Nucula Marl of Misol. TEXT-FIG. 7. Plagiostoma nudum (Parona), LL404, xO-9, from Lopha Beds, a. Left valve showing concentric colour bands; b, outline of anterior view; c, right valve showing radial and concentric colour bands (a and c, coated with oil). Genus plagiostoma Sowerby 1814 Plagiostoma nudum (Parona) Text-figs, la-c Lima (Plagiostoma) nuda Parona 1889, p. 83, pi. 4, fig. 5; Wohrmann 1893, p. 652. Lima (Plagiostoma) mysica Bittner 1891, p. 109, pi. 2, fig. 1. Material. LL404 (text-fig. la-c). Lopha Beds, Sumra Formation. Remarks. The surface of the unweathered shell is completely smooth except for growth- lines. These are fine over most of the shell but coarse in the lunule and on the anterior ear. Weathering reveals a fine radial shell-structure. The one specimen collected shows clear concentric colour-bands over the whole shell, and radial colour-bands on the anterior dorsal part of the right valve. This colour banding, like that of Indopecten, 26 PALAEONTOLOGY, VOLUME 4 Strongly suggests that the Sumra Formation was laid down in the photic zone of the sea (see above). In outline, size, and total lack of radial ornament, the Oman specimen agrees very well with the type specimens (Parona 1889) which came from the Carnian of Lombardy. The internal cast which Reed (1927, p. 229, pi. 18, fig. 31) recorded as Lima (Plagio- stoma) cf. mida shows rather strong concentric folds and hence is probably not very close to the true L. imda. L. (P.) mysica Bittner from the Upper Trias of Balia in Anatolia does not seem to differ essentially from P. nudum. L. (P.) sp. (Krumbeck 1913, p. 33, pi. 1, fig. 17) is probably closely related to the Oman specimen but shows weak radial ornament. Plagiostoma subvaloniense Krumbeck PJagiostoma subvaloniense Krumbeck 1923, p. 202, pi. 12, figs. 17-19. Lima (Plagiostoma) snbvaloniensis Krumbeck. Lees 1928, p. 637. Material. L52751, Lees coll, (a poor right valve). Elphinstone Beds, 5 miles east of Ras al Khaima. LL491, Misolia Limestone. Remarks. Though badly preserved, the Oman specimens agree with the type specimens (Krumbeck 1923, pi. 12, figs. 17-19) in every ascertainable particular. Krumbeck’s figured specimens vary considerably in height/length ratio and the Oman specimens correspond to the taller form (Krumbeck 1923, pi. 12, fig. 17a). Krumbeck was wrong to describe the internal cast of this species as smooth: in his figures and on the larger Oman specimen (L52751) the internal cast clearly reflects the external radial ribs. The ribs of the present species are broader and less numerous than those of P. praecursor (Quenstedt) or P. valoniense (Defrance) which are probably its closest relatives. The types of P. subvaloniense are from the Norian Kanike Beds of Ceram. Family myophoriidae Genus costatoria Waagen 1907 Costatoria omanica (Diener) Text-figs. 3c, 8a-c Myophoria aff. chenopus Laube. Stoliczka in Blanford 1872, p. 76. Myoplioria omanica Diener 19086, p. 156, pi. 24, figs. 1-3; Lees 1928, p. 635. Material. LL405-6, Lopha Beds, Sumra Formation. LL407 (juv.), LL408-21 (LL410, text-figs. 8a-c), Modiolus Beds, Sumra Formation. Morphology. Shell equivalve, umbones slightly prosogyrous. Ornament the same in both valves. On flank are about eight radial ribs (not counting marginal carina), narrower than the intercostal furrows and strongly crenulate, the crenulations being elongated concentrically. Siphonal area radially concave, divided at about two-thirds of its height above the base by radial groove, and separated from escutcheon by crenulate external carina. Lunule somewhat sunken, smooth except for growth-lines. Hinge of left valve (text-fig. 3c) seen in one juvenile specimen (LL407). 2a strong, not bifid, ventral border convex; 4a fairly strong, narrow, as long as 2a, with fine striae perpendicular to com- missure on posterior face; 4b weak, marginal. Socket for 3a (of right valve) much deeper than socket for 3b. The whole supported on a cardinal plate. Remarks. The hinge of this species is undoubtedly Myophoriid rather than Trigoniid TEXT-FIGS. 8a-c. Costatoria omanica (Diener), LL410, X 1-4, Modiolus Beds, a. Right valve; b, posterior view; c, dorsal view. 8c/ and e, Lopha blanfordi (Lees), LL135, X 1-4, Lopha Beds, d. Left valve; e, right valve. 8y-/z, Palaeocardita bwuca (Krumbeck), LL451, x2-3. Modiolus Beds./, Right valve showing impression of myophorial buttress behind anterior adductor; g, dorsal view; h, anterior view. The types of Costatoria omanica are from the Elphinstone Beds of the Elphinstone Inlet. The species was also recorded by Lees (1928) from 5 miles east of Ras al Khaima. Costatoria ?vestitaeformis (Krumbeck) Text-figs. 3e, 9a-e ?Myophoria vestitaeformis Krumbeck 1923, p. 210 (nom. nov. for. M. vestita subvestita Jaworski 1915, p. 112, pi. 44, figs. 20, 2\a, b, c; not M. subvestita Krumbeck 1913). Material. LL423, LL424 (small left valve, text-fig. 9d, e) LL425 (large damaged right valve, text-figs. 9a-c), Lopha Beds, Sumra Formation. LL426 (small right valve). Modiolus Beds, Sumra Formation. HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 27 and the species must be referred to Costatoria (Waagen 1907) because of its strong radial ribs. Striae may have been present on other parts of the hinges besides the posterior face of 4a. Three European Carnian species closely resemble C. omanica externally. Myorphia inaequicostata Klipstein (see Bittner 1895, p. 94, figs. 1-14) has the flank ribs in two groups, the anterior ones being closer together than the posterior. M. chenopits Laube is still more like C. omanica but is longer relative to its height. M. w/iateleyae Buch has weaker and sparser ribs. 28 PALAEONTOLOGY, VOLUME 4 Morphology. Shell probably slightly inequivalve with left valve more convex than right (see Jaworski 1915, pi. 44, figs. 2\h, c). Ornament the same on both valves. Seven to nine prominent angular radial ribs on flank between lunule and marginal carina. These flank-ribs are steep-sided with weak, radially elongate crenulations. Anterior flank-ribs crossed by weak oblique ribs which form elongate crenulations at the intersections. Lunule smooth. Hinge of right valve with two elongate narrow subequal cardinals (3a and 3b), the anterior face of the posterior cardinal (3b) being coarsely grooved. Stria- tions or grooves may be present also in other parts of the hinge but could not be proved on the specimen examined (LL426). Remarks. Myophoria vestitaeformis Krumbeck (1923, p. 210) was a new name for the form which Jaworski (1915) called Myophoria vestita subvestita (not Myophoria sub- TEXT-FiG. 9. Costatoria ?vestitaefonnis (Krumbeck), X 2-5, Lopha Beds, a-c, LL425. a, Lateral view of left valve; b, posterior view of left valve; c, dorsal view of left valve, d and e, LL423, juvenile specimen. d. Lateral view of right valve (anticarinal sulcus has been reduced in width by crushing); e, right valve showing ornamentation of lunule. vestita Krumbeck 1913). Krumbeck summarized the differences from M. subvestita as follows: M. vestita subvestita Jaworski obviously differs from M. subvestita by being slightly inequivalve (the left valve is higher and thicker than the right), by the charac- teristic wing-like extension of the upper part of the area, by the absence of an areal rib, and by being less convex. The most important of these distinctions is the alate extension of the area. The slightly inequivalve nature of M. vestitaeformis, which Krumbeck insisted on, is clear from Jaworski’s figures (1915, figs. 2\b, 21c) though it disagrees with his description (1915, p. 112). The principal reasons for identifying the Oman material with M. vestitaeformis are the anterior ornament (oblique ribs surrounding a smooth lunule), the general outline, and the alate extension of the area. The identifica- tion is not certain, however, since the hinge is unknown in Indonesia, and double- valved forms, which would show whether the shell was inequivalve, are not known from Oman. The hinge of the Oman material is definitely Myophoriid for, though the teeth are in places coarsely grooved, the anterior right cardinal (3a) is too narrow for a Trigoniid. The hinge is very like that of M. subvestita Krumbeck (1913, pi. 4, fig. la). In view of the hinge and the strong, unequally spaced, radial ribs, M. subvestita, M. ?vestitae- formis, and probably M. vestitaeformis should be placed in Costatoria Waagen 1907. M. seranensis Krumbeck 1923 is like M. vestitaeformis in anterior ornament and general HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 29 outline (though without the alate area). Its hinge, however, is Trigoniid with 3a wide and triangular. The species should therefore be placed in Myophorigonia Cox 1952. Apart from Oman, Costatoria vestitaeformis (Krumbeck) is known to the authors only from the Niiciila Marl of Misol. Genus myophoria Bronn 1835 Myophoria verbeeki (Boettger) mansuyi Reed Plate 2, fig. 26 Myophoria siibvestita Krumbeck Mansuyi Reed 1927, p. 215, pi. 18, figs. 12-14. Myophoria verbeeki (Boettger) curia Reed 1927, p. 216, pi. 18, figs. 15-17. Myophoria cf. napengensis Healey. Reed 1927, p. 217, pi. 18, fig. 26 (not Myophoria napen- gensis Healey 1908). Myophoria gigantea Lees 1928, p. 635, pi. 44, figs. \a, b. ?Myophoria verbeeki (Boettger). Douglas 1929, p. 636; Robinson 1937. Material. L51449 (holotype of Myophoria gigantea Lees 1928,p. 635, pi. 44, figs. \a, b) from Elphinstone Beds, 5 miles east of Ras al Khaima. LL422 (PI. 2, fig. 26) from Lopha Beds, Sumra Formation. Morphology. Ornament of both valves the same. The flank bears six strong, regularly spaced, radial ribs with concentrically elongate crenulations. Lunule anterior to anterior flank rib is flat, smooth except for weak growth-lines, and perpendicular to commissural plane. Remarks. In 1927 Reed described a number of Myophoria from a single bed and locality in Yunnan and referred them to M. subveslita Krumbeck Mansuyi Reed, M. verbeeki (Boettger) curia Reed, and M. cf. napengensis Healey. In the opinion of the authors, all the specimens figured belong to the same form and the question arises as to their valid name. With one exception (pi. 18, fig. 17) all the figures are of internal casts. The exception, which Reed called M. verbeeki curia, has the same ornament as M. verbeeki (Boettger) from Sumatra (see Krumbeck 1914, p. 249, pi. 17, figs. 8-11) in that it has a non-crenulate marginal keel and wide-spaced, crenulate flank ribs but differs from it in having the posterior margin vertical instead of sloping. It can therefore be justifiably considered a subspecies of M. verbeeki (Boettger). Reed’s reason for allocating his sub- species mansuyi to M. subvesiiia Krumbeck was the smoothness of its ribs — a feature of the internal cast and of no diagnostic value: otherwise it is much closer to M. ver- beeki than to M. subvesiiia. M. subvesiiia mansuyi (1927, p. 215) has page priority over M. verbeeki curia (1927, p. 216). The various forms are therefore renamed M. verbeeki mansuyi Reed. As its author recognized (1928, p. 635), M. giganiea Lees is very like M. verbeeki (Boettger) but differs in outline since the posterior margin is vertical instead of sloping, a feature characteristic of the Myophoria recorded by Reed (1927) from Yunnan and renamed above. There seems no reason therefore why M. giganiea should be separated from M. verbeeki mansuyi. Lees (1928, p. 635) stated that M. giganiea was larger than M. verbeeki but there is little difterence in size between his only specimen and Krum- beck’s largest figured specimen (1914, pi. 17, fig. 10). Examination of the holotype shows that M. giganiea is not, as suggested by Lees (1928, p. 635), slightly inequivalve, the structure which suggests this being due to slight crushing. 30 PALAEONTOLOGY, VOLUME 4 The unfigured records of M. verbeeki in Douglas 1929 and Robinson 1937 should be accepted with reserve. Since they occur in Persia and Armenia the specimens referred to may be M. verbeeki mansuyi rather than M. verbeeki verbeeki which is only known in Indonesia. The hinges of the present subspecies and of M. verbeeki verbeeki are not known, and may be Trigoniid or Myophoriid. If Trigoniid the species would belong to Mine- trigonia Kobayashi and Katayama 1938: if Myophoriid to Costatoria Waagen 1907. Pending more evidence it seems best to leave it in Myophoria s.I. M. verbeeki mansuyi is thus known from the Upper Triassic of Yunnan and probably from the Norian of Armenia and Persia. M. verbeeki verbeeki is known from the Norian Padang Beds of Sumatra. Family carditidae Genus palaeocardita Conrad 1867 Palaeocardita buruca (Krumbeck) Text-figs. 8/-/z VenericanUa buruca Boehm 1906, now. nud. p. 400. Cardita buruca Krumbeck 1913, p. 60, pi. 4, figs. 6-13. Palaeocardita globiforwis Boettger. Jaworski 1915, p. 115, pi. 45, figs. 1, 2 (not Cardita globi- formis Boettger 1880). Palaeocardita buruca Krumbeck 1924, p. 248, pi. 19, figs. 28, 29; Douglas 1929, p. 637. Material. LL450, LL45 1 (text-figs. Sf-h). The former from the Lopha Beds, the latter from the Modiolus Beds, Sumra Formation. Jaworski (1915, p. 115) seems to have been wrong to unite P. globiformis Boettger with P. buruca Krumbeck, for the latter is less quadrate, less elongate, and has less anterior umbones. Furthermore, nothing is yet known about the lunule or the hinge of P. globiformis (see Krumbeck 1924, p. 249) and the asymmetric lunule of P. buruca is the most striking feature of the species. The Oman specimens agree exactly in appearance with P. buruca as figured by Krumbeck from Buru (1913) and Timor (1924) and the number of ribs (about 23) is within the range (20-30) that Krumbeck (1924, p. 249) quoted for typical Buru specimens of P. buruca. It seems doubtful if P. buruca var. miso- lensis Krumbeck (= P. globiformis Boettger of Jaworski 1915) and P. buruca var. seranensis Krumbeck 1923 are really distinct from typical P. buruca. The commissure of P. globiformis Boettger var. healeyi Reed from Yunnan seems to pass through the lunule instead of to the left of it (Reed 1927, pi. 18, fig. 6a) \ this variety is, therefore, probably not very close to P. buruca. P. mansuyi Reed 1927 differs from P. buruca in having the crenulations on the ribs restricted to the part of the shell away from the umbo and also seems to have a symmetrical lunule. P. cjuadrata Trechmann (1917) from the New Zealand Carnian is more quadrate and has more anterior umbones than P. buruca, and Cardita singiilaris Healey from the Burmese Rhaetian is much more quadrate, more elongate, and probably much narrower. P. buruca occurs in the Fogi Beds of west Buru, the Nucula Marl of Misol, and possibly in the Upper Triassic of Armenia and the Norian of Naiband, Persia. HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 31 Palaeocardita trapezoidalis trapezoidalis (Krumbeck) Text-fig. 10a Cardita trapezoidalis Krumbeck 1913, p. 147, pi. 4, figs. 15a, b, c. Cardita trapezoidalis Krumbeck nov. var. Jaworski 1915, p. 117, pi. 45, fig. 5. ? Cardita {Palaeocardita?) cf. trapezoidalis Krumbeck. Reed 1927, p. 224 . Material. LL149Z), a single left valve (text-fig. 10a). Modiolus Beds, Sumra Formation. L52742, Lees coll., Elphinstone Inlet, Oman, and LL369Z? from Modiolus Beds are P. trapezoidalis subsp. indet. Morphology. Umbones slightly opisthogyrous. Outline trapezoidal, expanding pos- teriorly. Eseutcheon slightly concave, meeting the commissural plane at right angles, invisible in lateral view; lunule deeply sunken. Primary crenulate radiating ribs, nine on siphonal area, ten on flank, separated by furrows each bearing, on the siphonal area TEXT-FIG. 10a. Palaeocardita trapezoidalis trapezoidalis (Krumbeck), left valve, LL149ti, X4, Modiolus Beds. Mb, Palaeocardita trape- zoidalis leesi, subsp. nov., holotype, left valve, L52744, x4. Elphinstone Inlet, Oman. and the posterior flank, a fine secondary rib. Lunule and escutcheon probably orna- mented by fine radiating ribs. P. trapezoidalis trapezoidalis is recorded from the Fogi Beds of west Burn, the Niicula Marl and Atliyris Limestone of Misol, and, possibly, the Upper Triassic of Yunnan. Palaeocardita trapezoidalis leesi subsp. nov. Text-fig. 106 Cardita cf. siugularis Healey. Lees 1928, p. 637 (not Cardita singularis Healey 1908). Material. L52744 (text-fig. 106), two well exposed left valves and a number of badly exposed valves. Lees coll., Elphinstone Beds, Elphinstone Inlet. Comparison. Similar to P. trapezoidalis trapezoidalis except in the following features : (a) More elongate. Dimensions (respectively C^llA^a and 6); length, 13 mm., 10 mm.; height, 8 mm., 8 mm.; width 1-4 mm. (one valve). (b) Escutcheon less steeply inclined to commissural plane and hence clearly visible in lateral view. (c) Less convex. id) With fewer ribs on the siphonal area (7 instead of 9) and more on the flank (13-15 instead of 10). There are six radial ribs on the escutcheon. Remarks. Krumbeck seems to have made a mistake in describing the umbones of P. trapezoidalis as prosogyrous (1913, p. 147). They are clearly opisthogyrous in Jaworski’s figure of the species (1915, pi. 45, fig. 56), Reed describes them as retrorse (1927, p. 224), 32 PALAEONTOLOGY, VOLUME 4 and Krumbeck’s anterior and posterior views (1913, pi. 4. figs. 5b and c) give the impres- sion of opisthogyrous umbones. Lees compared his material with Cardita singuJahs Healey: in the opinion of the authors it agrees better with P. trapezoidalis since the umbones are opisthogyrous and the shape is trapezoidal with the greatest depth near the posterior end. A series of good specimens of P. trapezoidalis from Oman would probably show that the subspecies leesi grades into the typical form: numerous bad specimens from Wadi Milaha and the Elphinstone Inlet cannot be placed in one or the other. It is just possible that the lower convexity and laterally visible escutcheon of leesi are really due to crushing though the specimens seem to be true shells rather than casts and do not seem distorted. TEXT-FIG. 11. Anoclontophora griesbaclii Bittner, x2, Modiolus Beds, a-c, LL476, X 2. a. Right valve; b, dorsal view; c, anterior view, d. Left valve of carinate variety, LL475, x2. e. Right valve of tall variety, LL473, X 2. Family anthracosiidae Amalitzky Genus anodontophora Cossman 1897 Anodontophora griesbaclii Bittner Text-figs. 3f, I \ a-e Anodontophora Griesbachi Bittner 1899, p. 60, pi. 8, figs. 14-16; Diener 1908a, p. 130, pi. 23, fig. 9; Krumbeck 1913, p. 55, pi. 3, figs. 21-23; Jaworski 1915, p. 109, figs. 22-24; Patte 1926, p. 163, pi. 10, fig. 36. Anodontophora (Ancplophora) cf. Griesbachi Bittner. Mansuy 1908, p. 70, pi. 18, figs. 22, 23. Material. LL463-LL484 (LL473, text-fig. 1 le; LL475, text-fig. Ik/; LL476, text-figs. 1 \a-c). All from Sumra Formation (mainly Modiolus Beds). HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 33 Morphology. Shell variable in outline, sometimes slightly carinate. Umbones slightly anterior and slightly prosogyrous, projecting above hinge-line and rather angular in lateral view. Hinge edentulous, with a weak cardinal plate in both valves. Strong ligament-nymphs present. Comparison. Species of Anodontophora are variable and thus difficult to separate. A. griesbachi, for instance, varies in shape from almost trigonal to oblong (Krumbeck 1913, p. 56). The normal form also lacks a keel and has a convex posterior margin yet some Oman specimens are slightly carinate with almost straight backward-sloping posterior margin. A. griesbachi is like A. fassaensis (Wissmann) except that the latter has opisthogyrous instead of prosogyrous umbones (Bender, 1921, p. 55). Distribution. A. griesbachi is known from the Fogi Beds of west Burn, the Athyris Lime- stone and Nucula Marl of the Misol Archipelago, from the Tropites Beds (= Proclydo- nautilus griesbachi Beds and Halorites Beds), the Spiriferina griesbachi Beds and Sagenites Beds of Painkhanda, and in the Monotis Beds and possibly the Juvavites Beds, and Quartzite Series of Spiti. It is also known from the Triassic of Tonkin. It may possibly occur in Europe as well since Bender (1921) stated that similar forms to A. fassaensis reached the Rhaetian in the Alps. Anodontophora cf. lettica (Quenstedt) Text-figs. 12a-c Material. LL121, LL122 (text-figs, \2a-c). Modiolus Beds, Sumra Formation. Umbones prosogyrous; no lunule, no escutcheon. No ornament except for variable concentric growth-lines. Apart from being thicker and having a straighter ventral margin this form resembles Anodontophora lettica from the Lettenkohle. Family megalodontidae Zittel Genus megalodon Sowerby 1827 Megalodon ?himgaricum Kutassy Plate 2, figs. 13, 17 COMPARE Megalodos hungaricus Kutassy 1933, p. 17, pi. 2, figs. 4a-c; Terranini 1958, p. 164, pi. 6, fig. 11. Material. LL4276 (pi. 2, figs. 13, 17). Sumra Formation (exact horizon not known). Morphology. Shell inequivalve with right valve two-thirds thickness of left. Umbones involute, prosogyrous. Left umbo more involute and prominent than right umbo. Lunule small, elongate, excavated. Siphonal area large, elongate, perpendicular to commissural plane and hence invisible in lateral view, about twice as wide on left valve as on right, separated from flanks in each valve by a very strong sharp keel; a very weak radial groove just anterior to keel in each valve. Ligament opisthodetic, supported by nymphs lodged in elongate ligament area about one-quarter the length of siphonal area. Escutcheon absent. Ornament of weak concentric growth-lines. Remarks. M. himgariciim Kutassy was based on two internal casts, whereas the Oman specimen has the shell still preserved. This difference in preservation, together with the B 7879 D 34 PALAEONTOLOGY, VOLUME 4 fact that the hinge is unknown, prevents a definite identification. Ascertainable features, however, agree very well. These include the strongly inequivalve nature, the very sharply defined siphonal area, and the absence of an escutcheon. The groove corresponding to the posterior adductor ridge in the left valve of the casts figured by Kutassy is probably represented in the Oman specimen by the shallow groove just in front of the siphonal area. M. complanatwn Giimbel, M. laczkoi Hoernes, and M. boeckbi Hoernes are less inequivalve than M. himgaricum and have the siphonal area less well defined. ^4. cassianum is less inequivalve. M. ladakhense Bittner is very similar to M. himgaricum but much less inequivalve. M. himgaricum is recorded from the Norian Hauptdolomit of Hungary, and from the Norian of Songavazzo in Lombardy. ?Megalodon rostratiforme Krumbeck Plate 2, fig. 22 ? Megalodon rostratiforme Krumbeck 1913, p. 64, pi. 4, figs, \la-c, 18-21, 11a, b. Material. LL428, slab with numerous internal casts. LL429, slab with small weathered single valves (PI. 2, fig. 22). Both from Modiolus Beds, Sumra Formation. Morphology. Umbones prosogyrous. A rather strong keel, convex dorsally, runs from umbo to postero-ventral angle. Another rather strong keel from umbo to postero- dorsal angle defines the elongate narrow excavated escutcheon. A rather weak keel running forward from the umbo defines a deep lunule. Posterior muscle scar shows on some internal casts as a slightly raised rounded tetragonal area near the posterior end of the siphonal area. Remarks. The Oman specimens agree almost exactly with those figured by Krumbeck and some of them show clearly the alate siphonal area that Krumbeck emphasized. The species varies greatly in height/length ratio but, like Krumbeck, we can see no reason to subdivide it on this basis. An extensive discussion of the affinities of this species is given by Krumbeck. M. misolense (Wanner and Knipscheer 1951, p. 59, pi. 5, figs. 6-9) is small like the present species but has only a weak siphonal keel and has the right valve somewhat more convex than the left. The type of ? Megalodon rostratiforme is from the Fogi Beds of west Burn. Family pleuromyidae Zittel Genus pleuromya Agassiz 1842 Pleuromya himaica Diener Plate 2, fig. 25 Pleuromya himaica Diener 1908«, p. 132, pl. 23, fig. 15. Material. LL454-LL462: LL454-8, LL462 (PI. 2, fig. 25) well preserved; LL459-61 ill preserved. All from Modiolus Beds, Sumra Formation. Deseription. Umbones slightly prosogyrous. Dorsal part of posterior margin with fairly strong gape. Anterior gape possibly absent, at most only slight. Outline and height/length ratio very variable. Usually with a weak keel running vertically downwards HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 35 from umbo and with slight sulcus behind the keel. Lunule cordate, defined by a sharp line on surface of shell. Escutcheon elongate, defined by a weak keel running backwards from umbo. Hinge margin (as deduced from internal cast) strongly thickened just before and behind the umbo of both valves. Just before and beneath the umbo is a flat tri- angular extension of the margin of the right valve. This overlaps a weaker extension of the margin of the left valve just beneath and behind the umbo. The posterior thicken- ings of the hinge margins of both valves probably correspond to ligament-nymphs. DIMENSIONS (in mm.) Length Height Thickness LL455 38 27 17 LL456 28 22 14 LL457 28 19 15 LL458 33 20 14 Remarks. The hinge of the Oman specimens, in so far as it can be studied, agrees best with Pleuromya as Douville (1907) described it. It might possibly indicate Fanopea but we have found no sign of the enlarged, arched, left ligament nymph of that genus, which, moreover, usually has a much bigger posterior gape than the Oman specimens. F. himaica Diener was founded on a single specimen and no others have since been described. Consequently nothing is known of the range of variation in this species. However, it was probably as variable as other species of Fleuromya. For this reason we identify the Oman specimens with it though none exactly agrees in shape with the type specimen. This also has a weak keel running almost vertically down from the umbo followed by a weak sinus, a feature which also occurs in many of the Oman speci- mens. A similar keel and sinus occur in the German Muschelkalk species F. musculoides (Schlotheim) figured by Bender (1921, p. 79, pi. 2, figs. 1-5, pi. 2, fig. 1). This species resembles F. himaica in shape and the two may perhaps be identical. This cannot be decided, however, without examining good material of both. There are four published figures of the New Zealand Ladinian species F. mariana (Wilckens). Three of these figures (Marwick 1953, pi. 6, fig. 5; Wilckens 1927, pi. 8, figs. 12(7, b, as Fleuromya? sp.) show the same specimen, which is like F. himaica and might at first be thought identical. The fourth published figure (Wilckens, 1927, pi. 8, fig. 6, as Nucula mariana) has, however, a much sharper umbo than F. himaica. The two species are therefore not the same though it is possible their ranges of variation overlap considerably. F. suevica Rolle (1857, pi. 1, figs. 2-3), with which Diener compared the present species, is variable in shape but has more prominent, less anterior umbones than F. himaica. The same is true of the umbones of F. cf. suevica (Goetel 1917, pi. 9, fig. 8). F. sulcatiss- ima Krumbeck (1913, p. 71, pi. 5, figs. 1 la, b) may be related to F. himaica but has a much sharper vertical sulcus. F. himaica occurs in the Monotis Beds of Spiti. Family cardiidae Fleming Genus protocardia Beyrich 1842 Frotocardia rhaetica (Merian) Plate 2, figs. 12, 16, 21 36 PALAEONTOLOGY, VOLUME 4 Cardiiim rhaeticum Merian in Escher v. d. Linth 1853, p. 19, pi. 4, figs. 40, 41. Protocardia atf. coutusa Healey. Krumbeck 1913, p. 67, pi. 4, figs. 24-28; ?Douglas 1929, p. 628. Not Protocardia contusa Healey 1908. Protocardia proteus Krumbeck 1913, p. 69, pi. 5, figs. 2-10; ?Douglas 1929, p. 628. Protocardia rhaetica (Merian). Jaworski 1915, p. 122, pi. 94, figs. 15, 16. For other references to this species see Diener (1923, p. 224) and Kutassy (1931, p. 412). Material. LL430 (PI. 2, figs. 12, 16, 21), LL431-3. All internal casts from Modiolus Beds, Sumra Formation. L52748, Lees coll, (slab of limestone with several ill preserved specimens). Elphinstone Inlet, Oman. Morphology. Umbones mesogyrous, prominent, touching. Shell sometimes slightly crenulate. Siphonal area with about thirteen fine radial ribs. Adductor scars sub-equal, limited towards umbo by fairly strong myophorial buttresses. Dorsal margin of posterior scar arcuate; dorsal margin of anterior scar bifid. Comparison. We agree with Jaworski (1915, p. 123) who could see no essential difference between P. proteus Krumbeck 1913 and P. rhaetica (Merian). Both are highly variable in outline and in the prominence and position of the umbo and both have in common the absence or extreme weakness of the keel. P. proteus was said (Krumbeck 1913, p. 71) to have taller, more anterior, and more prosogyral umbones than the type specimens of P. rhaetica figured by Merian. This is true, but so have many English examples of P. rhaetica. The prominence of the umbones in P. proteus is probably partly due to the fact that the species was based on internal casts, most of them large. The smaller com- plete shells which Krumbeck (1913, p. 67) called P. aflf. contusa Healey are probably well preserved juveniles of the P. proteus population. P. contusa Healey 1908 is more quadrate than most English P. rhaetica, though some of the latter are identical in form with P. contusa (Healey 1908); this, however, does not prove, as Healey asserts, that P. contusa occurs in England. According to Krumbeck (1923, p. 216) P. subrhaetica is likewise more uniform in outline than P. rhaetica. Though close, the two species are not identical. P. rhaetica is a widespread species in the Rhaetic of Europe. In Asia it is known from the Nucula Marl of Misol, the Fogi Beds of west Burn (as P. aflF. contusa and P. proteus), and from the Naiband Calciferous Sandstone of Persia (as P. aff. contusa and P. proteus). Family panopaeidae Zittel Genus homomya Agassiz 1 842 ?Homomya sublariana Krumbeck Plate 2, figs. 10, 11, 14 ? Homomya sp. ind. aflf. larianae Stoppani. Diener 1908n, p. 99. ? Homomya sp. ind. Diener 1908n, p. 133. Homomya sublariana Krumbeck 1913, p. 72, pi. 5, figs. 12-14; ?Douglas 1929, p. 637. Material. LL452 (PI. 2, figs. 10, 11, 14), LL453. Loplia Beds, Sumra Formation. Morphology. Shell equivalve, gaping posteriorly. Umbones rather prominent, proso- gyrous. Weak keels run from the umbo to the postero- and antero-ventral angles. Ornament of coarse, rounded, concentric folds which increase in amplitude ventrally. Near the umbo the primary folds are accompanied by secondary concentric folds. HUDSON AND JEFFERIES: UPPER TRIASSIC BRACHIOPODS 37 Krumbeck (1913) describes radial rows of granules near the umbo but these are not visible in the Oman specimens. Remarks. The generic allocation of this species is uncertain since nothing is known of its hinge. The best preserved of the above specimens does not seem to gape anteriorly which, if original, would not only exclude it from H. sublariana which is definitely stated by Krumbeck to gape anteriorly but also from Homomya. The apparent absence of an anterior gape, however, may be due to crushing. It is noteworthy that some of the forms recorded from the German Muschelkalk as H. alberti Voltz also have no obvious anterior gape (Bender 1921, pi. 1, fig. \b). H. lariana (Stoppani) differs from H. sublariana in not having anterior and posterior keels : it therefore does not have the characteristic cylindrical flank of H. sublariana. H. sublariana is recorded from the Fogi Beds of west Burn, the Calciferous Sandstone of Naiband, and, probably, from the Juvavites and Monotis Beds of Spiti. TEXT-FIGS, \2a-c. Aiioc/ontop/iora cf. lettica (Quenstedt), LL122, x2-5. Modiolus Beds, a. Anterior view; b, dorsal view; c, right valve, \2d-f. Thracia proavita sp. nov., holotype, LL123, x 2-5, Modiolus Beds, d. Dorsal view; e, left view; /, right valve. Family thraciidae Dali Genus thracia Leach 1824 Thracia proavita sp. nov. Text-figs, \2d-f Material. LL123 (text-figs. 12r/-/), LL 124-5. From the Beds, Sumra Formation. 38 PALAEONTOLOGY, VOLUME 4 Description. Shell thin-shelled, rather strongly inequivalve, right valve being more con- vex than left. Probably closed. Ornament of weak growth-lines. Umbones slightly posterior (beak distance = six-tenths), slightly opisthogyrous. Escutcheon clearly de- fined and siphonal area delimited by weak carina. Posterior part of shell somewhat rostrate, posterior margin straight and vertical. Ventral margin divided into two almost straight portions by obtuse angle directly beneath umbo. Length (LL123) c. 22 mm., height 14 mm., thickness c. 10 mm. Comparison. Few Thracia are known from the Trias. T. applanata Krumbeck (1913, p. 74) is much larger and more elongate than T. proavita, and T. prisca Healey (1908, p. 61), from the Napeng Beds of Burma, has rather coarse concentric ribs. T. proavita is similar in outline to the form described by Philippi (1898, p. 177, pi. 7, fig. 9) as T. mactroides (Schlotheim) from the Trigonodusdolomit. This German form, however, has the left valve more convex than the right. There is, incidentally, little resemblance between T. proavita and Myacites mactroides Schlotheim, which Bender (1921, p. 95) placed in Pleuromya, or T. mactroides (Schlotheim) as figured by von Seebach (1861, p. 636, pi. 15, figs. 5a, b, c). Among Jurassic species of Thracia perhaps that most like T. proavita is T. lens (Agassiz 1845, p. 267, pi. 36, figs. 1-15, as Corimya) from the oolite inferieur of Switzer- land. This species, however, lacks the blunt angle dividing the ventral margin of T. proavita, and is also less inequivalve. REFERENCES AGASSIZ, c. 1840-5. Etudes critiques siir les moUusques. 287 pp., 39 pis. Neuchatel. ACER, D. V. 1956. A Monograph of the British Liassic Rhynchonellidae, pt. 1, Mon. Pal. Soc. 1-50, pi. 1-4. 1958. Ibid. pt. 2, 51-84, pi. 5-7. ARKELL, w. J. 1932. In Arkell 1929-37, A Monograph of British Corallian Lamellibranchia. Mon. Pal. Soc. 1-392, pi. 1-56. 1956. Jurassic Geology of the Work!, xv+806 pp. London. BENDER, G. 1921. Die Homomyen und Pleuromyen des Muschelkalk.es der Heidelberger Gegend. Z. Deutsch. Geol. Ges. 73 (1, 2), 24-112, pi. 1^, tab. 1. BERNARD, F. 1896. Sur le developpement et la morphologie de la coquille chez les lamellibranches. Deuxieme note. Taxodontes. Bull. Soc. geol. France, (3) 24, 54-82. BITTNER, A. 1890. Brachiopoden der Alpinen Trias. Abh. K.K. geol. Reichsanst. 14, 1-325, pi. 1-41. 1891. Triaspetrefakten von Balia in Kleinasien. Jalirb. K.K. geol. Reichsanst. 41 (1), 13-116, pi. 1-3. 1892. Neue Arten aus der Trias von Balia in Kleinasien. Ibid. 42 (1), 78-89, pi. 4-5. 1895. Lamellibranchiaten der Alpinen Trias. I, Revision der Lamellibranchiaten von Set. Cassian. Abh. K.K. geol. Reichsanst. 18 (1), 1-235, pi. 1-24. 1899. Trias Brachiopoda and Lamellibranchiata. Pal. Indica, (15) 3 (2), 1-76, pi. 1-12. ■ 1912. Lamellibranchiaten aus der Trias des Bakonyer Waldes. Res. fViss. Erf. Balatonsees, 1 (2), 1-106, pi. 1-9. BLANEORD, w. J. 1872. Note on Maskat and Massandim on the East Coast of Arabia. Rec. Geol. Surv. India, 5 (3), 75-77. BOEHM, G. 1906. Geologische Mittheilungen aus dem Indo-Australischen Archipel. I. Neues aus dem Indo-Australischen Archipel. N. Jahrb. Min. 20, 385-412, pi. 15. BOETTGER, o. 1880. Die Tertiarformation von Sumatra und ihre Tierreste. 3. Die Conchylien der unteren Tertiarschichten. Palaeontograph. Suppl. 3, 8a, 1-120, pi. 1-12. BUCKMAN, s. s. 1918. The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Pal. Indica, N.s., 3 (2), 1-254, pi. 1-21. HUDSON AND JEFFERIES; UPPER TRIASSIC BRACHIOPODS 39 COX, L. R. 1935. The Triassic, Jurassic and Cretaceous Gastropoda and Lamellibranchia of the Attock District. Ibid, n.s., 20 (5), 1-27, pi. 1, 2. — ■ — 1944. On Pseudolimea Arkell. Proc. Mai. Soc. London, 26, 74-88, pi. 2, 3. — — 1952. Notes on the Trigoniidae, with outlines of a classification of the family. Ibid. 29, 45-70, pi. 3, 4. DAVIDSON, T. 1866. Notes on the Carboniferous Brachiopoda collected by Cpt. Godwin- Austen in the valley of Kashmere. Quart. J. Geol. Soc. London, 22, 39-45, pi. 2. DAVIES, A. M. 1935. Tertiary Faunas. 1, 1-406, London. DiENER, c. 1908fl. Ladinic, Carnic and Noric Faunae of Spiti. Pal. Indica, (15) 5 (3), 1-157, pi. 1-24. 19086. Notes on some fossils from the sedimentary rocks of Oman. Rec. Geol. Surv. India, 36 (3), 156-63, pi. 24. 1912. The Trias of the Himalayas. Mem. Geol. Surv. India, 36 (3), 1-176. 1913. Triassic faunae of Kashmir. Pal. Indica, N.s., 5 (1), 1-133, pi. 1-13. ■ 1923. Lamellibranchiata triadica. Foss. Cat. Animalia, 19, 1-257. DOUGLAS, J. A. 1929. A marine Triassic fauna from Eastern Persia. Quart. J. Geol. Soc. London, 85, 624-50, pi. 43-46. and ARKELL, w. J. 1932. The stratigraphical distribution of the Cornbrash. 2. The North- Eastern Area. Ibid. 88, 112-70, pi. 10-12. DOUviLLE, H. 1907. Les Lamellibranches cavicoles ou Desmodontes. Bull. Soc. geol. France, (4) 7, 96-114. ESCHER V. d. LiNTH, A. 1853. Gcologische Bemerkungen iiber das nordliche Vorarlberg und einige angrenzenden Gegenden. Nouv. Mem. Soc. Helvet. Sci. Nat. 13, 1-135, pi. 1-10. FISCHER, p. H. 1925. La persistance des couleurs parmi les fossiles du trias moyen. J. Conchyliologie, 69 (1), 5-12, pi. 1-6. FLEMING, c. A. 1953. A Triassic Oyster from New Zealand. N. Zealand J. Sci. Tech. 35, 276-8. GOETEL, w. 1917. Pietro retyckie i najdolniejszy lias seryi relowej w. Tatrach. Die rhatische Stufe und der unterste Lias der subtatrischen Zone in der Tatra. Bull, international Acad. Sci. Cracovie, 1-231, pi. 7-12. HAUER, F. u. 1857. Ein Beitrag zur Kenntnis der Fauna der Raibler-Schichten. Sitzb. Ak. IViss. Wien, 24, 537-66. HEALEY, M. 1908. Fauna of the Napeng Beds or Rhaetic Beds of Upper Burma. Pal. Indica, N.s., 2 (4), 1-88, pi. 1-10. HOHENSTEiN, V. 1913. Beitriige zur Kenntnis des mittleren Muschelkalkes und des unteren Trochiten- kalkes am ostlichen Schwarzwaldrand. Geol. Pal. Abh. n.f., 12 (2), 173-272, pi. 12-19. HUDSON, R. G. s. 1960. The Permian and Trias of the Oman Peninsula. Geol. Mag. 97 (4), 299-308. , MCGUGAN, A., and MORTON, D. 1954. The structure of the Jebel Hagab area, Trucial Oman. Quart. J. Geol. Soc. London, 110, 121-52, pi. 5-8. and CHATTON, m. 1959. The Musandam Limestone (Jurassic to Lower Cretaceous) of Oman, Arabia. Notes Mem. Moyen-Orient, 7, 69-93. Mus. nat. d’Hist. nat., Paris. JAWORSKI, E. 1915. Die Fauna der Obertriadischen Nuculamergel von Misol. Pal. Timor, 2 (5), 73-174, pi. 43-45. KRAFFT, A. VON 1900. Stratigraphical notes on the Mesozoic Rocks of Spiti. Gen. Rep. for 1899-1900, Geol. Surv. India, 199-230. KRUMBECK, L. 1913. Obcrc Trias von Buru und Misol. Palaeontograpli., Suppl. 4, 1 (1), 1-161, pi. 1-11. ■ 1914. Obere Trias von Sumatra. Ibid. 2 (3), 197-266, pi. 15-17. 1922. Stratigraphische Ergebnisse von Niedermayers Reise durch Persien. Centralbl. Min. 1922. 19-23. 1923. Brachiopoden, Lamellibranchiaten und Gastropoden aus der oberen Trias der Insel Seran. Palaeontograpli., Suppl. 4, 3 (5), 186-245, pi. 12-15. 1924. Die Brachiopoden, Lamellibranchiaten und Gastropoden der Trias von Timor. 2, Pala- ontologischer Teil. Pal. Timor, 4, 143-417, pi. 179-98. KUTASSY, A. 1931. Lamellibranchiata triadica, 2. Foss. Cat. Animalia, 51, 260-477. 1933. Beitrage zur Kenntnis der Fauna des Norischen Hauptdolomites in Ungarn. Fdidt. Kozldny, 63, 12-19, pi. 1-2. 40 PALAEONTOLOGY, VOLUME 4 KUTASSY, A. 1934. Het Palaeozoikum en de Trias van Oost Celebes. Verh. GeoJ.-Mijnb. Gen. Neder- land en Kol., Geol. ser. d, 10, (3), 295-305, pi. 3, 4. — — 1935. Ket uj Indopecten faj az erdelyi triaszbol — Zwei neue Indopecten- Kritn aus der Sieben- biirgischen Trias. Mat. u. Natiirw. Anz. (Ung. Akad. Wiss.), 53 (2), 498-507. LEES, G. M. 1928. The geology and tectonics of Oman and of parts of South-Eastern Arabia. Quart. J. Geol. Soc. London, 84 (4), 585-670, pi. 41-51. MANSUY, H. 1908. Contribution a la carte geol. Indochine. Paleontologie. Service des Mines, Hanoi, 1-73, pi. 1-18. MARWICK, J. 1953. Divisions and faunas of the Hokonui System (Triassic & Jurassic). Pal. Bull. New Zealand Geol. Siirv. 21, 1-141, pi. 1-17. MERLA, G. 1933. Fossili triasici della Depsang. Spediz. Fillippi, (2) 11, 1-124, pi. 4-6. MiDDLEMiss, c. s. 1909. Gondwanas and related marine sedimentary systems of Kashmir. Rec. Geol. Snrv. India, 37, 286-327, pi. 26-34. MOISEEV, A. s. 1936. Les nouveaux genres des Rhynchonellidae du triasique et liasique. Tr. Soc. Nat. Leningrade (Sec. Geol. Min.), 65 (1), 39-50, pi. 1. OPPEL, A. 1865. 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JEFFERIES Dept, of Palaeontology, Manuscript received 9 November 1959 British Museum (Natural Flistory), London, S.W. 7 THE PERMIAN BRACHIOPOD GENUS HORRIDONIA CHAO by ^ . GOBBETT Abstract. Honidonia is redefined to include two variable species, H. honida and H. timanica. The lectotype of the former is redescribed and figured. H. timanica is a Russian and Arctic species, H. hon ida European. Both species occur in Greenland. The genera Sowerbina Fredericks emend. Dunbar and Pleiirohorridonia Dunbar are considered synonymous with Honidonia. In the classification of the Productidae, the surface sculpture of the ventral valve has always played an important role (discussion in Chao 1927). However, Tschernyschew (1902) considered the form of both valves and the shell cavity, and Fredericks (1915) defined three groups on this basis which he called Prochicti typici oc, P. typici and P. proboscidei. He criticized Thomas’s (1914) classification and considered that the surface sculpture was an adaptive character, depending on the mode of life of the organism. Chao (1927) recognized three principle factors: surface sculpture, the form of the valves and the shell cavity, and the internal characters. He defined Horridonia (p. 24) as : ‘Characterised by strong median sinus and fold, slightly convex brachial valve and a few but very stout hollow spines. Type, Productus horhdus Sowerby and Productus limanicus Stuckenberg.’ The following year he expanded this slightly (Chao 1928, p. 62) as follows: ‘Forms belonging to this sub-section, [Horridonia] . . . possess essentially the same characteristic outline of typical Productus, but are without either plicae or wrinkles. The median sinus and fold are rather pronounced and the surface is marked only by irregularly distributed, strong and erect spines. Some indefinite plicae are some- times present, indicating occasional survival of the plica-making impulse.’ In 1928 Fredericks, presumably ignorant of Chao’s work, produced a classification of the genus Productus based primarily on his three morphological groups and secondarily on the surface sculpture of the visceral part of the valves. He defined a genus Sowerbina in Russian (Fredericks 1928) with an English summary (p. 789) as follows: ‘The shell is productiform and has a plain surface. Sometimes a thin granulation is observed on the surface of the valves. Sometimes are seen marks of a punctate structure. Type Productus tinianicus Stuckenberg spec.’ Neither of these authors has given a satisfactory definition of a genus which includes P. horridus Sowerby and P. tinianicus Stuckenberg. Chao’s name, Horridonia, has priority. He designated two genosyntypes, P. horridus Sowerby and P. tinianicus Stucken- berg, the first of which was selected as genolectotype by Schuchert and LeVene (1929). Later writers have enlarged the genus to include various forms having a smooth shell surface with scattered spines and often a ribbed trail. Branson (1948) lists thirteen species, some of which had been referred to Avonia by previous authors; some were put into new genera by Muir- Wood and Cooper (1960) and others are synonyms or in- adequately described. Palaeontology, Vol. 4, Part 1, 1961, pp. 42-53, pis. 3-5.] D. J. GOBBETT: BRACHIOPOD GENUS HORRIDONIA CHAO 43 Dunbar (1955) has recognized the genus Sowerbina Fredericks as distinct from Horh- donia Chao. Dunbar’s diagnosis of Sowerbina (p. 96) is as follows: ‘Productids of moderate to strong curvature (not geniculate), having a narrow ventral sulcus between strong visceral humps; cardinal extremities extended into conspicuous auricles; surface non-costellate, ornamented by minute crinkly pustules; spines large, specialized, and localized as follows; the dorsal valve bears a single row of cardinal spines plus a pair (rarely more or less) of large spines on each auricle, ventral valve without cardinal or auricular spines but having 1 to 3 (rarely more) radial rows of spines on the visceral humps. Generotype: Productus timanicus Stuckenberg.’ Sowerbina as dehned by Dunbar differs essentially from Horridonia Chao in the absence of cardinal and auricular spines on the ventral valve. Except in this character, the extent and size of the spines in P. horridus and P. timanieus are extremely variable. It seems best at present to refer both species to Horridonia. Genus horridonia Chao 1927 Horridonia Chao, p. 25. 1928 Sowerbina Fredericks, p. 778. 1955 Plenrohorridonia Dunbar, p. 89. 1955 Sowerbina Fredericks, Dunbar, p. 95. Generie description. Productids, trapezoidal in outline, with auricles moderately to strongly developed. Ventral valve moderately to strongly convex, not geniculate; median sulcus deep to very shallow, dividing more or less prominent visceral humps. Dorsal valve almost flat to markedly concave, with median fold. Surface of both valves smooth or with a very fine granular sculpture; visceral surface of ventral valve usually with erect spines; anterior part of this valve often with irregular costae. Long cardinal and auricular spines present on both valves or dorsal valve only. Interior of ventral valve with a prominent adductor muscle platform. Interior of dorsal valve with median septum be- tween triangular adductor muscle impressions. Cardinal process trilobed, the central lobe bifid, posterior surface of lobes pectinated. Type species by subsequent selection of Schuchert and LeVene (1929, p. 68): Productus horridus }. Sowerby 1823. Horridonia horrida (J. Sowerby) Plate 3, figs. 1-12; Plate 5, figs. 5, 7-8 1823 Productus horridus J. Sowerby, p. 17, pi. 319, fig. 1. 1829 Prodncta calva J. de C. Sowerby, p. 115, pi. 560, figs. 2-6. 1846 Productus geinitzianiis de Koninck, p. 264, pi. 1 5, figs. 3 a-d (reprinted in de Koninck 1847, p. 156, pi. 15, figs. 3a-d). 1848 Productus latirostratus Howse, p. 256. 1848 Productus umboniUatus King, p. 8. 1850 Productus horridus Sow.; King, p. 87, pi. 11, figs. 1-13. 1850 Productus umboniUatus King, p. 92, pi. 11, figs. 14-18. 1858 Productus sulcatus Sow, var. borealis Haughton, part, p. 242, pi. 7, figs. 1 and 7. 1861 Productus horridus Sow.; Geinitz, p. 103, pi. 19, figs. 11-17. 1861 Productus latirostratus Howse; Geinitz, p. 102, pi. 19, figs. 7-10. 1861 Productus geinitzianiis de Koninck; Geinitz, p. 105, pi. 19, figs. 18-21. ? 1908 Productus borealis Whitfield, part, not Haughton, p. 55, pi. 2, fig. 11. 44 PALAEONTOLOGY, VOLUME 4 1909 Productiis horridus Sow.; Eisel, p. 33, figs. 1-10. 1933 Productiis horridus Sow.; Frebold, pp. 18, 20, 21, pi. 2, figs. 10-13, pi. 3, figs. 9a-d. 1937 Productiis horridus Sow.; Malzahn, p. 8, pi. 1, figs. 1-23, pi. 2, figs. 1-20. 1955 Pleiirohorridonia scoresbyensis, Dunbar, p. 90, pi. 11, figs. 1-10. 1959 Horridoiiia horrida (Sow.); Stepanov, p. 191, pi. 1, figs. 1-6. Type specimen. The specimen figured by J. Sowerby (1823, pi. 319, fig. 1), British Museum No. B60972, has been generally accepted as the type, e.g. King 1850, p. 89, footnote. It is here formally designated the lectotype. Type locality. The origin of the lectotype is obscure. Sowerby (1823, p. 17) records the locality as follows: ‘Not very rare in Derbyshire, communicated by Mr. White Watson, from the seventh bed of his first Limestone, probably Magnesian, as it is above the coal series.’ White Watson (1811, p. 5) describes the seventh bed of his first limestone, which forms the base of the Lower Magnesian Lime- stone, as follows: ‘Shell-Limestone, of a more compact texture, of a bluish grey colour, containing petrified Bivalve Shells; this stone is in request for making Lime for Agriculture, and quarries of it are worked at Bolsover, Oxcroft, Barlborough, Palterton, and Houghton.’ Gibson and Wedd (1913, p. 90) record disused quarries at Limekiln Lield, north of Bolsover. This exposure is now much overgrown and on a recent visit no fossils were found. However, farther north at Aldfield, near Ripon, and at Last Thickley in County Durham, H. horrida occurs in a hard, bluish limestone at about the same horizon as the limestone at Bolsover. The type locality of//, horrida may well be the disused quarry in Limekiln Lield, Bolsover, Derbyshire (Grid. Ref. SK/474712). There is little doubt that the lectotype was col- lected from the Lower Magnesian Limestone. Specific diagnosis. Horridonia with cardinal and auricular spines on both valves. Description. The lectotype is figured on Plate 3, figs. \a-c. It has a strongly convex auriculate ventral valve with a very broad sulcus and a double row of cardinal spines. On the anterior part of the ventral valve are irregular and rather coarse costae. The dorsal valve is moderately concave and has two rows of cardinal spines, the anterior row consisting of two or three spines only. The auricle is deflected to allow the passage of a large auricular spine. Sowerby’s figure, although crude, is truer than King’s (1850, pi. 11, fig. 2) which is an imagined restoration. In other specimens the sulcus may be narrower (PI. 3, fig. 2b) or be almost absent (PI. 3, fig. 7). The relative size of the auricles varies (PI. 3, cf. figs. 4-6) and costae may be absent from the anterior part of the ventral valve. Only one row of cardinal spines may be present (PI. 3, fig. 2 a) and the auricular spine or spines are often small, though rarely absent. A variable number of visceral spines is present on the ventral valve (PI. 3, cf. figs. 8-10), and occasionally on the dorsal valve (PI. 3, fig. 12). In some specimens visceral spines are completely absent. The internal features are best studied on the internal moulds abundant in the Middle Magne- sian Limestone at Humbledon Hill quarry. County Durham. Latex casts were made EXPLANATION OF PLATE 3 Ligs. 1-12. Horridonia horrida (J. Sowerby). Natural size. \a-c. Dorsal, antero-ventral and lateral views of the holotype, B.M. B60972, figured by Sowerby 1823, pi. 319, fig. 1. Lower Magnesian Limestone, ? Bolsover, Derbyshire, la-b. Dorsal and ventral views, S.M. G823, Lower Magnesian Limestone, Harworth Main Sinking, Doncaster, Yorkshire. 3, Lateral view, B.M. B39307, Lower Zechstein, Trebnitz, Gera. 4, Dorsal view, B.M. B8727, Lower Zechstein, Gera. 5, Dorsal view, B.M. 65631, Budenguen. 6, Dorsal view, B.M. B39300, Posneck, Thuringia. 7, Ventral view, S.M. G1074, Lower Magnesian Limestone, Scar Lime Kilns, Well, Ripon, Yorkshire, G.R. SL/267813. 8, Ventral view, B.M. B5817, Lower Magnesian Limestone, Last Thickley, Durham. 9, Ventral view, B.M. B39302, Lower Zechstein, Trebnitz, Gera. 10, Ventral view, B.M. 73248, same locality as fig. 9, 1 1-12, Ventral and dorsal view of two specimens, B.M. 73163, same locality as fig. 9. Palaeontology , Vol. 4. PLATE 3 GOBBET T, Honidonia hoirida, X 1 D. J. GOBBETT; BRACHIOPOD GENUS HORRIDONIA CHAO 45 from these specimens (PI. 5, figs. 5, 7-8). In the interior of the ventral valve, the umbone and hinge-line are quite smooth. The adductor muscle impressions lie on a raised plat- form which is parallel-sided, rounded anteriorly, and extends slightly anterior to the divaricator impressions. The latter are rounded-triangular in outline and are abruptly terminated anteriorly. The anterior and lateral parts of the valve are studded with small elongated pits. In the dorsal valve interior there is a smooth, flat area at the base of the cardinal process. The latter has three serrated lobes, the central one being bifid (PI. 5, fig. 5). The adductor muscle impressions form a convoluted pattern and are triangular in outline. A median septum arises between these and runs anteriorly as far forward as the anterior border of the ‘brachial impressions’. The latter are approximately oval with a raised rim. The posterior part of the valve is smooth or pitted. The anterior part has evenly spaced pustules, becoming larger and more densely spaced anteriorly. Discussion. The representatives of this species show a great variation in external ap- pearance. Forms from the English Zechstein were early recognized as distinct species, Productus honidus J. Sowerby, P. calviis J. de C. Sowerby, and P. latirostratus Howse = P. umbonillatus King. The last of these differs from other forms of H. horrida in its smaller size, low convexity of the ventral valve, and ffattened umbo. It appears to be a stunted form, which perhaps lived in a less favourable environment. Eisel (1909) named and described six forms from the Zechstein of the Gera basin. He considered these to be varieties of P. honidus. The first of Eisel’s varieties, var. initialis, was not found above bed 3, the ‘Dachffoz’ of the Gera Zechstein, but all the other varieties occurred together in bed 4, the ‘Unterer Kompakter Zechstein’. Malzahn (1937) gave a full discussion of Productus honidus and its varieties. He thought P. timanicus was a closely related ancestral species, connected with P. honidus by transitional forms. A specimen from central east Greenland described by Erebold (1933) as P. honidus Sow. var. granulifera Toula was cited as one of these transitional forms. Toula’s variety is in fact Honidonia timanica (Stuck.). Erebold’s specimen has cardinal spines on the ventral valve and belongs to H. horrida. Malzahn investigated the distribution of Eisel’s varieties in new exposures of beds 3-5 in the Gera Zechstein. He confirmed that, although initialis was restricted to bed 3, any one of the other varieties was not restricted to any particular horizon within bed 4 and was thus of no stratigraphic use. In order to ascertain the relations between the varieties of P. honidus and P. timanicus, Malzahn selected three shell characters, the length of the hinge-line, the height of the ventral valve and the curvature of the ventral valve from umbo to anterior border. He subjected these to a statistical analysis and concluded that, with regard to these three characters, P. timanicus and four varieties of P. honidus form a genetically connected group. One variety, var. hoppeianus, does not fall into this group and on this statistical basis cannot be shown to be genetically related to it. However, if characters other than those selected for analysis are used, e.g. cardinal spines, hoppeianus would agree with the other varieties of P. honidus while P. timanicus would appear as the exception. A similar result would probably be obtained if internal characters were treated, e.g. the relative length of the septum in the dorsal valve. Malzahn considered also the dependence of individual varieties on the type of sedi- ment on which they lived. The shells in the Zechstein of Gera are commonly found with well preserved cardinal spines reaching a length of 10 cm., so that it may be assumed 46 PALAEONTOLOGY, VOLUME 4 that they constitute a biocoenose. They are restricted to a limestone or marly facies and are not found in the basal Zechstein conglomerate nor in the upper beds, which approach an evaporite facies. He concluded that the CaCOg content of the sediment may be directly related to the size but not the form of the shells. However, populations do not seem to be centred round one particular variety and may include several varieties with transitional forms (Eisel 1909; Malzahn 1937). The two syntypes of P. sulcatus var. borealis Haughton, which were kindly lent to me from the National Museum of Ireland, represent two species. The larger specimen belongs here. It is well preserved and agrees precisely with a specimen in the Sedgwick Museum, G 832 (PI. 3, fig. 2a-b), from the Lower Magnesian Limestone of Yorkshire. The smaller specimen, described by Haughton as a juvenile specimen, is generically distinct from Horridonia. Some specimens from central east Greenland were described by Dunbar (1955) as a new species, Pleuroliorridonia scoresbyensis. The diagnostic characters of this species, i.e. the ribbed anterior part of the ventral valve, the auricular spines, and the concentric granular surface sculpture, are all present on Horridonia horrida. Dunbar’s form is perhaps nearest to Eisel’s var. hoppeianus. The great variation of H. horrida is illustrated in Plate 3. Varietal names are not recognized by the International Commission on Zoological Nomenclature and, although it may be convenient to describe the forms of H. horrida as subspecies, I think this is unwise. The variable characters, external form and spinosity, may be phenotypic. Also, intermediate forms occur and the ‘varieties’ do not appear to be of stratigraphical use. Distribution (text-fig. 1). H. horrida is found in the English Zechstein from the Marl Slate to the middle part of the Middle Magnesian Limestone (Reef B of Trechmann 1925), after which it was presumably exterminated by an inimical environment. In Germany it occurs in the Kupferschiefer and Zechsteinkalk of the Lower Zechstein. Again it seems that an inimical environment set in after these beds had been deposited. In central east Greenland this species appears common and widespread. Dunbar records it from the Schucherts Plod area in southern Scoresby Land, Clavering 0, Nathorsts Pjord area, and at many other places. It is also found in blocks of Permian limestone in Triassic conglomerate of the Kap Stosch area. Haughton’s specimen came from Hillock Point, Melville Island; Whitfield’s was collected from Cape Sheridan, at 82° 27' N. in Ellesmere Island. Recently Stepanov (1959) has described a Zechstein brachiopod fauna including H. horrida from two bore-holes in southern Lithuania. H. horrida is unknown in arctic Europe and Russia. Horridonia timanica (Stuckenberg) Plate 4, figs. 1-4; Plate 5, figs. 1-4, 6, 9-13 1875 Productus timmiicus Stuckenberg, p. 86, pi. 1, figs. 1-7. 1875 Productiis horridiis Sow. var. gramdiferus Toula, p. 232, pi. 6, figs. 2a-c. 1902 Productiis timaniciis Stuck., Tschemyschew, p. 638, pi. 30, fig. 5; pi. 57, figs. 1-6; text- figs. 78, 79. 71908 Productiis borealis Whitfield, part, not Haughton, p. 55, pi. 1, fig. 1. 1914 Productiis timaniciis Stuck.; Wiman, p. 75, pi. 17, figs. 19-21, pi. 18, figs. 1-6. 1914 Productiis inflatus Wiman, part, not McChesney, pi. 14, fig. 1, pi. 15, figs. 3, 5. 1934 Ruthenia granidifera (Toula); Fredericks, p. 39, pi. 3, figs. 1-8, pi. 4, figs. 1-3. D. J. GOBBETT: BRACHIOPOD GENUS HORRIDONIA CHAO 47 1937 Prodiictus (Horridonia) borealis Stepanov, not Haughton, p. 115, 175, pi. 4, figs. 1-3, pi. 5, figs. 1-4. 1937 Productus (Horridonia) timaniciis Stuck.; Frebold, p. 21, pi. 4, fig. 4, pi. 7, figs. 2-3. 71939 Productus (Horridonia) borealis Licharew and Einor, not Haughton, p. 55, 206, pi. 10, figs. 6-11, pi. 11, figs. 1-5. 1955 Sowerbina 7??nv/;c; Dunbar, p. 97, pi. 13, figs. 1-9. 1955 Sowerbina rudis Dunbar, p. 101, pi. 14, figs. 1-7, pi. 15, figs. 1-6. Type specimen. Stuckenberg (1875) mentioned no holotype. I designate as lectotype the specimen figured by Stuckenberg (1875, pi. 1, figs. 3n-c). Type locality. The specimens described by Stuckenberg were collected from the River Indiga section of the Timan ‘mountain limestone’ (67° 30' N. 49° E.). Specific diagnosis. Horridonia with cardinal and auricular spines on the dorsal valve only. Description. This is based mainly on eighty specimens from Spitsbergen, now in the Sedgwick Museum, Cambridge. The shell is auriculate with a trapezoidal to pentagonal outline. It is generally larger than H. horrida and the valves are thicker. The ventral valve is gently to very strongly convex but rarely geniculate. A median sulcus separates well defined visceral humps, and irregular costae are often present on the anterior part. The visceral disk of the dorsal valve is flat with a median fold and is more rectangular in outline than the dorsal valve of H. horrida. The surface of both valves has a fine granular sculpture, often obscured by loss of the outer shell layer or by silicification. Spines on the ventral valve are limited to the visceral humps where they occur in one to three or more longitudinal rows. Cardinal and auricular spines are present on the dorsal valve ; they vary in number and thickness. The interior of the valve is similar to that of H. horrida but the divaricator muscle impressions are relatively larger and extend anterior to the adductor muscle platform. The interior of the dorsal valve has a median septum extending anterior to the brachial impressions and often reaching the anterior border. In Spitsbergen specimens the posterior half of the dorsal valve is raised and separated from the anterior half by a prominent step. The anterior border is often thickened and bears coarse pustules which may be sharply pointed. The cardinal process is similar in form to that of H. horrida but is rela- tively larger. Variation. Apart from a single Russian specimen, the only specimens I have seen are from Spitsbergen. These show variation in convexity of the ventral valve, development of the auricles, and number of auricular spines on the dorsal valve. However, these forms occur together at the same horizon. The variation in this species has been noticed by Fredericks (1934) and Stepanov (1936; 1937), both of whom described their specimens as specifically distinct from H. timanica Stuck. Fredericks thought (presumably) that the granular sculpture formed the bases of fine spines lying tangential to the surface. He put the species into Ruthenia (= Waagenoconcha). His three subspecies, R. gramdifera typica, R. gramdifera gibbosa, and R. gramdifera spitzbergensis, parallel Stepanov’s Horridonia borealis gramdifera, H. borealis borealis, and H. borealis gramdifera ab. 48 PALAEONTOLOGY, VOLUME 4 aiiriculata respectively. Stepanov distinguishes between the two subspecies of borealis as follows; borealis Ratio of curvature of ventral valve to length of dorsal valve not exceeding 3. Auricles strongly arched. Dorsal valve considerably concave. Anterior part of ventral valve distinctly costate. gra nil I if era This ratio not exceeding 2. Auricles not strongly arched. Dorsal valve less concave. Anterior part of ventral valve non-costate. Stepanov’s subspecies are also more or less equivalent to Dunbar’s rudis (= borealis) and maynci {= gramdifera). In the Spitsbergen specimens I have studied, all these forms are represented and are connected by transitional types. Diseussion. Toula described this species in 1875 as Productus horridus var. granidiferus. I have been unable to discover whether he has priority over Stuckenberg 1875. The publishers of Toula’s paper have no record of the date of its publication and I have been unsuccessful in tracing the date of publication of Stuckenberg’s work. However, Stuckenberg’s description and figures are more adequate than those of Toula and it seems justifiable to use Stuckenberg’s name. His description is fairly complete but he strongly suggests that cardinal spines are present on the ventral valve and his figures show spine bases in this region (PI. 5, fig. 10). The only Russian specimen I have seen was kindly lent to me by Professor Dunbar. It was collected by W. Kulien from the river Adz’va, 59° E., 67° N., and identified by Fredericks. This specimen is figured on PI. 4, fig. 4n-c; there is no trace of cardinal spines on the ventral valve. However, in this specimen and also in specimens from Spitsbergen, opposite each dorsal cardinal spine there is a depression in the rather thin cardinal border of the ventral valve, and between EXPLANATION OF PLATE 4 Figs. 1-4. Horridonia timanica (Stuckenberg). Natural size. \a-c. Dorsal, ventral and lateral views, S.M. E17817, Limestone A (Spirifer Limestone), Templet, Bunsowland, Spitsbergen. 2a-c, Dorsal, ventral and lateral views, S.M. E17832, same locality as fig. 1. 3, Dorsal view, S.M. E17833, same locality as fig. 1 . 4 a-c. Dorsal lateral and anterior views, P.M. S223 1 , River Adz’va, Bolshezemelskaya Tundra, U.S.S.R., 59° E, 67° N. EXPLANATION OF PLATE 5 Figs. 1-4. Horridonia timanica (Stuckenberg). Natural size. Silicified valves treated with dilute HCl. 1, Ventral valve interior, S.M. E17822, Mertonberget, Ny Friesland, Spitsbergen. 2, Ventral valve interior, S.M. El 75 17, Limestone A (Spirifer Limestone), Gipshuken, Bunsowland, Spitsbergen. 3, Dorsal valve interior, S.M. E17608«, Limestone A (Spirifer Limestone), Tyrellfjellet, Bunsowland, Spitsbergen. 4, Dorsal valve interior, S.M. E17821, same locality as fig. 1. Eigs. 5, 7, 8. Horridonia horrida (J. Sowerby). Latex casts from natural internal moulds. Middle Magnesian Limestone, Humbledon Hill Quarry, Sunderland. 5, Reverse view of cardinal process, X 2, B.M. 43384. 7, Ventral valve interior, x 1,B.M. 97553. 8, Dorsal valve interior, X 1, B.M. 43384. Figs. 6, 9-13. Horridonia timanica (Stuckenberg). 6, Reverse view of silicified cardinal process, x2, S.M. E17823, Mertonberget, Ny Friesland, Spitsbergen. 9-12, Reproduction of original figures of Productus timaniciis Stuckenberg 1875, pi. 1. figs. 1, 4, la, 2c, 9, Ventral valve anterior. 10, Ventral valve suggesting presence of cardinal spines (see discussion in text). 11, Dorsal valve interior. 12, Dorsal valve exterior. 13 a-c. Reproduction of original figures of Productus horridus Sow. var. granidiferus Toula 1875, pi. 6, figs. 3 a-c. a, Venfral view, b, Laferal view, c. Part of the shell surface, magnified. Palaeontology, Vol. 4. PLATE 4 GOBBETT, Horridonia timanica, X 1 Palaeontology, Vo!. 4. PLATE 5 G O B B E T T , Horridonia D. J. GOBBETT: BRACHIOPOD GENUS HORRIDONIA CHAO 49 these depressions the relatively raised shell simulates spine bases. I assume that Stucken- berg mistook these for spine bases. This species has long been known from Spitsbergen and Russia where its occurrence, along with other Productids and Spiriferids, was taken to indicate an Upper Carboni- ferous (Uralian) horizon in the sense of Tschernyschew (1902). The Nearctic forms were also referred to H. timanica by Tschernyschew and Stepanov (1916), Gronwall (1917), and Frebold (1931; 1942; 1950) and the strata containing them were thought to be equivalent in age to the Schwagerinakalk. Stepanov (1936; 1937) considered that the Spitsbergen specimens were intermediate between H. timanica and H. honida and indicated an age intermediate between that of the Schwagerinakalk and the Zechstein. He referred them to Productus (H.) borealis Haughton. Frebold (1942) discussed the whole question of the age of the Arctic Permian brachio- pod faunas and concluded that they corresponded to the Sakmarian and Artinskian brachiopods of the Timan and the Urals. He recognized the variation in the Arctic H. timanica but included the varieties in this species and criticized Stepanov’s use of Haughton’s poorly known species borealis. Finally Dunbar (1955) decided to make a fresh start and erected two new species, maynci and rudis, for the Greenland forms, both of which he identified with Spitsbergen forms. Distribution (text-fig. 1). Tschernyschew (1902) records H. timanica from the Timan as rare in the Korallen- and Omphalotrochuskalk but common in the Cora and Schwagerina horizons above. In the Urals it is restricted to the Cora horizon but on the River Ai, on the Ufa plateau (55° 35' N. 58° 30' E), it is found in the Kalk Dolomite horizon CPc. Wiman (1914), Stepanov (1936; 1937), and Frebold (1937) describe it from the Spirifer Limestone of Spitsbergen and Bear Island. It is also found in the Brachiopod Cherts above the Spirifer Limestone (= 1st A) in Central Vestspitsbergen. Fredericks (1934) records it from the Kanin Peninsula in the valley of the River Nottey, presumably in the small outcrop of Permian strata at about 67° 45' N. 45° 40' E. (1956 Geological Map of the U.S.S.R., Ed. D. V. Nalivkin). H. timanica also occurs in the ‘Productus Limestone’ of central east Greenland (Frebold 1931; Dunbar 1955) and in Amdrups Land and Holms Land in north-east Greenland (Gronwall 1917; Frebold 1950). The presence of this species in other parts of the Arctic is less certain. The specimens from Novaya Zemlya (Licharew and Einor 1939) are rather poorly figured; the general form of the shell is like that of Horridonia and the whole surface appears to have a granular sculpture but the cardinal spines are obscure. They were collected from two areas in the North Island, one in the Russian Harbour-Pankratiev Peninsula region and the other on the east coast near Cape Spory Na’volok (76° 15' N. 68° 15' E.). Those specimens described by Tschernyschew and Stepanov (1916) are all young shells, col- lected from Great Bear Cape, King Oscar’s Land, about 77° 35' N. 88° W. Whitfield described specimens, some of which may be H. timanica, from Cape Sheridan at 82° 27' N. on Ellesmere Island. In the past, the formations from which H. timanica has been obtained have been referred either to the Carboniferous or to the Permian. This depended on whether the rest of the fauna, largely of brachiopods, appeared to have Carboniferous or Permian affinities. Many of these brachiopods are probably facies fossils. Tschernyschew’s Cora and Schwagerina horizons are now considered Sakmarian to Lower Artinskian. The B 7879 E 50 PALAEONTOLOGY, VOLUME 4 Omphalotrochuskalk may belong to the Upper Carboniferous, Triticites Zone (Dunbar 1940) and L. C. Librovich (1958) puts it in the Gschelian, i.e. middle Upper Carboni- ferous. The Spirifer Limestone of Spitsbergen lies about 500 metres above the base of the Permian (Forbes, Harland, and Hughes 1958). The age of this formation is con- troversial: Stepanov (1957) makes it equivalent to the Russian Kungurian. Dunbar (1955) considers the east Greenland Permian to be of Zechstein age. The time-range of H. timauica thus extends from Upper Carboniferous to Upper Permian. DOUBTFUL SPECIES OF HORRIDONIA 1. Horriclonia texana King (1930, p. 85, pi. 21, figs. 25a-c). This species is based on a single specimen. According to King it is distinguished by its deeper sinus and triangular. D. J. GOBBETT: BRACHIOPOD GENUS HORRIDONIA CHAO 51 rather than pentagonal outline. It occurs in the Middle Word formation of the Glass Mountains. The material is obviously insufficient on which to base a new species. The figures show that only the posterior part of the ventral valve is preserved. This is silicified and no surface sculpture is visible. 2. ^ Productus' pseudohorridus^\m2in{\9lA, p. 74, pi. 17, figs. 1-11). P. pseudohorridus, which has a long synonymy and which appears to be widespread in the Arctic Permian, differs from Horridonia in the distribution of spines and in the internal character of the dorsal valve. The smaller of Haughton’s two syntypes of P. sidcatus var. borealis is probably this species. 3. ' Prodiictus’’ pseudotimanicus Gerassimov (1934, p. 404). Gerassimov (1952) described two forms of his species, typica and depressa. The figured specimens are all internal moulds. The illustrations are poor but the moulds appear to be conspecific with Horridonia timanica (Stuckenberg). I am indebted to Professor D. L. Stepanov of Lenin- grad University for a photocopy of the relevant part of Gerassimov’s 1952 paper. 4. Horridonia niitis Hill (1950, p. 17, pi. 8, figs. 7-10, pi. 9, fig. 1). Only the ventral valve has been described and the distribution of the cardinal spines is not dear. In size and shape this species resembles ‘P.’ pseudohorridus Wiman, but it differs in the dis- tribution of the visceral spines. Acknowledgements. I am indebted to Mr. J. S. Jackson of the National Museum of Ireland for the loan of Haughton’s syntypes of Prodnctns sulcal ns var. borealis'. Professor C. O. Dunbar of Yale University for the loan of a Russian specimen of Horridonia timanica, for supplying me with a translation of Stuckenberg’s original description of that species and a copy of the original figures; Dr. H. M. Muir- Wood of the British Museum (Natural History) for the loan of specimens of H. horrida, for supplying me with photographs of the lectoype of that species, for reading the manuscript and giving much helpful advice; Mr. W. B. Harland of this department for suggesting this study and making available Spitsbergen H. timanica'. Dr. K. S. W. Campbell of University of New England, Armidale, for general advice and encouragement ; Dr. M . J. S. Rudwick of this department for aiding me in matters of termino- logy and presentation; Mr. A. Barlow of this department for the photography; and Miss M. Potts for typing the manuscript. The work was carried out during the tenure of a D.S.I.R. Research Studentship. Repositories. B.M. — British Museum (Natural History). S.M. — Sedgwick Museum, Cambridge. P.M. — Peabody Museum, Yale University. REFERENCES BRANSON, c. c. 1948. Bibliographic Index of Permian Invertebrates. Mem. Geol. Soc. Amer. 26. CHAO, Y. T. 1927. Productidae of China, Part 1. Palaeont. sinica, B, 5, fasc. 2, 1-192. • 1928. Productidae of China, Part 2. Ibid. 5, fasc. 3, 1-81. DUNBAR, c. o. 1940. The Type Permian: its Classification and Correlation. Bull. Amer. Ass. Petrol. Geol. 24, 237-81. ■ 1955. Permian Brachiopod Faunas of Central East Greenland. Medd. Gronland, 110, no. 3, 1-169, pi. 1-32. EiSEL, R. 1909. Ueber die Varianten des Prodnctns horridns Sowerby, bei Gera. Jher. Ges. Fr. Natnrw. Gera, 49-50, 33-37, fig. 1-10. FORBES, c. L., HARLAND, w. B., and HUGHES, N. F. 1958. Palaeontological Evidence for the Age of the Carboniferous and Permian Rocks of Central Vestspitsbergen. Geol. Mag. 95, 469-90. FREBOLD, H. 1931. Das Marine Oberkarbon Ostgronlands. Medd. Gronland, 84, no. 2, 1-88, pi. 1-6. — — 1933. Weitere Beitriige zur Kenntnis des Oberen Palaozoikums Ostgronlands. Medd. Gronland, 84, no. 7, 1-61, pi. 1-6. 1937. Das Festungsprofil auf Spitzbergen, 4, Die Brachiopoden- und Lamellibranchiatenfauna und die Stratigraphie des Oberkarbons und Unterperms. Skr. Svalb. og Isliavet, 69, 1-85, pi. 1-11. 52 PALAEONTOLOGY, VOLUME 4 FREBOLD, H. 1942. ObcF die Productiden des Brachiopodenkalkes. Skr. Svalb. og Ishavel, 84, 1-68, pi. 1-4. 1950. Stratigraphic und Brachiopodenfauna des Marinen Jungpalaeozoikums von Holms und Amdrups Land (Nordostgronland). Medd. Gronland, 126, no. 3, 1-97, pi. 1-6. FREDERICKS, G. 1915. Notcs Paleontologiqucs. 1. Sur les Productus du Carbonifere superieure et de EArtinskien. Mhn. Com. Geol., St.-Petersb., n.s. 103, 1-63, pi. 1-5. — — 1928. Contribution to the classification of the genus Productus. Bull. Com. geol. U.S.S.R. 46, 773-92. 1934. The Permian Fauna of the Kanin Peninsula. Trans, arct. Inst., Leningr. 13, 5-42, pi. 1-5. GEiNiTZ, Ft. B. 1861. Dyas, oder die Zeclisteinformatiou und das Rothliegendes. 1, Leipzig. GERASSiMOV, N. p. and TIKHVINSKAYA, E. I. 1934. The classical section of the Kungur Deposits; results of the research carried out in 1931. Rec. Russ, miner. Soc. 63, 390-440. GERASSIMOV, N. p. et al. 1952. Productids of the Kungurian and Artinskian deposits of Molotovsk, Pre-Urals. Trans. Nat. Sci. Inst. Molotovsk State Univ. 10, parts 3, 4. GIBSON, w. and wedd, c. b. 1913. The Geology of the Northern Part of the Derbyshire Coalfield and bordering tracts. Mem. geol. Surv. U.K. GRONWALL, K. A. 1917. The marine Carboniferous of north-east Greenland and its brachiopod fauna. Medd. Gronland, 43, no. 20, 511-618, pi. 27-29. HAUGHTON, s. 1858. Gcological notes and Illustrations in McCIintock, F. L. Reminiscences of Arctic Ice Travel in search of Sir John Franklin and his Companions. J. Rov. Soc. Dublin, 1, 239-50, pi. 5-11. HILL, D. 1950. The Productinae of the Artinskian Cracow fauna of Queensland. Queensland Univ. Dept. Geol. Papers, 3, no. 2. HOWSE, R. 1848. A catalogue of the fossils of the Permian system of the counties of Northumberland and Durham. Trans. Tyneside Naturalists' Field Club, 1, 219-64. KING, R. E. 1930. Geology of the Glass Mountains, Texas, Pt. 2. Bull. Univ. Tex. 3042. KING, w. 1848. A Catalogue of the Organic Remains of the Permian Rocks of Northumberland and Durham. Newcastle upon Tyne. 1850. A Monograph of the Permian Fossils of England. Palaeontogr. Soc. KONiNCK, L. DE. 1846. Monographic du Genre Productus. Man. Soc. Sci. Liege, 4, 71-278. LiBROViCH, L. c. 1958. Carbonifcrous System, in Geological Formations of the U.S.S.R., 1, Stratigraphy, Ed. Ovechkin, N. K. 306-44. LiCHAREW, B. K. and EiNOR, o. L. 1939. Paleontology of the Soviet Arctic, Part 4. Contributions to the Knowledge of the Upper Paleozoic fauna of Novaya Zemlya, Brachiopoda. Trans, arct. Inst. Leningr. 127, 1-245. MALZAHN, E. 1937. The German Zechstein Brachiopoda. Abh. preuss. geol. Landesanst., n.s. 185. MUIR-WOOD, H. M. and COOPER, G. A. 1960. Morphology, classification, and life-habits of the Pro- ductoidea (Brachiopoda). Mem. Geol. Soc. Amer. 81. SCHUCHERT, c. and LEVENE, c. M. 1929. Brachiopoda (Generum et Genotyporum Index et Biblio- graphia). Fossilium Catalogiis, 1, Animalia, 42, 1-140. SOWERBY, J. 1823. The Mineral Conchology of Great Britain, 4, London. sowERBY, J. DE c. 1829. Idem. 6, London. STEPANOV, D. L. 1936. Contribution to the Knowledge of the brachiopod fauna of the Upper Paleozoic of Spitsbergen. Ann. Leningr. Univ. Geol.-Geogr. series, 2, 114-28, pi. 1-5. 1937. Permian Brachiopods of Spitsbergen. Trans, arct. Inst., Leningr. 76, 105-92, pi. 1-9. ■ 1957. A new stage of the Permian in the Arctic. Messenger of Leningrad University, 24, Geol. and Geogr. ser. 4, 21-24. 1959. Brachiopods of the Lithuanian Zechstein. Ann. Leningr. Univ. 268, Geol. Sci. ser. 10, 190-207. STUCKENBERG, A. 1875. Report on a geological voyage to the Petschora Land and the Timan Tundra. Collections to the Geology of Russia, 6, 1-126. (Edited by Imp. St. Petersburg Min. Soc.) THOMAS, I. 1914. The British Carboniferous Product!. 1. Geneva Pustula and Overtonia. Mem. geol. Surv. U.K. Palaeontology, 1, 197-366, pi. 17-20. TOULA, F. 1875. Permo-Karbon-Fossilien von der Westkiiste von Spitzbcrgen. Neues Jb. Min. Geol. Paldont. 225-64, pi. 5-10. D. J. GOBBETT: BRACHIOPOD GENUS HORRIDONIA CHAO 53 TSCHERNYSCHEW, T. 1902. Die Oberkarbonischen Brachiopoden des Ural und des Timan. Mew, Com. geoL, St.-Petersb. 16, no. 2. • and STEPANOV, p. 1916. La Faune du carbonifere superieure de la Terre du Roi Oscar et de la Terre de Heiberg. Mater. Geol. Riissid., 27, 1-105, pi. 1-12. TRECHMANN, c. T. 1925. The Permian Formation in Durham. Proc. Geol. Assoc. 36, 135-45. WATSON, WHITE. 1811. A Delineation of the Strata of Derbyshire forming the Surface from Bolsover in the East to Buxton in the West. Sheffield. WHITFIELD, R. p. 1908. Notcs and observations on Carboniferous fossils and semi-fossil shells, brought home by members of the Peary expedition of 1905-6. Bull. Amer. Mus. nat. Hist. 24, 51-58, pi. 1-4. wiMAN, c. 1914. Uber die Karbonbrachiopoden Spitzbergens und Beeren Eilands. Nova Acta Regiae Societatis Scientiarum Upsaliensis (4), 3, no. 8, 1-91. D. J. GOBBETT, Revised manuscript received 19 July 1960 Sedgwick Museum, Cambridge NEW NAMURIAN GONIATITES OF THE GENUS EUMORPHOCERAS by PATRICIA J. YATES^ Abstract. Two new species of Carboniferous goniatites, Eumorphoceras rota and E. medusa and a variety, E. medusa var. sinuosum, are described from the Craveuoceras leion zone on Slieve Anierin, Co. Leitrim, Ireland. These new forms were collected from the Craveuoceras Jeion Zone (E^a) on Slieve Anierin, Co. Leitrim, Ireland, during an investigation of the Namurian faunas of the area. Eumorphoceras rota is the earlier of the new species and occurs with typical Eumorphoceras pseudocoronula Bisat. Eumorphoceras medusa and E. medusa var. sinuosum are both found in later deposits which are, however, still within the Craveuoceras leion Zone. They are considered to show the later stages in the evolution of E. pseudocoronula. An example of the latter (occurring on the same level as E. rota) is figured (PI. 6, fig. 3) to illustrate the lines along which evolution has proceeded to result firstly in the species E. medusa and then in the probably slightly later variety, E. medusa var. sinuosum. Eumorphoceras medusa sp. nov. Plate 6, figs. 1, 2. Synonymy. Poorly preserved specimens of this species may in the past have been referred to Eumorpho- ceras pseudocoronula Bisat (1950, p. 19, pi. 2, fig. 4). Description. The adult individuals are platyconic, with the last whorl high. On the same slab as the holotype a young individual of 10 mm. diameter appears to be a less flattened form with less difference between whorl height and whorl thickness. There are strong constrictions which in the holotype number six in half a whorl. These constrictions show a forward bow close to the umbilical edge; over the flanks they are slightly concave before curving forward to end at the latero-ventral groove with a strongly defined termination. Between these constrictions the ornament consists of muted plications which persist across the flanks. The shoulder furrow is divided by a broad flattened ridge but the resulting ventro-lateral furrow is very faint. The latero-ventral furrow is shallow but still persistent at the largest diameter seen. The umbilicus is open but not large and has a raised rim around its edge. The very early stages are not well seen. At about 10 mm. the constrictions leave the umbilicus radially and arch smoothly forward to a salient at the shoulder [St. Ri. 2. 23 (PI. 6, fig. 2) and St. Ri. 2. 26]. A weak beading of the umbilical edge can be seen at these early diameters [see the early part of St. Ri. 2. 23 (PI. 6, fig. 2)]. With increasing diameter all indications of the umbilical beading disappear and the constrictions begin to develop the forward bow close to the umbilical edge. At large diameters the con- ^ Miss Yates died on 7 August 1960 while this paper was in the press. [Palaeontology, Vol. 4, Part 1, 1961, pp. 54-58, pi. 6.] P. J. YATES: GONIATITES OF THE GENUS EUMORPHOCERAS 55 strictions become less strongly incised over the flanks and the actual terminations are less distinct than the earlier definite end at the latero-ventral groove. Holotype. Doh. 6B. 10 (part and counterpart, PI. 6, fig. 1). Paratypes. Doh. 6B. 14, St. Ri. 2. 24 (part and counterpart). Doh. 6B. 7, St. Ri. 2. 25, St. Ri. 2. 23 (PI. 6, fig. 2). Dimensions. Doh. 6B. 10; diameter c. 21 mm., umbilical diameter 3-5-4 mm. Doh. 6B. 14: diameter c. 23 mm. St. Ri. 2. 23: diameter c. 10 mm. The other paratypes are too incomplete to allow exact measurements but appear to approxi- mate to the above figures. The specimens are in the author’s collection in the Murchison Museum, Department of Geology, Imperial College, London. The form is reasonably common and the material examined includes many incomplete specimens. Type locality. The material on which this new species is based was collected from the mountain of Slieve Anierin, Co. Leitrim, Ireland. Locality Doh. 6 is on Irish Ordnance Survey 6-inch sheet Leitrim 21 (14) and lies about 150 yards beyond the last field boundary on the east bank of the stream which flows to the east of the old coal-mine track. The section consists of about 30 feet of light-brown shales and the goniatites were collected about 20 feet above the base. Locality St. Ri. 2 is on 6-inch sheet Leitrim 20 (8) and lies on the south bank of the Stony River; the section consists of a sheer cliff about 40 feet high and the fossils were all collected within a few feet of the base of the section. Horizon. At both localities E. medusa is associated with Pseudanmssiiim cf. praeteniiis (von Koenen), Kazakhoceras sp. with a beaded venter, and Posidonia trapezoedra Ruprecht. The horizon is about 25 feet above an horizon rich in Cravenoceras leion Bisat and Eumorplwceras pseiidocoronida Bisat. Discussion. E. medusa is closely related to E. pseudocoromila Bisat, but dififers markedly in the absence of the intermediate ribs between the constrictions. These intermediate ribs were observed to occur in examples of Bisat’s species from the horizon 25 feet below the type horizon. An example of E. pseudocoromila is figured here (PI. 6, fig. 3) from the lower faunal band on Slieve Anierin. Both sides of the constrictions are usually raised into sharp rib-like edges and there are in addition two intermediate short ribs between the constrictions. These ribs fade some distance before the ventro-lateral groove. The umbilical edge is raised and beaded by the ribs. There is a groove on both sides of the shoulder ridge but the more ventral groove is less strong. The stratigraphically higher E. medusa therefore differs from the lower E. pseudo- corornda Bisat in that the short ribs beading the umbilical edge have been lost. The edge of the umbilicus is raised into a rim but is never beaded in the adult stage in E. medusa and the ornament between the constrictions consists of gentle plications which ap- parently persist across the flanks. The umbilicus is smaller in E. medusa than in E. pseudocoromila, and the ventral furrow has become almost non-existent in the former. The forward bowing of the constrictions near the umbilical edge and fine plications in the region of the umbilicus in E. medusa are likewise distinguishing features which are absent in E. pseudocoromila. Miller and Furnish (1940, pp. 364-6, pi. 47, figs. 6-12) describe and figure Girtyoceras limatum (Miller and Faber), which, judging from the plates, resembles E. medusa. The specimens are all internal moulds, the external form has not been seen, and the zonal position is too imprecise for exact correlation. The evidence is not sufficiently strong to prove identity with E. medusa. The Geological Survey specimen Ca. 4782 (from a stream in Bowland Shales 40 feet above the lowest Cravenoceras leion beds in Bateson Wood, 550 yards north-east of Crag House, Yorkshire) is here assigned to E. medusa. Bisat had previously identified 56 PALAEONTOLOGY, VOLUME 4 this Specimen as E. aff. hudsoni Gill but had commented on the label about the umbilical bowing and considered that it might be a new form. Eumorphoceras medusa var. sinuosum var. nov. Plate 6, figs. 4, 5 Description. The adult individuals are platyconic with the last whorl high. The young individuals are less flattened. In the adult form there are several sinuous constrictions which have a strong forward bowing close to the umbilicus. They are more strongly incised in this region than over the rest of the flank, where they become less strong as they curve forward to the latero-ventral groove. Between the constrictions there are frequent fine ribs or plications which pass over the flanks and can be seen on the shoulder ridge and on the venter. The latero-ventral groove persists but the ventro- lateral groove is scarcely visible. The umbilicus is relatively small, the edge slightly raised. Several specimens show rather strong spiral striae on the latero-ventral ridge. Holotype. Agh. 8. 1 (PI. 6, fig. 4). Paralypes. Agh. 8. 2 (PI. 6, fig. 5), Agh. 8. 4, Agh. 8. 10. Since no complete specimen has been observed it is not possible to give precise dimensions; they do not appear, however, to differ particularly in this respect from E. medusa sp. nov. All these specimens and several others are in the author’s collection in the Murchison Museum, Department of Geology, Imperial College, London. Type locality. Locality Agh. 8, Slieve Anierin, County Leitrim, Ireland, is on Irish Ordnance Survey 6-inch Series Leitrim 23 (4). It is the last accessible exposure of shale along the east side of the stream before the bridge, and is about 20 feet high. The bridge is not marked on the map but the road along which it lies appears to begin near B.M. 272. 1 on Leitrim 23 (8). This variety has also been seen, very rarely, at locality St. Ri. 2, associated with E. medusa (St. Ri. 2. 12a). Horizon. The material occurs about 25-30 feet above an horizon rich in Cravenoceras leion Bisat and Eumorphoceras pseudocoromda Bisat. The horizon is probably slightly higher than that in which E. medusa occurs. Discussion. This is a variant of E. medusa which can be distinguished by the larger number of constrictions, which are strongly incised close to the umbilicus but more subdued over the rest of their course to the latero-ventral groove. As a result of the more strongly developed forward bow at the umbilical edge the constrictions have a more sinuous appearance than in E. medusa. The spiral ornament on the latero-ventral ridge is particularly strong in this variety. EXPLANATION OF PLATE 6 Figs. 1, 2. Eumorphoceras medusa sp. nov., Slieve Anierin, Co. Leitrim, Ireland. 1, Holotype (Doh. 6B. 10), external impression, x4. 2, Paratype (St. Ri. 2. 23), external impression of an adolescent stage, x7-3. Fig. 3. Eumorphoceras pseudocoromda Bisat, Slieve Anierin, Co. Leitrim, Ireland. Agh. 21. 3 is shown here as a typical example of the earlier E. pseudocoromda to compare with the later species and variety. One fragment is seen as an impression, the other as a mould, X 3. Figs. 4, 5. Eumorphoceras medusa var. sinuosum var. nov. Slieve Anierin, Co. Leitrim, Ireland. 4, Holotype (Agh. 8. 1), external mould, x4-|. 5, Paratype (Agh. 8. 2), external mould, x4f. Figs. 6, 7. Eumorphoceras rota sp. nov., Slieve Anierin, Co. Leitrim, Ireland. 6, Holotype (Agh. 21. 3), external impression, x4|. 7, Paratype (Doh. 50. 1), external mould, X4J. Palaeontology, Vol. 4. PLATE 6 YATES, Eumorphoceras P. J. YATES: GONIATITES OF THE GENUS EUMORPHOCERAS 57 Elias (1956, pp. 132-3) erected a new subgenus of Eumorphoceras which he named Edmooroceras in honour of E. W. J. Moore, and included E. pseiidocoronida in this group. This subgenus is distinguished by ‘a sub-angular and noduse umbilical edge; a more discoidal conch; a greater flattening of the venter in youthful and subadult stages; and a very narrow and low ventral carina, sharply rising upon the flattened venter at these same stages’. At least in the young forms E. medusa has a nodose umbilical edge and is closely related to E. pseiidocoronida. The type species of Edmooroceras is E. phimmeri Miller and Youngquist which, however, judging from the description and plates given by these authors (1948, pp. 665-7, pi. 100, figs. 1-4, 20, 21) does not resemble E. pseiidocoronida, E. medusa, or E. medusa var. siniiosiim. I prefer to retain these species as Eumorphoceras and not to place them in Edmooroceras as the type species of the latter is similar to E. bisidcatiim Girty and is a strongly ribbed form and ap- parently without constrictions. Miller and Youngquist (1948, p. 666) comment that the type specimens of E. phimmeri appear to resemble closely the form figured by Moore (1946, pi. 22, fig. 3). This specimen is in fact E. hisidcatum Girty, s.l., from Sabden Shales, near Samlesbury Bottoms, River Darwen, Lancashire, and is from the Niiculoceras nucuhim subzone of E., age. It seems questionable, therefore, whether E. pseiidocoronida should be placed in the subgenus Edmooroceras. Eumorphoceras rota sp. nov. Plate 6, figs. 6, 7 Description. Adult individuals platyconic. The umbilicus is minute. The shoulder groove is divided into two furrows of equal strength by a strong, rounded ridge. The ornament consists of extremely subdued sickle-shaped striae with a well developed ventro-lateral salient. Periodically there appears to be a stronger plication of the surface, a feature seen faintly on the external impression Agh. 21. 3, where there are about five or six of these per quarter whorl. This feature is also seen on the external mould Doh. 50. 1. Holotype. Agh. 21. 3: diameter 12 mm. (PI. 6, fig. 6). Paratypes. Doh. 50. 1 : diameter 12 mm. (PI. 6, fig. 7). Agh. 21. 4: diameter 11 mm. The material, which consists of about twelve specimens, is in the author’s collection in the Murchison Museum, Department of Geology, Imperial College, London. All the specimens are external impressions and show no sutures. Type locality. The material was collected from two localities on Slieve Anierin, Co. Leitrim, Ireland. Locality Agh. 21 is on Irish Ordnance Survey 6-inch sheet Leitrim 24 ( 1 ) on the west side of the stream running to the west of B.M. 801 . 1 at the point where the 800-foot contour crosses the stream. Locality Doh. 50 is on 6-inch sheet Leitrim 21 (14) on the west of the stream which flows to the east of the old coal-mine track, and is almost due east of B.M. 1249. 8 on this same track. Horizon. Both localities are considered to be low in Ej. E. rota is associated with E. pseiidocoroniila Bisat and Cravenoceras leion Bisat. Discussion. E. rota is easily distinguished by its minute umbilicus, the marked pro- minence of the shoulder ridge and the subdued nature of the ornament. The sinuous nature of the ornament is reminiscent of that in Eumorphoceras sp. form A. (Moore 1946, pp. 418-19, pi. 25, fig. 2), but the latter has a much larger umbilicus, stronger ornament, and a less prominent shoulder ridge. Eumorphoceras tornqiiisti (WolterstorflT) is considered by Bisat (1950, pp. 20-21, pi. 2, fig. 2) to be very similar and possibly identical with E. sp. form A. Moore and like the latter is therefore easily distinguished 58 PALAEONTOLOGY, VOLUME 4 from E. rota. Girtyoceras? costatwn (Ruprecht), figured by Bisat (1950, pi. 1, fig. 6) and also by Ruprecht (1937, pp. 271-2, pi. 10, figs. 5, 6) as Sagittoceras costatum, is similar in having a minute umbilicus. However, Ruprecht’s description mentions only a deep furrow at the shoulder and the form has a much sharper ornament. It is also usually associated with Lyrogoniatites georgiensis Miller and Furnish and therefore occurs on a lower horizon than E. rota. Rayner (1953, p. 286) refers to Girtyoceras? costatum Ruprecht (G.S.M. 85050) from a boring at Mount Pleasant, one mile south-west of Barnard Castle, Yorkshire. This specimen has been examined and although rather indistinct in the region of the groove there is definitely no strong ridge and the ornament is much stronger than that of E. rota. This specimen is very similar to the better specimen from the Alport Boring Z1 4707 (figured by Bisat 1950, pi. 1, fig. 6) and is distinct from E. rota. There is, however, at the Geological Survey a specimen (84690) collected from Little Mearley Clough, Pendle, by E. W. J. Moore which has been identified as E. pseudo- coronula Bisat. Associated with this species there is an unidentified form which is now believed to be E. rota. I am indebted to Mr. Bisat who had previously noted this form and informed me of its existence on seeing examples of E. rota. Acknowledgements. I am indebted particularly to Mr. W. S. Bisat who has given me much advice and assistance in preparing this paper; also to Dr. Gwyn Thomas for advice during its preparation, and to Mr. M. Mitchell who provided me with easy access to Geological Survey material. REFERENCES BISAT, w. s. 1950. The junction faunas of the Visean and the Namurian. Trans. Leeds Geol. 6, 10-26, pi. 1,2. ELIAS, M. K. 1956. Upper Mississippian and Lower Pennsylvanian formations of south-central Oklahoma. In Petroleum Geology of Southern Oklahoma, Amer. Ass. Petrol. Geol. 56-134. MILLER, A. K. and FURNISH, w. M. 1940. Studies of Carboniferous ammonoids. J. Paleont. 14, 356-77, pi. 45-49. MILLER, A. K. and YOUNGQUiST, w. 1948. The cephalopod fauna of the Mississippian Barnett Formation of central Texas. Ibid. 22, 649-71, pi. 94-100. MOORE, E. w. J. 1946. The Carboniferous goniatite genera Girtyoceras and Enmorphoceras. Proc. Yorks. Geol. Soc. 25, 387-445, pi. 22-27. RAYNER, D. 1953. The Lower Carboniferous rocks in the north of England: a review. Proc. Yorks. Geol. Soc. 28, 231-315, pi. 19. RUPRECHT, L. 1937. Die Biostratigraphie des obersten Kulm in Sauerlande. Jahrb. preiiss. geol. Landesanst. 57, 238-83, pi. 9-10. LOWER CARBONIFEROUS GASTROPOD FAUNAS FROM OLD CANNINDAH, QUEENSLAND by W. G. H. MAXWELL Abstract. Gastropod faunas from Old Cannindah are the lowest found in a Lower Carboniferous sequence of strata, beginning with calcareous subgreywacke and detrital limestones and terminating with reef limestones. Rich faunas of molluscs, brachiopods, and corals occur throughout. The gastropod faunas include one new genus Aiistroworthenia, and six new species, as well as an indeterminate one — Euphemites minutus, Waagenella miaostriata, Straparolus australis, S. suhdionysii, Aiistroworthenia levis, Loxonema lamellosa, and Phymatifer sp. indet. The species have strong affinities with European forms of late Tournaisian-early Visean age. INTROD UCTION The present work deals with two small gastropod faunas, of Lower Carboniferous age, found near the western margin of the Yarrol Basin. It represents a contribution to the larger project of biostratigraphic research on the Yarrol Basin, initiated by Hill in 1934 and continued since by members of the University of Queensland. I am indebted to Professor D. Hill for valuable discussion and for her critical reading of the manuscript. Helpful advice from Dr. K. S. W. Campbell is also acknowledged. Photographs were taken by Mr. Chadwick and the map was drawn by Mr. A. Smith, both of the University of Queensland. The work was financed by a Research Grant held within the University of Queensland. Stratigraphy. The Yarrol Basin (Hill 1951) consists of a narrow belt of Upper Palaeo- zoic strata, extending from Mackay, south-south-eastward to Mundubbera, a distance of more than 400 miles. Maximum width of the basin is 50 miles. Marine sedimentation began in the Middle Devonian (Givetian) and terminated early in Permian (Sakmarian), and except for interruptions in the marginal regions, a complete Upper Palaeozoic marine sequence has been preserved over a large part of the basin. In the central western area of the basin, on Old Cannindah Station, the Tellebang and Baywulla formations, of Tournaisian and Visean age respectively, reach a thickness of 5,000 feet. The Tellebang formation consists of shale and subgreywacke in its lower part, with thin bands of oolitic and non-oolitic limestone interbedded with calcareous sub- graywacke, in the higher part. Fossils are abundant in the calcareous subgreywacke and become more numerous towards the top of the formation. The main gastropod assemblage, which is associated with a rich brachiopod fauna, occurs in a coarse calcareous breccia. The smaller gastropod fauna is preserved in a dark, fine-grained limestone approximately 750 feet below the breccia. The Baywulla Formation consists almost entirely of limestone. It begins with 1,000 feet of coarsely oolitic limestone containing sparse brachiopods, solitary corals, and crinoidal debris, followed by non-oolitic, reef limestone which reaches a maximum thickness of 600 feet and contains abundant compound corals, of Visean (D^-Da) age. Non-oolitic, crinoidal limestone, rich in solitary corals, cover the reef core for approxi- [ Palaeontology, Vol. 4, Part 1, 1961, pp. 59-70, pis. 7-9.] SECTION A-B. |::xi:Wx ! 1 ! 1 1 ' ^ 1 i ! ‘ ‘ 1 ‘ ‘ :X;X;X:X;:w jjif: ; ; : ::::::] TEXT-FIG. 1. Geological map of Old Cannindah, showing localities from which faunas have been collected. W. G. H. MAXWELL: LOWER CARBONILEROUS GASTROPOD LAUNAS 61 mately 300 feet, and the top of the formation is defined by a thin band (10 feet) of finely oolitic limestone rich in Palaeacis and with less numerous Daviesiella. Faunas and localities. The higher fauna described in this paper occurs at L.1970 im- mediately west of Splinter Creek. It contains Eiiphemites minutus sp. nov., Straparolus australis?>^. nov., Phyniatifer sp. ,Austroworthenia levis sp. nov., and Lo.xonema lamellosa. In addition to the gastropods, a rich brachiopod assemblage is present, and this is being described in a separate work. The lower fauna, found at L.1872 about 1,100 feet west from L.1970, includes Waagenella rnicrostriata sp. nov. and Straparolus subdionysii sp. nov., as well as brachiopods. Other numbers on the map indicate localities from which faunas have been collected. These faunas, now housed in the University of Queensland, are in the process of description, and are dominantly coralline and brachiopodan. SYSTEMATIC DESCRIPTIONS Class GASTROPODA Cuvicr Subclass STREPTONEURA Spcngcl Order aspidobranchia Schweigger Superfamily bellerophontacea Ulrich & Scofield 1897. Diagnosis. Symmetrical, planispiral, shell evolute, involute, or convolute; umbilicus open or absent; slit and selenizone present; ornament radial and transverse. Family bellerophontidae M‘Coy 1851 Diagnosis. Symmetrical, moderately thick shell, with wide, oval or elongate aperture; deep median slit on outer lip of aperture, and slit band or keel dividing rest of shell into two equal parts. Genus euphemites Warthin 1930 Type species by selection of Waagen (1880, p. 131) Belleroplion iirei Fleming 1828, p. 338; from Brankumhall Quarry, 1 mile north-east of East Kilbride, Lawrieston, Scotland; Lower Limestone, Hosie Group; Lower Carboniferous. Diagnosis. Shell thick, globose, with rounded dorsum; dorsal lip bilobed; narrow slit and selenizone; parietal inductura extensive; 20-26 revolving costae well developed; early stage without umbilicus, later stages umbilicate. Remarks. Knight (1941, pp. 122-3) and Weir (1931, pp. 841-55) have described the type species, Belleroplion urei Fleming, in detail, and Weir has identified and described other specimens from the type locality. Although the holotype of B. urei has been lost, Weir’s interpretation of the species seems to be based on reliable evidence, and is followed in the present work. In Europe the genus is represented by two species in the lower part of the Tournaisian (Zo zone), becomes abundant in the Visean, and ranges into the Namurian. The type species occurs in the Scottish sequence in Coral Zones 2 and 3 and goniatite zones Pi, Pa, and Ej. The Namurian-Visean boundary is fixed at the Po-Ei junction. Weir (1931, pp. 841-55) and Demanet (1941, pp. 263-4) have described the European species. 62 PALAEONTOLOGY, VOLUME 4 Several species have been described from the Mississippian and Pennsylvanian of North America, in beds of post-Tournaisian age. Euphemites minutus sp. nov. Plate 7, figs. 1-4 Holotype. F. 28610 Univ. Qld. Collection; from L. 1970 between Splinter Creek and Mt. Cannindah Portion 91, Parish Cannindah, County Yarrol, Queensland; Late Tournaisian-early Visean. Description. This is a small, globular, thin-shelled form, with minute umbilicus. The umbilical depression is narrow and deep. The anterior portion of the shell has not been preserved, and so the characters of the aperture are not known. In cross section, the whorl is transverse oval, slightly flattened, and extended laterally, towards the umbilicus. The ornament consists of well-marked linear ribs separated by wider, flat based grooves, and finer concentric growth-lines. Ribs vary from twelve in the early stages, to sixteen in later stages. The selenizone is narrow and inconspicuous, and is bordered by two ribs slightly higher than the others. Remarks. E. minutus is characterized by its small size and comparatively coarse orna- ment. It differs from E. urei in the possession of fewer ribs and a less conspicuous selenizone. Its closest affinities are with E. urei var. hindi from Scotland, but this differs in having a closed umbilicus. The American species E. lenticoformis Weller from the Mississippian and E. nodocarinatus Hall from the Pennsylvanian difl'er markedly in shape and ornament. E. vittatus McChesney from the Pennsylvanian is similar in shape but has tuberculate ornament on the umbilical slopes. E. minutus occurs in a calcareous grit, below the Visean (Di-Dg) reef limestones of Old Cannindah. Its associated brachiopod-gastropod fauna is suggestive of a late Tournaisian-early Visean age. Genus waagenella de Koninck 1883 Type species by seiection of de Koninck (1883, p. 123)); Bellerophon dumouti d’Orbigny 1838, pi. 2, figs. 16-20 from Vise, Belgium; Visean, Lower Carboniferous. Diagnosis. Subglobose, involute shell, with regularly arched dorsum and large semilunate callosities curving back from the aperture margins over the umbilical region ; umbilicus EXPLANATION OF PLATE 7 Figs. 1-4. Euphemites minutus sp. nov., Tellebang Formation, L. 1970, For. 91, Parish Cannindah. \a. Periphery and outer whorl, holotype (F. 28610), X2. \b. Apical view of same specimen, la. Apical view (F. 28612), x2. 2b, Apertural view (F. 28613), x2. 2c, Peripheral view, x2. 3, Apical view (F. 28613), X 2. 4, Apertural view with part of whorl removed to show revolving striae on earlier whorl (F. 28611), x6. 5, Apical view (F. 28612), x3-5. Figs. 6-8. Waagenella microstriata sp. nov., Tellebang Formation, L. 1 872, Por. 91 , Parish Cannindah. 6a, Inner whorl profile and aperture, holotype (F. 28666), X 2. 6b, Periphery and outer whorl, X 2. 6c, Apical view, x2. 7, Apical view (F. 28665o), x2. 8, Part of external mould (F. 2S665b) showing selenizone and fine transverse striations, X 3-5. Fig. 9. Phymatifer sp. Tellebang Formation, L. 1970, Por. 91, Parish Cannindah. 9a, Part of upper surface of whorl showing strong nodes (F. 28649). 9b, Same specimen, oblique view (nat. size). Palaeontology, Vol. 4. PLATE 7 MAXWELL, Lower Carboniferous Gastropods W. G. H. MAXWELL: LOWER CARBONILEROUS GASTROPOD LAUNAS 63 closed; outer lip with broad shallow sinus, with eentral slit; narrow slightly raised selenizone, bordered by strong lirae; growth-lines fine, sharp; revolving costae fine. Remarks, de Koninck (1882, p. 81) proposed the name Waagenia for speeies with refleeted semilunate callosities at the margin of the aperture, and in 1883 (p. 123) indicated Bellerophon dumonti d’Orbigny as the type species. However, in a footnote to the explanation of his plate 38 (1883) he stated that the name Waagenia was pre- oceupied for an ammonoid genus and so he introduced the new name Waagenella for his bellerophontid genus. Weir (1931, p. 813) quoted Bellerophon fenmaci d’Orbigny 1840 as the type species, apparently unaware of de Koninck’s previous designation. Knight (1941, pp. 383-4) redeseribed and figured the holotype of B. dumonti d’Orbigny from Vise, Belgium, and the present interpretation of the genus is based largely on Knight’s description. In his comprehensive study of the British and Belgian Carboniferous Bellerophontidae, Weir (1931, pp. 753-861) recognized six genera, viz.: Bellerophon de Montfort, Waage- nella de Koninck, Bucaniopsis Ulrich, Patellostium Waagen, Tropidoeyehis de Koninek, (= Tropidodiscus Meek & Worthen), Zonidiseus and Euphemus M‘Coy (= Euphe- mites Warthin), as well as minor groups within these. Generie distinction was based mainly on the nature of the aperture and induetura, the nature of the selenizone, and surface ornament. Shell shape (whorl cross-section) described by Weir appears to be quite variable within eaeh genus, although Weir separated groups of speeies mainly on this character. Examination of the holotype figured by Knight (1941) has shown that in many cases, the charaeters of generie importanee — aperture, selenizone, surface ornament — are not preserved, and consequently interpretation of the type species and their respective genera is both difficult and not wholly reliable. In the case of Waagenella, the author has supplemented Knight’s description of the type species with material figured by de Koninck from the same locality. De Koninek’s figures illustrate the finer surface ornament, which is not apparent on d’Orbigny’s original specimen, and which is regarded by the present author as having generic signi- ficance. Exeept for W. portloeki de Koninck, a small form found in the Upper Tournaisian, Waagenella in Belgium and Britain is restricted to beds of Visean (S-D2 zones) age. In North America Bellerophon erassus Meek and Worthen from the Pennsylvanian is the species with closest affinities to Waagenella. Waagenella mierostriata sp. nov. Plate 7, figs. 6-8 Holotype. F. 28666 Univ. Qld. Collection; from L. 1872 between Splinter Creek and Mt. Cannindah, Portion 91, Parish Cannindah, County Yarrol, Queensland; Tournaisian. Deseription. The shell is of medium size and globular shape, with the whorl widening rapidly towards the aperture. The aperture is transversely elliptical, and its lateral margins are extended and curved baekwards over the umbilical region. The inner lip is somewhat thickened. A slightly raised selenizone extends posteriorly from the centre of the outer lip. Fine eoneentrie growth-lines eurve across the surface from the umbilieal 64 PALAEONTOLOGY, VOLUME 4 regions, meeting the selenizone more or less at right angles. Intersecting the growth- lines are small regular striae, parallel with the selenizone, and averaging thirty per 10 mm. on the dorsum. Remarks. W. microstriata is characterized by its expanding whorl diameter and its ' finely striate surface ornament. Its closest affinities are with W. dumonti figured by de Koninck (1883, pi. 35, figs. 11-14) from the Carboniferous limestone of Vise. De Koninck’s specimen is somewhat more globose than W. microstriata, but both have , similar surface ornament. BeUerophon stanvellensis Etheridge (1892), from the Lower Carboniferous beds of the Stanwell district, probably belongs to the genus Waagenella. It is readily distinguished from W. microstriata by its much greater size, coarser growth- lines, absence of revolving striae, relatively smaller selenizone, and less rapidly expand- ing whorl width. Etheridge’s type specimen has the recurved, much thickened apertural ! margins of Waagenella. Another, undescribed species of Waagenella has been found in i the Lower Carboniferous beds of Delgalgil Creek, north of Monto in the Glassford : district. This species is similar to BeUerophon stanvellensis, but is much smaller in size, has growth-lines curving backward from the selenizone, which is higher than that of B. stanvellensis. The exact locality and age of Etheridge’s specimens from Stanwell and the age of the Delgalgil Creek species are not known. W. microstriata has been found only at the one locality so far. It occurs in a limestone, below the main reef development at Old Cannindah. Its associated fauna as well as its affinities with European species sug- gest a Tournaisian age. Eamily euomphalidae de Koninck 1881 Diagnosis. Low spired, discoidal to subtrochoidal, dextrally coiled shell; wide umbilicus ; whorls rounded or angular; sinus in the upper part of the outer lip; ornament of con- centric growth-lines, and in some genera, revolving striae. Remarks. The euomphalids range from the early Palaeozoic to Cretaceous, reaching their maxima in the Devonian-Carboniferous and in the Triassic. The Carboniferous genera are characterized by the disappearance of the sinus and the tendency towards angularity in whorl cross-section. Further development of this tendency results in the appearance of nodes on the shoulders of the whorls. Knight (1934, pp. 142-5) recognized only one Carboniferous genus, Straparolus Montfort 1810, and one subgenus Eiiomphalus Sowerby 1812 in the Euomphalidae, and he referred the genera Schizostoma Bronn 1834, Phymatifer de Koninck 1881, and Phanerotinns Sowerby 1 844 to the synonymy of Straparolus. The main variation within the family Euomphalidae appears to be in shell form and whorl contour. Straparolus has the most trochiform shell, with evenly arched whorls, Euomphalus has a low, coiled shell, with angulation of the whorl and a tendency towards nodal development. If such differences are of generic value then Phymatifer de Koninck 1881 can be separated on the basis of nodal development on the upper shoulders of its whorls, and on its discoidal, depressed shell. Phanerotinns Sowerby can be distinguished by its open coiling and leaf- like expansions of the outer whorl. The shell of Schizostoma Bronn is similar to that of Euomphalus but the whorls are more angular. In view of their differences, it would seem advisable to accept the generic status of these forms. W. G. H. MAXWELL: LOWER CARBONIFEROUS GASTROPOD FAUNAS 65 Genus straparolus de Montfort 1810 Type species by original designation Straparolus dionysii Montfort 1 8 10, p. 1 74, from Namur, Belgium ; Lower Carboniferous. Diagnosis. Subdiscoidal to subtrochiform shell, with nueleus flatly coiled; rounded whorls, wide umbilicus ; low, revolving ridge on upper whorl surface, and sutures at line of contact of whorls, parietal lip with thin inductura, outer lip bent slightly backward to form weak sinus; ornament of fine growth-lines and fine revolving lirae. Remarks. The genus has been treated exhaustively by Knight (1934; 1941; 1947), who has given its range as Devonian to Lower Pennsylvanian. Straparolus australis sp. nov. Plate 8, figs. Holotype. F. 28615, Univ. Qld. Collections; from L.1970 between Splinter Creek and Mt. Cannindah, Portion 91, Parish Cannindah, County Yarrol, Queensland. Late Toumaisian-early Visean. Description. The shell is subtrochiform in shape with the first two whorls almost plani- spiral, and subsequent whorls becoming weakly trochiform. Sutures are relatively deep. Slight angularity of the upper shoulder develops in the later whorls, and this is separated from the upper suture by a somewhat flattened band. The tendency towards angularity is less apparent in the lower shoulder of the later whorls. The umbilicus is wide and steep sided. Ornament consists of numerous fine concentric growth-lines which curve slightly over the upper shoulder; no revolving striae can be distinguished. Dimensions. Holotype Syntypes Number of whorls 4 3-f 5 Height of whorl 10 mm. 7 9 Width of whorl 13 mm. = 10 10 Height of shell 17 mm. Width of shell 33 mm. Remarks. Straparolus australis resembles the species identified as S. dionysii from the Carboniferous of England and Ireland, but is generally larger and slightly less trochiform. Of the Belgian species, its closest affinities are with S. explanatus de Koninck 1881 (p. 125, pi. 21, figs. 5-7) from the Visean limestones of Vise. Like the type species, its whorls are well arched and not noticeably angular. It differs in this respect from the American species S. savagei Knight which has three distinct angular ridges. An undescribed species of this genus occurs in beds of Tournaisian age in the Rock- hampton district, Queensland. This form differs from S. australis, in that a row of rounded nodes occurs on the upper shoulder of the whorls, and its shape is less trochi- form. S. subdionysii sp. nov. is the second species which occurs in the limestones between Splinter Creek and Mt. Cannindah. It first appears about 500 feet below the bed with S. australis, and is also found associated with S. australis. S. subdionysii is a smaller, higher shell with distinct revolving bands. B 7879 F 66 PALAEONTOLOGY, VOLUME 4 Straparohis subdionysii sp. nov. Plate 8, figs. Sa-c Holotype. F. 28637, Univ. Qld. Collection; from L. 1872, between Splinter Creek and Mt. Cannindah, Portion 91, Parish Cannindah, County Yarrol, Queensland; Toumaisian. Description. The shell is symmetrically coiled, subtrochiform in shape, with a steep- sided umbilicus of moderate width. The whorls are fairly well arched in profile, and separated from earlier whorls by small sutures. A low ridge or shoulder is developed on the upper surface of the whorl, while the lower surface is well rounded. A band consist- ing of three minute ridges extends along the outer face of the whorl, and is bordered by slight depressions. The ornament consists of fine growth-lines. Dimensions. Holotype Syntype A Number of whorls 4 4 Height of whorls 10 mm. 6-5 mm. Width of whorls 10 mm. 8 mm. Height of shell 15 mm. 9 mm. Width of shell 23 mm. 17 mm. Remarks. S. subdionysii has marked affinity with the type species S. dionysii, and is distinguished from S. australis by its more trochiform shape. It resembles S. savagei Knight in the development of the raised band, but differs from the American species in shape. It occurs in beds of Toumaisian age. Genus phymatifer de Koninck 1881 Type species by selection of Knight 1941, p. 243; Eitomphaliis pugilis Phillips 1836, p. 225; from Bolland, Yorkshire, England; Lower Carboniferous. Diagnosis. Discoidal, evolute shell; depressed spire, wide umbilicus; whorls angular, with noses on upper and lower surfaces ; suture sharp, deep ; ornament of faint growth- lines, slightly curved over nodes. Remarks. De Koninck (1881, p. 149) erected the genus for species with tubercles developed on the upper and lower surfaces of the whorl. Knight believed that this tendency was apparent in species of Euomphalus s.s. and that it was not of generic significance. Consequently he suggested that Phymatifer was a synonym of Euomphalus. The tuberculate species and the non-tuberculate ones may form a gradational series, but EXPLANATION OF PLATE 8 Figs. 1-4. Straparohis australis sp. nov., Tellebang Formation, L. 1970, Por. 91, Parish of Cannindah. In, Apertural row and shell profile, holotype (F. 28615), x2. \b. Apical view, X2. 2, Apical view (F. 28618), x2. 3, Apertural view and shell profile (F. 28617), x2. 4, Part of whorl showing fine transverse striation, x 2. Figs. 5a-c. Straparohis siibdonysii sp. nov., Tellebang Formation, L. 1872, Por. 91, Parish Cannindah. 5a, Apertural view and shell profile, holotype (F. 28637), x2. 5b, Apical view, x2-25. 5c, Shell profile, x2-5. Palaeontology, Vol. 4. PLATE 8 MAXWELL, Lower Carboniferous Gastropods W. G. H. MAXWELL: LOWER CARBONILEROUS GASTROPOD LAUNAS 67 this has not yet been demonstrated. On the other hand, the discoidal, tuberculate forms are fairly readily distinguished from the others, and their grouping into a separate genus may have practical taxonomic and stratigraphic value. Because of this, the present author regards Phymatifer de Koninck as an acceptable, valid genus. Phymatifer occurs in the limestones of Holland, England, and Vise, Belgium, which are Visean in age. No American species appear to belong to the genus. In Queensland one species occurs in the limestones at Old Cannindah, and a smaller related species occurs in beds of Tournaisian age at Rockhampton. Phymatifer sp. Plate 7, fig. 9 Locality. L. 1970 between Splinter Creek and Mt. Cannindah, Portion 91, Parish Cannindah, County Yarrol, Queensland; late Toumaisian-early Visean. Remarks. Parts of the whorl showing trapezoidal cross-section, and the upper shoulder with well-developed nodes which continue towards the inner margins as low ridges have been found. Spacing of nodes is about 7 mm. The shape of the whorl cross-section and the nature of the nodes are strikingly similar to those of Phymatifer pugilis, the type species, from Holland, Yorkshire. Phymatifer tuberosus de Koninck (1881, pi. 13, figs. 4-7) from the Tournaisian limestones of Tournai, Belgium, has similar nodal development, but differs in that the shell is subtrochiform in shape. Family pleurotomariidae d’Orbigny Diagnosis. Conical dextrally coiled, shell; wide spiral angle; angular to subangular whorls flattened base; well-defined selenizone; ornament of transverse and revolving lines, variable in development. Remarks. The family ranges from the Silurian through to the Jurassic, the greatest number occurring in the Silurian, Devonian, and Carboniferous. Genus austroworthenia gen. nov. Type species Austroworthenia levis sp. nov. Diagnosis. Small, anomphalous, trochiform shell; selenizone slightly concave, broad, bordered by two carinae; whorl profile with two angulations, upper one coinciding with top Carina of selenizone, and projecting as ridge; lower angulation less prominent; surface weakly ornamented with fine transverse growth-lines ; no revolving or nodular ornament. Remarks. Austroworthenia has been erected for those species which are similar in shape to Worthenia de Koninck, Baylea de Koninck, and Hypselentonia Weller, but lack the strong revolving ornament of these genera. In Australia only one species, the genero- type, has so far been recognized, and this occurs in beds of late Tournaisian-early Visean age. Worthenia munsteriana de Koninck (1883, p. 66, pi. 32 bis, figs. 6, 7) from the Tournaisian of Tournai, Belgium, is the only European species which could be referred to the new genus. The other species figured by de Koninck all have marked revolving ornament. 68 PALAEONTOLOGY, VOLUME 4 Austroworthenia levis sp. nov. Plate 9, figs. 1-5 Holotype. F. 28645, Univ. Qld. Collection; from L. 1970, between Splinter Creek and Mt. Cannin- dah, Portion 91, Parish Cannindah, County Yarrol, Queensland. Late Toumaisian-early Visean. Description. The shell is comparatively small (9-19 mm. high), anomphalous and trochi- form. The upper whorl surface is flattened, and slopes at an angle of 125° from the axis to the upper angulation which is strongly carinate. The upper angulation coincides with the Carina bordering a wide, slightly concave selenizone. A smaller, less clearly defined Carina occurs along the lower edge of the selenizone. The lower angulation is less prominent and slightly rounded. Ornament consists of extremely fine growth-lines, directed backward at approxi- mately 30° on the upper surface, but curving forward across the selenizone, and then backward across the lower whorl surface. The growth-lines are very difficult to identify. No revolving costae or carinate nodes have been found. Dimensions. Holotype (F. 28645) F. 28646 F. 28647 F. 28648 F. 28643 Height (mm.) 19 15 12 11 7-5 Width of base (mm.) 16 14 10 11 6 Pleural angle 55° 60° 56° 56° 53° Remarks. Dimensions and proportions of A. levis are similar to those of the majority of species of Worthenia described from Belgium. In general, species of Baylea from that country are much larger. Order ctenobranchia Schweigger Family loxonematidae Termier and Termier Diagnosis. Turbinate, long shells, without selenizone; ornament of regular growth- lines, sometimes sinuous; revolving striae sometimes developed. Genus loxonema Phillips 1841 Type species by selection of King 1850, p. 209: Terebra simiosa J. de C. Sowerby 1839, p. 619; from Garden House, Aymestry, Shropshire, England; Silurian. EXPLANATION OF PLATE 9 Figs. 1-5. Austroworthenia levis sp. nov., Tellebang Formation, L. 1970, For. 91, Parish Cannindah. \a. Shell profile, holotype (F. 28645a), X2. \b. Latex impression of external mould of holotype (F. 286456), x2. 2, Shell profile (F. 28646), X2. 3, Shell profile (F. 28643), X2. 4, Shell profile (F. 28647), x2. 5, Shell profile (F. 28648), x2. Figs. 6-11. Loxonema lamellosa sp. nov., Tellebang Formation, L. 1970, For. 91, Parish Cannindah. 6, Cross-section of higher whorls and entire lower whorl (F. 28642), x 2. 7, Shell profile, showing aperture; specimen decorticated (F. 28641), x2. 8, Latex impression of external mould showing transverse costation (F. 28644), X2. 9, Shell profile and inner lip; specimen decorticated, holotype (F. 28639), X2. 10, Same view (F. 28643), X2. 11, Shell profile (F. 28644), X2. Palaeontology, Vol. 4. PLATE 9 MAXWELL, Lower Carboniferous Gastropods W. G. H. MAXWELL; LOWER CARBONIFEROUS GASTROPOD FAUNAS 69 Diagnosis. Small, high-spired, medium-sized shell; no umbilicus; whorl profile evenly convex; sutures deep; no selenizone, notch, or slit; outer lip with deep sinus; ornament of fine growth-lines curving backward from upper suture to lower shoulder then forward. Remarks. Loxonema was erected by Phillips 1841 for high-spired shells with fine oblique ornament. As defined by Phillips and later authors, the genus embraces a widely ranging group from the Ordovician to the Carboniferous. Finer subdivision, based possibly on external ornament, might seem desirable, but the narrow limits of variation make this difficult. The species from the Belgian Carboniferous appear to be separable into two main groups, namely, those with fine, regular growth-lines and those with concentric ribs or nodal ridges extending across the whorl from upper to lower suture. De Koninck (1881, p. 40) recognized this difference and separated his species into ^Laevigata' and ‘ Costal a \ It is doubtful, however, whether this division has any stratigraphic value since both costate and laevigate forms range through from the Devonian into the Carboni- ferous. Loxonema lamellosa sp. nov. Plate 9, figs. 6-1 1 Holotype. F. 28639, Univ. Qld. Collection; from L. 1970, between Splinter Creek and Mt. Cannindah, Portion 91, Parish Cannindah, County Yarrol, Queensland; late Toumaisian-early Visean. Diagnosis. Medium-sized, turbinate shell, with five to seven whorls; whorls convex with slight shoulders adjacent to upper and lower sutures, no umbilicus, no selenizone; orna- ment of regular growth lamellae. Description. The shell is turbinate, ranging in height from 19 to 45 mm. and in basal width from 1 0 to 1 8 mm. Its apical angle averages 25°. Five to seven whorls are developed. The whorl profile is moderately arched, with low shoulders developed between the periphery and the upper and lower sutures. The sutures are deep. No umbilicus is formed. The ornament consists of comparatively regular, arcuate growth lamellae which curve backwards from the upper suture to the periphery and then forwards to the lower suture. Remarks. L. lamellosa differs from the type species in the curvature of the growth lamellae. In L. sinuosum, the growth-lines extend forward from the upper aperture at approximately 45°, and continue across the lower shoulder, without interruption. In L. lamellosa, the growth-lines are concave towards the aperture, being almost per- pendicular to the sutures, and arching backwards over the periphery. Of the species in the Belgian Carboniferous faunas, it is most similar to the one from the Visean lime- stone of Vise, figured by de Koninck (1881, pi. 6, fig. 18) as L. pulclierrimum M‘Coy. No American species is comparable with L. lamellosa. Etheridge (1892, p. 285, pi. 15, fig. 17) figured a species from the Rockhampton district, which he compared with L. rugifera Phillips. This form is readily distinguished from L. lamellosa by its coarse ornament, shell shape, and whorl profile. L. lamellosa occurs in the Mundubbera district, in beds of Late Tournaisian-early Visean age. 70 PALAEONTOLOGY, VOLUME 4 REFERENCES BRONN, H. G. 1834. Lethaea Geognostica, 1, Stuttgart [not seen]. DEMANET, F. 1941 . Faune et stratigraphie de TEtage Namurien de la Belgique. Mem. Mits. Hist. Nat. Belg. 97, 1-327, pi. 1-18. ETHERIDGE, R. jun. 1892. The Geology and Palaeontology of Queensland and New Guinea. Publ. geol. Surv. Qd. 92, 1-756, pi. 1-68. FLEMING,!. 1828. A history of British animals. London [not seen]. HILL, D. 1951. Geology of Queensland. Handbook A. N.Z. A. A. S., Brisbane, 13-24. KING, w. 1850. A Monograph of the Permian fossils of England. Palaeontogr. Soc. KNIGHT, J. B. 1934. The gastropods of the St. Louis, Missouri, Pennsylvanian outlier, VI, the Euom- phalidae and Platyceratidae. /. Paleont. 8, 139-66, pi. 20-26. ■ 1941. Paleozoic Gastropod Genotypes. Spec. Pap. geol. Soc. Amer. 32, 1-510, pi. 1-96. KONiNCK, L. G. DE. 1881. Faune du calcaire carbonifere de la Belgique, 3® partie, Gasteropodes. Ann. Mas. Hist. nat. Belg., Ser. Paleont. 6. ■ — — 1882. Notice sur la famille des Bellerophontidae suivie de la description d’un nouveau genre de cette famille. Ann. Soc. geol. Belg. 9, 72-90. • 1883. Faune du Calcaire carbonifere de la Belgique, 4^ partie, Gasteropodes (suite et fin). Ann. Mas. Hist. nat. Belg., Ser. Paleont. 8. m‘coy, F. 1844. A synopsis of the characters of the Carboniferous Limestone fossils of Ireland. Dublin. 1851. On some new Silurian Mollusca. Ann. Mag. nat. Hist. (2), 7, 45-63. MONTFORT, p. D. DE. 1810. Conclivliologie systematique, et classification methodique des coquilles; off rant leiirs figures, leur arrangement generiqiie, leurs descriptions caracteristiques, leurs noms ; ainsi que leur synonymie en plusieurs langues. 2, Coquilles univalves, cloisonnees. Paris [not seen]. ORBiGNY, A. d’. 1 838. Histoire naturelle generale et particuliere des cephalopodes acetabuliferes vivants et fossiles. Paris [not seen]. PHILLIPS, J. 1841. Figures and descriptions of the Palaeozoic fossils of Cornwall, Devon, and West Somerset. London. SHiMER, H. w. and shrock, r. r. 1944. Index fossils of North America. Massachusetts. Inst. Techno- logy. sowERBY, J. 1812. No. Ill of the Mineral Conchology of Great Britain, 1, London. sowERBY, J. DE c. 1839. Ill MURCHISON, R. I., The Silurian System. London. — — 1844. Mineral Conchology of Great Britain, 7, London. TERMiER, G., and TERMiER, H. 1950. Iiivertebres de BEre Primaire. Tome II, Fasc. Ill, Mollusques. Paris. WAAGEN, w. H. 1880. Salt Range Fossils. Pt. 2. Palaeont. Indica (\3),l,13-\?,3,y)\.l-\6. WARTHiN, A. s. 1930. Micropaleontology of the Wetumka, Wewoka, and Holdenville formations. Bull. geol. Surv. Oklahoma, 53. WEIR, J. 1931. The British and Belgian Carboniferous Bellerophontidae. Trans, roy. Soc. Edin. 56, 767-865, pi. 1-9. W. G. H. MAXWELL Department of Geology, University of Queensland Manuscript received 7 March 1960 CAMBRIAN TRILOBITES FROM THE AMANOS MOUNTAINS, TURKEY by w. T. DEAN and r. krummenacher Abstract. Certain Palaeozoic rocks of the Amanos Mountains in southern Turkey have been investigated, and their stratigraphical relationships are briefly reviewed. Trilobites of Middle Cambrian, or Acadian, age have been collected from strata previously assigned to the Devonian. The specimens described here include the genus Pardailhania, together with an indeterminate agnostid, and suggest affinities with North African and eastern North American faunas of similar age. In the summer of 1957 one of the writers (R. K.) was sent by the Shell Petroleum Company of Turkey to study geological sections in the Amanos Mountains. A detailed examination was made of a series of rocks previously attributed to the Devonian (Dubertret 1953), though palaeontological proof was lacking. From these were col- lected trilobites, now known to be of Middle Cambrian age, which are described in this paper. The writers are indebted to the management of the N. V. de Bataafsche Petroleum Maatschappij for permission to publish the following results, and to Professor W. F. Whittard who has kindly read and criticized the manuscript. The Amanos is the southernmost massif in the succession of coastal ranges running north-south along the Mediterranean coast from Turkey towards Israel. About the latitude of Iskenderun the Belen Pass (680 metres) divides the Amanos into two well- defined blocks, the Kizil Dag in the south, and the Giaour Dag, or Nurdaglari, in the north (text-fig. 1). The latter, culminating in the Migher Tepe (2,224 metres), exhibits on its eastern flank various geological formations which have not been encountered elsewhere in the area. A geological map on the scale 1:200,000, drawn by Dubertret, was published in 1952 by the Institut Geographique National, Paris, whilst Blumenthal and Turkenal, two geologists of the Maden Teknik Ve Arama Enstitusu, Ankara, had earlier, in 1944, completed the Malatya sheet of the 1 ; 800,000 geological map of Turkey. In the Amanos the latter map shows mainly undifferentiated Palaeozoic rocks, limited on their eastern side by a narrow strip of Permo-Carboniferous(?) limestones. STRATIGRAPHY Owing to the broken nature of the terrain of the Giaour Dag, continuous successions can be followed for only short distances. The best-exposed section that has been examined lies west-south-west of Saylak, 12 kilometres north by east of Kirikhan, and it was here that trilobites were found. Access to the section is still diflicult, and the following succession was established mainly along a mule track connecting Araplisagi with the mountains, and completed along a forestry road which, in 1957, was being built south-east of Dortyol. Owing to the absence of local stratigraphical names the formations in this description are given the letters A to E in ascending order (text- fig. 2). [Palaeontology, Vol. 4, Part 1, 1961, pp. 71-81, pi. 10.] TEXT-FIG. 1. Map of southern Turkey showing the Kizil Dag and Giaour Dag blocks of the Amnos Mountains. TEXT-FIG. 2. Section across the Amnos Mountains near Saylak. Vertical scale doubled. W. T. DEAN AND R. KRUMMENACHER: CAMBRIAN TRILOBITES 73 Formation A. A monotonous series of alternating, well-bedded, quartzitic sandstones and phyllitic shales, dark red to dark green-brown in colour. The rocks are unfossili- ferous and more than 1,000 metres thick. At Araplisagi they dip to the east-south-east at 45 degrees, but become steeper towards the Migher Tepe. The beds are separated by a strong, angular unconformity from; Formation B. Massive, pinkish, quartzitic sandstones and conglomerates with some thin intercalations of ferruginous, micaceous shale. Pebbles of pale quartzite, dark schist, and igneous material occur throughout, and cross-bedding is common. The rocks become more ferruginous and shaly towards the top, culminating in an horizon of ferruginous shales a few metres thick. No fossils have been found and the total thickness is about 600 metres. There is a gradual passage to : Formation C. The lower beds include lenses of blue-grey limestone, or coarsely crystal- line, dark, dolomitic limestone, in a ferruginous, shaly matrix. Higher in the succession coarsely crystalline, dark-blue to black, dolomitic limestones or dolomites form beds from 20 to 50 cm. thick, with thin, shaly intercalations. The rocks are 185 metres thick, apparently unfossiliferous, and followed conformably by; Formation D. The basal beds comprise current-bedded, calcareous shales and shaly limestone, whilst higher in the succession are dark green, calcareous shales, both laminated and cross-bedded, with vugs at some points. The basal beds contain com- minuted shell fragments and worm tracks. Middle Cambrian trilobites have been col- lected 5 metres above the base of the formation, along the road climbing from Saylak to the Alan Plateau (text-fig. 2). Total thickness is 250 metres and the rocks are separated by a disconformity from the overlying; Formation E. Massive, pale, coarse to conglomeratic, quartzitic sandstones. Green, sandy, micaceous shales alternate with nodular, green-brown, quartzitic sandstones higher in the succession. The topmost strata comprise a few layers of soft, sandy shale, of a characteristic deep-purple colour. No fossils have been found and the thickness, as measured above Dortyol, is 85 metres. The outcrop of Formation E was traced northwards as far as the village of Ayran, 8 kilometres north-north-west of Fevzipasa, where it was found to be much better developed. The sediments there, 1,115 metres thick, exhibit structures attributed to slumping in the upper part of the section, where worm tracks and the so-called trilobite tracks known as 'Fraena' were encountered. The only stratigraphically useful fossil yet found in this formation is a badly damaged trilobite; at one time this was supposed to belong to the Silurian genus Acaste (Freeh 1916, p. 51), but the specimen has since been redetermined by R. Richter as Dalmanitina sp. and held to indicate an Ordovician age (Dubertret 1953). Above Dortyol, Formation E is transgressed, though without angular unconformity, by a massive, blue-grey, dolomitic breccia which passes upwards gradually into a well- bedded, pale, gypsiferous, dolomitic limestone with some thick intercalations of yellowish mudstone. The only fossils found were a few indeterminate algae and polyzoa, but a regional study of the formation suggests that it can be equated with the Devonian rocks of Hassanbeyli to the north (Blankenhorn 1891, p. 60). The Middle Cambrian or, more precisely. Lower Acadian age of Formation D is 74 PALAEONTOLOGY, VOLUME 4 shown by the contained trilobites, belonging to the genus Pardailhania. Formations B, C, and D form a conformable succession, the whole of which is believed to be Cambrian in age, and the lower beds may represent an undetermined portion of the Lower Cambrian. Formation A is thought to be Pre-Cambrian in age as it is strongly trans- gressed by the supposed Cambrian of Formation B. The Ordovician age of Formation E has been indicated in the Aryan area, and subsequently a general transgression at the base of the series of calcareous and dolomitic rocks of Devonian age occurred through- out the Amanos (text-fig. 3). Generally speaking, the deposition of the Cambrian rocks throughout the Middle East commenced with a continental or littoral environment which produced mainly coarse elastics, together with occasional evaporites, viz. the ‘Cambrian Salt’ of Persia. In the Middle Cambrian these conditions were terminated by a marked marine trans- gression directed approximately southwards, carbonates being deposited as far south as Persia and the Gulf of Akaba, though they have not been reported from Saudi Arabia. At about the end of Cambrian times, sometimes following a marked discon- formity, deposition of elastics recommenced and continued through the Ordovician and Silurian. The great accumulation of Lower Palaeozoic clastic rocks found in the north of the Amanos, with their general lack of fossils and abundance of worm-tracks, slumping features, and nodular shales, suggests rapid, flysch-like sedimentation under unstable tectonic conditions. The facies of the Lower Palaeozoic rocks of the Amanos are comparable with those of the Anti- Atlas, probably forming part of the same geosynclinal area, and it is interest- ing that the Middle Cambrian trilobites described in this paper bear most resemblance to a Moroccan species which, in turn, exhibits affinities with an eastern North American form. The Cambrian rocks of the Amanos apparently escaped the effects of the Caledonian Orogeny, and it is expected that they will be found to pass laterally into part of the highly metamorphosed series of the Taurus Mountains farther north. Prior to Devonian times some of the Ordovician and ?Silurian rocks were eroded in the south of the area, but during the remainder of the Palaeozoic deposition the Amanos acted as a stable ‘platform’ which received considerably reduced sedimentation. SYSTEMATIC PALAEONTOLOGY All the fossils found in the Cambrian rocks of the Amanos are trilobites from only one locality. Ten specimens, preserved as internal and external moulds, were collected; nine belong to one species, described below as Pardailhania cf. barthouxi, and one to a generically indeterminate agnostid. Family solenopleuridae Angelin 1854 Subfamily solenopleuropsinae Thoral 1948 {nom. transl. herein ex solenopleuro- psiDAE Thoral 1948) = saoinae Hupe 1953 The genera Pardailhania Thoral 1947, Rimouskia Resser 1938, Sao Barrande 1846, and SoJenopleuropsis Thoral 1947, have been grouped together by Poulsen (1954, pp. 445-6; in Moore 1959, p. O 276) in the subfamily Saoinae, a name used originally as Family Saoidae Hupe 1953. If these genera are accepted as belonging to the same W. T. DEAN AND R. KRU M MENACHER: CAMBRIAN TRILOBITES 75 ssw 4A KM. NNE HASSA-DORTYOL AYRAN AREA AREA DEVONIAN FAUNA TEXT-FIG. 3. Vertical sections in the northern Amnos Mountains. ORDOVICIAN -r’SILURIAN 76 PALAEONTOLOGY, VOLUME 4 subfamily, then the name Solenopleuropsinae, derived from the familial name proposed earlier by Thoral (1948, p. 82) for the genera Solenopleuropsis and Pardailhania, has priority. Genus pardailhania Thoral 1947 Type species Solenoplewa? hispida Thoral, 1935, by original designation Pardailhania cf. barthouxi (Mansuy) Plate 10, figs. 1, 2, 4, 7, 9, 10-13 1922 Ptychoparia barthouxi n. sp., Mansuy, p. 288, pi. 10, figs. Aa-g. Description. Cephalon roughly semicircular in outline, with median length about half the breadth. Though the specimens are somewhat flattened, the glabella appears to be moderately convex, with basal breadth about one-third that of the cephalon and three- quarters or more of its own length. Glabellar outline almost a trapezium, its sides con- verging forwards gradually to the frontal lobe at about 20 to 25 degrees ; the latter is delimited by a shallow preglabellar furrow, generally transversely straight or gently convex forwards. Almost all the specimens have a smooth, unfurrowed glabella, but one (PI. 10, fig. 7) shows three pairs of faintly impressed glabellar furrows. First pair of furrows barely discernible; second furrows straight, extending only a short distance adaxially from axial furrows. Basal glabellar furrows run adaxially and then rearwards from the axial furrows without reaching occipital furrow, each extending across the glabella about one-quarter of its basal breadth. The three glabellar lobes so defined are of roughly equal length {exsag.), each about one-quarter the median length of the glabella. Axial furrows deep, almost straight or slightly convex abaxially; in only the largest specimen do they contain a pair of poorly developed anterior pits. In front of the preglabellar furrow is a broad (sag.), flat or slightly convex, preglabellar field, equal to about one-quarter of the glabellar length ; in front of this the anterior border rises EXPLANATION OF PLATE 10 Figs. 1, 2, 4, 7, 9, 10-13. Pardailhania cf. barthouxi (Mansuy). Lower or lower Middle Acadian, road leading to the Alan Plateau above Saylak, north-north-east of Kirikhan, Turkey. 1, Km 565 dl, internal mould of immature cranidium. 2, 4, Km 565 d2, external mould and corresponding latex cast of cranidium showing smooth glabella and broad {sag.) preglabellar field. 7, Km 565 d3, latex cast from external mould to show occipital ring and traces of glabellar furrows. 9, 13, Km 565 c, external mould and latex cast of most complete specimen showing form of ocular and fixigenal ridges, and thoracic segments. 12, Km 565 b, internal mould of same individual. 10, 11, Km 566 e, external mould and latex cast of incomplete cephalon to show course of facial suture, and posterior portion of free cheek with genal angle. Fig. 3. Pardailhania hispida (Thoral). Lower Acadian, Route de St. Jean de Pardailhan, Coulouma, Herault, France. In. 42020, external mould of incomplete cranidium showing transverse arrangement of tubercles on glabella. Ocular ridge not well developed. Figs. 5, 6. Pardailhania granieri (Thoral). Lower Acadian, Vigne de Cauquil, Coulouma, Herault, France. In. 49479, latex cast and external mould of cranidium showing fusion of tubercles on glabella to form transverse ridges, and strong development of ocular and fixigenal ridges as in the Turkish specimens above. Fig. 8. Agnostid gen. and sp. indet. Km 566 b, poorly preserved internal mould of cephalon. Horizon and locality as fig. 1 . Palaeontology, Vol. 4. PLATE 10 X 2-9 X 2.9 X 32 X 2-8 DEAN and K R U M MEN ACH ER, Pardailliaiiia W. T. DEAN AND R. KRUMMENACHER: CAMBRIAN TRILOBITES 77 Steeply, in outline convex longitudinally, and thickening medially. Occipital furrow moderately deep and transversely straight; occipital ring convex, fairly long (j'ag.) becoming shorter {exsag.) towards the axial furrows. Immediately outside the axial furrows the posterior border is strongly convex, becoming narrower {exsag.) and less well developed abaxially until it meets the blunt genal angles. None of the specimens has the eyes preserved. Each fixigena carries a pronounced ocular ridge which commences at the axial furrows, slightly behind the line of the pre- glabellar furrow, arches abaxially and backwards until, opposite the mid-point of the glabella, it turns adaxially slightly and then ends abruptly about in line with the basal glabellar furrows, when the latter are visible. In the best-preserved specimens each ocular ridge is seen to be thin and vertical frontally, becoming less steep postero- laterally and at the same time thickening slightly so as to form an overhanging palpebral lobe (see PL 10, fig. 13). On its adaxial side the ocular ridge is bounded by a faint palpebral furrow in the vicinity of the eye. Just to the rear of the junction of each ocular ridge and axial furrow, another ridge of similar height and thickness begins. There seems to be no suitable term in use for such a structure, and Professor Whittard has suggested {in Hit.) that the name ‘fixigenal ridge’ be employed. At first each fixigenal ridge runs backwards and slightly abaxially, parallel to and bordering the axial furrow, but just before reach- ing the pleuroccipital furrow it turns abaxially through about 110 degrees and extends laterally, almost straight and parallel to the furrow, reaching a point a short distance adaxially from the lateral border, where it is truncated by the posterior branch of the facial suture (see PI. 10, figs. 10, 11). As already stated, the eyes are not preserved but it is possible to determine their extent from the position of the facial suture. Anterior branches run straight forwards for a short distance from the posterolateral end of the ocular ridges, and then become slightly sigmoidal, curving first abaxially and finally forwards again to intersect the anterolateral margins. Posterior branches extend ab- axially and slightly backwards from the rear ends of the ocular ridges and then curve sharply backwards, first to truncate the outer ends of the fixigenal ridges and then to cut the posterior margin of the cephalon a short distance adaxially from the genal angles. The posterior margin of the cephalon between the facial suture and the genal angle is straight and cut forwards obliquely to the blunt genal angle. The free cheeks thus differentiated are small. Dorsal surface of the exoskeleton in all the available specimens is smooth. Hypostome unknown. One specimen (PI. 10, figs. 9, 12, 13) possesses at least nine thoracic segments but is so badly preserved that it is impossible to determine the total number present. Each segment has a moderately long {sag.) axial ring which curves forwards slightly at either end towards the axial furrows to form small axial nodes. Large articulating half-ring separated from axial ring by broad {sag.), deep, articulating furrow. Each pleura curves gently rearwards from the axial furrow, and then forwards, terminating in a broad, rounded tip (see PI. 10, fig. 13). Pleura divided into two bands of unequal size, of which the anterior is the smaller, by deep pleural furrow which, commencing at the axial furrow in a median position, runs abaxially and at the same time draws nearer to the anterior margin of the pleura, finally dying out without reaching the tip. Dorsal surface smooth like that of the cephalon. Pygidium unknown. 78 PALAEONTOLOGY, VOLUME 4 Locality and horizon. All the Turkish specimens described and figured in this account are from the road leading to the Alan Plateau above Saylak, 12 kilometres north-north- east of Kirikhan, Province of Hatay, Turkey (see Fig. 1). No associated fossils have been found which might indicate a precise horizon within the Middle Cambrian, or Acadian, but by analogy with material from southern France the age of the fauna is probably Lower Acadian. As originally described by Mansuy (1922) Pardailhania barthouxi is a member of a fauna which includes also a Paradoxides said to be P. rugidosus Hawle and Corda, though this is possibly a misidentification. According to Strand (1929, pp. 314-15, 337, 350) the latter species is characteristic of Stage Ic 8 (equivalent to the Zone of Para- doxides davidis, Middle Cambrian) of Norway, and a similar horizon is listed by Cobbold and Pocock (1934, pi. 39) for other successions. The Turkish and Moroccan specimens are probably older. Figured specimens. Pardailhania cf. barthouxi, Km 565 b (PI. 10, fig. 12), Km 565 c (PI. 10, figs. 9, 13), Km 565 dl (PI. 10, fig. 1), Km 565 d2 (PI. 10, figs. 2, 4), Mm 565 d3 (PI. 10, fig. 7), Km 566 e (PI. 10, figs. 10, 11). All these specimens are in the collections of the N. V. de Bataafsche Petroleum Maatschappij, Gravenhage, Netherlands. The two cranidia of other species figured for comparison with the above are as follows: Pardailhania hispida, In. 42020 (PI. 10, fig. 3); Pardailhania granieri. In. 49479 (PI. 10, figs. 5, 6). Both specimens are in the British Museum (Natural History), London. Discussion. The genus Pardailhania was founded by Thoral (1947, p. 60) on his earlier described species Solenopleura? hispida, from the Lower Acadian of Coulouma, Herault, southern France, and used by him to include a number of species, all of Acadian age. In these the surface details of the cephalon vary considerably, ranging from forms in which the glabella carries tubercles arranged in transverse rows, or even fused together into transverse ridges, to others in which the surface of the glabella is smooth. Although the type-species was later described by Thoral (1948, pp. 52-55) as possessing both genal and occipital spines, in the present paper Pardailhania is considered to include also species lacking these features, a course followed by Thoral (1947) in his original diagnosis. Generally speaking, the species usually assigned to the genus fall into two groups as follows: Group A. Surface of glabella ornamented with tubercles arranged in transverse rows or fused together to form transverse ridges separated by a smooth, longitudinal, median band as in the related genus Sao. Pair of ocular ridges usually well developed; sometimes a pair of fixigenal ridges present. Species include P. hispida (Thoral), P. granieri (Thoral), P. multispinosa Thoral, and P. hispanica Sdzuy ex R. and E. Richter MS. ; P. couloumana (Miquel) may also belong here. All these species are easily distinguished by their ornate cephala from the Turkish specimens, and the first two listed above are figured here for comparison (PI. 10, figs. 3, 5, 6). Group B. Surface of glabella smooth, occasionally showing three or four poorly defined pairs of glabellar furrows. Pair of ocular ridges and, generally, one pair of fixigenal ridges well developed, though one species P. paschi Sdzuy, probably belonging here, has three pairs of fixigenal ridges, two of them small. Species include P. tenera (Hartt), P. barthouxi (Mansuy), and P. pasehi. W. T. DEAN AND R. KRUMMENACHER: CAMBRIAN TRILOBITES 79 The trilobite determined by G. and H. Termier (1950, p. 25, pi. 204, fig. 21) as Par- dailhania cf. coiiloumana (Miquel) is poorly illustrated and may not belong to the genus. Two species of North American Middle Cambrian trilobites have been referred by Shimer and Shrock (1944, p. 605) to the genus Andrarina, namely A. ouangondiana and A. lenera. Andrarina, type-species Liostracus acideatus Angelin, 1854, was proposed by Raymond (1937, p. 1106) on the grounds that Angelin 18 54 was preoccupied by Leiostracus Albers 1850. This argument does not conform to the International Rules of Nomenclature and, in fact, Liostracus was first used by Morch (1852, p. 26). His name was, however, an invalid emendation of Leiostracus Albers 1850, and as such it preoccupies Liostracus Angelin 1854, even though it has no validity as a generic name itself. The species Andrarina ouangondiana was described by Hartt {in Dawson 1868, p. 651) as Conocephalites ouangondianus but was figured for the first time by Walcott (1884, p. 37, pi. 5, figs. 4, 4a-/) who referred the species to Ptychoparia. The species appears to be a typical Andrarina, and Strand (1929, p. 339) has claimed that it is synonymous with A. aculeata. The so-called Andrarina tenera was also first described by Hartt {in Dawson 1868, p. 652) from the Saint John Formation of Portland, New Brunswick. Again the species was illustrated for the first time by Walcott (1884, pi. 5, figs. 6, 6a, b) who referred it to Ptychoparia and placed another species, described by Hartt (loc. cit., p. 654) as Conocephalites negleetus in the synonymy. There can be no doubt, however, that we are dealing with a typical Pardailhania of Group B as listed above. Walcott’s diagrams of P. tenera show only the cranidium but they indicate that it differs from those of the Turkish specimens in having a more pointed glabellar out- line, and a small median tubercle on the occipital ring. In addition, the largest specimen has a pair of basal glabellar furrows which meet across the centre of the glabella to form a single transglabellar furrow. The same species was redescribed as Liostraeus tener by Matthew (1888, p. 137, pi. 1, figs. 3a-c) who illustrated a whole individual for the first time. The thorax of this specimen possesses fifteen segments, apparently about the same as those of the Turkish specimen described above, and an extremely small pygidium. Matthew’s drawings show an even more pointed glabellar outline than do those of Walcott, with four pairs of glabellar furrows which were said to be visible only on the internal mould. The Turkish specimens of Pardailhania most resemble the species first described by Mansuy (1922, p. 288, pi. 10, figs. 4a-g) as Ptychoparia barthouxi from Marakech, Morocco. All the specimens figured by Mansuy appear to be distorted by cleavage to a greater or lesser degree, but their cephala agree in all essentials with those of the Turkish material and are probably conspecific, though this cannot be certain in the absence of uncrushed specimens. The pygidium of the Moroccan species is not properly known, but the thorax consists of fifteen segments similar to those of both Pardailhania tenera and P. cf. barthouxi (PI. 10, figs. 9, 12, 13). P. pasehi (Sdzuy 1958, p. 24, pi. 2, fig. 1) from the middle Murero-Schichten of Spain is easily distinguished from P. barthouxi by its possession of three pairs of fixigenal ridges, the two anterior pairs being small and convergent forwards, and the posterior pair comprising only transverse ridges. The carapace is smooth as in the other members of Group B, and the thoracic segments are of similar construction. The age of this species is Lower Acadian, as it has been recorded in association with P. hispida and P. granieri (Lotze 1958, p. 731). 80 PALAEONTOLOGY, VOLUME 4 Middle Cambrian fossils have been recorded elsewhere in Turkey from the Mardin region (Stubblefield in Tolum and Ternek 1952, p. 17) where the fauna includes Para- doxides and Solenopleura cf. hispida, indicating the presence of Pardailhania of Group A, though there is no record of any species of Group B. Family agnostidae M‘Coy (s.l.) Genus and species indet. Plate 10, fig. 8 Only one other trilobite has been found with the specimens of Pardailhania cf. barthouxi described above. The state of preservation is extremely poor, but the fossil is figured here for the sake of completeness. It consists of the cephalon of an agnostid trilobite, about 3 mm. long and of similar breadth at the base, preserved as a damaged internal mould. Sufficient detail cannot be observed to make a firm generic determina- tion, though numerous agnostids are known from strata of similar age in southern France (Howell 1937), some in association with Pardailhania, and Stubblefield {in Tolun and Ternek 1952, p. 17) has recorded Peronopsis and Pardailhania (= Soleno- pleura cf. hispida) elsewhere in Turkey. Figured specimen. Km 566 b. REFERENCES BLANKENHORN, M. 1891. Gruudzuge der geologic imd physikaUschen geographic von Nord-Syrien. Berlin. COBBOLD, E. s. and POCOCK, R. w. 1934. The Cambrian area of Rushton (Shropshire). Phil. Trans. Roy. Soc. Lond., B 223, 305-409, pi. 38-45. DAWSON, J. w. 1868. Acadian Geology. The geological structure, organic remains and mineral resources of Nova Scotia, New Brunswick, and Prince Edward Island. 2nd ed. London. DUBERTRET, L. 1953. Note explicative de la feuille an 200.000 ‘d’Antioche’. Institut Geographique National, Paris. FRECH, F. 1916. Geologic Kleinasiens im Bereich der Bagdadbahn. Zeit. deutsch. geol. Ges. 68, 1-325, pi. 1-24. HOWELL, B. F. 1937. Cambrian and Ordovician trilobites from Herault, southern France. /. Paleont. 9, 222-38, pi. 22-23. LOTZE, F. 1958. Zur stratigraphic des Spanischen Kambriums. Geologic, 7, 727-50. MANSUY, H. 1922. Description de quelques trilobites du Cambrien du Maroc. Bull. Soc. geol. France, 22, 285-90, pi. 10. MATTHEW, G. F. 1888. Illustrations of the fauna of the St. John Group. No. 4. Trans. Roy. Soc. Canada, 5 (4), 115-66, pi. 1-3. MOORE, R. c. 1959. Treatise on Invertebrate Paleontology. Part O. New York. MORCH, o. A. L. 1852. Catalogus Conchyliorum quae reliquit D. Alphonso d'Aguirra & Gadea Comes de Yoldi, Regis Daniae cubiculariorum princeps, ordinis Dannebrogici in prima classe & ordinis caroli terth eques. Hafnia. POULSEN, c. 1954. Attempt at a classification of the trilobite family Solenopleuridae. Meddel. Dansk. geol. Foren. 12, 442-7. RAYMOND, p. E. 1937. Upper Cambrian and Lower Ordovician trilobita and ostracoda from Vermont. Bull. Geol. Soc. Amer. 48, 1079-146, pi. 1-4. SDZUY, K. 1958. Neue trilobiten aus dem Mittelcambrium von Spanien. Senckenbergiana Feth. 39, 235-53, pi. 1, 2. SHiMER, H. w. and shrock, r. r. 1944. Index fossils of North America. New York and Cambridge, Mass. W. T. DEAN AND R. KRUMMENACHER: CAMBRIAN TRILOBITES STRAND, T. 1929. The Cambrian beds of the Mjosen district in Norway. Norsk, geol. tidsskr. 10, 308-65, pi. 1, 2. TERMiER, G. and TERMiER, H. 1950. Palcontologie Marocaine. 2, Actual. Sci. Industr. 1095. Paris. THORAL, M. 1947. Trois nouveaux genres de trilobites acadiens du Languedoc et d’Espagne. Comptes Rend. Seances Acad. Sci. 224, 59-60. 1948. Solenopleuridae et Liostracidae Languedociens. Ann. Univ. Lyon, C, Sci. Nat. 5, 1-89, pi. 1-6. TOLUN, N. and ternek, z. 1952. Notes Geologiques sur la Region de Mardin (Resume). Bull. Geol. Soc. Turkey, 3 (2), 15-19. WALCOTT, c. D. 1884. On the Cambrian faunas of North America. Preliminary Studies. Bull. U.S. Geol. Surv. 10, 281-354, pi. 1-10. Manuscript received 10 March 1960. w. t. dean, British Museum (Natural History), South Kensington, London, S.W. 7 R. KRUMMENACHER, Shell Condor, S.A., Bogota, Colombia, S.A. B 7879 G THE SEXUAL ORGANIZATION OF CRETACEOUS PERMOCALCULUS (CALCAREOUS ALGAE) by G. F. ELLIOTT Abstract. Permocalculus ampuUacea Elliott, from the lower part of the Lower Cretaceous of Algeria and Iraq, is believed to be based on plants of the sexual generation of the botanical species, including female plants; and associated fossils are interpreted as representing both male and asexual plants, so indicating a sexual organization like that of the comparable living chaetangiacid alga Galaxaura. In the living marine chaetangiacid alga Galaxaura separate individuals are either of dioecious sexual plants or asexual plants ; the two categories are often morphologically dissimilar, and were originally classified as different taxonomic sections of the genus. Howe (1917, 1918) assumed from this that the two were related on the basis of an alternation of generations. The recognition of sexual and asexual forms of the same species has, however, proved very difficult, and in spite of very detailed studies Svedelius (1953) concluded that only by experimental spore-culture could such a relationship be definitely established. For this reason the writer (Elliott 1956, 1960), dealing with largely fragmentary remains of the extinct alga Permocalculus, similar to Galaxaura, stressed the impossibility of classifying these fossils other than on a strictly morpho- logical basis. From the Cretaceous of Iraq three such species were described, distinguish- able on average typical pore-diameter, size and shape of whole segments, and the nature of typical fragments, which depends on calcification and size of segment. These species (Elliott 1956, 1958, 1959) are P. ampuUacea (Valanginian-Hauterivian), P. inopinatus (Barremian-Aptian), and P. ireuae (Albian-Cenomanian). The present note deals primarily with the first of these. Remains of Permocalculus ampuUacea Elliott. This species occurs in north Iraq from the Jurassic-Cretaceous passage level through Valanginian and Hauterivian, as evidenced by its occurrence in the local Zangura, Garagu, Lower Sarmord, and Lower Qamchuqa formations of various deep wells in the Mosul and Kirkuk areas. In Algeria the species also occurs at these Lower Cretaceous levels. As described from the type material (Elliott 1959), P. ampuUacea is a species of ‘waxing-and-waning’ morphology, roughly circular in cross-section, with variable calcification, and fine surface pores of about 0-012 mm. diameter (PI. 11, fig. 1). Occa- sional specimens show scattered internal sporangial cavities (fig. 4). Associated commonly with it are fragments and debris of a much more coarsely pored but thin-walled form, with pore-diameter of 0-025-0-040 mm. (fig. 4). This has not yet been found as a complete segment, but certain pieces suggest that the segments were probably circular in cross-section. Also, rarely, there are associated remains of peculiar structures, flattened in cross-section, showing very numerous crowded cavities, smaller in size than the sporangial cavities of P. ampuUacea s. str. ; the mesh between these cavities is sometimes partly disintegrated (figs. 2, 3). [Palaeontology, Vol. 4, Part 1, 1961, pp. 82-84 pi. 11.] G. F. ELLIOTT: CRETACEOUS PERMOCALCULUS 83 Comparison of Galaxaura and PermocalciiJus. Now in living Galaxaura the reproductive cavities (cystocarps) of female plants of the sexual generation are scattered in segments of the plant which are more or less rounded in cross-section (text-figs, la, 2b), and which are mechanically as stout as other segments. In the male plants, however, the cavities are smaller than in the female, and crowded in special, rather fragile, terminal segments TEXT-FIG. 1. Galaxaura glahriusciila Kjellm. Recent; x4. a. Female branch with cystocarps; b, male branch with spermatangial cavities. After Svedelius (1953). TEXT-FIG. 2. Galaxaura glabriuscula Kjellm. Recent; x23. Cross-sec- tions of a, male branch; b, female branch. After Svedelius (1953). which are flattened in cross-section (text-figs. \h, 2a): these segments, after discharge of the spermatangial contents, probably drop off (Svedelius 1953, p. 17) and are replaced by proliferation shoots. In the asexual plants the little tetraspores are borne amongst the coarse threads or hairs of the surface, and leave no reproductive cavities in the subdermal calcification comparable with those of the sexual plants. It is therefore suggested that Permocalcuhis ampuUacea as described is based on plants of the sexual generation of the botanical species, female when the sex is recognizable; that the rare structures described above represent reproductive segments from male plants; and that the abundant coarsely pored debris is from the asexual plants. The analogies on size and arrangement of cavities, and on the form of the containing seg- ments, already indicated above between sexual Galaxaura and Permocalcuhis, are supported by the rarity of the fragile spent male structures, shed before the break-up 84 PALAEONTOLOGY, VOLUME 4 ! of the whole plant which provides most of the debris for fossilization, and by the very coarsely pored presumed asexual debris. For as already stated, the asexual plants of | Galaxaura differ markedly in appearance from the sexual ones, and the coarsely pored j thin subdermal calcification in the fossil Permocalculus is what one would expect from j a hairy rough-surfaced plant, such as is known in Galaxaura. It may also be of signifi- : cance that Howe (1917, p. 622) records that in dried herbarium specimens of the Recent Galaxaura only the single superficial cell-layer exfoliates in sexual plants, whereas in the asexual plants two outer cell-layers come away. Possibly this mechanical consequence of cell-structure correlates with the differentiated fragmentation seen in the fossils. This tripartite association has not yet been seen in the later Cretaceous species, P. inopiiiatus and P. irenae. This may be remedied by future collecting, but an alternative I explanation is possible. Svedelius (1953, pp. 10, 50) has indicated the possibility of various Recent Galaxaura spp. being able to exist without alternation of generations, either solely in the sexual phase or solely as spore-producing individuals. Algae are ’ primitive plants, and it may well be that the evolution of Permocalculus during the Cretaceous included a simplification of reproductive mechanism. ^ Acknowledgements. I am grateful to Mrs. Y. M. Butler, in charge of marine algae at the British Museum (Natural History), Dept, of Botany, with whom I discussed the observations set out here; to M. J. Emberger, of Algiers, who sent me comparison-material from the North-African Cretaceous; and to the Management of Iraq Petroleum Company, Ltd., for permission to publish this note. The text figures are reproduced by courtesy of the Royal Society of Sciences of Uppsala. s REFERENCES j ELLIOTT, G. F. 1956. Galaxoiim (calcareous algae) and similar fossil genera. J. Wash. Acad. Sci. 46, 341-3. I 1958. Algal debris-facies in the Cretaceous of the Middle East. Palaeontology, 1, 254-9, pi. 45^8. 1959. New calcareous algae from the Cretaceous of Iraq. Rev. Micropaleont. 1, 217-22, 2 pi. 1960. Fossil calcareous algal floras of the Middle East. Quart. J. geol. Soc. Land. 115, 217-32. HOWE, M. A. 1917. A note on the structural dimorphism of sexual and tetrasporic plants of Galaxaura obtusata. Bull. Torrey hot. Cl. 43, 621-4. I 1918. Further notes on the structural dimorphism of sexual and tetrasporic plants in the genus jj Galaxaura. Mem. Brooklyn bot. Gdn. 1, 191-7, pi. 3, 4. ! SVEDELIUS, N. 1953. Critical studies on some species of Galaxaura from Hawaii. Nova Acta Soc. Sci. j upsal. (4) 15 (9). j G. F. ELLIOTT [ Iraq Petroleum Co. Ltd., I Manuscript received 18 March 1960 London, W. 1 j| Note. Similar structures have recently been seen in Permocalculus inopiiiatus from the Barremian- ii Aptian of the Hadhramaut, Southern Arabia. EXPLANATION OF PLATE 11 Fig. 1. Permocalculus ampullacea Elliott, longitudinal thin-section, X50. Lower Cretaceous, Hauteri- vian; south flank of Djebel Harraza, Algeria. Brit. Mus. (Nat. Hist.) Dept. Palaeont., reg. no. V. 41663. Fig. 2. Presumed male branch of this species, oblique-transverse thin-section, x 50. Lower Cretaceous, i Hauterivian; Kirkuk well no. 116, Iraq. Reg. no. V. 41733. j Fig. 3. Presumed male branch, longitudinal thin-section, X50. Locality and horizon as for fig. 2. Reg. no. V. 41732. | Fig. 4. Random cut showing presumed female branch with incompletely calcified sporangia on viewer’s j right, and fragments of coarsely pored presumed asexual form on left, x 50. Locality, horizon, and | registered number as for fig. 1. PLATE 11 Palaeontology, Vol. 4. ELLIOTT, Cretaceous calcareous Algae EOCENE CRABS IN A LONDON CLAY NODULE by J. COLLINS Abstract. The outstanding features of a number of crabs, belonging to three species, present on a single nodule from the London Clay (Upper Ypresian), are here described. Comparisons made with existing descrip- tions reveal certain new structures to one of the species; a new geographical recording is also made. This paper describes a nodule which, although only 60 mm. in length and 40 mm. at its broadest part, contains no less than twelve individual crabs visible on its surface. All the specimens, which are casts, are preserved with their original convexity and represent three species: Campylostoma matuliforme Bell, Laeviranina gottschei (J. Bohm), and Mithracia libinioides Bell. C. matutifonne is the most prolific, there being seven examples, all juveniles; whereas of the other two species, each represented by one example, L. gottschei may by comparison with other specimens — in the British Museum (Natural History) — be regarded as approaching the adult stage, and M. libinioides (PI. 12, figs. 3, 7>a) as being an adult. The remaining three specimens are obscured by matrix and are indeterminable. Occurrence. London Clay (Upper Ypresian), Lower Eocene, Isle of Sheppey. The nodule is now in the University Museum, Oxford, the individual specimens being numbered L55 to L66. Campylostoma matutiforme Bell Plate 12, figs. 1, 1a Although the specimens (L55-L61) are juveniles, they show to a marked degree the characteristics of the adult ; they are, however, rather more rounded in outline. The five antero-lateral spines (of which the external-orbital forms the first) are well developed, and although no one specimen is entire a sound composite conception may be formed of their structure. The second to fourth pairs are about the same size, tri- angular in outline, rounded above and slightly upturned. The fifth is considerably more robust and is produced to a length almost equal to three-quarters of the carapace width at the base of these spines. The spine projects at right angles to the antero-lateral margin and is granulated like the carapace. Its borders are parallel for almost half the length, after which the anterior border, armed with five or six spinules, curves back towards the apex. On the specimens examined by Bell (1857) this spine had been broken off close to the carapace, and although he thought it might have been produced into a long spine, he claimed that the short length of spine preserved in one individual (1857, pi. 3, fig. 9) was hypertrophied. This diagnosis has led to some misrepresentation of the outline of this species and it has been figured (e.g. Salter and Woodward 1865) with all the antero- lateral spines of nearly equal size. Measurements (taken from the most complete example, L55): length, along median line, 13-3 mm.; width, anterior to fifth spine, 13-9 mm. Total width, including fifth spine, c. 32-0 mm. [Palaeontology, Vol. 4, Part 1, 1961, pp. 85-86, pi. 12.] 86 PALAEONTOLOGY, VOLUME 4 Loeviranina gottschei (J. Bohm) Plate 12, figs. 2, 2a Coming as it does from the Isle of Sheppey the geographical range of this rare species, hitherto recorded in Britain from Herne Bay, Highgate, Oxshott (Brown and Castell 1954), and Tolworth, is yet further extended. Measurements (L62): length, along median line, 15-9 mm.; width, 10-5 mm. Acknowledgements. Sincere thanks are due to Mr. J. M. Edmonds of the University Museum, Oxford, for kindly loaning the nodule for examination; to the Officers of the British Museum (Natural History) for providing access to specimens; and to Mr. E. J. Kentish who prepared the photographs. REFERENCES BELL, T. 1857. Fossil Malacostracous Crustacea of Great Britain. Palaeontogr. Soc. BOHM, J. 1918. liber Raninoides gottschei n. sp., aus dem Eocan vonHemmoor. Z. dents, geol. Ges. 70, Monatab. 35. 1922. In K. Martin, Die Fossilien von Java, Bd. i, Abt. 2, Hft. iv Arthropoda, Crustacea. Samml. geol. Rclunns. Leiden, n.f., 1, 251-535, pi. 63. 1927. Raninellopsis gottschei nov. gen. n. sp. Jahrb. preuss. geol. Landesanst. 48, 563-6. BROWN, M. M. and castell, c. p. 1954. Additions to the London Clay Fauna of Oxshott, Surrey. London Naturalist, 34, 47. GLAESSNER, M. F. and WITHERS, T. H. 1931. On London Clay Crabs of the family Raninidae. Ann. Mag. Nat. Hist. ( 10), 8, 47. SALTER, J. w. and woodward, h. 1865. Catalogue and Chart of Fossil Crustacea. London. J. COLLINS 63 Oakhurst Grove, Manuscript received 8 June 1960 London, S.E. 22 explanation of plate 12 Fig. 1. The nodule (x 1) showing dorsal view of Campylostoma matutiforme (L55) and left lateral view of Laeviranina gottschei. The anterior part of another C. matutiforme may also be seen, la. Portion of fig. 1 enlarged, X 2. Fig. 2. The nodule (x 1) showing dorsal view of L. gottschei and frontal view of C. matutiforme (L55). 2a, Portion of fig. 2 enlarged, x 2. Fig. 3. The nodule (x 1) showing the carapace of Mithracia libinioides', the right lateral margin of L. gottschei, part of specimen L55 (at the top of the photograph) and several other examples of C. matutiforme may also be seen. 3a, Portion of fig. 3 enlarged, X 2. Eocene, Upper Ypresian, London Clay, Isle of Sheppey. Palaeontology, Vol. 4. PLATE 12 COLLINS, Eocene crab: NEW RHAETIC AND LIASSIC BEETLES by B. G. GARDINER Abstract. An isolated coleopteran elytron from the Lower Lias of Lyme Regis is described and named Ekiterina liassica gen. et sp. nov. Six fragments of coleoptera including five pieces of elytra and one metasternum were collected from a fissure of Rhaetic age in the Carboniferous Limestone of South Wales. Their relationship with the present-day Cupedidae is considered and the fragments have been named Metaciipes harrisi gen. et sp. nov. All except one of the present insects were discovered as a result of a programme of field work which has been carried out in South Wales for the past eight years by Dr. K. A. Kermack of University College, London, and his co-workers (Kermack and Mussett 1958). Professor T. Harris of Reading, while investigating the plants (Harris 1957) from a fissure in Cnap Twt quarry near Bridgend, found a number of insect fragments which he kindly put at my disposal for description. At first sight the colour and nature of much of the matrix in many of the fissures in the Bridgend area suggest the age to be Keuper (Kermack, Kermack, and Mussett 1956), although Harris (1957) from the contained flora suggests that it is Upper Rhaetic or Basal Lias in age. This apparent discrepancy is explained by a recurrence in the Rhaetic of conditions similar to those under which the Keuper Marls were deposited. In several places west of Bridgend the Rhaetic shows an interbedding of some thin bands of red and green marls indistinguishable from the Keuper Marl in the upper part of the Pteria (Avicula) conlorta zone (Strahan and Cantrill 1904). The last of these insects was discovered while preparing in acetic acid a specimen of Osteorachis macrocephahis Egerton from the Lower Lias of Lyme Regis. The elytron of a beetle was found within the orbit of this fish. SYSTEMATIC ACCOUNT Family elateridae Eschsholtz 1829 Genus elaterina gen. nov. Type species. Elaterina liassica gen. et sp. nov.. Lower Lias, Lyme Regis. Diagnosis. An elaterid with its elytron bluntly rounded posteriorly and with a distinct groove running round both lateral edges. Elaterina liassica gen. et sp. nov. Text-fig. 1 Holotype. British Museum (Nat. Hist.) IN 50351, Lower Lias, Lyme Regis. Diagnosis. The elytron measures 12-5 mm. in length and 5 mm. at its widest point. Posteriorly slender striations run about one-quarter of the length of the elytron. The ornamentation consists of minute raised tubercles which cover the entire dorsal surface. Remarks. From a comparison with figures published in Bode (1953) and with living {Palaeontology, Vol. 4, Part 1, 1961, pp. 87-89.] 88 PALAEONTOLOGY, VOLUME 4 species, the elytron is that of a beetle very similar in structure to the present-day Elateridae (click beetles). Since, however, there is no one genus with which it corre- sponds more than superficially, I propose to designate it by a new name {Elalerina Uassica, gen. et sp. nov.). Family cupedidae Lacordaire 1857 Genus metacupes gen. nov. Type species. Metacupes hanisi gen. et sp. nov., Rhaetic, Bridgend. I TEXT-FIG. 1. Elaterina Uassica, n. gen. et n. sp. B.M. N.H. IN 50351, Lower Lias, Lyme Regis. Scale represents natural size. TEXT-FIG. 2. Metacupes han isi, n. gen, et n. sp. B.M. N.H. IN 50352, frag- ment of elytron, Rhaetic, Bridgend. TEXT-FIG. 3. Metacupes harrisi, n. gen. et n. sp. B.M. N.H. IN 50352, Rhaetic, Bridgend. Metasternum in a, dorsal view; b, ventral view. Diagnosis. Elytron with a deeply punctate, regularly arranged ornamentation. Meta- sternum triangular and with characteristic strengthening bars on its inner surface. Remarks. The insect remains collected from the fissure near Bridgend numbered six fragments. Of these five were pieces of elytra, and the sixth a metasternum of a beetle. Metacupes harrisi gen. et sp. nov. Text-figs. 2, 3 Holotype. British Museum (Nat. Hist.) IN 50352, Rhaetic, Cnap Twt quarry, near Bridgend. Diagnosis. The fragments of elytra are all similar. The largest piece shows a distinct B. G. GARDINER: NEW RHAETIC AND LIASSIC BEETLES 89 groove running down one of its lateral edges (text-fig. 2) and has a deeply punctate, regularly arranged, ornamentation (areolate). The metasternum measures 2-2 mm. in length and its general shape is given in text-fig. 3. It is roughly triangular and strengthened on its inner surface by two bars, which together form a cruciform structure. The locations of these strengthening bars are apparent on the external surface. The ornamentation consists of a tuberculate sculpturing. Remarks. At first sight these few remains (B.M. N.H. IN 50352 and IN 50353) appear too fragmentary to identify with certainty, however the metasternum is probably a more diagnostic character than the elytron, and the only living family I have observed possessing a metasternum of this shape is the Cupedidae. Rohdendorf (1958) has recently figured many new and interesting forms of fossil Coleoptera from the Permian of Siberia. One of these Protociipes martynovi Rhod. has an elytron with a very similar ornamentation to that of Metaciipes harrisi gen. et sp. nov. With the additional evidence obtained from the metasternum there is every justification in putting the above fragments together with his in the same family, the Cupedidae. The fragments seem to be near the living genus Omnia Newman and very similar to a fossil genus Mesothoris described by Tillyard (1916). Discussion. Since these Permian and Rhaetic members of the Cupedidae looked so much like living species of today, there must be in the younger rocks intermediates differing little from the Rhaetic forms on one hand, and the living species on the other. On examination of the appropriate collections in the British Museum (Nat. Hist.) this has proved to be the case, and Dr. R. Crowson of Glasgow University will shortly be describing many of these forms in a review of the Cupedidae. REFERENCES BODE, A. 1953. Die Insekten fauna des Ostniedersachsischen overon Lias. Palaeoiitogrophica, 103a, (1-4), 1-375. HARRIS, T. M. 1957. A Liasso-Rhaetic flora in South Wales. Proc. Roy. Soc. B, 147, 289-308. KERMACK, D. M., KERMACK, K. A., and MUSSETT, F. 1956. New Mesozoic mammals from South Wales. Proc. Geol. Soc. Loiul., no. 1533, 31. KERMACK, K. A. and MUSSETT, F. 1958. The jaw articulation of the Docodonta and the classification of Mesozoic mammals. Proc. Roy. Soc. B, 148, 204-15. ROHDENDORF, B. B. 1958. Les Inscctcs Paleozoiques du sud de la Siberie. Proc. 10th Internat. Congr. Ent. 1, 853-9. STRAHAN, A. and CANTRiLL, T. c. 1904. Gcology of the South Wales coalficId. Part IV, The country around Bridgend. Mem. Geol. Survey. TILLYARD, R. J. 1916. Mesozoic and Tertiary insects of Queensland and New South Wales. Qcl. Geological Survey, 253, 1 1-60. B. G. GARDINER Department of Biology, Queen Elizabeth College, Manuscript received 25 May 1960 London MICROPLANKTON FROM THE KELLAWAYS ROCK AND OXFORD CLAY OF YORKSHIRE by W. A. S. SARJEANT Abstract. Assemblages of microplankton from the Kellaways Rock and Oxford Clay of Yorkshire are de- scribed. They consist dominantly of hystrichospheres, including new species of Cymatiosphaera and of Canno- sphaeropsis. Dinoflagellates are also prominent, with Gouyaulax jurassica Deflandre most abundant: two new species of Gouyaulax are described. Organisms incertae sedis, probably microplankton, are present: three new genera, Stephanelytron, Autrosphaera, and Netrelytron, and a new species of fVaiiaea are described. The character and stratigraphic significance of the assemblages are discussed. Four assemblages of fossil microplankton are dealt with here, all from the Upper Jurassic of the Yorkshire coast. The lowest horizon examined was the Kellaways Rock {Sigaloceras callovieiise Zone), a rather sparse assemblage being obtained from a sample of calcareous sandstone 1 foot below the base of a thick argillaceous sandstone and approximately 45 feet below the base of the Oxford Clay, in the exposure in the cliff below Scarborough Castle (grid reference 053890). The Hackness Rock (Quenstedtoceras lamberti Zone) from the same locality was also examined: however, the sample of ferruginous oolite from the uppermost Hackness Rock yielded planty remains and abundant wood fragments, but very little pollen and no microplankton. Three horizons of the Oxford Clay {Quenstedtoceras mariae Zone) were examined: each sample was of grey clay, quite highly calcareous, and each yielded an abundant microplankton assem- blage. The lowest horizon studied was 1 foot above the top of the Hackness Rock, exposed at the base of Scarborough Castle cliff. The other samples were from High Red Cliff, Cayton Bay (grid reference 077843), 31 miles south-east of the previous locality, and from horizons respectively 25 feet above and between 90 and 100 feet above the top of the Hackness Rock (henceforth referred to as the ‘25-foot’ and ‘100- foot’ horizons). Each sample examined was crushed mechanically, treated with hydrochloric acid to remove carbonates, then heated in hydrofluoric acid to remove silicates. The residue was then macerated in Schultz solution for periods of between 15 minutes and 1 hour, maceration time varying according to the amount of residue and its appearance on microscopic examination; the object of maceration was to remove by oxidization the bulk of plant tissues and of structureless ‘humic’ substances. The resultant concentrates were mounted in various fashions; polyvinyl acetate resin, Santolite, Lakeside cement, and solid and liquid Canada balsam were experimented with, but glycerine jelly was found the most satisfactory mountant. Safranin stain, mixed with the glycerine jelly, successfully stained and gave satisfactory contrast to the rather colourless microfossils, its only disadvantage being the unavoidable masking of the original colour of the micro fossils. In the mounts of Kellaways Rock material, microplankton formed only about 5 to 10 per cent, of the total microfossil assemblage, the remainder comprising spores, pollen, and the shell linings of foraminifera. The assemblage of microplankton, domi- [Palaeontology, Vol. 4, Part 1, 1961, pp. 90-118, pis. 13-15.] W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 91 nantly hystrichospheres with dinoflagellates forming only 7 per cent., described from this material was thus numerically relatively small; it proved intermediate in character between the Oxford Clay assemblage and a Cornbrash assemblage described in an earlier paper (Sarjeant 1959). The Oxford Clay mounts proved considerably richer in microplankton, the latter making up 60-70 per cent, of the total microfossil assemblage. Hystrichospheres again dominated the microplankton, but this time the dinoflagellates proved more abundant. In the lowest horizon, dinoflagellates form 20 per cent, of the microplankton; in the 25-foot horizon, 10 per cent.; and in the 100-foot horizon, 40-45 per cent. Spores and pollen form the remainder of the assemblage, with the shell linings of foraminifera very subordinate (less than 1 per cent.). There are in addition a small number of simple sacs, probably but not certainly pollen. The fossil microplankton are on the whole very well preserved, and in damaged forms the damage seems in many cases to have occurred before fossilization. Eight species of dinoflagellates were identified, Gonyaulax jurassica Deflandre being the most abundant at all horizons; twenty species of hystrichospheres were distinguished; and six species of organisms incertae sedis but probably also microplankton. All specimens described are now in the collection of the Micropalaeontology Laboratory of the Department of Geology, University of Sheffield. DESCRIPTION OF THE ASSEMBLAGES Class DINOFLAGELLATA Family gonyaulacidae Genus gonyaulax Diesing Gonyaulax jurassica Deflandre 1938 Plate 13, figs. 1, 9-12; te.xt-figs. 1-3 Remarks. This species, previously recorded from the Bathonian (Valensi 1953) and Oxfordian of France (1938) and from the Kimeridgian of England (Downie 1957), proved extremely abundant. Observed distribution; Kellaways Rock 4; Oxford Clay, lowest 40, 25-foot 6, 100-foot 79. Of these, six have been attributed to Deflandre’s variety longicornis (see later). The tabulation corresponds in its general features with that described by Deflandre. Plate 1 however, shows some variation in shape ; in all specimens from the lowest and 25-foot horizons of the Oxford Clay where this plate can be clearly seen, its shape is triangular (the figured specimen CB56/11/29 shows this well). In specimens from the Kellaways Rock and highest Oxford Clay by contrast, plate V" was reduced and elon- gate as in the type. The significance of this variation remains obscure. Considerable variation is exhibited in height and degree of denticulation by the crests on sutures, seven principal variations being noted (see text-fig. 1). All were observable in specimens from the lower horizons, variation d being displayed by only one specimen (SC2/31/2). However, variation in specimens from the 25-foot and highest Oxford Clay horizons was restricted to types a, b, or c, i.e. high crests with widely spaced, slender denticles of varying height. Deflandre has commented on the extreme variability of general form in G. jurassica, noting all intermediates from specimens with convex flanks to others with concave flanks. He records a range of overall lengths from 92 PALAEONTOLOGY, VOLUME 4 65 to 100 /14; this corresponds closely with the range observed from these specimens (55-102 /x). Eighty specimens from the Oxford Clay, comprising 37 specimens from the lowest, 5 from the 25-foot, and 38 from the 100-foot horizons, were measured; the accompany- ing graphs represent the results of this study. In the first (text-fig. 2) thecal length with- out crests is plotted against thecal breadth without crests. Whilst the deformability of the theca certainly affects these measurements in some degree, the result shows that increase in length is accompanied by increase in breadth, the correlation not being, however, very close. The second graph (text-fig. 3) shows overall length plotted against abode f g TEXT-FIG. 1. Tabulation of a specimen of Gonyaulax jiimssica Deflandre showing a triangular plate V". Left: in ventral view. Right; in dorsal view. The specimen figured is CB56/1 1/29, X 600. t.f., transverse furrow; /./., longitudinal furrow. Below: different forms of sutural crests developed by G. jurassica [based on CB81/15/12 (a), CB81/6/18 (b), CB81/12/5 (c), SC2/31/2 (^/), SC2/32/16 (e), SC2/29/10 {f), and SC2/32/22 (^)], x 500. horn length: an increase of length of horn with increasing size is evidenced. Separate plotting of measurements of the faunas from each horizon produced no indication of differences between horizons. Deflandre comments: ‘. . . stains fix in a very capricious manner’. He lists twelve stains, all of which were taken up in varying degree by his specimens and mentions carmine and safranin as tried without success. The Yorkshire specimens took up safranin very readily, emphasizing the validity of Deflandre’s comment. Gonyaulax jurassica var. Jongicornis Deflandre 1938 Text-figs. 2-3 Remarks. Three specimens from the lowest and three from the 100-foot Oxford Clay horizons were attributed to this variety, previously described only from the Oxfordian of France. All have a horn length at least one-third of the overall length. Their dimen- sions have been plotted on the graphs (text-figs. 2 and 3). On the graph on which thecal length and breadth are related they do not form any distinct group. From the second graph, where horn length is plotted against overall length, it may be seen that there is W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 93 TEXT-FIG. 2. Relationship of thecal length and breadth in Gonyaulax jurassica. Diagram based on an assemblage of eighty specimens from the Oxford Clay of Yorkshire. Measurements are given in ft. A, type of G. jurassica', ▲, type of G. Jurassica var. longicornis; +, Yorkshire specimens of G. jurassica var. longicornis. TEXT-FIG. 3. Relationship of overall length to horn length in Gonyaulax jurassica. Diagram based on an assemblage of eighty specimens from the Oxford Clay of Yorkshire. Measurements are given in /x. 94 PALAEONTOLOGY, VOLUME 4 no clear distinction between this variety and the normal G. jurassica and that these are merely forms at the extreme end of the scatter. Gonyaulax cladophora Deflandre 1938 Plate 13, fig. 2 and Plate 14, figs. 1-2 Remarks. Deflandre’s remark may be echoed: ‘Although plentiful . . . this species is most often in a bad state of preservation.’ Observed distribution ; Kellaways Rock 2, Oxford Clay, lowest 30, 25-foot 7, 100-foot 29. Only one, specimen CB81/10/5, was sufficiently well preserved for the full tabulation to be determined (plate 2" being miss- ing). It is in somewhat oblique position; the dimensions given are thus taken from specimen SC2/36/4 : overall length 120 /x with apical horn c. 23 jj., overall breadth 100 /X, spines on crests around 8 /x high. Relatively few specimens were well enough preserved for satisfactory measurement; however, all appear to fall within the range overall length 65-125 p. The character of the spines is as described by Deflandre except that they are always isolated and never linked at the base, as is sometimes the case in his specimens. This species has been previously recorded from the Bajocian (Mercier 1938; Valensi 1953), the Oxfordian (Deflandre 1938), and the Lower Kimeridgian (Deflandre 1941) of France. Gonyaulax acanthosphaera sp. nov. Plate 13, fig. 14; text-fig. 4 Holotype. SC2I32I23, lowest Oxford Clay, Scarborough Castle cliff. Dimetisious of type. Length 65 /x, breadth 65 /x, transverse furrow c. 5 /x in width. Spines on sutures c. 1 fx in length, spines elsewhere c. 0-3 p in length. Specimen SC2/34/12 similar; other specimens too damaged for measurement. Diagnosis. A species of fossil Gonyaulax having a globular theca with the tabulation ? 3', la, 6", ? 6"', ?2pv, V"' and without an apical horn. A dense cover of extremely short, blunt, stubble-like spines covers the entire theca, being somewhat reduced on the transverse and longitudinal furrows. Sutures between plates not raised, but ornamented EXPLANATION OF PLATE 13 Microplankton from the Kellaways Rock of Yorkshire. All figures are x 500. Fig. 1. Gonyaulax jurassica Deflandre, SC33/16/4, in dorsal view. Fig. 2. Gonyaulax cladophora Deflandre, SC33/16/3, in dorsal view. Figs. 3-4. Micrhystridium fragile Deflandre. 3, SC33/17/5. 4, SC33/11/5. Fig. 5. Micrhystridium inconspicuum Deflandre, SC33/15/1. Fig. 6. Cyniatiosphaera parva Sarjeant, SC33/5/15. Fig. 7. Antrosphaera calloviensis gen. et sp. nov., SC33/5/16, holotype. Fig. 8. Cannosphaeropsis caulleryi (Deflandre), SC33/14/2. Microplankton from the Oxford Clay of Yorkshire. Figs. 9-12. Gonyaulax jurassica Deflandre. 9, CB81/15/12, in dorsal view. 10, SC2/33/10, in dorsal view. 1 1, SC2/4/29, in ventral view. 12, CB56/1 1/29, in oblique ventral view. Fig. 13. Gonyaulax areolata sp. nov., SC2/34/21, holotype, in ventral view. Fig. 14. Gonyaulax acanthosphaera sp. nov., SC2/32/23, holotype, in ventral view. Fig. 15. Gonyaulax sp., SC2/28/9. Fig. 16. Pareodinia ceratophora Deflandre, CB8 1/6/4. Fig. 17. Pareodinia ceratophora Deflandre var. pachyceras Sarjeant, SC2/33/25. Palaeontology, Vol. 4. PLATE 13 SARJEANT, Jurassic microplankton m i ' .'-p IT* ' '■ ■ • RHk: W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 95 with rows of short spinelets, some bifurcating, longer than those of the general spine cover. Description. Theca yellowish in colour. Tabulation not easy to determine since sutures are not raised and their longer spines readily escape notice against the dense background of shorter spines. Apparently three apical plates: however, plate 1' of type gives sug- gestion of possible subdivision into two. One anterior intercalary plate and six pre- equatorial plates, with plate 1" reduced. Transverse furrow extends around theca in laevo-rotatory spiral such that its two ends differ in antero-posterior position by the furrow’s width. Longitudinal furrow broad: small posterior ventral plate present, corresponding to its hypothecal extension and adjacent to the more posterior of the two ends of the transverse furrow. A second posterior ventral plate, somewhat larger in size, appears to be present between this and the polygonal antapical plate. Six post- equatorial plates present. Holotype somewhat damaged; tabulation of the dorsal TEXT-FIG. 4. Tabulation of Goiiyaiilax acanthosphaera sp. nov. Left: in ventral view. Right: in dorsal view. Figures based on the holotype SC2/32/23, and a paratype, SC2/34/ 1 2. p.v., posterior ventral plate, x 500. surface therefore based on specimen SC2/34/12. Holotype encloses (below plate 1") a round brownish body, apparently of organic material and with an irregular spiny margin. Remarks. It is probable that this dinoflagellate is more numerous than appears from the number of specimens recorded (six); however, other specimens seen may well have been confused with the hystrichosphere Baltisphaeridiwn cf. fimbriatum, abundant in this material and also having a cover of short spines. All specimens recorded were from the lowest Oxford Clay horizon. In its spherical shape and dense spine cover G. acanthosphaera differs from all eight described fossil species of GonyauJax lacking apical horns. It finds its closest comparison in Palaeoperidiniwn castanea Deflandre 1935 from the Cretaceous of France, a globose form with a cover of short spines, but differing from G. acanthosphaera by possession of a denticulate apical horn and a definitely different tabulation. GonyauJax areolata sp. nov. Plate 13, fig. 13; text-fig. 5 Holotype. SC2/34/21, lowest Oxford Clay. Scarborough Castle cliff. Dimensions. Holotype: overall length 155 p, length of horn 25 p, overall breadth 125 p\ transverse furrow c. 10 p wide, longitudinal 96 PALAEONTOLOGY, VOLUME 4 furrow c. 5 [j, wide. Range of dimensions observed: overall length 120-170 /i, relative proportions being fairly constant. Diagnosis, A species of fossil Gonyaulax with an ovoid theca having the tabulation ?', la, 6", 6"', ? Ip, and with a strong, tapering apical horn rounded at its extremity. The whole thecal surface except the longitudinal and transverse furrows is covered by low ridges forming an irregular reticulate patterning; the thecal wall is very thin but consists of two layers, the outer layer bearing the ridges. The boundaries of plates and the furrow margins bear low alveolate crests. The longitudinal furrow extends from apex to antapex; it is narrow, as is the transverse furrow. Description. Theca yellowish. Tabulation not easily discerned and a composite text- figure therefore given. Apical tabulation obscure. An anterior intercalary plate clearly TEXT-FIG. 5. Tabulation of Gonyaulax areolata sp. nov. Left: in ventral view. Right: in dorsal view. Diagram- matic, based on the holotype SC2/34/21 and on several paratypes. x300. present, plus six pre-equatorial plates, of which the first (1") is reduced. Transverse furrow extends around theca in a strong laevo-rotatory spiral such that its two ends differ in antero-posterior position by approximately three times the furrow’s width. Six post-equatorial plates certainly present ; a posterior intercalary plate appears present but could not be definitely confirmed. No posterior ventral plates present, longitudinal furrow extending to polygonal antapical plate. Surface reticulation of ridges dense; fields delimited by these ridges always small, not regularly polygonal but varying con- siderably in relative size and shape. Reticulation extending on to apical horn but absent from furrows. Crests consist of linked processes (links sometimes broken) arising from sutures, their points of origin corresponding with junctions of ridges with sutures. Remarks. Observed distribution: Oxford Clay, lowest 9, 100-foot 15. Not recorded from the Kellaways Rock. Three fossil species previously recorded also bear reticulate patterning. One, Gony- aulax obscura Lejeune-Carpentier, from the Cretaceous of France and Germany (1946), differs by having a polygonal theca with a very thick membrane and a very different tabulation clearly marked by high sutures. Palaeoperidinium ventriosum O. Wetzel, a Cretaceous dinoflagellate recorded by the German author from the Baltic region (1933) W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 97 and by Deflandre from France (1936), is similar in outline, but the theca is globular and its crests bear ‘thin and transparent veils’. Its tabulation, which has led Lejeune- Carpentier to suggest its attribution to the genus Peridmium, is quite different. Closest comparison is found in the Oxfordian Polaeoperidinium dictyophonmi Deflandre, attri- buted to that genus in absence of precise knowledge of the tabulation but considered by its author probably relatable to Gonyaidax. This species, recorded from Villers-sur- Mer, France, differs from G. areolata in the shape of its apical horn, broad and very blunt, in the absence of raised crests, and in the greater breadth of the longitudinal furrow. Specimen. SC2/28/9, lowest Oxford Clay, Scarborough Castle cliff. Dimensions. Overall length 47 /x, length of horn 5 p,; overall breadth 45 p, width of transverse furrow c. 5 p. Description. Theca globular to polyhedral, yellowish in colour and lacking any pro- nounced granulation, divided into plates by raised sutures. Apex occupied by strong tapering horn, appearing to comprise three apical plates. Anterior intercalary plate present, situated on right-hand side of posterior extension of plate 1'; six pre-equatorial plates present, plate 6" reduced. Transverse furrow extends around theca in a laevo- rotatory spiral such that its two ends differ in antero-posterior position by the furrow’s width. The more posterior of its two ends separated from longitudinal furrow by a small pentagonal plate. Longitudinal furrow very broad extending to antapex. Six post- equatorial plates, the first being reduced to accommodate a posterior intercalary plate. A single polygonal plate occupies the antapex. Character of the raised sutures obscure in the single specimen found; the suture between plates 5" and 6" appears high and with a denticulate edge, resembling sutures of Gonyaidax jurassica, but other sutures appear low, with isolated simple spines. Remarks. In its shape, the character of its apical horn, and its tabulation this specimen is distinctive. In view of the obscure nature of its sutural crests and the fact that only B 7879 H Gonyaidax sp. Plate 13, fig. 15; text-fig. 6 TEXT-FIG. 6. Tabulation of Gonyaidax sp. Left: in ventral view. Right: in dorsal view. Holotype SC2/28/9. x 1,000. 98 PALAEONTOLOGY, VOLUME 4 one specimen of it has been found (from the lowest Oxford Clay horizon) it was thought inadvisable to erect a new species until further specimens become available. ? Family deflandreidae Genus scriniodinium Klement 1957 Scriniodmium crystallinwn (Deflandre 1938) Klement 1957 Plate 14, figs. 9-12 Remarks. This species has been recorded from the Oxfordian of France (Deflandre 1938), from the Upper Jurassic of Germany (Klement 1957), and from the Upper Jurassic of Western Australia and Papua (Cookson and Eisenack 1958). Observed distribution: Oxford Clay, lowest 14, 25-foot 3, 100-foot 33; absent from the Kellaways Rock. Specimen CB81/10/8 exhibits typical dimensions: length of cyst 78 jd., breadth 75 /a, length of theca 62 /x, breadth 55 jx, transverse furrow c. 5 /x wide. The largest seen was specimen SC2/ 15/30, with a cyst 95 /x long and 80 /x broad, and a theca 65 ix long and 65 ix broad. Specimen CB8 1/22/7 shows a greater proportionate breadth : cyst 78 /x long and 8 1 ix broad, theca 63 fx long and 63 /x broad. All these dimen- sions are within the range recorded by Deflandre (cyst 65-92 /x x 65-85 jx). Some speci- mens have the appearance of possessing a longitudinal furrow (notably CB81/7/16 and SC2/11/18), but this may be due merely to folding of the thecal membrane. Scriniodinium galeritum (Deflandre 1938) comb. nov. Plate 14, fig. 6 1938 1 Gymnodinium galeritum Deflandre, p. 167, pi. v, figs. 7-9, pi. vi, fig. 1. Diagnosis. Epitheca in the form of a truncated cone, separated by a narrow transverse furrow from the rounded hypotheca. Enclosing cyst similar in shape but having a pro- tuberant portion which appears to cap the apex. Remarks. One well-preserved and two broken specimens from the 100-foot Oxford Clay horizon have been attributed to this species, previously recorded only from the Oxfordian of Villers-sur-Mer, France. Specimen CB81/23/17 (figured) has an overall length 118 j(x and overall breadth 103 dimensions considerably greater than those recorded by Deflandre (length 78 to 87 /x, breadth 60 to 65 ix). The theca gives suggestion of a broad longitudinal furrow: however, this may be due entirely to folding of the thecal membrane. In view of its possession of an enclosing cyst this species has been EXPLANATION OF PLATE 14 Microplankton from the Oxford Clay of Yorkshire. All figures are X500. Figs. 1-2. Gonyaulax ckidophora Deflandre. 1, CBS 1/10/5, in dorsal view. 2, SC2/36/4, in ventral view. Figs. 3-5. Baltisphaeridium pilosum (Ehrenberg) comb. nov. 3, CB81/24/2. 4, CB81/15/7. 5, SC2/35/9. Fig. 6. Scriniodinium galeritum (Deflandre) comb. nov. CB81/23/17. Fig. 7. Polystephanosphaera calatlius sp. nov., SC2/11/9, holotype. Fig. 8. Baltisphaeridium pilosum (Ehrenberg) var. longispinosum nov., SC2/4/10, holotype. Figs. 9-12. Scriniodinium crystallinum (Deflandre). 9, SC2/15/30. 10, CB81/18/7. 11, CB81/10/8. 12, cmxjiin. Fig. 13. Baltisphaeridium ci. fimbriatmn (White). CB81/18/17. Palaeontology, Vol. 4 PLATE 14 SARJEANT, Jurassic microplanktoii W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 99 removed from the genus Gymnodium Stein in which Deflandre tentatively put it, and attributed to the newer genus Scriniodinium Klement. Family pareodinidae Genus pareodinia Deflandre Pareodinia ceratophora Deflandre 1947 Plate 13, fig. 16 Remarks. The typical specimens of this species have a horn tapering to a point. Twelve specimens seen, all from the 100-foot Oxford Clay horizon, show this character; all have a coarsely granular pale-yellowish membrane. Specimen CBS 1/6/4 is among the best preserved: it has a length of 75 p, of which the horn comprises 15 p, and a breadth of c. 40 p. The other specimens seen are of similar dimensions, falling well within the range of dimensions (length 65-78 p) recorded by Deflandre from specimens from the Callovian of the Baltic region and the Bajocian of France. Pareodinia eeraiophora Deflandre var. pachyceras Sarjeant 1959 Plate 13, fig. 17 Remarks. This variety was originally described from the Cornbrash of Cayton Bay. Four specimens attributable to it were found, all from the lowest Oxford Clay horizon. Specimen SC2/33/25 is typical; overall length 59 p, of which the horn comprises c. 12 p, and breadth 34 p, dimensions within the range exhibited by the Cornbrash specimens. No representatives of the genus Pareodinia were noted from the Kellaways Rock. Order hystrichosphaeridia Family hystrichosphaeridae Genus hystrichosphaeridium Deflandre 1937 emend. Eisenack 1958 Hystriehosphaeridium salpingophorum (Deflandre 1935) Plate 15, fig. 7 Remarks. A long-ranging species, described already from the Oxfordian (Deflandre 1938: France), the Lower to Upper Cretaceous (Deflandre 1935 and 1937 and others from France, Lejeune-Carpentier 1940 from Belgium, and Deflandre and Cookson 1955 from Papua), from the Eocene (Pastiels 1948: Belgium), and from the Oligocene (Gocht 1952: Germany). Observed distribution: Oxford Clay, lowest 8, 25-foot 3. The illustrated specimen (SC2/28/6) has an overall diameter 100 p, shell diameter 50 p, and processes around 25 p long, dimensions closely comparable with those of the French Oxfordian specimens. Hystrichosphaeridium cf. tnmcigerum Deflandre 1937 Plate 15, fig. 6 Specimen. CB81/12/20, 100-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimensions. Overall long diameter 68 p, overall short diameter 56 p, long diameter of shell 58 p, short diameter of shell 48 p, spines c. 5 p long, tubes c. 7-5 p long 100 PALAEONTOLOGY, VOLUME 4 Description. Shell oval, yellowish, with thin walls bearing a very faint granulation. Processes of two kinds: a. Hollow conical spines, closed, thickening (slightly) at the tip to form a knob, b. Short, broad, roughly parallel-sided tubes not widened at their extremity, bearing very faint striations. Slightly longer than the spines. Processes quite widely separated and without apparent arrangement. On a complete specimen it is estimated that there would be thirty to forty processes : of these about one-third would be tubes. Remarks. Only one damaged specimen was seen of this interesting microfossil. In the general appearance of its processes it accords well with Deflandre’s Hystrichosphaeri- diuni truncigerum from the Cretaceous of France (1937). In four respects it differs from this species, however; in the oval, rather than spherical, shape of the shell, in the some- what knobbed tips of some spines, in the absence of denticulations on the outer margins of the tubes, and in the smaller relative length of the processes (one-sixth to one-quarter short diameter, as against nearly half diameter). It is thus probable that this single specimen will be attributed to a new species when further specimens of similar type are found. Genus baltisphaeridium Eisenack 1958 BaJtisphaeridium stimidiferum (Deflandre 1938) comb. nov. Plate 15, fig. 5; text-fig. 8g 1938 Hystrichosphaeridiinn stiinuliferum Deflandre, p. 192, pi. x, fig. 10. Diagnosis. A species of Baltisphaeridium having a globular shell bearing a small number (about fifteen) of simple spines, generally curved, in length of the order of the diameter of the shell. The spines are inserted in such fashion that there is no mark at their base and the wall of the shell appears continuous with each spine. EXPLANATION OF PLATE 15 Microplankton from the Oxford Clay of Yorkshire. All figures are X 500. Fig. 1. Caimosphaeiopsis aemula (Deflandre), CBS 1/7/1 5. Fig. 2. Micrhystridium steUatum Deflandre, CB81/14/20. Fig. 3. 1 Micrhystridium sp., CBS 1/1 7/22. Fig. 4. Caimosphaeiopsis caidleryi (Deflandre), CB56/8/4. Fig. 5. Baltisphaeridium stimidiferum (Deflandre) comb, nov., SC2/10/17. Fig. 6. Hystrichosphaeridiinn cf. truncigerum Deflandre, CBS 1/1 2/20. Fig. 7. Hystrichosphaeridiinn salpingophorum Deflandre, SC2/28/6. Fig. 8. Baltisphaeridium ehrenbergi (Deflandre) var. brevispinosum nov., SC2/34/8, holotype. Fig. 9. Cymatiosphaera teichophera sp. nov., CBS 1/1 9/1 7, holotype. Fig. 10. 1 Cymatiosphaera sp. indet., CB56/12/18. Fig. 11. Stephaiielytron redclijfense gen. et sp. nov., CBS 1/26/6, holotype. Figs. 12-13. Stephaiielytron scarburghense gen. et sp. nov. Two views of the holotype, SC2/31/2 (obliquely positioned) at different focal planes. Fig. 14. Wanaea fimbriata sp. nov., CB56/8/15, holotype. Fig. 15. Netrelytron stegastum gen. et sp. nov., CB81/16/10, holotype. Fig. 16. Stephaiielytron caytonense gen. et sp. nov., CB56/14/1, holotype. Palaeontology, Vol. 4. PLATE 15 SARJEANT, Jurassic microplankton W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 101 Remarks. This species has been described from the Bajocian and Bathonian (Deflandre 1947; Valensi 1953) and Oxfordian (1938) of France. Observed distribution: Oxford Clay, lowest 6, 25-foot 3, 100-foot 2. The spines were originally thought by the author to be solid; after repeated examina- tion, however, it was established that they are hollow but closed at the tips. The species has therefore been transferred to Eisenach’s genus BaJtisphaeridiwn. Specimen SC2/10/17 (figured) has an overall diameter of 47 and shell diameter of 26-5 /X, with spines c. 12 /u, long. This spine length is proportionately shorter than that of typical forms, and the greatest length observed was only three-quarters the diameter. However, Valensi has already included specimens of similar relative dimensions (shell 20 /X, spines 10-15 /x long) within the species (1953). Baltisphaeridium pilosiim (Ehrenberg 1843) comb. nov. Plate 14, figs. 3-5 1843 Xanthidiiim pilosiim Ehrenberg, pp. 61-63. 1854 Xanthidiiim pilosiim Ehrenberg, pi. 37, fig. viii, no. 4. 1904 Ovum hispidum (Xanthidiiim) pilosiim (Ehr.) Lohmann, Ergebnisse der Planktonexpedi- tion der Humboldt-Stiftung, pp. 21-25. 1933 Hystrichosphaera pilosa (Ehr.) O. Wetzel, p. 43. 1937 Hystrichosphaeridiiim pilosiim (Ehr.) Deflandre, p. 31. Figured specimen CB81/15/7, 100-foot horizon of Oxford Clay, High Red Clifif, Cay ton Bay. Dimensions. Figured specimen: overall long diameter 62 p, short diameter 40 p\ long diameter of shell 55 p, short diameter 33 p, spines around 3| p long. Relatively complete specimens from which both major dimen- sions could be taken were few: the range of overall long diameters was 40-60 p. Ehrenberg’s holotype (53 p) falls within this range. Diagnosis. A species of Baltisphaeridium having a shell ellipsoidal to oval in shape, frequently broken at one termination. Shell wall very thin. Processes short (between one-quarter and one-eighth of short diameter in length), slender, pointed, and hollow (connecting directly to the interior of the shell); very numerous. Description. Shell yellowish; all specimens seen in some degree broken, one extremity usually being missing, although quite frequently also the shell is split longitudinally. Processes very densely set, the spacing none the less being such as to allow each to be seen throughout its length; 150-200 present around the periphery in relatively complete specimens. Remarks. This hystrichosphere was listed by Ehrenberg from the Corallian of Krakow, Poland (1843); in 1854 a figure of it was included in his massive Mikrogeologie. All subsequent generic reattributions of this species were on taxonomic grounds only; the form nanum of this species described by O. Wetzel from the Cretaceous (1933), dis- tinguished by small size (shell diameter less than 16 p) and a frequently spherical shape, is perhaps better attributed to the genus Micrhystridium. Ehrenberg gave no full dia- gnosis of this species and his holotype appears to be lost ; however, the Yorkshire speci- mens correspond exactly with his figure. Observed distribution: Oxford Clay, lowest 33, 25-foot 9, 100-foot 43. All seen are broken in some degree (see above); this may well 102 PALAEONTOLOGY, VOLUME 4 indicate that eggs or cysts of microplankton are being dealt with here, a suggestion already made by O. Wetzel. Baltisphaeridiimi piloswn (Ehrenberg 1843) var. Jongispinosum nov. Plate 14, fig. 8 Holotype. SC2/4/10, lowest Oxford Clay, Scarborough Castle cliff. Dimensions. Holotype: overall long diameter 70 /x, short diameter 47 /x; long diameter of shell 51 /x, short diameter 28 ju; spines around 12 ju. long. Diagnosis. A variety of Baltisphaeridiimi piloswn having spines between one-quarter and one-third the short diameter of the shell in length. Remarks. The single specimen dealt with here is in appearance quite distinct from all others seen. The shell shows no signs of breakage; its spines are more than three times longer than those of the figured specimen of B. piloswn and considerably in excess of the range of relative lengths exhibited. This distinctive specimen from the lowest Oxford Clay may well be a representative of a species distinct from B. piloswn. However, in the absence of further specimens the making of such a major distinction was not thought justifiable. Baltisphaeridiimi cf. fiinbriatwn (White 1842) Plate 14, fig. 13 Figured specimen. CB81/18/17, 100-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimen- sions. Figured specimen: overall diameter 70 p, diameter of shell 58 p, spines c. 6 p in length. The range exhibited is from 50 to 75 p overall diameter. Description. Shell yellowish-brown, spherical to oval in shape, very frequently damaged. Processes very numerous, typically 100-150 observable around the periphery: short, sometimes simple but more frequently forked or capitate, their length typically around 10 per cent, of the shell diameter. Remarks. Hystrichospheres of this type proved frequent. Observed distribution: Kellaways Rock 3, Oxford Clay, lowest 18, 25-foot 5, 100-foot 22. However, despite examination at magnifications of x 2,000, whether or not the spines are hollow could not be decisively determined and their attribution to this genus remains doubtful. The closest comparison is found in Baltisphaeridiimi fimbriatwn (White), originally described from Cretaceous flints from England (1842) and subsequently redescribed by Deflandre and Cookson from the Lower Cretaceous of New South Wales (1955). This species has spines of comparable length and with capitate or furcate apices; it differs in the total absence of simple spines and the somewhat longer spine branches. Another described character of this species is the constancy of the length of the spines, giving almost the aspect of an outer shell : two of the Kellaways Rock specimens have some- what this appearance, but the Oxford Clay specimens do not give it, their spines being slightly variable in length. It is likely that these Upper Jurassic specimens are not W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 103 genetically related to the Cretaceous species, but the morphological distinctions listed above are not adequate to justify nomenclatural separation. In dimensions, the Juras- sic assemblage is closer to White’s specimens (overall diameter 51-77 /x) than to the Australian specimens (31-46 ju-). Baltisphaeridium ehreiibergi (Deflandre 1947) comb. nov. 1938 Hystrichosphaeridiiim cf. hirsutum (Ehrenberg) Deflandre, pi. x, fig. 9. 1947 Hystrichosphaeridiiim ehrenbergi Deflandre, fig. 1, no. 5. 1955 Hystrichosphaeridiiim ehrenbergi Valensi, p. 587, pi. iii, fig. 1. Diagnosis. Shell globular, bearing simple processes, straight or slightly curving, about one-third the shell diameter in length. Points of insertion of processes equidistant. Remarks. On the basis of Valensi’s description of the processes this species is trans- ferred to Baltisphaeridium on taxonomic grounds. Baltisphaeridium ehrenbergi (Deflandre) var. brevispinosum nov. Plate 15, fig. 8; text-fig. 8a Holotype. SC2/34/8, lowest Oxford Clay, Scarborough Castle cliflf. Dimensions. Holotype: overall diameter 34 /x, shell diameter 25 p, length of spines 5 p. Diagnosis. A variety of Baltisphaeridium ehrenbergi having shorter spines, one-fifth to one-quarter of the shell diameter in length. Description. Shell yellowish-brown in colour, not granulous. Spines regularly spaced, about 3-5 p apart in the holotype. Shell wall thin. Remarks. A single specimen from the lowest Oxford Clay, excellently preserved, was found to correspond with Deflandre’s species B. ehrenbergi, from the Oxfordian of Villers-sur-Mer, France, in the character and regularity of spacing of its spines. Since the sole difference is in the length of its spines, it has been created a new variety of this species. Genus cannosphaeropsis O. Wetzel 1933 emend. Deflandre 1947 Cannosphaeropsis caulleryi (Deflandre 1938) Plate 13, fig. 8 and Plate 15, fig. 4 Remarks. This species was originally recorded from the Oxfordian of Villers-sur-Mer, France (1938), and subsequently from the Kimeridgian of Dorset, England (Downie 1957), the Neocomian of Germany (Gocht 1959), and the Eocene of Australia (Deflandre and Cookson 1955). Observed distribution: Kellaways Rock 1, Oxford Clay, lowest, 28, 25-foot 22, 100-foot 15. There was considerable variation in size, overall diameter varying from 55 to 120 p; the figured specimen (CB56/8/4) has average dimensions, with an overall diameter of 92 p and shell diameter 50 p. This range is not exceptional: the French specimens range from about 65 to 85 p and the Australian from 67 to 1 15 /x. 104 PALAEONTOLOGY, VOLUME 4 Cannosphaeropsis aemula (Deflandre 1938) Plate 15, fig. 1 Remarks. This species was originally described from the Oxfordian of Villers-sur-Mer, France (1938), and subsequently from the Upper Jurassic of Papua and Western Australia (Cookson and Eisenack 1958). It was found only in the 100-foot Oxford Clay horizon (9). The figured specimen (CB81/7/15) has average dimensions (overall diameter 106 ijl, shell diameter 52 ix), the range being from 95 to \20 jx overall diameter; this is somewhat larger than that exhibited by the French specimens (60 to 100 ix). Genus polystephanosphaera Sarjeant 1960 Polystephanosphaera calathus sp. nov. Plate 14, fig. 7; text-fig. 7 Holotype. SC2/11/9, lowest Oxford Clay, Scarborough Castle cliff. Dimensions. Holotype: overall diameter 88 /x, shell diameter 45 p, length of process clusters c. 22 fx. Paratype (CB56/8/24) : overall diameter 90 )x, shell diameter 45 /x, length of process clusters c. 23 [x. Diagnosis. A species of Polystephanosphaera in which the processes are solid and are arranged in circles and connected together by trabeculae in the form of a ring, each cluster of processes thus forming an open-walled and open-ended tube. It is estimated that on a complete specimen there would be twelve to sixteen such tubes, each ring trabecula borne by five to ten processes. Deseription. The trabecula linking each group of processes appears to arise from the bifurcation of one process in Y- shaped fashion, the tips of the two arms of the Y being extended parallel to the shell surface and meeting the extremities of the other processes of the group almost at right angles. Shell membrane brownish-yellow in colour, processes pale-yellowish. Remarks. Only two specimens found of this very characteristic microfossil, one each from the lowest and 25-foot horizons. The processes of Cannosphaeropsis cauUeryi are similar in basic type but are not arranged in circles. Those of P. urnaformis from the Oligocene of Australia (Cookson 1953) differ in that this latter species has processes whose bases coalesce, giving the impression rather of a perforated tubular process than of a group of linked processes. It might be suggested purely on morphological grounds that P. calathus represents an intermediate stage in evolutionary development from C. cauUeryi to P. urnaformis. However, the geographic and chronologic separation is immense and an actual genetic relationship must be at present considered improbable. TEXT-FIG. 7. Polystephano- sphaera calathus sp. nov., showing the form of the groups of processes. Holo- type SC2/11/9. X600. W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 105 Genus micrhystridium Deflandre 1936 Micrhystridium inconspicuum (Deflandre 1935) Plate 13, fig. 5; text-fig. 8/ Remarks. A long-ranging species, previously recorded from the Middle Jurassic of France (Valensi 1953), the Cornbrash of England (Sarjeant 1959), and the Cretaceous of France (Deflandre 1935). Observed distribution: Kellaways Rock 3, Oxford Clay, lowest 2, 25-foot 8, 100-foot 9. Specimen CB81/14/12 (illustrated) has an overall diameter 25 p and shell diameter 12 p, spines being around 7 p long. This is rather larger than specified by Deflandre: however, a range of shell diameters from 15 p down to 8 was observed and in all other characters these specimens agree with Deflandre’s definition of the species. f TEXT-FIG. 8. Smaller hystrichospheres from the Oxford Clay, a, Baltispliaeridium ehienbergi (Defl.) var. brevi- spiiiosum nov. (Holotype SC2/34/8); b, Micrhystridium recurvatum forma reducta Valensi (CB81/26/10); c, M. cf. inendax Deflandre (SC2/30/11); d, M. stellatum Deflandre (CB81/14/20). e, ?M. sp., showing the two layers of the shell wall (CB8 1/1 7/22); /, M. inconspicuum (Deflandre CB81/14/12);^, Baltispliaeridium stimidiferum (Deflandre) (SC2/10/1 7). X 600. Micrhystridium fragile Deflandre 1947 Plate 13, figs. 3-4 Remarks. Two specimens found in the Kellaways Rock, but this species is absent from the Oxford Clay horizons studied. It has previously been described from the Bajocian 106 PALAEONTOLOGY, VOLUME 4 and Bathonian of France (Deflandre 1947, Valensi 1953) and from the Cornbrash of England (Sarjeant 1959). Specimen SC33/17/5 is the better preserved; its dimensions are overall diameter 52 /x, shell diameter 24 jix. These dimensions are considerably larger than those recorded by Deflandre (overall diameter 12 to 14 jn); however, Valensi noted a considerable range of dimensions, the diameter of the shell alone in one case attaining 40 /x, so that the Kellaways specimens are not exceptional. Micrhystridium s tel latum Deflandre 1942 Plate 15, fig. 2; text-fig. 8d Remarks. This species was originally recorded from the Silurian (1942). Morphologically similar forms, probably not genetically related, have been recorded from the Bajocian of France (Valensi 1953) and the Cornbrash of Yorkshire (Sarjeant 1959). Their signifi- cance has already been discussed (1959). No representatives were seen from the Kella- ways Rock, but the species was present at all three horizons of the Oxford Clay (lowest 16, 25-foot 7, 100-foot 15). The figured specimen (CB81/14/20) exhibited typical dimen- sions: shell diameter 14 ix, spines around 12-5 /x in length; range of shell diameters from 10 to 25 /X. Micrhystridium recurvatum forma reducta Valensi 1953 Text-fig. 86 Remarks. This species and form were originally described from the Bathonian of France. Specimens corresponding to the diagnosis of this form are present in low numbers in all horizons studied (Kellaways Rock 3, Oxford Clay, lowest 3, 25-foot 1, 100-foot 3). Little variation in dimensions was exhibited, the figured specimen (CB81/26/10) being typical with overall diameter c. 35 /x, shell diameter 12-5 yi. Comparable dimensions are recorded by Valensi: shell diameter 11 to 15 y, overall diameter 20-30 /x. Despite the considerable morphological similarities with Micrhystridium stellatum Deflandre, there was no suggestion of intergradation between the two species in the assemblages examined. Micrhystridium cf. mendax Deflandre 1945 Text-fig. 8c Figured specimen. SC2/30/11, lowest Oxford Clay, Scarborough Castle cliff. Dimensions. Figured specimen: shell 1 1 /x in cross measurement, spines 1-5/x long. The two other specimens seen were similar in dimension. Description. Shell polygonal, pale-yellowish in colour, composed of a series of more or less flat fields whose intersections form low ridges. Short simple spines arise at the junctions of ridges; they are hollow and connected directly to the interior. Remarks. One specimen showing these characters was found in the lowest and two in the 25-foot Oxford Clay horizons. The closest comparison is found in Micrhystridium mendax Deflandre, from the Silurian of the Montagne Noire, France. This has the characters listed in the description: its spines are, however, proportionately shorter. W. A. S. SARJEANT; MICROPLANKTON FROM YORKSHIRE 107 only one-seventh to one-eighth the cross measurement as against one-fifth; the shell is also somewhat smaller, the Silurian specimens measuring 14 to 16 [x. These differences are by no means sufficient to justify the setting up of a new species, but the tremendous chronologic separation makes any genetic relationship unlikely. ? Micrhyslridium sp. Plate 15, fig. 3; text-fig. 8e Figured specimen. CB81/17/22, 100-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimen- sions. Figured specimen: shell diameter 21 /x with walls c.2 p thick. Spines 7 /x long. The other speci- mens seen have closely similar dimensions. Description. Shell exactly spherical, brownish-yellow, composed of two layers, a thick outer layer (striate) and a thin inner layer (not striate). Spines short (c. one-third to one-quarter diameter), simple, usually curving, solid and embedded in the outer layer of the shell wall. Remarks. The forms included here, in their possession of a two-layered shell wall, differ from all other Mesozoic hystrichospheres described to date, and resemble certain Palaeozoic forms (cf. Sannemann 1958). Their attribution to the Order Hystricho- sphaeridia is not necessarily correct; many pollen possess a two-layered body wall and the differentiation of the simpler pollen grains from hystrichospheres at this order of size is by no means easy. For this reason they have been only tentatively allotted to this order and genus. Microfossils of this type occur at all three Oxford Clay horizons (lowest 15, 25-foot 7, 100-foot 9) but were not noted from the Kellaways Rock. Family pterospermopsidae Genus cymatiosphaera O. Wetzel 1933 emend. Deflandre 1954 Cymatiosphaera teichophera sp. nov. Plate 15, fig. 9; text-figs. 9a,b Holotype. CBS 1/1 9/1 7, 100-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimensions. Holotype: overall long diameter 50 /x, overall short diameter 40 /x, crests around 9 /x high. Diagnosis. A species of Cymatiosphaera having a broadly ellipsoidal shell divided into a low number (12-16) of polygonal fields. The membranes delimiting fields are high, their height equal to about one-third of the short diameter; they bear striations normal to the shell surfaces. Description. Shell walls of moderate thickness and of brownish-yellow colour. Fields vary considerably in size; their separating membranes are thin and relatively readily crumpled, lacking supporting spines at the junctions but having a distinct outer edge on to which striations do not extend. Remarks. A single specimen only was found of this distinctive microfossil. Four known species have crests of similar proportional height. All are very much smaller in size 108 PALAEONTOLOGY, VOLUME 4 than C. teichophera, lack striations on their crests, and also differ as follows: Cytnatio- sphaera eupepJos Valensi, from the Middle Jurassic of France (1948), has membranes supported by spines at their junction. The other three comparable species have been described by Deunff from the Devonian of Canada. C. cornifera (1955) has fields with a short spine at their centre. C. cubus (1954) has a distinetly cubic outline and fewer fields. C. prismatica (1954) has a prismatic outline. Thus this new species is seen to be clearly distinct from all others of this genus so far described. TEXT-FIG. 9a, b, Cyniatiosp/iaera teichophera sp. nov., showing the two opposed surfaces, with the structure and arrangement of crests; the striations are less prominent than the drawing suggests. Holotype CBS 1/1 9/ 17. c, Membranilarnax oviilum Deflandre (SC2/24/1). X600. Cymatiosphaera parva Sarjeant 1959 1959 Cymatiosphaera parva Sarjeant, pp. 342-3, pi. xiii, fig. 6, text-fig. 8. Emended diagnosis. A species of Cymatiosphaera with a low number (c. 12-25) of polygonal fields demarcated by low ridges. Short slender spines arise at the junctions of the ridges. Remarks. This species, originally described from the Cornbrash (1959), was the most abundant in the Kellaways Rock (31 specimens seen), but was not observed from the Oxford Clay. The number of plates is generally twelve to fifteen. Specimen SC33/5/15 shows characteristic dimensions — overall diameter 13 jx, shell diameter 10 /u. There was little variation in dimensions exhibited; the shell diameters of the Kellaways specimens are thus almost exactly half that of the type specimen (20 p). The rather low plate number (12-15 as against 17-20) appears merely a function of size. The definition of a new variety on the basis of size alone seems scarcely warranted, particularly since size may be merely a reflection of age or environmental conditions. The diagnosis of the species has therefore been modified slightly to accommodate the Kellaways assemblage. ? Cymatiosphaera sp. indet. Plate 15, fig. 10 Remarks. Two poorly preserved specimens from the 25-foot Oxford Clay horizon may be attributable to this genus. Their shape was probably originally spherical; the test surface is divided into very numerous polygonal fields by low membranes sustained by spines at their junctions, these spines being sometimes bifurcate. The overall diameter of the better speeimen (CB56/12/18) is 65 /x, the spines being 4 ju in height. In view of W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 109 their poor preservation these two specimens cannot be attributed with any certainty to this genus, particularly since certain Mesozoic pollen grains, such as Lycopodium- sporites clavat aides Couper (present in this material), have a similar ornament. Genus membranilarnax O. Wetzel 1933 Membrmdarnax ovidum Deflandre 1947 Text-fig. 9c Remarks. This species has been described from the Bajocian and Bathonian of France (Deflandre 1947, Valensi 1953). A single poorly preserved specimen (SC/224/1) attribut- able to it was found in the lowest Oxford Clay horizon; its dimensions, long diameter 30 /X, short diameter 25 p, with crests around 4 p high, are smaller than the range quoted by Valensi (long diameter 38-60 p, short diameter 34-50 p). INCERTAE SEDIS Genus stephanelytron gen. nov. Type species. Stephanelytron redcliffense sp. nov. Diagnosis. Organic shells of spherical to ovoidal shape, bearing on one face (at one end in ovoidal forms) one or more structures consisting of a circular membrane rising up- wards from the shell surface and everted, surrounding a matte of short hairs or spines ; this structure is henceforth termed a ‘corona’. Elsewhere the shell bears tubular pro- cesses of varied character and arrangement. Remarks. In view of the uncertain function and character of the corona, any orientation imposed must be quite arbitrary. By analogy with other members of the marine plankton in which groups of cilia confined to one surface act as propellants it has been decided to term the surface bearing the corona or coronas the antapex, and the opposed surface the apex; it must be realized, however, that no comparison of function is implied. The presence of tubular processes makes it possible to relate this genus to the Order Hystricho- sphaeridia, but the corona has no parallel in any known hystrichosphere, so that it seems best for the present that this genus should remain incertae sedis. Stephanelytron redeliffense sp. nov. Plate 15, fig. 11; text-fig. 10 Holotype. CBS 1/2/66, 100-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimensions. Holotype; overall length 50 p, breadth 40 p, length of shell c. 36 p, breadth c. 30 p; height of corona 10 p, outer diameter c. 27 p. Tubes around 5 in length. Two other relatively complete specimens, similar in dimensions, were seen, and in addition several broken specimens. Diagnosis. A species of Stephanelytron having an oval shell, neither granular nor per- forate, bearing six rows of tubular processes extending from the apex to the corona, a transverse row of tubular processes extending around the apex in a broad circle, and a further row of processes, incomplete in all specimens seen, surrounding the antapex no PALAEONTOLOGY, VOLUME 4 close to the base of the corona. The processes have everted lips and their walls are not |j perforate. All specimens seen had a single corona, broad-based and bearing striations. Description. The surrounding membrane of the corona seems to show a somewhat thickened lip on to which the striations do not extend. The matted fibres within seem to vary in length, with those at the centre longer than those at the fringes, but this appearance may result entirely from the curvature of the shell surface from which they | arise. i Remarks. Each of the three Oxford Clay horizons studied seems characterized by I a particular species of Stephanelytron, the genus not having been recorded from the Kellaways Rock. The representatives of this species occur only in the 100-foot horizon. TEXT-FIG. 10. Stephanelytron redcliff'ense gen. et sp. nov. Upper and lower surfaces (x600); an individual tube (X 1,250); and a sketch to illustrate the structure of the corona. Holotype CBS 1/26/6. Stephanelytron caytonense sp. nov. Plate 15, fig. 16; text-fig. 1 1 Holotype. CB56/14/1, 25-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimensions. The holotype has a somewhat damaged shell; its overall dimensions, length 65 p and breadth 60 p, probably do not therefore reflect its true shape. The corona is 17 /a high; its outer diameter is 25 p, its basal diameter about 14 p. The tubes are around 8 in length. Diagnosis. A species of Stephanelytron having a spherical to oval shell, not granular or punctate, bearing rows of tubes similar in distribution to those of S. redclijfense but with lips less pro- nouncedly everted and having about eight to ten rows of perforations aligned parallel to the length of the tube and quite closely spaced. The corona has a relatively small base and flares out widely; its mem- brane is somewhat folded, with a coarsely granular surface and a distinct outer lip devoid of granulation. Remarks. The single specimen found of this species was the only representative of the genus noted at this horizon. However, its perforate tubes and the character of its corona afford a ready distinction from all other specimens of the genus and warrant specific status. TEXT-HG. 11. Stephanelytron cayto- nensis sp. nov. (x600) and an isolated tube (xl,00). Holotype CB56/14/1. W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 111 Stephanelytron scarburghense sp. nov. Plate 15, figs. 12-13 Holotype. SC2/31/2, lowest Oxford Clay, Scarborough Castle cliff. Dimensions. Holotype: overall length 41 p, overall breadth 30 p (oblique view). Specimen SC2/31/12, seen in lateral view, gives more satisfactory dimensions (overall length 45 p, breadth 40 p, corona 1 2 p high and 28 /x in outer diameter, tubes about 5 /x in length) but was unfortunately damaged. These dimensions appear typical. Diagnosis. A species of Stephanelytron having a spherical to oval shell, not granular or punctate, bearing tubes similar in character and distribution to those of S. redcliffense but with in addition further tubes of similar character distributed in an irregular scatter within the fields delimited by these tube rows. The everted lips of the tubes in the rows overlap to some extent, giving an appearance of linkage. The corona or coronas have a surrounding membrane striated in similar fashion to that of S. redcliffense: however, the membrane slopes regularly outwards instead of having a distinctly everted lip. Description. Whereas all other specimens seen of this genus have a single large corona, as does the type of S. scarburghense, one specimen seen (SC2/33/6) has two smaller coronas, situated together on the antapical surface. In the character of these coronas and in the type and distribution of tubes this specimen corresponds to S. scarburghense and it has therefore been attributed to this species, the drawing of a varietal distinction not being considered warranted in view of the absence of knowledge of the character and functions of the corona. Remarks. This species, typical of the lowest Oxford Clay, is proportionately more abundant than the species of Stephanelytron of the higher horizons. Broken specimens are relatively numerous, an estimated thirty to fifty being seen, but only five relatively complete specimens were noted. The character of the corona and tubes suggests a closer relation to S. redcliffense than to S. caytonense, so that no evolutionary sequence can be postulated satisfactorily. Genus antrosphaera gen. nov. Type species. Antrosphaera calloviensis sp. nov. Diagnosis. Organic shells of spherical shape, hollow, without processes, patterned with depressions of varied shape, size, and arrangement. Remarks. The extreme simplicity in form of the representatives of this genus makes their attribution to any group uncertain. In the organic nature of the test there is a resemblance to both spores and pollen and to microplankton. However, there are no traces of a trilete or monolete mark; moreover, some specimens (including the type of A. calloviensis) were seen to contain irregular greenish bodies considered probably chloroplasts, and if these were indeed chloroplasts then these organisms could not be pollen. The absence of any trace of tabulation or of traces of a transverse furrow makes a relationship with the Order Dinoflagellata unlikely. The absence of processes is a distinction from the majority of genera and species of the Order Hystrichosphaeridia; the genus Leiosphaeridia comprises simple, spherical to ovoidal bodies without pro- cesses or ornamentation (other than granules), but comparison with specimens of that 112 PALAEONTOLOGY, VOLUME 4 genus suggested that the cell wall of Antrosphaera was composed of a quite different j substance. Nevertheless, the possibility of a relationship with Leiosphaeridia remains. I Until more evidence of relationship becomes available, therefore, this genus must i remain incertae sedis. \ Antrosphaera calloviensis sp. nov. ! Plate 13, fig. 7; text-fig. 12 Holotype. SC33/5/16. Kellaways Rock, Scarborough Castle cliff. Dimensions. Holotype: diameter 14 /x; the six other specimens seen were of comparable dimensions. Diagnosis. A species of Antrosphaera of small size, having a granular shell surface ornamented with small ovoid depressions, regularly spaced, in arrangement as shown ! on the figure; about thirty such depressions appear present on either surface. Deseription. Shell moderately thick, greenish in colour; outline undulose, there being some indication that the depressions are situated in the crests of slight bulges in the shell surface. Focusing indicated that the holes in the surface become smaller with depth and appear to close; they are thus considered depressions and not , perforations. The type specimen contains a greenish body with a somewhat irregular surface ; this was thought probably a chloroplast (discussed earlier). Remarks. Representatives of this species were found only in the Kellaways Rock assemblage. In view of its extremely small size this organism readily escapes notice; it may well be considerably more abundant at this horizon than the numbers recorded would suggest. Genus wanaea Cookson and Eisenack 1958 Wanaea fimbriata sp. nov. Plate 15, fig. 14; text-fig. 13 Holotype. CB56/8/15, 25-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimensions. Holotype: height of shell c. 65 p, diameter of base 100 p, fringe up to 20 p broad. The other specimens seen vary little from these dimensions. Diagnosis. A species of Wanaea with a shell broadly cone-shaped, narrowing to a short, rounded apex. The edge is ornamented for four-fifths of its length by a fringe, relatively broad but narrowing towards the gap ; this fringe is in the form of a small-meshed net- work of irregular structure, its edges free. Deseription. Fringe meshwork extremely variable in character; in some cases two adjacent processes anastomose only twice in their length, in others, they do so four times. Mesh fragile and frequently torn; it is not rigid, its surface frequently being undulose. Remarks. Three species of this genus have so far been erected, W. spectabilis (Deflandre and Cookson), W. digitata Cookson and Eisenack, and W. clathrata Cookson and Eisenack. On the basis of time sequence Cookson and Eisenack have suggested that TEXT-FIG. 12. Antro- sphaera calloviensis gen. et sp. nov. X 1,425. Holotype SC33/5/16. W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 113 these represent an evolutionary series with W. spectabilis the simplest and W. clathrata the most highly developed (1958). All are from successive horizons in the Upper Jurassic of Australia and Papua. Wanaea fimbriata occurs in all three Oxford Clay horizons examined (lowest 7, 25-foot 1, i 00-foot 3) but was not recorded from the Kellaways Rock. In the form of the shell it resembles W. digitata and W. spectabilis and differs from W. clathrata', its fringe on the other hand shows closest similarity with that of W. clathrata but differs in that it lacks an outer edge. On morphological considerations alone an evolutionary TEXT-FIG. 13. Wanaea fimbriata sp. nov. Holotype CB56/8/15. X600. position might be tentatively assigned after W. digitata and possibly before W. clathrata; but without more precise knowledge of the comparative ages of the Australasian horizons in relation to the Oxford Clay this remains no more than a possibility. Genus netrelytron gen. nov. Type species. Netrelytron stegastiim sp. nov. Diagnosis. Micro-organisms formed of a spherical, ovoidal, or ellipsoidal central body enclosed in a spindle-shaped outer membrane. Remarks. Four existing genera possess a central body surrounded by an outer membrane. The new genus differs from Ptcrocystidiopsis Deflandre in the distinctive and well- defined shape of its outer membrane; from Deflandrea Eisenack, Scriniodinium Klement, and Muderongia Cookson and Eisenack in that the outer membrane has only two opposed prominences {Scriniodinium lacks horns; Deflandrea has one extremity, a single horn, and the other, two horns; Muderongia has four equidistant horns) and from Deflandrea and Scriniodinium also in that the central body lacks a transverse furrow, these latter genera being undoubtedly encysted dinoflagellates. The affinities of this genus are doubtful. It is possible that it comprises encysted dinoflagellates ; however, as stated above, the central body shows no transverse furrow or girdle. Deflandre comments on the equally problematical genus Ptcrocystidiopsis (1941): ‘Should one see in this organism some peculiar member of the microplankton, I B 7879 114 PALAEONTOLOGY, VOLUME 4 or is this on the contrary a spore of a being higher in the organisation? Nothing permits the solving of that question, for the moment.’ This comment is equally applicable to the genus Netr elytron. Holotype. CB81/16/10, 100-foot horizon of Oxford Clay, High Red Cliff, Cayton Bay. Dimensions. Holotype: overall length 125 /x, breadth 55 jj,, long diameter of inner shell 55 /x, short diameter 45 p; the paratype figured (CBS 1/23/ 18) is of similar dimensions. Diagnosis. A species of Netrelytron having an outer membrane of almost spherical shape, with conical horns arising from it at two opposed extremities. These horns have rounded tips and tend to be inclined rather than vertical in their relation to the surface of the ovoidal central body, to whose long axis their position corresponds. Description. All specimens found are invested almost completely in a mass of formless organic matter; this follows the rough outline of the outer membrane and may represent a protective envelope formed around itself by the living organism. Outer membrane thin, devoid of ornamentation. In two specimens seen it is perforated by a roughly oval aperture on one flank, a corresponding gap in the cloak of extraneous material being noted. Character of the ovoidal inner shell difficult to determine; it appears of moderate thickness and devoid of ornamentation save possibly for a very faint granulation. Both inner shell and outer membrane frequently folded in some degree. The type specimen and a paratype are both stained with safranin; however, the two other specimens seen are unstained, having a yellowish-brown hue, the inner shell more strongly coloured than the outer membrane. Remarks. The perforation in the outer membrane may be interpreted as a pylome, in Netrelytron stegastum sp. nov. Plate 15, fig. 15; text-fig. 14 TEXT-FIG. 14. Netrelytron stegastum gen. et sp. nov. The holotype CB8 1/1 6/10 and a paratype, CB8 1/23/1 8, figured without the investing material, x 600. W. A. S. SARJEANT; MICROPLANKTON FROM YORKSHIRE 115 which case this surface would be termed dorsal (cf. Eisenack 1958). If this interpretation were correct, a relationship to the Order Dinoflagellata would be suggested ; however, no aperture was observable in the two other specimens seen, and its constancy cannot be affirmed. Similarly, since only four specimens of this distinctive microfossil have been seen, the constancy of the envelope of organic matter cannot be vouched for. All specimens found derived from the 100-foot Oxford Clay horizon, the material from which was very well oxidized; other microfossils from this horizon rarely show any degree of investment in extraneous material, and it is improbable that all specimens of a relatively smooth form such as this should have become fortuitously enwrapped when hystrichospheres bearing complex spines, such as the two species of Camwsphaeropsis present, remain free. CONCLUSIONS In the assemblages described eight species of dinoflagellates and sixteen species of hystrichospheres were recognized. Gonyaulax jurassica Deflandre proved by far the most abundant dinoflagellate at all horizons, G. cladophora Deflandre coming second in abundance. Of the hystrichospheres Cymaliosphaera parva Sarjeant is the commonest species in the Kellaways Rock assemblage but is not present in the Oxford Clay assem- blages; in these assemblages Baltisphaeridium pilosum (Ehrenberg) is the most common species. In addition four genera of organisms incertae sedis, presumed microplankton, are present, three of the genera and all six species being described for the first time. Text-fig. 15 shows the distribution of species in the horizons considered, in comparison with their distribution as previously recorded. Progressive change in the character of the microplankton with time is indicated. Some assessment may be made of the stratigraphic value of the fossil microplankton by comparing this assemblage as a whole with other assemblages described. On the basis of previous published records three species have ranges spanning the Callovian and Lower Oxfordian: Gonyaulax jurassica (Bathonian to Kimeridgian) and G. cladophora (Bajocian to Kimeridgian), both of which species probably attained their acme in the Oxfordian, and Micrhystridium inconspicuum (Bajocian to Upper Creta- ceous). Five species were previously known only from lower horizons: Micrhystridium fragile and M. stellatum (Bajocian to Lower Callovian [Cornbrash]), M. recurvatum f. reducta (Bathonian), Membranilarnax ovuluni (Bajocian to Bathonian), and Cymatio- sphaera parva (Lower Callovian [Cornbrash]). Two species have known ranges from the Middle Jurassic to the Callovian or Lower Oxfordian, but are not recorded from younger sediments: Pareodinia ceratophora (Bajocian to Callovian) and Baltisphaeridium stimuliferum (Bajocian to Lower Oxfordian). Two species have known ranges from the Lower Oxfordian upwards: Caimosphaeropsis caulleryi (Lower Oxfordian to Eocene) and Hystrichosphaeridium salpingophorum (Lower Oxfordian to Oligocene). Finally four species have been recorded only from comparable horizons elsewhere: Scrinio- dinium crystallimim (Lower Oxfordian and ‘Upper Jurassic’ of Australia), S. galeriturn (Lower Oxfordian), Baltisphaeridium pilosum (‘Corallian’), and Camwsphaeropsis aemula (Lower Oxfordian and ‘Upper Jurassic’ of Australia). Thus the known stratigraphic occurrences of fossil microplankton would indicate a position for these horizons within the stratigraphic range Bathonian-Lower Oxfordian; 116 PALAEONTOLOGY, VOLUME 4 Pre-Callovian horizons Lower Callovian — Cornbrash of Yorkshire Lower Callovian — Kellaways Rock of Yorkshire Middle-Upper Callovian Lower Oxfordian O.xford Clay of Yorkshire Lowest 25-foot 100-foot Gonyaulax jurassica . X X X X X G. jurassica var. longiconiis X X G. cladophora .... X X X X X G. cladophora var. imdtispinosa X G. acanihosphaera X G. areolata .... X X G. sp. X Scriniodinium crystcdlinum . X X X S. galeritian .... X Pareodinia ceratophora X ? . . X P. ceratophora var. pachyceras X X Hystrichosphaeridium salpingo- phorum ..... X X H. cf. trimcigerum X Baltisphaeridiiim stinuiliferum X X X X B. pi/osiiin .... X X X B. pilosum var. longispinosiim X B. cf. fimbriatian X X X X B. ehrenbergi var. brevispinosum . X Cannosphaeropsis caidleryi . X X X X C. aeimda .... X Polystephanosphaera calathiis X X Micrhystridium inconspicuum X X X X X X M. fragile .... X X X M. stellatuw .... X X X X X X M. recurvatum f. reducta X X X X X M. cf. mendax .... X X 1 M. sp. . X X X Cymatiosphaera teichophera X C. parva ..... X X ? C. sp. indet. .... X Membranilarnax ovidum X X Stephanelytron scarburghense X S. caytonense .... X S. redcliff'ense .... X Antrosphaera calloviensis X Wanaea fimbriata X X X Netrelytron stegastiim X X X X X X X X II II II TEXT -FIG. 15. Known stratigraphic distribution of fossil microplankton species present in the Yorkshire assemblages. Lower Oxfordian of France W. A. S. SARJEANT: MICROPLANKTON FROM YORKSHIRE 117 this, of course, corresponds with the stratigraphic position as determined by macro- fossils, a satisfactory degree of correlation in view of the present paucity of knowledge of the fossil organic-shelled microplankton. Acknowledgements. This work has been carried out at the Geology Department, University of Sheffield, under tenure of a Town Trustees Fellowship and a State supplemental award. The author would like to record his thanks to Professor L. R. Moore for the use of Departmental facilities and to Dr. Charles Downie for help and guidance unstintingly given at all stages of this study. REFERENCES COOKSON, I. c. and eisenack, a. 1958. Microplankton from Australian and New Guinea Upper Mesozoic sediments. Proc. Roy. Soc. Victoria, 70, 19-79, 12 pi. DEFLANDRE, G. 1935. Considerations biologiques sur les organismes d'origine planctonique conserves dans les silex de la craie. Bull. Biol. Fr. et Belg. 19, 213-44, 5 pi. ■ 1936-7. Microfossiles des silex cretaces. Ann. Paleont. 25, 151-91, 8 pi.; 26, 1-55, 10 pi. ■ 1938. Microplancton des mers jurassiques conserve dans les marnes de Villers-sur-Mer (Calvados). Trav. Stat. Zool. Wimereux, 13 (Vol. Jub. M. Caullery), 153-200, 7 pi. 1941. Microplancton kimeridgien d'Orbagnoux. Mem. Acad. Sci. Paris. 65, 1-32, 7 pi. 1943. Sur les hystrichospheres des calcaires siluriens de la Montague Noire. C.R. Acad. Sci. Paris, 215, 475-6, 16 fig. 1947. Le probleme des hystrichospheres. Bull. Inst. Oceanogr. Monaco, no. 918, 1-23. ■ — ^ — • 1947. Sur quelques micro-organismes planctoniques des silex jurassiques. Ibid., no. 921, 1-10. 1954. Systematique des hystrichosphaerides : sur I’acception du genre Cymatiosphaera O. Wetzel. C.R. Somm. Soc. Geol. Fr. 257-9. DEUNFF, J. 1954. Sur un microplancton du Devonien du Canada recelant des types nouveaux d’hystricho- spheres. C.R. Acad. Sci., Paris, 239, 1064-6. ■ — — • 1955. Un microplancton fossile Devonien a hystrichospheres du continent Nord-Americain. Extrait du Bull. Microsc. Applique, (2) 5, nos. 11-12, 138-49. DOWNIE, c. 1957. Microplankton from the Kimeridge Clay. Quart. J. Geol. Soc. Lond. 113, 413-34, 1 pi. EHRENBERG, c. G. 1838. Uber das Massenverhaltnis der jetzt lebenden Kiesel-infusorien und fiber ein neues Infusorien-conglom. als Polierschiefer von Jastraba in Ungarn. Abhand. K. Akad. IViss. Berlin, 1836, f. 1, 109-35, 2 pi. 1843. Uber einige Jura infusorien-arten des Corallrags bei Krakau. Monatsber. Akad. Wiss. Berlin, 61-63. 1854. Mikrogeologie. Leipzig. 40 pi. EISENACK, A. 1935. Mikrofossilien aus Doggergeschieben Ostpreussens. Zeitschr. fiir Geschiebeforsch. 17, 167-84, 2 pi. ■ 1936. Dinoflagellaten aus dem Jura. Ann. Protist. 5, 59-64, 1 pi. ■ 1957. Mikrofossilien in organischer substanz aus dem Lias Schwabens. Neu. Jb. Geol. Pal. Abh. 105 (3), 239-49. 1958. Mikroplankton aus dem norddeutschen Apt nebst einiger bemerkungen fiber fossile Dino- flagellaten. Ibid. 106 (3), 383^22, 8 pi. GOCHT, H. 1952. Ftystrichosphaerideen und andere Kleinlebewesen aus Oligozanablagerungen Nord- und Mitteldeutschlands. Geologic 1, 301-20, 2 pi. 1959. Mikroplankton aus dem nordwestdeutschen Neokom. Palaont. Zeitschr. 33, 50-89, 6 pi. KLEMENT, K. w. 1957. Revision der gattungszugehorigkeit einiger in die Gymnodinium Stein einge- stufter Arten jurassischer Dinoflagellaten. Neu. Jb. Min. u.s.w. Monatsbefte, 408-10. MERCiER, J. 1938. Micro-organismes du bajocien et du bathonien. C.R. Somm. Soc. Geol. Fr., 114-15. PASTiELS, A. 1948. Contributions a I’etude des microfossiles de I’Eocene beige. Mem. Mus. Roy. Hist. Nat. Belg. 109, 1-77, 6 pi. 118 PALAEONTOLOGY, VOLUME 4 SARJEANT, w. A. s. 1959. Microplankton from the Combrash of Yorkshire. Geol. Mag. 96, 329-46, 1 pi. ■ 1960. New Hystrichospheres from the Upper Jurassic of Dorset. Geol. Mag. 97, 137-44. VALENSi, L. 1953. Microfossiles des silex du Jurassique Moyen. Mem. Soc. Geol. Fr. 68, 1-100, 16 pi. WETZEL, o. 1933. Die in organischer substanz erhaltenen mikrofossilien des Baltischen Kreide- Feuersteins. Palaeontographica, 77, 141-98 and 18, 1-110, 7 pi. WHITE, H. H. 1842. On fossil Xanthidia. Microscop. Jnl. 11, 35-40, 1 pi. W. A. S. SARJEANT, Department of Geology, Revised manuscript received 20 March 1960 University of Sheffield PERMIAN PELECYPODS NEWLY RECORDED FROM EASTERN AUSTRALIA 1 by J. M. DICKINS Abstract. Atomodesma (Atomodesma) bisulcata sp. nov., Pseudomyalina sp., and Oriocrassalella queens- landica sp. nov. are described from Queensland, and Etheridge jun.’s figured specimen of Sangidnolites concen- Jriciis (Etheridge sen.) is referred doubtfully to Pyramus. Atomodesma (Aphanaia) is recorded from Queensland and Schizodiis from Queensland and New South Wales. Atomodesma, Pseudomyalina, and Oriocrassatella have 1 not previously been described from Eastern Australia. On the basis of the pelecypod fauna the Cattle Creek I Formation of Queensland is regarded as most likely of early Artinskian (Lower Permian) age and the Crocker I Formation, which is considered to be the equivalent of the Mantuan Productiis Bed, is regarded as of Kungurian to Kazanian age. During an examination of the collections of the Geological Museum of the University of Queensland, Brisbane, several genera or subgenera hitherto unrecognized in Eastern Australia, were identified. They are of importance for the correlation of the Permian rocks of Queensland, particularly of the Bowen Basin, with those of Western Australia and elsewhere. The genera or subgenera described are Atomodesma {Atomodesma), Pseudomyalina, and Oriocrassatella. Schizodus (sensu lato), although it has not so far been described, is represented in Queensland and New South Wales by a number of species, but they require an extensive study which is outside the scope of this paper. In addition Atomodesma {Aphanaia), which occurs in New South Wales, is also found in Queensland, but the specimens are fragmentary and are not described here. Because of its possible relationship to Oriocrassatella, the figured specimen of Sangidnolites concen- triciis (Etheridge sen.) (1872, p. 328, pi. 13, fig. 2), Etheridge jun. (1892, p. 281, pi. 43, fig. 7) is refigured and described. PERMIAN ROCKS IN QUEENSLAND AND WESTERN AUSTRALIA The succession in the Springsure (eastern) area of the Bowen Basin, taken from Hill (1957), is shown in the accompanying text-figure and is tabulated below. Earlier accounts include Hill (1955) and Webb (1956). Hill (1957, p. 12) says, ‘the successive rich marine faunas, Dilly, Cattle Creek, Ingelara and Mantuan must form the standard for the correlation of the entire Queensland Permo-Carboniferous’. 8. Bandanna Formation 1,000 feet Shale, sandstone, calcareous sandstone and sandy limestone, with coal and oil shale seams and plant fossils. 7. Mantuan productus Bed 100 feet Limestone to calcareous sandstone, with brachiopods, bryozoans and corals. 6. Catherine Sandstone 400-700 feet Sandstone and occasional calcareous sandstone; with brachiopods and plants. 5. Ingelara Formation 90-500 feet Shale, sandstone, thin bands of limestone, with a rich marine fauna. 4. Aldebaran Sandstone 1,500-2,500 feet Sandstone with quartz pebbles, intercalated shale and clay, no fossils recorded. [Palaeontology, Vol. 4, Part 1, 1961, pp. 119-130, pi, 16.] BOWEN BASIN CARNARVON BASIN TEXT-FiG.I Springsure Area Northern end Kennedy Range BANDANNA FM. MANTUAN PRODUCTUS BED CATHERINE SS. INGELARA FM. ALDEBARAN SS. CATTLE CREEK FM. STAIRCASE SS. DILLY BEDS. 1 1 1! 0 ■ ■ ^6) 9 <^9 o: o >- n kJ LU a. ID O oc o o (T > GQ @ 9 e, LU <3) BINTHALYA SUBGROUP MUNGADAN SS. COOLKILYA GW. BAKER FM. NORTON GW. WANDAGEE FM. QUINNANIE SHALE CUNDLEGO FM. BULGADOO SHALE MALLENS GW. COYRIE FM MOOGOOLOO SS. CALLYTHARRA FM. I ’ I Sandstone I*.*.* I Quartz greyivacke Si/tstone or shale Limestone Vertical Scale lOOO' to /" Regional subaena! erosion % Formation with marine fossils '?> Formation with plant fossils Coal TEXT-FIG. 1 J. M. DICKINS: PERMIAN PELECYPODS FROM AUSTRALIA 121 3. Cattle Creek Formation 500 feet in surface outcrop Shale, marl, marly limestones, with a rich marine fauna. 2. Staircase Sandstone 1,600 feet Sandstone with quartz conglomerate and clay. Brachiopods, pelecypods, and gastropods. 1 . DiUy Beds 2,000 feet exposed Sandstone, shale, mudstone, calcareous sandstone with marine fossils and some plants. Hill (1955) correlated the beds at Mount Britton (Homevale Beds) approximately with the Cattle Creek Formation. Webb (1956) extended the Cattle Creek Formation downward from subsurface evi- dence and the Cattle Creek Formation of Webb may include the Staircase Sandstone and the Dilly Beds or part of the Dilly Beds of Hill. The succession at the northern end of the Kennedy Range in the Carnarvon (north- west) Basin, Western Australia, is derived from Condon (1954) and McWhae, Playford, Lindner, Glenister, and Balme (1958), somewhat modified by later work (see Konecki, Dickins, and Quinlan 1959). 14. Binthalya Subgroup 1,725 feet Quartz sandstone and quartz greywacke, with a poor marine fauna. 13. Mungadan Sandstone 184 feet Quartz sandstone, with a poor marine fauna. 12. Coolkilya Greywacke 625 feet Predominantly quartz greywacke, with many marine fossils; mainly molluscs and brachiopods. [The ‘greywackes’ in the succession are in fact all quartz greywackes (defined by Condon (1953, p. 9) as an arenite ‘composed of more than 50% quartz, 10-30% fine-grained matrix, and 0-20% feldspar’).] These three subdivisions are placed in the Kennedy Group. 11. Baker Formation 210 feet Siltstone and quartz greywacke. 10. Norton Greywacke 250 feet Predominantly quartz greywacke. 9. Wandagee Formation 545 feet Siltstone and quartz greywacke, with a very rich marine fauna in places. 8. Quinnanie Shale 85 feet Shale and thin quartz greywacke. 7. Cundlego Formation 700 feet Quartz greywacke and siltstone, with some calcareous beds. 6. Bulgadoo Shale 500 feet Siltstone, carbonaceous shale, and thin quartz greywacke. 5. Malleus Greywacke 300 feet Predominantly quartz greywacke. 4. Coyrie Formation 500 feet Siltstone and quartz greywacke. The above seven formations, together with the top of the Coyrie Formation, are placed in the Byro Group. In the top part of the Coyrie Formation and the other formations of the Byro Group, marine fossils are well represented and in places rich faunas are present. Fossils include brachiopods, bryozoans, foraminifera, ostracods, corals, trilobites, pelecypods, gastro- pods, a few ammonoids, blastoids, criiioids, and shark and fish remains. Wood and leaves also occur. In the lower part of the Coyrie Formation marine fossils are poorly repre- sented or absent. PALAEONTOLOGY, VOLUME 4 122 3. Moogooloo Sandstone 122 feet Mainly quartz sandstone. Marine fossils poorly represented. [Name proposed by Condon (in McWhae et al. 1958, p. 66) to replace the Wooramel Sandstone as previously used by him in the Carnarvon Basin proper. The bottom arenaceous part of the Coyrie Formation and the Moogooloo Sandstone together represent the Wooramel Group of the Byro area.] 2. Callytharra Formation 250^00 feet Limestone, quartz greywacke and siltstone, with a rich marine fauna throughout. 1. Lyons Group 73,700 feet Silty and sandy ‘tillite’, quartz greywacke and siltstone, boulders beds, marine fossils in places. The Norton Greywacke appears to be the same formation as the Nalbia Sandstone of Teichert (1950; 1952) and the Baker Formation is apparently the bottom part of Teichert’s Coolkilya Sandstone. Teichert (1957) and McWhae et al. (1958, p. 69) have suggested that the name Norton Greywacke is a synonym of Nalbia Greywacke. McWhae et al. (1958, p. 67) have also suggested a return to the use of Teichert’s (1950, p. 1791) name ‘Coyrie Shale’ for the upper argillaceous part of the Coyrie Formation placed in the Byro Group and that the arenaceous bottom part of the Coyrie Formation placed in the Wooramel Group be named as a separate formation. In the Fitzroy Basin of Western Australia the lower marine beds of the Liveringa Formation (Lightjack Member) are correlated with the Baker Formation and Coolkilya Greywacke and are considered to be of Upper Artinskian to Kungurian age (see Thomas and Dickins 1954). The upper marine beds (Hardman Member) of the Liveringa Forma- tion are considered to be of Upper Permian (possibly Tatarian) age. The lower and upper marine beds are separated by a plant-bearing sequence. Correlation. The ages of the Western Australian formations have been discussed by, inter alia, Thomas and Dickins (1954). Among the forms which first appear in the Callytharra Formation and its equivalents are Atomodesma, Pseudomyalina, and Orio~ crassatella. On the other hand some genera, notably Eurydesma, have only been found in the Lyons Group (Dickins 1957). But in Queensland the beds at Mt. Britton, Atomo- desma (= Aplianaia) and Pseudomyalina occur with Eurydesma; and in the Springsure area, Pseudomyalina and Oriocrassatella^ occur in strata mapped as Dilly Beds which certainly are not as young as the Cattle Creek Formation in the restricted sense of Hill. An advanced species of the Aviculopecten subquinquelineatus line has been found in the outcropping Cattle Creek beds and the beds at Mt. Britton: in the Carnarvon Basin species of this type have not been found below the Byro Group. This evidence on the whole suggests that the Cattle Creek Formation is of the same age as, or more likely slightly younger than, the Callytharra Formation which is gener- ally regarded as lowermost Artinskian (see Thomas and Dickins 1954) though it may possibly be uppermost Sakmarian. So the Cattle Creek Formation is almost certainly early Artinskian. Other authors (Maxwell 1954; Hill 1955) have reached the same general conclusion although Hill suggested a slightly older age. If the Cattle Creek Formation is Artinskian, this supports a previous suggestion (Dickins 1957, p. 18) that Eurydesma may have slightly different ranges in different places ; it survived longer in Queensland than in Western Australia. 1 Maxwell (1959) records Schizodus and Oriocrassatella from the Rands and Burnett Formations of the Yarrol Basin, v/hich he refers to the Upper Carboniferous and Lower Permian (Sakmarian) respectively. J. M. DICKINS: PERMIAN PELECYPODS FROM AUSTRALIA 123 The correlation of the Ingelara Formation is considered in detail in the following paper; it is correlated with the upper part of the Byro Group (Cundlego-Baker Forma- tions) on the evidence of Platyteichum and Glyptoleda and is considered to be of late Artinskian age. An Atomodesma with two anterior grooves, A. bisulcata sp. nov. was found in beds in the Crocker Formation, which are considered (S. S. Derrington, pers. comm.) to be the equivalent of the Mantuan Productus Bed. A species with one anterior groove, A. exarata Beyrich, is found in the Baker and Coolkilya Formations of the Carnarvon Basin and the lower marine beds (Lightjack Member) of the Liveringa Formation in the Fitzroy Basin (Dickins 1956); and an undescribed form with three grooves is present in the upper marine beds (Hardman Member) of the Liveringa Formation. A two-grooved form might be expected to occur between the Lightjack and Hardman Members, thus suggesting the Crocker Formation is Kungurian to Kazanian in age. Two-grooved forms, indeed, have already been recorded from the Basleo Beds of Timor (Wanner 1922). The Basleo Beds appear to be of Kazanian age (see Ruchencev 1956, table 4). Popov (1957) also records a two-grooved Atomodesma from north-eastern Siberia which he refers to A. variabilis Warner 1922 and considers to be from beds of Kazanian age. Campbell (1959, p. 341, 342) has reached the same conclusion for the age of the upper- most marine beds in the Bowen Basin, Queensland. SYSTEMATIC DESCRIPTIONS Family myalinidae Freeh Genus atomodesma Beyrich 1864 Type species. Atomodesma exarata Beyrich (1864, p. 71, pi. 3, figs. 4a, b) by subsequent designation of Wanner (1922, p. 63). Discussion. The relationship of Atomodesma to Posidionella de Koninck 1885 from the Carboniferous and Aphanaia de Koninck 1877, Maitaia Marwick 1935, Kolymia Licharew 1941, and Intodesma Popov 1958, is rather unsatisfactorily understood. It is proposed discussing this in detail elsewhere but the following comments seem pertinent here. In 1956 (p. 23) I proposed that Aphanaia be placed in synonymy with Atomodesma. Later Waterhouse (1958) showed that, as in Maitaia, specimens of Atomodesma from Timor, including A. exarata, had more than one groove on the ligament area; accord- ingly he placed Maitaia in synonymy with Atomodesma, and left the position of Aphanaia unresolved until it was found whether or not it had an umbonal septum. I have now examined specimens of the type species, Aphanaia mitcheUi (M‘Coy), in the Australian Museum, Sydney, and an umbonal septum is present. Waterhouse (1959) proposes that Aphanaia stnd Kolymia be regarded as subgenera of Atomodesma, and places Maitaia and Intodesma in synonymy with Aphanaia. He regards the longitudinal grooves in the liga- ment area as formed by strongly developed growth ridges, and not as analogous with the ligament grooves of Myalina. I agree with this interpretation and Waterhouse’s proposal to regard Aphanaia and Kolymia as subgenera of Atomodesma. The species described below has two anterior grooves or plications and is placed in the subgenus Atomodesma. 124 PALAEONTOLOGY, VOLUME 4 Atomodesma (Atomodesma) bisidcata sp. nov. Plate 17, figs. 15-19 Diagnosis. Of medium size, distinguished by two anterior grooves and the elongation at about right angles to the hinge-line. Description. Holotype (impression of a right valve). The shell is oval elongated normal to the hinge-line. The anterior-ventral part extends for a considerable distance in front of the umbo. (This feature does not show in the other specimens which are, however, con- siderably smaller.) A marked feature is the strong development of two anterior grooves which are shallow in the middle part of the shell and become deeper towards the margin; the posterior groove is the deeper. The umbo is not preserved. No posterior groove or sulcus is visible. The concentric furrows and rugae are well marked and fairly regular. The ligamental structure is not shown. Paratype A, a right valve, shows the umbo and two anterior grooves. In Paratype B, also a right valve, the umbo is missing. The posterior of the anterior grooves is distinct, but, as might be expected in a young shell, the front groove is poorly developed. Dimensions (in mm.) Length Height Width Holotype (QUM F27,124) 31 40 11 Paratype A (QUM F27,121) . 17 19 5 Paratype B (QUM F27,122) . 12 14 4 Occurrence. The material consists of four specimens from a single locality, 6-5 miles south of Tolmies (abandoned); it was collected by S. S. Derrington and D. M. Traves of Mines Administration Pty. Ltd. from 15-20 feet above the base of the Crocker Formation (Derrington and Morgan 1959). This formation is considered by the Mines Administration geologists to be the equivalent of the Mantuan Productus Bed. The fossils are contained in a white to grey medium to coarse-grained quartz sandstone which has some kaolinized feldspar grains. Discussion. Two-grooved forms have been recorded from Timor, where Wanner (1922) assigns specimens from Basleo and ‘Abbang von Niki Niki gegen Noil Fatoe’ to A. variabilis Wanner 1922, and specimens from Noil Mahatissa to A. elongata Wanner 1922. Although Wanner considers A. elongata to be of Lower Triassic age this seems unlikely (see Dickins 1956, p. 25). The Queensland species differs considerably in shape from the Timor species which are all obliquely elongated. In the elongation of the shell, however, it is similar to Atomodesma mitchelli (M‘Coy) 1847, Dickins (1956, pi. 4, fig. 1) from the Permian of New South Wales. The age of the Queensland species is considered to be Kungurian or Kazanian. Genus pseudomyalina Dickins 1956 Type species. Pseudomyalina obliqua Dickins (1956, p. 26, pi. 3, figs. 1-7) by original designation (ibid., p. 25). Pseudomyalina sp. Plate 16, figs. 1 1-12 Description. Two specimens are figured. One shows the shape and the other is a frag- mentary individual showing the hinge structure and the external ornament. In the first J. M. DICKINS; PERMIAN PELECYPODS FROM AUSTRALIA 125 specimen the elongation is only slightly oblique to a line at right angles to the hinge; in shape it is not unlike species of Atomodesma (Aphanaia), but the beak and the umbonal fold are turned over towards the front, so that the anterior margin is concave inwards below the beak to an extent not known in Atomodesma, where the anterior margin immediately below the beak is usually straight or convex. The second specimen is the umbonal part of an external impression; five longitudinal grooves are visible on the flattish ligament area of the right valve. On the left valve, distinct radial ornament is developed in addition to the concentric growth ornament. Two orders of radial ribbing are formed, either by subdivision or intercalation. Dimensions (in mm.) Length Height Thickness Figured Specimen A, left valve (QUM F27,405) 65 59 11 Occurrence. Figured Specimen A, KOE6, Orion Creek, 6 miles west of the Springsure-Rolleston Road, Springsure 4-mile map sheet 643,978, mapped as Dilly Beds, but may be equivalent of the lower part of the Staircase Sandstone (D. Hill, pers. comm.). Figured Specimen B (QUM F21,006), Homevale Bed 9, f mile east of Homevale Station, Mt. Britton 1-mile map sheet 200,198 (from unpublished work of Campbell and Tweedale; G. W. Tweedale, pers. comm.). Discussion. Pseudomyalina is represented in the collection in Queensland only by a few fragmentary specimens, so that the species cannot be accurately described or compared with Western Australian species. In Pseudomyalina the prisms which make up the outer shell layer are readily visible to the naked eye, whereas in specimens of Atomodesma I have examined, they are hardly visible. This may be useful for distinguishing shell fragments of the two genera. Family crassatellidae Dali Genus oriocrassatella Etheridge jun. 1907 Type species. Oriocrassatella stokesi Etheridge jun. (1907, p. 9, pi. 6, figs. 2-5) by monotypy. Synonym. Procrassatella Yakovlev 1928 (type species Schizodus planus Golovkinsky (1868, p. 358, pi. 3, figs. 21-23) by monotypy). Discussion. Since I gave additional information on Oriocrassatella (Dickins 1956, p. 32) Newell (1958) has discussed in detail the character of Oriocrassatella and its relationship to Procrassatella. After Newell’s analysis I have no hesitation in placing Procrassatella in synonymy with Oriocrassatella. For convenience Newell’s diagnosis (1958, p. 6) is reproduced : ‘Lenticular, ovoid to elongate, crassatelliform, unornamented shells without well- defined lunule and escutcheon; ligament furrow opisthodetic, internal, separated by a heavy septum from a triangular resilifer; 3a and 46 narrow. Dental formula: AI3a— 3b— rsl— Pin All— 2— 4b rsl PIE 3a may be poorly developed or possibly absent altogether in some specimens and AI and All poorly developed. 126 PALAEONTOLOGY, VOLUME 4 Oriocrassatella queenslandica sp. nov. Plate 16, figs. 3-10 Diagnosis. Shell rather elongated, anterior and posterior lateral teeth well developed; septum separating ligament from resilium very heavy. Scar of the posterior adductor muscle high on the posterior umbonal ridge. Description. Compared with other species these shells are rather elongated. The external ornament is composed of concentric growth-lines; low concentric rugae separated by shallow furrows are developed, especially towards the back. The growth-lines are evenly rounded except towards the back where they bend sharply over the posterior umbonal TEXT-FIG. 2. Oriocrassatella queenslandica sp. nov. Diagrammatic restoration X 1 approx. A, Hinge and musculature of left valve, b. Hinge of right valve, pig, groove for posterior lateral tooth ; /, ligament ; s, septum; r, resilium; alg, groove for anterior lateral tooth; al, anterior lateral; pi, posterior lateral; 2, 3a, 36, and 4, cardinal teeth. ridge and run towards the cardinal margin, forming a posterior truncation of the shell. Internally the anterior adductor muscle is oval, elongated in a dorso-ventral direction. The posterior muscle is also oval but less elongated; the direction of elongation is at only a slight angle to the posterior part of the cardinal margin and almost parallel to the low umbonal ridge which runs down from the umbo towards the junction of the ventral and posterior margins. The left valve shows distinct grooves for the reception of an anterior and posterior lateral tooth of the right valve. The septum separating the ligament from the resilium EXPLANATION OF PLATE 16 Figs. 1-2. Pyramus? concentriciis (Etheridge sen.) 1872, xl, Geol. Surv. of Qld. F1557. 1, Lateral view. 2, Dorsal view. Figs. 3-10. Oriocrassatella queenslandica sp. nov., X 1 . 3-4, Holotype, Queensland University Museum (QUM) F26,795, front and lateral view. 5, Paratype D, QUM26,853, latex impression of hinge. 6, Paratype C, QUM26,790, internal impression showing muscle scars and pallial line. 7-8, Para- type A, QUM F26,794, dorsal and lateral views. 9-10, Paratype B, QUM F26,786, latex impression of hinge, and lateral view. Figs. 11-12. Pseudomyalina sp., X 1. 11, Figured Specimen B, QUM F21,006, plasticine impression showing lateral view of dorsal part of left valve and ligament area of right valve. 12, Figured specimen A, QUM F27,405, lateral view of a left valve. Palaeontology, Vol. 4. PLATE 16 m Die KINS, Permian Pelecypods J. M. DICKINS: PERMIAN PELECYPODS FROM AUSTRALIA 127 is very thick. The posterior cardinal tooth is distinct and separated from the anterior cardinal tooth by a groove for the posterior cardinal tooth of the right valve. The anterior cardinal is incompletely preserved but was probably bifid as in other species. In the right valve, two cardinal teeth are also visible, the anterior of which is poorly differentiated from the front part of the cardinal plate. During the growth of the shell the ligament moved from an external to an internal position as shown by the nymph formed by the top part of the septum. The species has the full dentition found in ‘ Procrassatella ’. Dimensions (in mm.) Length Height Width Holotype (QUM E26,795) 56 approx. 39 1 Paratype A (QUM F26,794) . 64 37 8 Paratype B (QUM F26,786) . 62 approx. 42 5 Paratype D (QUM F26,853) . 50 34 approx. 8 approx. Occurrence. Holotype and Paratypes A and B, KOE6, Orion Creek, 6 miles west of the Springsure- Rolleston road, Springsure 4-mile map sheet 643,978. Paratype C (QUM No. 26,790), KOE 5, Orion Creek, 5 miles west of Springsure-Rolleston road, Springsure 4-mile map sheet 645,978. KOE6 is stratigraphically lower than KOE5 and both are mapped as Dilly Beds but may be from the equivalent of the lower part of the Staircase Sandstone (D. Hill, pers. comm.). Paratype D, E. A. Webb Col- lection outcrop 464, 3 miles east-north-east of Birralee Hill, in the Glendoo Sandstone, the marine member of the Collinsville Coal Measures. Discussion. Oriocrassatella queensJandica is readily separable from O. stokesi by its greater transverse elongation, the heavier septum which separates the ligament from the resilium, and the higher position of the posterior adductor muscle. The Queensland species also appears to be rather different from Oriocrassatella brenensis (Reed) (1932, p. 58, pi. 7, figs. 1 and 2) and O. intermedia (Reed) (1932, p. 59, pi. 7, figs. 3-5; pi. 8, fig. 8) from the Permian of Kashmir, but O. lapidaria Reed (1932, p. 57, pi. 7, fig. 7) has similar dimensions and apparently the posterior muscle is in a similar position. Reed’s material, however, does not allow a reliable comparison. Family ?edmondiidae King 1849 Genus pyramus Dana July 1847 Type species. Pyramus myiformis Dana (1847, p. 57; 1849, p. 697, pi. 6, figs. 4a-c) by subsequent designation of Newell (1956, p. 10). Synonyms. Pyramia Dana (1849, p. 695), variant spelling of Pyramus; Clarkia de Koninck (1877, p. 128), based on same type species. Family position. Newell (1956) proposed placing Pachydonms Morris 1845 (= Megades- nms Sowerby 1838), Myonia Dana 1 847, Pyramus Dana 1 847, in the family Pachydomidae. He regards Astartila Dana 1847 as a synonym of Pachydonms, Maeonia Dana 1849 and Pachymyonia Dun 1932 as synonyms of Myonia, and Notomya M‘Coy November 1847, Pyramia Dana 1 849, and Clarkia de Koninck 1 877 as synonyms of Pyramus. He discusses the ligamental structure and draws the important conclusion that all are burrowing forms. Many of them do not seem to differ sufficiently from the Edmondiidae to be placed in a separate family, but Pyramus is rather transversely elongated and the hinge 128 PALAEONTOLOGY, VOLUME 4 appears to be rather different from that of Edmondia so that it has only been tentatively plaeed in this family. Discussion. Notomya is more robust and has a more distinctly developed umbo, and the muscle scars are more strongly marked than in Pyramus; and for the present Newell’s proposal to regard Notomya as a synonym of Pyramus is not followed. Similarly it is not proposed to regard Astartila as a synonym of Pachydomus (= Megadesmus). Pyramus? concentriciis (Etheridge sen.) 1872 Plate 16, figs. 1-2 1872 Edmondia concentrica Etheridge sen., p. 328, pi. 13, fig. 2. 1892 Sangiiinolites concentriciis Etheridge jun., p. 281, pi. 43, fig. 7. Description of Etheridge jun." s figured specimen. As can be seen from the photograph the figure is accurate. Only concentric ornament is present, made up of growth-lines which are more distinctly developed at regular intervals, forming the ‘band-like zones’ de- scribed by Etheridge sen. The change of direction of the growth-lines at the posterior ventral angle is less sharp than that characteristic of Oriocrassatella, so that posterior truncation is absent. A slight ridge runs from the umbo to the posterior-ventral angle with a shallow sulcus running to the ventral margin in front of the ridge. Dimensions (in mm.) Length Height Width Geological Survey of Queens- landNo. F1557 58 28 6 Occurrenee. Gasworks, Gympie, Queensland. Permian. Discussion. In addition to Etheridge jun.’s specimen, other specimens of this species from Gympie are in the collections of the Geological Survey of Queensland. None of those seen, however, showed any additional features. There is little doubt that Etheridge sen.’s specimen, which also came from Gympie, belongs to the same species; the asso- ciated fauna indicates that the beds are of Permian age. Although Reed (1932, p. 58) suggests that P. concentricus may belong to Oriocrassatella, the considerable transverse elongation, the more central position of the umbo, and the roundness of the posterior margin afford evidence against this conclusion; it appears more likely to belong to Pyramus. Acknowledgements. This work was partly carried out in the Department of Geology of the Univer- sity of Queensland in fulfilment of the requirements for the Ph.D. degree. The help of Prof. D. Hill and Mr. F. S. Colliver of the Department of Geology, Messrs. D. M. Traves and S. S. Derrington of Mines Administration Pty. Ltd., and Mr. A. K. Denmead, Chief Government Geologist, and Mr. R. J. Paten of the Geological Survey of Queensland, is gratefully acknowledged. The paper is published by permission of the Director of the Bureau of Mineral Resources, Geology and Geophysics. REFERENCES BEYRiCH, E. 1864. Ueber eine Kohlenkalk Fauna von Timor. Abh. Akad. Wiss. Bert. 61-98. CAMPBELL, K. s. w. 1959. The Martiniopsis-like Spiriferids of the Queensland Permian. Palaeontology, 1, 333-50. J. M. DICKINS: PERMIAN PELECYPODS FROM AUSTRALIA 129 CONDON, M. A. 1953. Nomenclature of sedimentary rocks — glossary. Bur. Min. Resour. Aust. Rec., 1953/131 (unpubl.). • 1954. Progress Report on the geology of the Carnarvon Basin. Bur. Min. Resow. Aust. Rep. 15. DANA, J. D. 1847. Description of fossils from Australia. Ainer. J. Sci. 54, 151-60. 1849. In United States exploring expedition during the years 1838-1842, under the command of I Charles Wilkes, U.S.N. ; 10, Geology, 681-713. |t DERRiNGTON, s. s. and MORGAN, K. H. 1959. Ncw names in Queensland Stratigraphy. Part I, Central Bowen Syncline. Aust. Oil Gas J. 5, (8), 33-35. I DICKINS, J. M. 1956. Permian Pelecypods from the Carnarvon Basin, Western Australia. Bur. Min. Resour. Aust. Bull. 29. — — 1957. Lower Permian Pelecypods and Gastropods from the Carnarvon Basin, Western Australia. Ibid. 41. I ETHERIDGE, R., juu. 1 892. In JACK, R. L. aiid ETHERIDGE, R., jun., Geology and Palaeontology of Queens- land and New Guinea. Brisbane and London. I 1907. Official contributions to the palaeontology of South Australia. S. Aust. pari. Pap. 55 , (1906), Supp., 1-21. j ETHERIDGE, R., sen. 1872. Description of the Palaeozoic and Mesozoic fossils of Queensland. Quart. J. geol. Soc. Lond. 28, 3 1 7-60. GOLOVKiNSKY, N. A. 1868. Materiaku zur Geologie Russlands, 1, 273-415, St. Petersburg (not J seen). HILL, D. 1955. Contributions to the correlation and fauna of the Permian in Australia and New Zealand. J. geol. Soc. Aust. 2, 83-107. > 1957. Explanatory Notes, Springsure, 4-mile Geological Series. Bur. Min. Resour. Aust., Note Ser. 5. KONECKi, M. c., DICKINS, J. M., and QUINLAN, T. 1959. The geology of the coastal area between the Lower Gascoyne and Murchison Rivers, Western Australia. Bur. Min. Resour. Aust. Rep. 31. KONiNCK, L. G. DE. 1877. Rccherchcs sur les Fossiles paleozoiques de la Nouvelles-Galles du Sud (Australie). Man. Soc. roy. Sci. Liege, 2, 2 (trans. into English as Mem. geol. Surv. N.S. W., Palaeont. 6, 1898). 1885. Faune du Calcaire Carbonifere de la Belgique, 5® partie, Lamellibranches. Ann. Mus. Hist. nat. Belg. 11. LiCHAREW, B. K. 1941. In LiCHAREW, B. K. and EiNOR, o. L., Qn the problem of the age of the Upper Palaeozoic deposits of the south-east part of the Kolyma Basin. Acad. Sci. U.S.S.R. Dokl. 31 (2), 150-2. m‘coy, F. 1847. Qn the fossil botany and zoology of the rocks associated with the coal of Australia. Ann. Mag. nat. Hist., ser. 1, 20, 145-57; 226-36; 298-312. MCWHAE, J. R. H., PLAYFORD, P. E., LINDNER, A. W., GLENISTER, B. F., and BALME, B. E. 1958. The Strati- graphy of Western Australia. /. geol. Soc. Aust. 4 (2). MARWICK, J. 1935. Some new genera of the Myalinidae and Pteriidae of New Zealand. Trans, roy. Soc. N.Z. 65, 295-303. MAXWELL, w. G. H. 1954. Stroplialosia in the Permian of Queensland. J. Paleont. 28 (5), 533-59. 1959. New names in Queensland Stratigraphy, Part II, Yarrol Basin. Aust. Oil Gas J. 5 (9), 29-31. NEWELL, N. D. 1956. Primitive Desmodont Pelecypods of the Australian Permian. Amer. Mus. Nov. 1799. 1958. A note on Permian Crassatellid Pelecypods. Ibid. 1878. POPOV, u. N. 1957. Some Permian Pelecypods, Gastropods and Ammonites of Verchoyan. Sci. Inst. Geol. Arctic, Coll. Pap. Palaeont. Biostrat. 1, 45-60 (also in Mater. Geol. Min. Resour. N.E. U.S.S.R., 1958 (12), 137-50). REED, F. R. c. 1932. New fossils from the Agglomeratic Slate of Kashmir. Palaeont. Indica, N.s. 20, 1. RUCHENCEV, V. E. 1956. Lower Permian Ammonites of the Southern Urals. II. Ammonites of the Artinskian Stage. Trudy Pal. Inst. Acad. Sci. U.S.S.R. 60 (in Russian). sowERBY, J. 1838. Fossils, in t. l. mitchell. Three expeditions into the interior of Australia, 15. TEiCHERT, c. 1950. Some recent additions to the stratigraphy of Western Australia. Bull. Amer. Ass. Petrol. Geol. 25 (3), 371-415. B 7879 K 130 PALAEONTOLOGY, VOLUME 4 TEicHERT, c. 1952. Carboniferous, Permian and Jurassic in the North-West Basin, Western Australia. Congr. geol. int., XIX'^^ sess., Alger. Symp. on Gondwanciland, 115-35. 1957. Notes on the geology of the Carnarvon (North-west) Basin, Western Australia. J. roy. Soc. W. Aiist. 40 (2), 65-72. THOMAS, G. A. and DiCKiNS, J. M. 1954. Correlation and age of the marine Permian formations of Western Australia. Aust. J. Sci. 16 (6), 219-23. WANNER, c. 1922. Die Gastropoden und Lamellibranchiaten der Dyas von Timor. Paldont. Timor, 11 (18). WATERHOUSE, J. B. 1958. The occurrence of Atomodesma Beyrich in New Zealand. N.Z.J. Geol. Geophys. 1 (1), 166-77. 1959. Note on New Zealand species of Atomodesma Beyrich. Ibid. 2 (2), 259-61. WEBB, E. A. 1956. Review of exploratory oil wells penetrating Permian sections in Central Queensland, Australia. Bull. Amer. ^55. Pet. Geol. 40 (10), 2329-53 (reprinted in Aust. Oil Gas J. 3 (7), 3-22, ,! 1957). ! J. M. DICKINS I Geological Section, ^ Bureau of Mineral Resources, I Geology and Geophysics, Canberra, a.c.t., Australia Manuscript received 21 December 1959 THE GASTROPOD PLATYTEICHUM IN THE PERMIAN OF WESTERN AUSTRALIA by J. M. DICKINS Abstract. Platyteichum johnstoiiei sp. nov., P. jofmstonei? and P.? sp. nov. are described. The holotype of P. costatum Campbell 1953, the type species, and of P. (Etheridge jun.) 1892 are figured and discussed; P. costatum may be a synonym of P. coniforme. Platyteichum Campbell 1953 appears to be closely related to Mourlonia de Koninck 1883 and Mourlonopsis Fletcher 1958. The species of Platyteichum occurring in Western Australia is considered to afford additional evidence for the correlation of the Ingelara Formation of the Bowen Basin of Queensland with the upper part of the Byro Group of the Carnarvon (North-west) Basin of Western Australia. With the exception of those from the lower (Sakmarian) part of the Permian sequence, the marine Permian faunas of Western Australia differ sufficiently from those of Eastern Australia (Queensland, New South Wales, and Tasmania) to be placed in different faunal provinces (see Dickins and Thomas 1959). Thus correlation between the two areas has presented more than usual difficulties. The occurrence in Western Australia of the genus Platyteichum Campbell (1953, p. 23) with the type P. costatum Campbell (1953, p. 23, pi. 7, figs. 1 1-14) from the Ingelara Formation of Queensland is of interest, especially as one of the species described resembles the type species. The opportunity is taken of refiguring the holotype and discussing the relationship of the type species, P. costatum, to Mourlonia? coniformis Etheridge jun. (1892, p. 287, p. 41, fig. 5). Correlation of the Ingelara Formation with the sequence in Western Australia. Evidence from the pelecypods considered in the previous paper indicates that the Ingelara Forma- tion, which lies stratigraphically between the Cattle Creek Formation and the Mantuan Productus Bed, is younger than the Callytharra Formation but is not likely to be much younger than the Coolkilya Formation, the lowest formation of the Kennedy Group. Previous authors (Teichert 1941; Fletcher 1945) have suggested an approximate cor- relation between the Cundlego Formation of the Carnarvon (North-west) Basin and the Ingelara Formation (for a summary of the stratigraphical sequences in Western Australia and in Queensland see the immediately preceding paper). Fletcher based his conclusion on the occurrence of similar species of Glyptoleda in the Cundlego Formation and the Ingelara Formation. Because of its relative position in the Byro Group and its faunal relationship with the other formations of the Group, the Cundlego is regarded as of late Artinskian age (see Thomas and Dickins 1954). With regard to the age of the Ingelara Formation Campbell (1953, p. 5) states; ‘Correlation with overseas faunas . . . would thus appear to suggest an age toward the region of the Artinskian-Kungurian boundary.’ Campbell’s conclusion thus supports that of the previous authors. The present evidence adds additional support to this correlation which may be modified to indicate that the Ingelara Formation can be correlated with the upper part of the Byro Group (Cundlego-Baker Formations). In undescribed Glyptoleda-Wke forms from the lower part of the Byro Group, the V-ribbing characteristic of Glyptoleda is poorly developed, and forms with complex [Palaeontology, Vol. 4, Part 1, 1961, pp. 131-137, pi. 17.] B 7879 K 2 132 PALAEONTOLOGY, VOLUME 4 ribbing similar to those of the Ingelara Formation are found in the Cundlego and Wandagee Formations. The species of Platyteichum which resembles P. costatum is found in the Wandagee Formation, the Norton Greywacke, and possibly the Coolkilya Greywacke. Another rather different species is found in the Norton Greywacke and in the younger Coolkilya Greywacke of the Kennedy Group. Relationship of platyteichum to some other Pleurotomariid genera. Although Platy- teichum resembles Mourlonia, it differs especially in having a flat upper whorl profile, whereas Mourlonia has a gently convex upper whorl. On the other hand it differs con- siderably from such genera as Peruvispira and Ptychomphalina. (The relationship of Mourlonia and Ptychomphalina is being dealt with elsewhere (Dickins 1961).) Its whorl cross-section is rounded and its outline simple; the ornament is composed of both spiral elements and elements parallel to the growth-lines and may have nodes where the two intersect. The spiral elements are simple, comprising threads which are more or less equidistant and of equal prominence. The umbilicus, as in Mourlonia, may be closed in the adult and a ‘false umbilicus ’ may be present. Platyteichum also resembles Mourlonop- sis Fletcher (1958, p. 129), which appears to differ mainly in having the whorl cross- section entirely convex as in Mourlonia, whereas in mature specimens of Platyteichum the upper part of the whorl is flat or concave where it rises to meet the previous whorL Platyteichum also has some resemblance to Baylea de Koninck 1 883, which, however, can be readily separated by the marked step-like character of its whorls and the width of its slit-band. Amongst long-established genera it seems to come closest to Mourlonia and it is thus significant that in its earlier whorls Platyteichum is even closer to Mourlonia. SYSTEMATIC DESCRIPTIONS Genus platyteichum Campbell 1953 Type species. Platyteichum costatum Campbell (1953, p. 23, pi. 7, figs. 1 1-14) by original designation of Campbell (1953, p. 23). Discussion. Platyteichum costatum seems to be a synonym of Mourlonia? coniformis Etheridge jun. (1892, p. 287, pi. 41, fig. 5) but until further, better-preserved, topotype material of M.7 coniformis is available, this problem cannot be satisfactorily solved. How- ever, no change in the generic diagnosis would be required. Both the holotype of Campbell’s species and Etheridge’s single specimen of M.? coniformis (Queensland Museum No. FI 7/ 1220) are refigured in the accompanying plate. Etheridge records the locality of his specimen as ‘Banana Creek, near Banana’; the lithology and the rest of the fauna recorded by Etheridge (1892) from this locality leave no doubt that the specimen is from the Flat Top Formation (Glover 1959) identified by Glover’s un- published report to Mines Administration Pty. Ltd. Dr. D. Hill (pers. comm.) considers that this formation is faunally intermediate between the Ingelara Formation and the Mantuan Productus Bed. Collections from this formation are housed in the Museum of the Department of Geology of the University of Queensland. Unfortunately none of the other specimens of Platyteichum is better preserved than Etheridge’s. Although some have an even lower spire than Etheridge’s specimen, many of these are squashed and distorted. J. M. DICKINS: THE GASTROPOD PLATYTEICHUM 133 To allow a more accurate comparison of the two specimens, the dimensions have been related to the slit-band of the fifth whorl as shown in the text-figure. TEXT-FIG. 1. Platyteichum CamphcW, xl. P. conifonne (Qld. Mus. No. F17/1220) P. costatinn (Holotype. Qld. Univ. Geol. Mus. No. F14,181) Height ...... 12 mm. 15 mm. Width ....... 19 mm. 20 mm. Apical angle — fifth-whorl stage 63° 61° third-whorl stage 95° 91° Number of spiral lirae on upper surface of fifth whorl ..... About 14 About 13 Number of spiral lirae on lower surface of fifth whorl ..... About 22 The only difference in dimensions of possible significance is that in the height of the spire. This is probably an original feature because, although Etheridge’s specimen is squashed laterally, the aboral side does not appear to be markedly distorted. My examination, however, of the type specimens and many other specimens from the type locality indicates considerable variation in the height of the whorl relative to width, and Etheridge’s specimen of P. conifonne appears to come within these limits of varia- tion. Apart from the dimensions the two appear to be similar in every important respect: the width of the slit-band on the fifth whorl, the number and character of the spiral lirae, and the shape of the growth-lines. In P. cost at wn some of the growth-lines are more distinctly marked than others, whereas they are more uniform in Platyteichum conifonne', but this can hardly be regarded as significant. The earlier whorls in both are similar, and differ from the later whorls : the upper surfaces of the second and third whorls are rounded, in contrast to the fifth whorl in which the upper surface is straight or even slightly concave, and the sutures are deeper and more distinctly marked. In these features the fourth whorl is intermediate between the third and fifth. The apical angle of the 134 PALAEONTOLOGY, VOLUME 4 earlier whorls is considerably greater than in the later whorls. Both the sutures and the shape of the second and third whorls are thus closer to Mourlonia than the later whorls. An examination of the type specimens also shows that the umbilicus was narrow and open at the earlier growth stages but that in at least some mature specimens the umbilicus is closed by callus. Removal of matrix from the holotype shows that the original open umbilicus is closed by callus, but a small external umbilicus (‘false umbilicus’) is left between the base of the whorl and the columellar lip. Platyteichum johnstonei sp. nov. Plate 17, figs. 9-12 Diagnosis. Similar to P. costatwn (see Plate 17, figs. 4-6), distinguished by having the slit-band slightly higher above the periphery and the whorl cross-section slightly more rounded, lacks the slight but distinct changes in direction of the outline at the bottom of the slit-band and below the slit-band. Description of holotype. Spire of moderate height, probably originally with five whorls; but the top part of the spire has not been preserved. The sutures are shallow but distinct. The upper surface meets the preceding whorl just below the slit-band at an angle near to that of the apical angle so that the outline is only slightly indented. The earlier whorls are convex and rounded, but the uppermost part of the final whorl is straight or slightly concave. The slit-band is situated slightly above the periphery. The ornament comprises transverse lirae paralleling the growth, and spiral lirae more or less equal to each other in prominence. The lirae bounding the slit-band are hardly more distinct than the rest of the spiral ornament. The growth-lines (or transverse lirae), after leaving the suture, swing backwards in an even curve to the slit-band. Below the slit-band they swing slightly forward and then down over the outer surface of the whorl and backwards over the base in a gentle even curve. Where the transverse and spiral ornament cross, nodes are formed. Most of the base including the umbilical region is not exposed. Paratypes. These confirm the features found in the holotype. Paratype B has five whorls ; the width relative to the height of the spire is greater than in the holotype but this, at least in part, results from squashing. Paratype C, which is also partly squashed, shows a narrow external umbilicus. Dimensions (in mm.) Height Width Apical angle No. of lirae above slit- band on last whorl No. of lirae below slit- band on last whorl Holotype . 22 (approx.) 18 11° 9 17+ Paratype A 31 (approx.) 24 (approx.) c^ o 9 Paratype B 32 26 (approx.) 00 00 o Paratype C 29 22 o oo kO 9 30 (approx.) J. M. DICKINS; THE GASTROPOD PLATYTEICHUM 135 Occurrence. Holotype (CPC108)/ lat. 24° 12' 26" S., long. 115° 10' 00", 4-5 miles west ofsouthof Merlin- leigh Homestead, 97 feet above base of Norton Greywacke. Paratype A (UWA42,115), there is some doubt about the locality from which the specimen was collected but it appears to be from about 2 miles north-north-east of Trig. K56, from top part of Bulgadoo Shale or more likely from bottom part of Cundlego Formation in fault block south of Barrabiddy Creek. Paratype B (UWA42,1 16), from lower part of Wandagee Formation, west side of Minilya syncline, south of Minilya River, west of Coolkilya Pool. Paratype C (UWA42,117), from lower part of Wandagee Formation, west side of Minilya syncline, south of Minilya River, west of Coolkilya Pool. The description is based on five specimens. Discussion. P. johnstonei appears to be most closely related to P. costatiim, from which it can be distinguished by the more rounded whorl outline and by having the slit-band higher and the upper surface slightly less concave. Less closely related is Pleiirotomaria brenensis Reed (1932, p. 64, pi. 12, figs. 2-4u) from the Agglomeratic Slate of Kashmir, which seems also referable to Platyteichum. The species is named after Mr. M. H. Johnstone, formerly of the Bureau of Mineral Resources, Geology and Geophysics, and now of West Australian Petroleum Pty. Ltd. Mr. Johnstone has done considerable geological work in Western Australia and collected material from the type locality of this species. Platyteichum johnstonei Dickins? Plate 17, figs. 1-3 Description. A single specimen similar in general shape to Platyteichum johnstonei but distinguished by having the whorl cross-section slightly more symmetrical so that the spire is more step-like. A narrow umbilicus penetrates between the whorls. The character of the slit-band and the ornament is similar to that of P. johnstonei. Dimensions (in mm.) Height Width Apical angle No. oflirae above slit- band on last whorl No. of lirae below slit- band on last whorl CPC109 . 27 (approx.) 20 -J o o 9 About 29 Occurrence. Figured specimen (CPC109), Registered No. FI 7,076, If miles south-east of Muderong Bore, Middalya Station, from the Coolkilya Greywacke. Discussion. Because of the difference in shape and the presence of an umbilicus it seems best to separate provisionally this specimen from P. johnstonei, although additional specimens may show that it is only a variety. The specimen is preserved as a limonitic replacement and the umbilicus may be open because the callus is not preserved. Both P. johnstonei and P. johnstonei? somewhat resemble Pleurotomaria timorensis Wanner (1922, p. 20, pi. 151 (1), figs. 9a-b) from the Permian Basleo Beds of Timor. In Pleurotomaria timorensis, however, the step-like character of the spire is strongly developed and it does not seem possible to include it in Platyteiehum unless a rather wide meaning is given to the genus. 1 CPC — Commonwealth Palaeontological Collection, Canberra; UWA — University of Western Australia Collection. 136 PALAEONTOLOGY, VOLUME 4 Platyteichum? sp. nov. Plate 17, figs. 7-8 Description. The spire is of moderate height, with five whorls in mature specimens. The sutures are shallow but distinct. The slit-band is situated slightly above the periphery, the suture lying slightly but definitely below the slit-band. The whorl cross-section is gently convex except immediately below the suture, where it is fiat or concave for a short distance as it rises to the previous whorl; it is sufficiently symmetrical to give a stepped character to the spire. The ornament comprises spiral and transverse elements and is similar to that of P. johnstonei except that there are more spiral lirae. The spiral lirae are of about equal prominence and the lirae bounding the slit-band are similar or only slightly more prominent than the others. The growth-lines are similar to those in P. johnstonei. In mature specimens the umbilicus was probably almost filled with callus, leaving only a small external umbilicus. The early whorls of all the specimens are poorly preserved. Dimensions (in mm.) Height Width Apical angle IVo. of lirae above slit- band on last whorl No. of lirae below slit- band on last whorl Figured Specimen A 19 (approx.) 20 O 00 11 23 + Figured Specimen B 22 (approx.) 23 74° About 15 CPCl 12 22 24 (approx.) About 12 Occurrence. Figured Specimen A (CPCIIO), lat. 24° 22' 26" S., long. 115° 10' 00", 4-5 miles west of south of Merlinleigh Homestead, 97 feet above base of Norton Greywacke. Figured Specimen B (CPClll), lat. 24° 51' 21" S., long. 115° 10' 53", miles from K38 on a bearing of 197° and 5 miles from Walbarune Peak (K40) on a bearing of 340°, Coolkilya Greywacke, 108 feet above base. CPCl 12, 1| miles south-east of Muderong Bore, Middalya Station, from Coolkilya Greywacke. One specimen from near Merlinleigh, four specimens from near K38, and two specimens from near Muderong Bore. Discussion. In the ornament and the general character of the spire P.? sp. nov. is similar to P. johnstonei. It differs particularly, however, in the lesser proportion of the length to width, the greater number of spiral lirae and the greater symmetry of the whorl cross- EXPLANATION OF PLATE 17 Figs. 1-3. P/nprc/c/mmyoA/rsto/rc/ Dickins?, three views CPC109, Xl. Figs. 4-6. Platyteichum costatum Campbell 1953, Queensland University Museum (QUM) F14,181, three views of the holotype, x 1 . Figs. 7-8. Platyteichum? sp. nov., xl. 7, Figured specimen A, CPCIIO. 8, Figured specimen B, CPClll. Figs. 9-12. Platyteichum johnstonei sp. nov. 9, Holotype, CPC108, X 2. 10-1 1, Two views of ParatypeB, UWA42,116, xl. 12, ParatypeA, UWA42,115, xl. Figs. 13-14. Platyteichum coniforme (Etheridge jun.) 1892, Queensland Museum No. F17/1220, two views of holotype, X 2. Figs. 15-19. Atomodesma (Atomodesma) bisulcata sp. nov., x 1. 15, Paratype B, QUM F27,122. 16, 18-19, Holotype QUM F27,124, lateral, anterior and dorsal views. 17, Paratype A, QUM27,121. Palaeontology, Vol. 4. PLATE 17 DICK INS, Plaivteicinim J. M. DICKINS; THE GASTROPOD PLATYTEICHUM 137 section which makes the spire distinctly step-like. Whether these differences are im- portant taxonomically or are variable features within this group of shells is not clear from the present material. The differences of these shells from the type species of Platyteichum are such that I hesitate to place them positively in the same genus. I do not consider the material adequate for the erection of a specific name and the choice of type specimens. In shape P.? sp. nov. somewhat resembles Pleurotomaria conglobata Wanner, Hamlet (1928, pi. 11, figs. 3u-c) from the Permian of Wesleoe, Timor. Hamlet’s figured specimen, however, is slightly more step-like and the number of spiral ribs is not clear. It does not closely resemble Wanner’s figured specimen of Pleurotomaria conglobata (1922, pi. 151 (1), fig. 10). Acknowledgements. Part of this work was carried out in the Department of Geology of the University of Queensland in partial fulfilment of the requirements for the Ph.D. degree. Mr. G. Mack, Director, and Mr. J. T. "Woods of the Queensland Museum are thanked for making specimens available for study, and the co-operation of Mr. F. S. Colliver and Mr. J. M. Lindsay, Curators of the Geological Museums at the Queensland and Western Australian Universities respectively, is gratefully acknowledged. The paper is published by permission of the Director of the Bureau of Mineral Resources, Geology and Geophysics. REFERENCES CAMPBELL, K. s. w. 1953. The fauna of the Pcrmo-Carboniferous Ingclara Beds of Queensland. Univ. Qld. Pap. Dep. Geol. 4 (3), 1-30. DICKINS, J. M. 1961. Eiirydesma and Pernvispira from the Dwyka Beds of South Africa. Palaeontology, 4 (1). DICKINS, J. M. and thomas, g. a. 1959. The marine fauna of the Lyons Group and the Carrandibby Shale of the Carnarvon Basin, Western Australia. Bar. Min. Resoiir. Anst. Rep. 38. ETHERIDGE, R., juu. 1 892. In JACK, R. L. and ETHERIDGE, R., jun., Geology and Palaeontology of Queens- land and New Guinea. Brisbane and London. FLETCHER, H. o. 1945. A new genus Glyptoleda and revision of the genus Nuculana from the Permian of Australia. Rec. Aust. Mus. 21, 293-312. 1958. The Permian gastropods of New South Wales. Ibid. 24 (10), 1 15-64. GLOVER, J. J. E. 1959. New names in Queensland stratigraphy: Permian of the south-eastern part of the Bowen Syncline. Aust. Oil Gas J. 5 (8), 30. HAMLET, B. 1928. Permische Brachiopoden, Lamellibranchiaten und Gastropoden von Timor. Jaarb. Mijnw. Ned.-Oost-lnd. 56 (2), 1-115. HILL, D. 1955. Contributions to the correlation and fauna of the Permian in Australia and New Zealand. /. geol. Soe. Aust. 2, 83-107. 1957. Explanatory notes, Springsure 4-mile Geological Series. Bur. Min. Resour. Aust. Note Ser. 5. REED, F. R. c. 1932. New fossils from the Agglomeratic Slate of Kashmir. Palaeont. Indica, n.s. 20, 1. TEiCHERT, c. 1941. Upper Palaeozoic of Western Australia: correlation and palaeogeography. Bull. Amer. Ass. Petrol. Geol. 25, 371-415. THOMAS, G. A. and DICKINS, J. M. 1954. Correlations and age of the marine Permian formations of Western Australia. Aust. J. Sci. 16 (6), 219-23. WANNER, c. 1922. Die Gastropoden und Lamellibranchiaten der Dyas von Timor. Paldont. Timor, 11 (18). WEBB, E. A. 1956. Review of exploratory oil wells penetrating Permian sections in Central Queensland, Australia. Bull. Amer. A.ss. Petrol. Geol. 40 (10), 2329-53 (reprinted in Aust. Oil Gas J. 3 (7), 3-22, 1957). J. M. DICKINS, Geological Section, Bureau of Mineral Resources, Geology and Geophysics, Canberra, a.c.t., Australia Manuscript received 21 December 1959 EURYDESMA AND PERUVISPIRA FROM THE DWYKA BEDS OF SOUTH AFRICA by J. M. DICKINS Abstract. Eurydesma mytiloides Reed 1932 and Pemvispira vipersdorfensis sp. nov. are described and figured. The distribution and origin of Ewydesma are considered. Eurydesma has been recorded from South Africa, India, Western and Eastern Australia, and South America: in all areas it is associated with deposits of glacial origin. It may have evolved from early Mytilacean forms and was apparently adapted to cold-water conditions and became extinct when these conditions ended. The characters of Pemvispira are discussed. It is separated from Ptychomphalina Fischer 1885, to which it is closely related, mainly by the possession of a distinct revolving concave area below the slit-band. Pleurocinctosa Fletcher 1 958 is regarded as a synonym of Pemvispira. The fossils indicate a Tower Permian age, most likely Sakmarian but possibly early Artinskian. Although the occurrence of Eurydesma in association with the Dwyka tillites was first recorded many years ago, up to the present no palaeontological description has been undertaken. As well as Eurydesma cf. globosum Dana,“ Range (1912, p. 29-31, pi. 6) recorded conularians, fish, gastropods, and an Inoceramus-\ike pelecypod from beds he considered to be associated with the Eurydesma beds. Although the specimens figured by Range were too incomplete to allow definite identification at the species level, the hinge structure shown established the presence of Eurydesma. Reed (1935, p. 161, pi. 5) described Aphanaia haibensis from the Upper Dwyka Shales near Haib, South-west Africa. The present specimens were collected by Dr. H. Martin of the Geological Survey of South Africa and were forwarded for examination to Dr. C. Teichert, then at the Department of Geology, University of Melbourne. By arrangement with Dr. Teichert, Dr. Martin, and the Director of the Geological Survey of South Africa, the specimens were passed to the author for description. The stratigraphical occurrence of the fossils is described in detail by Martin (1953). The marine invertebrate fossils are found in the Mariental-Keetmanshoop area, in the bottom part of the sequence, which lies discordantly on the Nama Beds. The Nama Beds are of Upper Precambrian to Lower Palaeozoic age (for a recent account see Haughton and Martin 1956). Martin shows that the layers with marine fossils are inter- bedded with deposits of glacial origin and of the total thickness of 1,400-1,700 feet he considers 800-1,000 feet to be glacial. The beds with marine fossils are separated by several hundred feet of shales from the Mesosaurus horizon. In addition to the Eurydesma, which is described as Eurydesma mytiloides Reed, the collection contains Pemvispira vipersdorfensis sp. nov., an unidentified bryozoan and crinoid plates. Thus the occurrence in South Africa of elements of ikt'' Eurydesma-^2LV^n2L‘’ other than Eurydesma (elements which are characteristically developed in India and in Western and Eastern Australia) is of considerable interest. ' Etheridge and Dun (1910, p. 72) regard the specimens on which Dana based his description of Eurydesma globosum as young of E. cordatiim and thus E. globosum is placed by them in synonymy. There certainly seems ample justification for Etheridge and Dun’s conclusion. [Palaeontology, Vol. 4, Part 1, 1961, pp. 138-148, pi. 18.] J. M. DICKINS: EURYDESMA AND PERUVISPIRA 139 WORLD DISTRIBUTION AND ORIGIN OF EURYDESMA Eurydesnm is known to occur in South Africa, India, Western and Eastern Australia, and South America. In all these areas it is associated with sediments showing marked signs of glacial influence. The author has recently discussed (1957, p. 18) the association of Eurydesma with cold, shallow-water sediments and taking into consideration the recent work on turbidity currents and deep-water deposition, there appears no reason to revise the conclusions made. The origin of Eurydesma remains almost as obscure as when the subject was discussed by Etheridge and Dun in their classic monograph of 1910. Despite a wide search, no close ancestor is apparent in the Carboniferous Period. The relationship of Eurydesma to the living pteriids is not as close as was thought by Etheridge and Dun. Eurydesma differs especially from all other forms in its marked dental process at the anterior end of the hinge, in the anterior position of a large adductor muscle and in the S-shaped series of muscle pits associated with the umbo. These impressions probably represent the pedal muscles and the pits of the pallial attachment. Waagen (1891, p. 140, pi. 6, figs. 3-6) suggests real cardinal teeth are present but these may represent rather folds of shelly material not analogous with hinge-teeth. Koken (1904, p. 101) says no such teeth are visible in his specimens from the Salt Range and I have never observed them in specimens from Australia. The ligament, which is lodged in a single elongated liga- ment groove, is of a type common in many groups of Palaeozoic shells, a type which has apparently formed the basis of that found in living mytilids. The ligament, the dental process, and the relatively complex shell structure (see Dickins 1957) would preclude close relationship to the living Pteriidae. The distinctiveness of Eurydesma from other late Palaeozoic pelecypods is emphasized by its arrangement in a separate family, Eury- desmidae Reed. Amongst earlier forms, Eurydesma appears to resemble Shaninopsis Isberg (1934, p. 336) from the Leptaenakalkes of Dalarna (Ordovician to Silurian). Shaniiwpsis has the same type of ligament, is similar in shape, and has a dental process not unlike that found in Eurydesma. It differs, however, in possessing a distinct anterior byssal opening. As such a long period of time separates Shaninopsis from Eurydesma, an alternative explanation to descent of Eurydesma from Shaninopsis may be that Eurydesma rapidly, probably from one of the Mytilacea, in the environment which came into existence towards the end of the Carboniferous Period. Eurydesma can be related to the Mytilacea in the following respects: 1. The shell structure, although differing from the Myalinidae, is not very different from that described by Newell (1942, p. 32) in the Mytilidae. 2. The ligament is of the same type as that found in Atomodesma which has been placed in the family Myalinidae (Newell 1942, and other authors). 3. The pattern of the pedal muscle scars and the pits of the pallial attachment would require only slight modification from that found in the Myalinidae. A similar muscle pattern, however, also occurs in the Pteriacea. 4. The dental process could be derived from the umbonal septum found in Atomodesma, and in other genera of Myalinidae. The Myalinidae, however, appear to lack the distinct byssal notch found in front of the dental process of the right valve of Eurydesma. The byssal notch is especially distinct in young Eurydesma. It thus seems possible that Eurydesma developed rapidly in cold-water conditions. J40 PALAEONTOLOGY, VOLUME 4 either accompanying or immediately after the late Palaeozoic glaciation. Once developed it became stabilized to these conditions and very little evolutionary development is apparent. ' Any large collection of specimens made at one locality (collection point) shows con- I siderable variation and some authors (Reed 1936; Harrington 1955; Sahni and Srivastava 1956) have proposed a considerable number of specific names in such cases. In samples 1 1 have examined, however, from Western Australia, New South Wales, and Queensland, | there have been no sharp morphological differences which could be used for specific differentiation and the whole appeared to be rather a single variable community. This variability has already been noted by a number of previous workers, including Etheridge and Dun (1910, pp. 47, 72), Fossa Mancini (1944, p. 91— fide Harrington 1955, p. 122) and Harrington (1955, p. 122). Many of the groups for which specific names have been proposed, therefore, should possibly be regarded rather as varieties. As frequently occurs with variable forms there seems to be considerable stratigraphical and geographical range of species, and the species found in different regions do not differ greatly. When the conditions to which Eurydesma was apparently specially adapted ceased to exist the genus rapidly became extinct. In Western Australia and Salt Range, India, this occurred in late Sakmarian or early Artinskian time, when the Gondwana ' Eurydesma- fauna’ was replaced, in the Lower Productus Limestone and the Callytharra Formation, respectively, by a more temperate Tethyan Fauna (Dickins 1957; Dickins and Thomas 1959). It is possible that in the Agglomeratic Slate of Kashmir Eurydesma lingered on slightly longer. In Eastern Australia, which was apparently partly isolated, either by climate or by geography, the earlier fauna persists with considerable diversification until at least late Lower Permian (Kungurian),^ when earth movements brought marine sedimentation to an end and initiated extensive intra-continental non-marine deposition. Eurydesma itself, however, does not appear to persist to the top of the marine sequence. AGE OF THE DWYKA FAUNA To the marine forms previously recorded (conulariids, ‘Aphauaia’ haibensis Reed 1935, unidentified gastropods and pelecypods and fish remains) can be added Eurydesma mytiloides Reed 1932 and Peruvispira viper sdorfensis sp. nov. which are described in the present paper. Amongst the molluscs E. mytiloides and P. vipersdorfensis are important with regard to the age of the South African deposits, as pelecypods similar to ‘Aphanaia' haibensis are known to occur in the Lower and Upper Permian of both North-eastern Siberia (Popov, 1957) and Western Australia (unpublished work of the author). Du Toit (1954, p. 356) apparently considered that the horizons with marine fossils lay above the glacial deposits and concluded that the Dwyka ice age must have embraced much, if not the whole, of the Upper Carboniferous, while the Upper Dwyka shales (with Eurydesma) were not younger than lowest Permian. Martin’s (1953) work, however, indicates that marine horizons are interbedded with the glacial horizons. Martin (written communication) considers it probable also that Eurydesma occurs in shales overlying ' General although not unanimous current Soviet opinion is followed with regard to the sub- division of the Permian System. The System is regarded as containing two main subdivisions, Lower and Upper, the Lower comprising the Sakmarian, Artinskian, and Kungurian Stages and the Upper, Kazanian and Tatarian (Kulikov, pers. comm.; and Stepanov 1958). The Australian deposits are correlated with the standard subdivisions and the names are used to indicate the age. J. M. DICKINS: EURYDESMA AND PERUVISPIRA 141 the highest glacial bed. The affinities of the marine fossils would suggest they are of a Lower Permian age, mostly likely Sakmarian but possibly early Artinskian. Some workers have concluded, for example Caster (1953), Beurlen (1953), Maack ( 1957), and Putzer (1957), that the " Glossopteris flora’ of South America associated with deposits of glacial origin and marine fossils is of Upper Carboniferous age. To some extent this seems to be based on the assumption that the Australian ‘ GJossopteris (and Gangamoptens) flora’ and the " Eurydesma fauna’ are of Upper Carboniferous age. Dickins and Thomas (1959) have considered evidence which indicates that in Australia the " Eurydesma fauna’ with associated glacials is mainly or entirely of Lower Permian age. If the ' Eurydesma fauna’ does begin earlier, which we do not think likely, it could only be in the very uppermost Carboniferous. If our conclusion is correct then it follows also that the ' Glossopteris flora’ first appears in the Lower Permian or less likely in the very uppermost Carboniferous because we do not know of any occurrence of the ‘ Glossopleris flora ’ in Australia significantly earlier than Eurydesma. In New South Wales evidence has been adduced for Carboniferous glaciation earlier than that associated with the "Eurydesma fauna’ (see David 1950, p. 292). This earlier glaciation appears to be confined to New South Wales and may be associated with Upper Carboniferous orogeny. In India also, some workers, for example Bhatia and Singh (1959), had made a similar assumption that the "Eurydesma fauna’ is Upper Carboniferous and have used this to support a conclusion that Talchir Series is of Upper Carboniferous age. The evidence from New South Wales for glaciation both in the Carboniferous and in the Lower Permian may have caused confusion with regard to the stratigraphical position and age of the "Eurydesma fauna’. Bhatia and Singh have also indicated that the arenaceous forams from the Talchir Series are similar to those of the Pennsylvanian of North America. They are similar also, however, to forms found in the Permian of Western Australia (see Crespin 1958). Although the possibility that the "Eurydesma fauna’ first appeared in the uppermost Carboniferous cannot be discarded, the close relationship of the South African fossils to forms from Kashmir, Umaria, the Salt Range, and Western Australia indicates a Lower Permian age (Sakmarian or possibly early Artinskian). E. mytiloides has so far been recorded from the Agglomeratic Slate of Kashmir and the Speckled Sandstone of the Salt Range, from Argentina, and recently by Sahni and Srivastava (1956) from the eastern Himalayas. Harrington, who described the Argentinian species, has also suggested (1955, p. 124) that a specimen from Eastern Australia referred to Eurydesma eordatum var. saeeulum by Etheridge and Dun may belong to E. mytiloides. I have recently suggested (Dickins and Thomas 1959) that E. mytiloides may be present at Umaria, from where P. umarieusis, which is closely related to P. vipersdorfensis, was first described. Dickins and Thomas, on the basis of the occurrence of similar productids and spiriferids, the gastropod P. umarieusis, and a calceolispongiid crinoid, correlate the Umaria Beds with the upper part of the Lyons Group, considering both to be of Sak- marian age. The Speckled Sandstone on the basis of its brachiopods and molluscs is also considered to be of similar age. Both the Umaria Beds and the Speckled Sandstone lie above or at the top of the Talchir Series. The Agglomeratic Slate of Kashmir, on the basis especially of the molluscs, productids, and spiriferids, as well as probably con- taining sediments of Sakmarian age, may also contain slightly younger sediments as the 142 PALAEONTOLOGY, VOLUME 4 sequence contains Oriocrassatella and a type of Deltopecten which, in Western Australia, appear in formations younger than Lyons Group and which are not recorded from the Umaria Beds and the Speckled Sandstone. As is considered in more detail later, P. vipersdorfensis appears to resemble the older (Sakmarian) species of Peruvispira more closely than the younger Artinskian. The conclusion made about the age of the Dwyka Beds is similar to that of Gurich (1923, p. 73) who described the fish from Ganikobis and considered they were late Carboniferous or early Permian. Recently Leschik has described spores from beds over- lying the Eurydesma horizon and underlying the Mesosaurus horizon; he regards the ! spore-bearing beds as Lower Permian (1959, p. 52). SYSTEMATIC DESCRIPTIONS Class PELECYPODA I Family eurydesmidae Reed 1932 Genus eurydesma Morris 1845 : Type species. Eurydesma cordata Morris (1845, p. 276, pi. 12, figs. 1, 2) by monotypy. Eurydesma mytiloides Reed 1932 Plate 18, figs. 1-6 1932 Eurydesma cordatum Morris var. mytiloides Reed, p. 50, pi. 11, figs. 1-36. 1936 Eurydesma cordatum Morris var. mytiloides Reed 1932; Reed, p. 18, pi. 3, figs. 1,2. ' 1955 Eurydesma mytiloides Reed 1932; Harrington, p. 124, pi. 25, figs. 5-8. | 1956 Eurydesma cordatum Morris var. mytiloides Reed 1932; Sahni and Srivastava, p. 205, pi. 34, figs. 1-3. Description. The shells are oval and of moderate size for Eurydesma. The ligament is characteristic of Eurydesma, lodged in an elongated groove running backwards from the umbo and narrowing toward both front and back. Fine longitudinal growth-lines are visible within the ligament groove. In the right valve the distinct byssal notch runs almost directly downwards, but is inclined slightly towards the back. The details of the dental process in the right valve are obscured by erosion. In the left valve the charac- teristic smaller process is developed at the anterior end of the hinge-line. When the two valves are in position the process of the left valve overlaps the right valve and covers from view the byssal opening (see Etheridge and Dun 1910, pi. 18, fig. 3; pi. 19, fig. 3; EXPLANATION OF PLATE 18 Figs. 1-6. Eurydesma mytiloides Reed 1932. All specimens figured are from Farm Hardap 1 10, about 10 miles north-west of Mariental. 1, Hypotype C, left valve. No. 7093, lateral view, X 1. 2, Hypo- type A, right valve. No. 7087, internal view showing the hinge, X 1 ; the hinge is damaged by weather- ing. 3, Hypotype B, left valve. No. 7094, internal view showing hinge, X 1 ; the back part of the shell is missing. 4, Hypotype E, right valve. No. 7090, dorsal view, X 1. 5, 6, Hypotype D, bivalved specimen. No. 7086, lateral view of left valve and front view respectively, x j; the specimen is crushed and telescoped in a dorso-ventral direction so that the shape is distorted. Figs. 7-11. Peruvispira vipersdorfensis sp. nov. x4. All specimens figured have the number 7081 and are from Farm Vipersdorf No. 63, Gibeon District. 7, Holotype, external matrix blotted out to show character of slit-band and concave revolving area. 8, Holotype showing shell in matrix. 9, Paratype B. 10, Paratype A. 11, Paratype C. Palaeontology , Vol. 4. PLATE 18 Die KINS, Eiiryclesnm and Peruvispira I'L J. M. DICKINS: EURYDESMA AND PERUVISPIRA 143 Dickins 1957, pi. 5, fig. 11). The external surface is ornamented only with concentric growth-lines. A distinct lobe is formed anteriorly and the umbo is developed in a similar manner to described specimens of E. mytiloides. The umbo appears to be more distinctly developed than in E. playfordi Dickins (1957, p. 33, pi. 5, figs. 1-11). The muscle pattern is not visible in any of the specimens. Dimensions (in mm.) Length Height Thickness Hypotype A (7087): right valve . 68 70 Hypotype B (7094): left valve 35 (approx.) 36 Hypotype C (7093): left valve 52 (approx.) 55 16 Hypotype D (7086): bivalved specimen . Crushing does not allow reliable measurement Hypotype E (7090): right valve 50 52 (approx.) 15 Occurrence. All the specimens come from the lower part of the Dwyka Succession, Farm Hardap 1 10 about 10 miles north-west of Mariental. The numbers are those of the Geological Survey, Union of South Africa, Pretoria, where the specimens are housed. Discussion. Taking into consideration the specimens available there does not seem to be any basis for their separation from A. mytiloides Reed. Range figured two umbonal fragments similar to the umbonal parts of Martin’s specimens, and they seem likely to belong to the same species. The reference of Range’s specimens to E. cL globosiim Dana by Professor Schroder (Range 1912, p. 29) was reasonable at the time, before Reed’s description of the Kashmir fauna became available, but the South African specimens are distinct from those of E. globosum ( = young specimens of E. cordatiim). The young specimen figured by Dana (1847, pi. 7, figs. 7; la) shows already the very tumid and prominent umbo characteristic of E. cordatum. When proposing the name E. cordata Morris (1845, p. 276) figured two shells. Apparently neither has been chosen as a type and if this is the case, the top figure of pi. 12, apparently fig. 1, is here designated as the lectotype. This designation safeguards usage and meets the suggestion of Etheridge and Dun (1910, p. 72): ‘The large number of specimens now before us conforming to Morris’s upper single figure, compels us to regard this as representing the type form of E. cordatum.' Morris states that his specimens are from Illawarra, New South Wales, but as with his specimens of Deltopecten illawarrensis there must be doubt whether this locality is correct (see Etheridge and Dun 1910, p. 69). It seems likely that Morris’s specimens came from Harpers Hill where E. cordatum is common and from where he also had specimens. I am grateful for the following comment to Mr. S. Ware of the British Museum (Natural History) where Morris’s specimens are housed: ‘The two specimens of E. cordata in question have a preserva- tion entirely different from the other six specimens from Illawarra. E. cordata (pi. 12, fig. 1) is identical with our material from Harpers Hill, and the other (pi. 12, fig. 2) compares most favourably with specimens preserved in a black or greyish black limestone labelled ‘? W. Maitland’ unfortunately, and also Eurydesma specimens from Tasmania.’ E. mytiloides is so different from E. cordatum especially with respect to the characters 144 PALAEONTOLOGY, VOLUME 4 of the umbo that I have no hesitation in agreeing with Harrington’s (1955, p. 124) decision to regard Reed’s variety as a species. Class GASTROPODA Family pleurotomariidae D’Orbigny Genus peruvispira Chronic 1949 Type species. Peruvispira delicata Chronic {in Newell, Chronic, and Roberts 1 949, p. 147 ; 1 953, p. 1 39, pi. 28, hgs. 9-12) by original designation of Chronic. Synonym. Pleurocinctosa Fletcher (1958, p. 139). Diagnosis. Similar to Ftvc/7om/>/w//>ta Fischer 1885 but characterized by the possession of a distinct revolving concave area about as wide as and below the slit-band. The concave area is bounded below by a ridge which may form a lira or carina. The growth-lines after leaving the base of the slit-band swing forward across the concave area and then back across the revolving ridge and over the base of the whorl. Family position. Because of the variability of certain important characters and thus the difficulty of choosing distinct groupings, the supra-specific subdivision of the Upper Palaeozoic pleurotomarioids presents considerable difficulties. The taxonomy of the family level is under review (see Batten 1958, p. 184) and in this paper Peruvispira is retained in the family Pleurotomariidae. This, however, must be regarded as provisional only. Discussion. Although all the described species of Peruvispira have a higher spire than is found in the type species of Plychomphalina P. striata (J. Sowerby) (figured and described in Knight 1941, p. 286, pi. 29, figs. 3a-c), such a difference alone can hardly be regarded as a reliable criterion for generic distinction. The spire will vary in height according to small variations in the whorl profile and the amount of involution, and indeed varies considerably within some ptychomphalinid species that I have examined. In Peruvispira the whorl cross-section in a general way is similar to that of the type species of Ptychom- phalina, and the differences in detail, except for the occurrence of the distinct concave area below the slit-band, would not appear to warrant generic separation. In proposing the generic name Peruvispira Chronic made no comparison of his new genus with Ptychomphalina; perhaps he assumed, following Thomas (1940), that it was a synonym of Mourlonia. On the other hand Peruvispira does not appear to be particu- larly closely related to Neilsonia Thomas (1940). Thomas based her conclusion regarding the synonymy of Ptychomphalina not on examination of the type specimens but on Fischer’s (1885) description of Ptychomphalina where it is stated that Ptychomphalina has spiral ornament. However, according to Knight’s (1941) description and figures, Ptychomphalina can be separated from Mourlonia by its lack of spiral ornament. None of the Western Australian Permian species referable to Ptychomphalina has any spiral ornament; this character appears to be consistent and of some importance. Ptychom- phalina also, according to Knight, has a distinct thickening of the columellar lip without an extension of callus outside the aperture and the Mourlonias and Ptychomphalinas form two distinct lines of development in the Carboniferous and Permian; so that, J. M. DICKINS: EURYDESMA AND PERUVISPIRA 145 although the two lines may be convergent in the Lower Carboniferous, it does not seem justifiable to place Ptychomphalina in synonymy with Mourlonia. In Ptychomphalina striata (J. Sowerby), as figured in Knight (1941), the growth-lines swing forward only slightly below the slit-band, and a narrow poorly developed concave area is present. Thus although Penivispira is distinguished only by the degree of develop- ment of these features, its recognition as a separate taxonomic group appears justifiable because it forms a rather compact group of high-spired forms which has a different stratigraphical distribution from Ptychomphalina. Fletcher (1958, p. 139) has proposed the new generic name Pleurocinctosa, with Pleurotomaria trifilata Dana (1847, p. 150) as the type species. He distinguishes Pleuro- cinctosa from Penivispira on the possession of a strongly developed columellar lip and other apertural features. However, in the specimens of Penivispira figured by Chronic {in Newell, Chronic, and Roberts 1953, pi. 28, figs. 9-12) the columellar lip seems to be incompletely preserved, so that proposal of a new name on the basis of the apertural features seems hardly justifiable. In other important characters such as whorl height and profile, nature of the slit-band, ornamentation, and the concave revolving area beneath the slit-band Penivispira and Pleiiroeinetosa are similar. It seems unlikely that, when complete specimens of Penivispira delieata are available, the apertural features will differ in any important way from those of Pleurotomaria trifilata', so I have no hesitation in regarding Pleiiroeinetosa as a synonym of Penivispira. Penivispira vipersdorfensis sp. nov. Plate 18, figs. 7-11 Diagnosis. Very similar to Penivispira trifilata (Dana)’ (1847, p. 150; 1849, p. 706, pi. 9, figs. 15, 15u) and Penivispira umariensis (Reed) (1928, p. 389, pi. 34, fig. 12, pi. 35, figs. 1 1-13). Separated, however, from P. umariensis by having a less well-rounded whorl cross-section and having the third lira or ridge situated farther away from the periphery of the shell. From P. trifilata it can be separated by the higher spire and the lesser apical angle. Deseription. Holotype: a natural vertical cross-section through the columella, slightly etched with acetic acid, shows the essential features of the species. The upper whorl surface is almost straight with the slit-band at the outer edge and approximately vertical. The slit-band is bounded on either side by a distinct ridge. Below the slit-band the outline is concave; the concave part being bounded below by a ridge. The outline then joins the base with an arc of low curvature. The columellar lip is distinctly thickened as in P. umariensis and P. trifilata. Other specimens : these confirm the characters shown by the holotype. Paratype B shows in addition that the adult was non-umbilicate. Apparently most mature specimens have four whorls, though some have five. ’ Fletcher (1958, p. 140) sets out reasons for considering that Pleurotomaria morrisiana M‘Coy (1847, p. 306, pi. 17, fig. 5) should be regarded as a synonym of Pleurotomaria trifilata. The choice by Fletcher of the specimen figured by Dana (1849, pi. 9, figs. 15, 15u) as the holotype thus ensures that P. morrisiana becomes a synonym of P. trifilata. The writer is in full accord with the proposals and conclusions of Fletcher in this regard. 146 PALAEONTOLOGY, VOLUME 4 Dimensions (in mm.) Height Width Apical angle Holotype 9 (approx.) 6 46° Paratype A 8 (approx.) 6 45° Paratype B 8 5-5 38° Paratype C 9 6 38° Occurrence. Holotype and Paratypes A, B, and C, No. 7081, Farm Vipersdorf No. 63, Gibeon District, other specimens No. 7082, Tses Native Reserve, near main road about 8 miles north of Tses Siding. The numbers are those of the Geological Survey, Union of South Africa, Pretoria, where the specimens are housed. Discussion. Although several pieces of rock are crowded with some hundreds of speci- mens apparently all belonging to this species, only a few specimens show the characters necessary for a generic and specific differentiation. The preservation is not good, but revolving ornament appears to be present only as ridges bounding the slit-band and the ridge at the lower boundary of the revolving concave area. Whorl cross-section and the height of the spire vary somewhat, so that some specimens approach more closely to P. trifilata and others to P. uniariensis. On the whole, however, the species appears to approach closer to P. uniariensis than to P. trifilata and it is tempting to identify specimens with more rounded whorls with P. uniariensis. It seems best, for the present at least, to recognize the overall difference of the South African specimens as a specific difference. P. vipersdorfensis also appears to be closely related to Peruvispira allandalensis (Fletcher) (1958, p. 141, pi. 11, figs. 7-9, pi. 12, figs. 2, 3) from the Lochinvar and Allandale ‘Formations’ of the Lower Marine Beds (= Dalwood Group of Hanlon in Hill 1955) of the Hunter Valley, New South Wales. P. allandalensis apparently has a greater number of whorls, a higher spire, and an overall lesser apical angle. P. vipersdor- fensis appears to be more closely related to the slightly older forms, P. uniariensis and P. allandalensis which occur in rocks of Sakmarian (Lower Permian) age than to the younger P. trifilata which occurs in rocks of Artinskian (Lower Permian) age. Acknowledgements. This work was partly carried out in the Department of Geology of the University of Queensland in partial fulfilment of requirements for a Ph.D. degree. The material has been obtained by arrangement with the Director of the Geological Survey of South Africa, Dr. C. Teichert, and Dr. H. Martin. The co-operation of Dr. F. C. Truter, Director of the Geological Survey of South Africa, is acknowledged and Dr. H. Martin has been most helpful at all stages of this study. The paper is published by permission of the Director of the Bureau of Mineral Resources, Geology and Geophysics, Canberra. REFERENCES BATTEN, R. L. 1958. Permian Gastropoda of the South-western United States. 2. Pleurotomariacea : Portlockiellidae, Phymatopleuridae and Eotomariidae. Bull. Amer. Miis. not. Hist. 114 (2). BEURLEN, K. 1953. Einige vorlaufige Mitteilungen fiber die Stratigraphie des Gondwana-Systems. Neiies Jb. Geol. Paldont., Abh. 97 (1/3), 241-56. BHATiA, s. B. and SINGH, s. K. 1959. Carboniferous (Uralian) Foraminifera from Manendragarth, Central India. Micropaleontology, 5 (1), 127-34. J. M. DICKINS; EURYDESMA AND PERUVISPIRA 147 CASTER, K. E. 1953. Stratigraphic and palaeontologic data relevant to the problem of Afro-American ligation during the Paleozoic and Mesozoic. Bull. Amer. Mus. iiat. Hist. 99 (3), 105-52. CRESPiN, c. 1958. Permian Foraminifera of Australia. Bur. Min. Resour. Aust. Bull. 48. DANA, J. D. 1847. Description of fossils from Australia. Amer. J. Sci. 54, 151-60. 1849. In United States Exploring Expedition during the years 1838-42 under the command of Charles Wilkes, U.S.N., 10, Geology, 681-713. DAVID, T. w. E. ed. BROWNE, w. R. 1950. The Geology of the Commonwealth of Australia, Vol. 1, London. DICKINS, J. M. 1957. Lower Permian Pelecypods and Gastropods from the Carnarvon Basin, Western Australia. Bur. Min. Resour. Aust. Bull. 41. DICKINS, J. M. and thomas, g. a. 1959. The marine fauna of the Lyons Group and the Carrandibby Shale of the Carnarvon Basin, Western Australia. Bur. Miu. Resour. Aust. Rep. 38. ETHERIDGE, R. jun. and DUN, w. s. 1910. A monograph of the Carboniferous and Permo-carboniferous Invertebrata of N.S.W., Vol. II — Pelecypoda, Part II — Eurydesma. Mem. geol. Surv. N.S.W., Palaeont. 5, 41-75. FISCHER, p. 1880-7. Manuel de conchyliologie et de paleontologie conchyliologiqiie, Paris. FLETCHER, H. o. 1958. The Permian Gastropods of New South Wales. Rec. Aust. Mus. 24(\Q),\\5-6A. FOSSA MANCiNi, E. 1944. Las transgresioncs marinas del Antracolitico cn America del Sur. Rev. Mus. La Plata, sec. Geol. 2, No. 49 [not seen]. GURiCH, G. 1923. Acrolepis Lotzi und andere Ganoiden aus den Dwyka-Schichten von Ganikobis Siidwestafrika. Beitr. geol. Erforsch. dtsch. SchGeb. 19 (2), 26-74. HARRINGTON, H. J. 1955. The Permian Eurydesma Launa of Eastern Argentina. /. Paleont. 29, 112-28. HAUGHTON, s. H. and MARTIN, H. 1956. The Nama System in South and South-West Africa. Congr. geol. int. XX sess., Mexico: Symp. Cambrian, 1, 323-39. HILL, D. 1955. Contributions to the correlation and fauna of the Permian in Australia and New Zealand. J. geol. Soc. Aust. 2, 83-107. ISBERG, o. 1934. Studien fiber Lamellibranchiaten des Leptaenakalkes in Dalarna. Beitrag zu einer Orientierung fiber die Muschelfauna ini Ordoviciiim und Silur. Lund, Hakan Ohlssons Buch- druckerei. KNIGHT, J. B. 1941. Paleozoic Gastropod Genotypes. Spec. Pap. geol. Soc. Amer. 32. KOKEN, E. 1904. Eurydesma und der Eurydesmen-Horizont in der Saltrange. Zbl. Miner. Geol. Paldont. 5, 97-107. LESCHiK, G. 1959. Sporen aus den ‘Karru Sandsteinen’ von Norronaub (Siidwest-Afrika). Senck. Leth. 40 (1/2), 51-95. MAACK, R. 1957. liber Vereisungsperioden und Vereisungsspuren in Brasilien. Geol. Rdsch. 45 0), 547-94. MCCOY, F. 1847. On the fossil botany and zoology of the rocks associated with coal of Australia. Ann. Mag. nat. Hist., ser. 1, 20, 145-57, 226-36, 298-312. MARTIN, H. 1953. Notes on the Dwyka Succession and on some Pre-Dwyka valleys in South-West Africa. Trans, geol. Soc. S. Afr. 56, 37-41. MORRIS, J. 1845. Descriptions of fossils, in strzelecki, p. de. Physical description of New South Wales and Van Diemen s Land, London, 270-91. NEWELL, N. D. 1942. Late Paleozoic Pelecypods: Mytilacea. Kansas geol. Surv. 10 (2), 1-115. NEWELL, N. D., CHRONIC, J., and ROBERTS, T. G. 1949. Upper Paleozoic of Peru, New York [not seen]. — — -1953. Upper Paleozoic of Peru. Mem. geol. Soc. Amer. 5^. POPOV, u. N. 1957. Some Permian Pelecypods, Gastropods and Ammonites of Verchoyan. Sci. Inst. Geol. Arctic, Coll. Pap. Palaeont. Biostrat. 1, 45-60 (also in Mater. Geol. Min. Resour. N.E. U.S.S.R., 1958 (12)). PUTZER, H. 1957. Beziehungen zwischen Inland-Vereisung und Kohlebildung im Oberkarbon von Siid-Brasilien. Geol. Rdsch. 45 (3), 599-608. RANGE, p. 1912. Geologic des deutschen Namalandes. Beitr. geol. Erforsch. dtsch. SchGeb. 2. REED, F. R. c. 1928. A Permo-Carboniferous marine fauna from the Umaria Coal Lield. Rec. geol. Surv. India, 60, 367-98. — 1932. New fossils from the Agglomeratic Slate of Kashmir. Paleont. Indica, N.s. 20 (1). 148 PALAEONTOLOGY, VOLUME 4 REED, F. R. c. 1935. A new Lamellibranch from the Upper Dwyka Beds of South-West Africa. Trans, roy. Soc. S. Afr. 23, 161-3. ■ 1936. Some fossils from the Eiirydesma and Cornilaria Beds (Punjabian) of the Salt Range. Palaeont. Indica, N.s. 23 (1). SAHNi, M. R. and SRIVASTAVA, J.p. 1956. Discovery of Eurydesma and Comdaria in the Eastern Himalaya and description of associated faunas. J. palaeont. Soc. India, 1 (1), 202-14. STEPANOV, D. L. 1958. The Carboniferous System and its main stratigraphic subdivisions — Report to the Commission on the Stratigraphy of the Carboniferous of the National Committee of Soviet Geologists. Copy distributed at Heerlen conference on Carboniferous stratigraphy, 1958. THOMAS, E. G. 1940. Revision of the Scottish Carboniferous Pleurotomariidae. Trans, geol. Soc. Glasgow, 20 (1), 30-72. TOIT, A. L. DU. 1954. The Geology of South Africa. Edinburgh and London. WAAGEN, w. 1891. Salt Range fossils. Pcdaeont. Indica, stx. IT), ^ {T),%9-2A1. J. M. DICKINS Geological Section, Bureau of Mineral Resources, Geology and Geophysics, Canberra, a.c.t., Australia Manuscript received 21 January 1960 THE PALAEONTOLOGICAL ASSOCIATION COUNCIL 1961 President Professor O. M. B. Bulman, Sedgwick Museum, Cambridge Vice-Presidents Professor T. N. George, The University, Glasgow Professor W. F. Whittard, The University, Bristol Treasurer'. Professor P. C. Sylvester-Bradley, Department of Geology, The University, Leicester Assistant Treasurer’. Dr. T. D. Ford, Department of Geology, The University, Leicester Secretary. Dr. Gwyn Thomas, Department of Geology, Imperial College of Science, London, S.W. 7 Assistant Secretary. Dr. C. H. Holland, Department of Geology, Bedford College, London, N.W. 1 Editors Dr. W. H. C. Ramsbottom, Geological Survey Office, Ring Road, Halton, Leeds, 15 Mr. N. F. Hughes, Sedgwick Museum, Cambridge Dr. W. S. McKerrow, University Museum, Oxford Other members of Council Dr. D. V. Ager, Imperial College of Science, London Dr. F, T. Banner, British Petroleum Company, Sunbury on Thames Dr. A. J. Charig, British Museum (Natural History), London Dr. L. R. Cox, British Museum (Natural History), London Dr. R. H. Cummings, The University, Glasgow Dr. R. Goldring, The University, Reading Dr. J. C. Harper, The University, Liverpool Professor F. Hodson, The University, Southampton Dr. M. R. House, The University, Durham Dr. R. G. S. Hudson, Trinity College, Dublin Dr. J. W. Neale, The University, Hull Dr. Dorothy H. Rayner, The University, Leeds Mr. J. D. D. Smith, Geological Survey and Museum, London Dr. C. D. Waterston, Royal Scottish Museum, Edinburgh Overseas Representatives Australia'. Professor Dorothy Hill, Department of Geology, University of Queensland, Brisbane, Queensland Canada’. Dr. D. J. McLaren, Geological Survey of Canada, Department of Mines and Technical Services, Ottawa New Zealand: Dr. C. A. Fleming, New Zealand Geological Survey, P.O. Box 368, Lower Hutt West Indies and Central America: Dr. L. J. Chubb, Geological Survey Department, Kingston, Jamaica Eastern U.S.A.: Professor H. B. WnririNaTON, Museum of Comparative Zoology, Harvard Uni- versity, Cambridge 38, Mass. Western U.S.A.: Dr. J. Wyatt Durham, Department of Paleontology, University of California, Berkeley 4, Calif. PALAEONTOLOGY VOLUME 4 • PART 1 CONTENTS Upper Triassic Brachiopods and Lamellibranchs from the Oman Peninsula, Arabia. By r. g. s. Hudson and r. p. s, Jefferies 1 The Permian Brachiopod genus Horridonia Chao. By d. j. gobbett 42 New Namurian goniatites of the genus Eumorphoceras. By Patricia j. yates 54 Lower Carboniferous gastropod faunas from Old Cannindah, Queensland. By w. G. H. maxwell 59 Cambrian Trilobites from the Amanos Mountains, Turkey. By w. t. dean and R. KRUMMENACHER 71 The sexual organization of Cretaceous Permocalculus (Calcareous Algae). By G. F. ELLIOTT 82 Eocene Crabs in a London Clay nodule. By J. collins 85 New Rhaetic and Liassic beetles. By b. g. gardiner 87 Microplankton from the Kellaways Rock and Oxford Clay of Yorkshire. By W. A. S. SARJEANT 90 Permian Pelecypods newly recorded from Eastern Australia. Byj. m. dickins 119 The Gastropod Platyteichum in the Permian of Western Australia. By j. m. DICKINS 131 Eurydesma and Peruvispira from the Dwyka Beds of South Africa. By j. m. DICKINS 138 PRINTED IN GREAT BRITAIN AT THE UNIVERSITY PRESS, OXFORD BY VIVIAN RIDLER, PRINTER TO THE UNIVERSITY VOLUME 4 • PART 2 4f,*4Z- 'l5 \&c\. Palaeontology JULY 1961 PUBLISHED BY THE PALAEONTOLOGICAL ASSOCIATION LONDON Price £2 THE PALAEONTOLOGICAL ASSOCIATION The Association was founded in 1957 to further the study of palaeontology. It holds meetings and demonstrations, and publishes the quarterly journal Palaeontology. Membership is open to individuals, institutions, libraries, &c., on payment of the appropriate annual subscription: Institutional membership £5. 5^. ($15.50) Ordinary membership £3. 'is. ($ 9.50) Student membership £2. 2s. ($ 6.50) There is no admission fee. Student members will be regarded as persons receiving full-time instruction at educational institutions recognized by the Council. Subscrip- tions are due each January, and should be sent to the Treasurer, Professor P. C. Sylvester-Bradley, Department of Geology, The University, Leicester, England. Palaeontology is devoted to the publication of papers (preferably illustrated) on all aspects of palaeontology and stratigraphical palaeontology. Four parts are published each year and are sent free to all members of the Association. Members who join for 1961 will receive Volume 4, Parts 1 to 4. Back parts may be purchased separately at a cost of £2 ($6) post free for each part; orders should be sent to the approved agents, Messrs. B. H. Blackwell, Broad Street, Oxford, England. Manuscripts on all aspects of palaeontology and stratigraphical palaeontology are invited. They should conform in style to those already published in this journal, and should be sent to Mr. N. F. Hughes, Sedgwick Museum, Cambridge, England. A sheet of detailed instructions for authors will be supplied on request. THE ORIGIN OF THE LOOP IN ARTICULATE BRACHIOPODS by k. WILLIAMS and A. d. wright Abstract. The lophophore of living articulate brachiopods develops from a pair of generative zones which are first located antero-medianly of the mouth, and are each responsible for the proliferation initially of a single set of filaments, constituting the trocholophe, and subsequently of a paired set of filaments. Brachidial supports are secreted within sheaths of outer epithelium and grow independently of the lophophore, but those developed in shells about 1 mm. in length invariably support a simple, subcircular lophophore; and since the earliest known loop, that of the spiriferoid Protozyga, was fully developed in sexually mature shells of that size, it probably appeared coenogenetically in a neotenous stock. The modal size of the earliest terebratuloid loops compares with that of the primary coils posterior of the jugum in contemporary spiriferoids, so that the terebratuloids could have been derived neotenously out of the spiriferoids. The loop of the pentameroid Enantiospheu is only super- ficially comparable with the centronellaceid one, but that found in the dalmanellaceid Tropidoleptus is a remark- able homeomorph of the terebratellaceid loop and probably differed only in the style of lophophore it supported. INTRODUCTION The presence of a calcareous loop in the brachial valve of an articulate brachiopod is usually taken to be diagnostic of a terebratuloid or a young spiriferoid shell and the structure is known, or is assumed, to have given support to the lophophore suspended within the brachial cavity. This type of skeletal support appeared rather late in brachio- pod evolution, for the earliest known loop bearer, the spiriferoid Protozyga, is hrst recorded from the Middle Ordovician. Nevertheless, it has since undergone a remark- able series of changes, some of them so complicated that they are only intelligible if a number of assumptions about the original growth and disposition of the lophophore are adopted. With this end in view one of us (Williams 1956, pp. 260-72) used some generaliza- tions derived from a study of living material to speculate on the nature of the lophophore in various extinct fossil groups. In 1959 four studies of this aspect of brachiopod mor- phology were published: two by Dr. D. Atkins on the development of the lophophores oiPIatidia and Macandrevia, a systematic study of some recent articulate brachiopods by Dr. H. M. Muir-Wood, and also a general account of the phylum by Dr. L. Hyman. All three authors were critical of some of the conclusions reached in 1956, but since their own interpretations either contradict one another or are, with one exception, unacceptable to any one familiar with the growth of the loop and the lophophore, some reappraisal of the present state of knowledge is necessary. In addition it has long been known that two Devonian loop-bearing brachiopods, Enantiosphen Whidborne and Tropidoleptus Hall, are characterized by other morpholo- gical features which are typical, not of the terebratuloids or the spiriferoids, but of the pentameraceids and dalmanellaceids, respectively. The two stocks are all the more per- plexing in that their restricted ranges coincided with the time when the terebratuloids first became common and widespread members of the Palaeozoic shelly faunas, a con- temporaneity which had prompted the original authors of the genera to suggest that they were really aberrant terebratuloids. Through the kindness of Mr. A. G. Brighton of the Sedgwick Museum, Cambridge, and Dr. G. A. Cooper of the U.S. National Museum, it [Palaeontology, Vol. 4, Part 2, 1961, pp. 149-76.] B 9425 L 150 PALAEONTOLOGY, VOLUME 4 has been possible to serial section specimens of both genera and thereby conduct a de- tailed examination of the growth of all features in an effort to resolve any doubts about their systematic status, and to find out if their brachidial skeletons were indeed compar- able in function and origin with those of contemporary terebratuloids. THE RELATIONSHIP BETWEEN THE LOPHOPHORE AND THE LOOP IN RECENT BRACHIOPODS In 1897 Beecher described the formation of the lophophore in living brachiopods as beginning with a proliferation of filaments to form a complete ring, the trocholophe, around an oral disk bearing a subcentral mouth. The trocholophe then becomes in- dented antero- or dorso-medianly (the schizolophous stage) and further growth of the lophophore results in a distortion of the original circle into a pair of spires (the spiro- lophe) or variably developed loops (ptycholophe) including a pair of long lateral ones (the side arms of the zygolophe) winch are commonly associated with a pair of median coils to form a plectolophe. It is important to realize that Beecher (p. 105) took the formation of filaments in the inarticulate Glottidia as being representative of the earliest stages of growth for all brachiopods. At that time observations made by various authors on the early development of the lophophore of certain articulate genera, as well as Beecher’s own investigations, appeared to confirm his assumption. In Glottidia (Brooks 1879) and also in Lingula according to Yatsu (1902), new filaments are budded off from either side of a lobe situated dorso-medianly of the mouth. This proliferation of new filaments from a median zone is responsible for the migration of the first formed pair along two curved arcs which meet ventro-medianly to form the completed trocholophous circle. In 1944 Percival (p. 13) described the growth of the lophophore in Terebrateiia inconspicua (J. de C. Sowerby) in an entirely different way. According to him the first pair of fila- ments arise ventro- or postero-medianly of the mouth and additional filaments grow in pairs one on either side of the earlier formed filaments. This pattern of growth, in contrast to that described by Beecher, involves a pair of generative zones expanding out- wards from the median line to surround the mouth and then to meet dorso- and antero- medianly. The schizolophous stage now becomes intelligible in that it represents that phase of development in which these two generative zones first meet medianly. Further growth is, of course, responsible for a distortion of the initial, encircling disposition of the filaments. The arrangement of filaments observed by Percival has been confirmed by Atkins ( 19596, p. 336) for Macandrevia, and judging from the early schizolophous stages of Terebratidina and Teguiorhynchia (text-fig. 16) re-examined by us, it is feasible to assume that this style of development is typical of the articulate brachiopods. Whether it represents an invariable deviation from the development of the inarticulates remains to be seen. In his account of lophophore development, Percival recorded that when eight pairs of filaments have been formed ‘there is a rapid extension of the anterior border of the mouth, between the latest filaments, without a corresponding increase in the diameter of the opening’. Williams (1956, p. 260) interpreted the resultant flap over the mouth as the brachial fold or lip of the food groove, but Atkins (1959n, p. 106 and 19596, p. 337) found that in Piatidia and Macandrevia the lip first becomes differentiated antero-medianly of the mouth and thence spreads laterally towards the antero-median portion of the trocholophe. The difference is important because in these two genera at least the con- 151 WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS verging tips responsible for the generation of filaments are not effectively separated from each other by the growth of the brachial lip. Atkins therefore concluded that, in the absence of this invagination from her growth series and also in the presence of a closed lophophoral ridge forming the base of the filament circle, the trocholophe was, after all, a complete ring as defined by Beecher. This is a repudiation of the suggestion by Williams (1956, p. 261) that, in the light of PercivaFs finding, the trocholophe ‘is in reality a crescent capable of accelerated and differential growth at the tips of the antero-median TEXT-FIG. 1. The plectolophe of Terebralulina (a) with enlargements to show the arrangement of the trocholophous filaments posterior of the mouth (a') and one of the median generative zones (a") and the early schizolophe of Tegiilorhyncliia (b). horns’. Certainly the lophophores of Platiciia and Maccmdrevia pass, during develop- ment, through a phase morphologically comparable with a closed ring. But the growth of the trocholophe involves a migration of a pair of generative zones, responsible for the proliferation of filaments, from a ventro-median position to a dorso- or antero-median one and it is surely reasonable to conclude that the pair of dorso-median generative zones identified by Williams (1956, p. 261) as typical of the early schizolophous stage and also described by Atkins ( 1959n, p. 107, 1959/5, p. 337) in the schizolophes o^Platidia and Macandrevia are the same as the migratory ones of the trocholophe. In effect, the indentation which defines the schizolophous stages of Beecher represents the confluence of two growing tips, which tend thereafter to curl back upon themselves, and not a division of the lophophore into two lobes of growth subsequent to an initial expansion in an opposite direction (Beecher 1897, p. 108). In any case the trocholophous stage is at present arbitrarily defined because it ends with the first suggestions of an antero-median indentation corresponding to the beginnings of introversion of the two contiguous 152 PALAEONTOLOGY, VOLUME 4 growing tips. The schizolophous stage, however, as understood by most students of the phylum is practically coincident with a marked change in the disposition of filaments (text-fig. In). In the initial stages of filament proliferation up to the encirclement of the j ' oral disk and the start of introversion, the filaments occur singly, but thereafter they bud ^ ' off in pairs, slightly in echelon, but effectively forming an outer and inner set arising - ' from each generative zone. Many authors have commented on this fact and have noted ] ■ that in adult lophophores those arranged in a single low have been pushed back to form | , the postero-median margin of the mouth. These are, of course, the first formed filaments | j and their disposition in both the larval and adult stages of growth so conveniently dis- ; tinguishes them from the double series which arise during schizolophous stages of growth i that we consider it preferable to define the trocholophe in terms of the filaments rather than in terms of a completed circle. The fully developed trocholophe of articulate • i brachiopods then may be described as that growth stage of the lophophore where primary ■ filaments, arranged in a single series surrounding the oral disk, have budded off from a pair : of migratory generative zones which are now contiguous antero-medianly and are about to give rise to two paired series of filaments. i The onset of paired filaments may be slightly delayed or accelerated during the de- \ velopment of the lophophore. Percival described the invagination of the anterior border | which gives rise to the brachial fold as occurring when about sixteen filaments surround i the oral disk. Fifteen or sixteen single filaments have been counted postero-medianly | of the mouths of four adult Terebratella inconspicua, so that according to our definition \ the invagination corresponds to the beginning of the schizolophous stage. In a similar ' manner the end of the trocholophous stage occurred in the early schizolophous sped- . men of Platidia davidsoni (E. Deslongchamps) figured by Atkins (1959a, p. 107, fig. 2) when the formation of thirty-six or thirty-seven single filaments had been completed , and in Macandrevia cranium (Muller) when about twenty-four filaments had appeared ' (Atkins 19596, p. 338). According to Atkins a slight indentation and interruption of the lophophoral ridge of this latter species occurs at the twenty-four filament stage and one ; or more pairs of buds are present in place of the asymmetrical bud which marks the end ^ of the trocholophous stage as interpreted by her and Beecher. This asymmetry of growth is due, as Percival noted (1944, p. 13), to a slightly staggered appearance of the filaments | during their spread from the postero-median region and confirms the presence of two generative zones in place of a single antero-median one as described by Beecher. The j number of primary filaments arising in the trocholophous stage is only slightly variable . for the species and probably even for the genus: in a small sample of adults of Tere- bratulina sp. from Crinan Loch, 8, 9, 10, 11, and 12 primary filaments were present postero-medianly of the mouth in 1, 0, 7, 1, and 2 specimens respectively. In describing more advanced stages of lophophore growth, Williams (1956, p. 263), i guided mainly by the enlargement of the skeletal support, supposed that a pair of | secondary generative zones become active antero-laterally of the primary median zones ! to give rise to the side arms of the zygolophe and plectolophe. Atkins (19596, p. 348) ; points out that if such zones existed proliferation of filaments should occur at the apices of the side arms. Filament buds, however, are found only in the primary median zones and any increase in the number of filaments on the side arms can only be accounted for by their migration from the median coils. The growth of the side arms need not involve the production of new filaments but simply an expansion of tissue relative to the rest of WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 153 the lophophore, and this does take place. In eleven brachial valves of Terebratulina sp., between 8 and 10 mm. long, counts of filaments were obtained for standard lengths of the lophophore antero-lateral of the crura, immediately posterior to the apical curve of the side arms and also along the middle part of the outermost coil. The incidence of filaments per unit length on the side arm was on an average 74 percent, and 82 per cent, the counts of those on the coil and the crural region, respectively. But this increase in overall size does not account for the entire elongation of the side arms, and, since the number of filaments along them does increase with age, the chief contribution to their forward expansion must be due to the addition of filaments from the median coils in the manner described by Atkins. The migration of filaments outwards from a pair of generative zones towards two points, beyond which no further relative movement is possible (initially represented by the ends of an extended trocholophe), makes the definition of ‘zones of transit’ neces- sary, because they may be responsible for the ultimate disposition of the lophophore. As far as we can judge, the only method of determining when a filament becomes incor- porated into the non-migratory part of the lophophore is by studying the transit of certain marked filaments in living material, an experiment which is beyond our present resources. In the meantime it seems reasonable to conjecture that migration ceases just lateral of the zones of maximum distortion of the initially circular outline of the lopho- phore. In the terebratuloids these are the side arms and it is quite possible that the posterior part of the lophophore together with the descending portions of the side arms (excluding their apices) represent the non-migratory zones, and that the apices and the ascending portions of the side arms, as well as the median coils, consist of filaments in transit. The fact that such unlike brachial arrangements as the spirolophe and the plectolophe are derived from similar, early schizolophes with medianly placed generative zones leads to some understanding of how these diverse patterns arise. In comparative terms the side arms and the median coils of the terebratuloids are equivalent to the first formed coil and the apical spires, respectively, of the rhynchonelloid arms (text-fig. 2). Some con- fusion exists over this rather obvious homology. Hyman (1959, p. 548) states that in the spirolophe of inarticulates and rhynchonelloids ‘the median arm [i.e. the median coils of the plectolophe] is wanting and the two lateral arms elongated still further and coiled into helicoidal spires’. This misinterpretation is later (p. 550) repeated in the assertion that ‘the structure [that is of the spirolophous arm] is the same as that of half of a plecto- lophous arm’. Muir-Wood (1959, p. 310) contends that the paired growing regions of the trocholophe are represented by the side arms of the plectolophe ‘while the median coil is developed from the region anterior to the mouth’ (caption to her text-fig. 4a-c, which is a reproduction of immature lophophores of Terebratulina from Morse 1871). The implication again is that the side arms are the homologues of the rhynchonelloid spires. But what she has taken as crescentic trocholophes are actually, as can be seen from the arrangement of the filaments in her text-fig. 4a-b, zygolophes of individuals about 4 mm. long. The difference then between the spirolophe and the plectolophe is simply dependent on the attitude of the first formed coil relative to the rest of the spire for either half of the lophophore. In the terebratuloids, the left side arm is essentially the first coil, narrowly compressed in the ventro-dorsal plane, which is added to from a piano-spire lying out- 154 PALAEONTOLOGY, VOLUME 4 side its periphery and coiling in a clockwise direction (text-fig. 2a, b). In rhynchonelloids, the first coil of the left half of the lophophore is not compressed so that the helicoidal spire lies within it, and coiling takes place in an anticlockwise direction (text-Fig. 2c, d). ! These changes in growth directions must be related to the disposition of the generative i zones, which are medianly paired in the schizolophous stage. For in the plectolophes . they persist in the median plane, and coiling can only begin with movement away from i the diaphragm, that is with a clockwise revolution of the left zone and an anticlockwise one of the right. In the rhynchonelloid spirolophes the generative zones migrate away ' TEXT-FIG. 2. Stylized ventral and lateral views of a terebratuloid plectolophe {a, b) and a rhynchonelloid spirolophe (c, d) to show the positions of the original trocholophes, the primary coils, and the genera- tive zones. from the median plane as the apices of two ever-increasing spires directed dorsally or -1 antero-dorsally and coiled anticlockwise on the left and clockwise on the right. The per- sistence of the generative zones on the median plane or migration laterally away from it now become matters of some importance, and, since the first condition is exclusive to the loop-bearing terebratuloids while the second is characteristic of those brachiopods equipped with nothing more than the crura, physical constraint by the brachidial skeleton may well account for the difference. Thus the terebratuloid schizolophe is either contained laterally by a pair of calcareous ribbons growing from the crural ends (in |j the terebratulaceids and the majority of the terebratellaceids) or is intimately associated with the median septum which separates the generative zones (in all terebratellaceids). The constraint exercised by the early growth of a loop and/or a median septum with divergent plates (e.g. Kraussina) is such that one of only four modifications can take place. Where the enlargement of the loop is as fast as the proliferation of the filaments and the lophophore, the structure retains the simplicity of the early stages in develop- ■ ment. This probably occurred in early terebratuloids like Rensselandia (see Williams | 1956, text-fig. 5 (10)) and is also characteristic of certain stocks like Argyrotheca. J In the second group, growth of the loop is slower than the total growth of the lopho- / ' phore, but more or less keeps pace with the enlargement of a pair of side arms. The dis- i|| WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 155 tortion of the subcircular outline of the schizolophe by the development of a pair of anteriorly directed bulges, which later become side arms, is to be expected when pro- liferation from medianly disposed generative zones is very much greater than postero- lateral migration of the lophophore. As a support to the side arms, the original simple loop of the majority of the terebratellaceids is refashioned by complex processes of resorption and secretion, and is greatly enlarged anteriorly. Nevertheless, the production of a lophophore at the two median tips is ultimately so much faster than its incorpora- tion into the lengthening side arms that the growth zones push themselves away from the diaphragm and begin to coil antero-ventrally, and so give rise to the terebratellaceid plectolophe. The third group includes those forms in which the growth of the skeletal supports to the lophophore is so much slower than the expansion of that organ that there is little morphological similarity between the calcareous and fleshy parts of the apparatus. The short terebratulaceid loop supports a plectolophous lophophore in such a way that only the posterior semicircle of the lophophore and the junctions between the side arms and the median coils rest upon it. Presumably proliferation at the growing tips is so much greater than the enlargement of the loop that the side arms are squeezed out of the confining circle antero-laterally, as a pair of closely united loops, and the generative zones themselves move away from the diaphragm to describe a pair of contiguous piano- spires. In the kraussinids, the growth of divergent lamellae from the median septum, to which the adjacent generative zones are attached, provide a similar restriction. The consequences are well seen in Pumilus antiqualus Atkins, because in this species the schizolophe of the adult shows an exaggerated sweep of the antero-lateral parts of the lophophore, which is precursory to the development of the ptycholophe or the plectolophe of Kraussina. The fourth group is visualized as including those forms in which the expansion of the loop is slower than the growth of the lophophore, but in which the excess length of the latter is supported by apophyses growing out from a relatively short loop. Imagine, for example, a pair of single ribbons growing out of the antero-lateral part of the Terebra- tulina loop to give support to the side arms, which are in any case so closely united as to be served by a single brachial canal. No living brachiopods display this pattern, but a Devonian centronellaceid, Cimcmella (Schmidt 1946), does, and it is believed that the calcareous spires of the spiriferoid brachiopods should be interpreted in this way (Williams 1956, pp. 269-71). These fossil stocks are more appropriately discussed below in the section concerned with the origin of the loop. In the preceding discussion reference has been made to the unequal growth rates of the lophophore and its skeletal supports, with the implication that the two structures are independently controlled in spite of a good deal of interdependent adjustment during development. The origin of the internal calcareous parts of brachiopods, whether they are crura, spires, or loops has aroused comment for over a century. Hancock (1859, p. 831) believed that the inner epithelium (i.e. his ‘lamina’) was responsible for their secretion. Morse (1871) asserted that the terebratulinid loop was formed by amalgama- tion of spicules. In 1956 Williams (p. 266) said that all such growths were secreted by outer epithelium in exactly the same way as the secondary layer of the shell. Serial sections of Terebratulina, Terebratella, and Terebratalia show that their apparatuses, continuous as they are with either the crura or the median septum, are contained in 156 PALAEONTOLOGY, VOLUME 4 sheath-like extensions of the outer epithelium, which is responsible for the secretion of those two structures. What happens when two calcareous pieces become united can be safely inferred from a study of the development of the Terebmtidina loop in sectioned specimens. The convergence of the lamellae descending from the crura towards the median plane brings the epithelial tips of the descending branches together. Secretion continues until both epithelial layers, one across each tip, are destroyed, but peripherally TEXT-FIG. 3. Some biometrical attributes of the growth of the Terebratidiua brachidial apparatus. they fuse to form one continuous sheath. This mode of secretion has been restated and enlarged upon because Hyman (1959, p. 549) repudiates the interpretation and favours the deposition of the loop by connective tissue presumably in the manner suggested by Morse. Her rejection of epithelial secretion appears to be founded on the failure of the author responsible for this idea (Williams 1956, not Elliott 1956 as given by her) ‘to explain how this epidermis could get inside the lophophore’. Invagination of one epithe- lial layer so that it grows in association with connective tissue surrounded by another layer is, however, a common feature of animal growth, and its role in the development of the loop may be confirmed in suitably prepared sections. The construction of skeletal supports to the lophophore by invaginations of the outer epithelium is demonstrably a complex interplay between secretion and resorption of fibrous calcite, which can be appreciated by considering some biometrical aspects of loop variation in a small sample of Terebratulina (text-fig. 3). The crura and the proximal WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 157 parts of the descending branches must be secreted when the lophophore is trocholophous and before the brachial valve has attained a length of 1 mm., because an early plecto- lophe supported by a nearly completed loop occurs in valves 2 mm. long. Fusion of the descending branches is usually effected before the valves are 4 mm. long, but one speci- men of that size has been sectioned in which the calcareous ribbons were still discrete. Thereafter, the loop increases steadily, laterally and also anteriorly, to maintain a length about half that of the valve. The calcareous ribbon also increases in width, but not at a rate which could account for the overall enlargement of the loop without a concomitant resorption taking place along its inner edge. The same sort of functional differentiation must also obtain in the epithelial sheath to the crura. These processes arise from the antero- lateral parts of the inner surfaces of the socket ridges. They are convergent towards the median plane, so that their growth in length should result in a narrowing of the distance between their tips. Instead, there is a widening of the gap, and this can only come about if the crural bases ‘move’ apart in antero-lateral directions away from the umbonal region. Such modification must again be due to resorption of the inner surfaces of the crura, and simultaneous secretion on the outer surfaces by the surrounding epithelium. Among the terebratellaceids this method of fashioning and enlarging the supports to the lophophore goes on with even more profound results. It involves, among other things, the degeneration of a septum and the development of long loops, ultimately a continuous calcareous ribbon disposed as a pair of U-shaped lateral lobes, by the fusion of two dis- tinct elements — the descending branches and the hood which first develops from the septum (Elliott 1953). These developments clearly involve both deposition and resorption over the entire surface of the supports, and there is no doubt that, although the growth of certain structural parts, like the descending branches, may be indicative of localized accelerated secretion, the entire epithelial surfaces must be capable of proliferation in a manner quite unlike that of the origin of the lophophore. Consequently, any conformity existing between the calcareous and fleshy parts of the feeding apparatus is really a com- promise between two entirely different processes of growth. THE LOOPS OF FOSSIL BRACHIOPODS Whatever the differences between the attitude of the fully grown lophophore and the disposition of its calcareous support (and, as in the terebratulaceids, the differences may be profound), two generalizations can be safely assumed for all fossil brachiopods, in- cluding extinct groups. The first is that the crura always lay within the body chamber and gave support to the postero-median strip of the lophophore which contained the mouth. This is as true for living rhynchonelloids as it is for Recent terebratuloids, and there is no justification for a different interpretation for comparable processes in other articulate brachiopods. The second is that the lophophore of any young specimen, less than 1 mm. in length, was either a simple trocholophe or a very early schizolophe with the generative zones located antero-medianly. This is so for Macandrevia cranium, Tere- bratella inconspicua, Pumilus antiquus, Platidia davidsoui, Terebratidina caput-serpentis (Linnaeus), Hemithyris psittacea (Gmelin), and Tegidorhynchia nigricans (J. de C. Sowerby), and it follows that the growth of a pair of descending branches from the crural ends, and their antero-median fusion to form a loop at this stage of development, represents the secretion of a peripheral support to a subcircular lophophore. Both assumptions are important, because they provide a means of assessing the nature and 158 PALAEONTOLOGY, VOLUME 4 disposition of the lophophore in wholly extinct groups, and, since the crura and the loop were developed in the spiriferoid brachiopods long before the terebratuloids first ap- peared, it is now appropriate to consider the origin of these supports. The earliest known spiriferoid is the Ordovician stock Protozyga Hall & Clarke. Cooper (1956, p. 681) has described a species, P. microscopica, from the Elway formation of TEXT-FIG. 4. The growth of the brachidial apparatus of Protozyga elongata Cooper with reconstruc- 'j tions of the trocholophe (a') and the schizolophe (c', g'). j ij Tennessee and a number of others are known from the post-Chazyan of America and the i; Caradocian of Scotland. A good sample of one of these, P. elongata Cooper, was col- i lected by one of us from the Bromide beds exposed one mile west of Dolese Brothers ’ Ij Crusher, Bromide, Johnson Co., Oklahoma. The majority of specimens, of all sizes, are Ij filled with clear calcite, so that by grinding away the exteriors of both valves it is possible ! to see the arrangement of the internal skeleton, and thereby infer development during j growth. The earliest growth stage examined is represented by shells with brachial valves | slightly less than 0-5 mm. long, in which a pair of delicate, shghtly divergent prongs extend anteriorly from the hinge line for slightly less than one-third the length of the valve. In the specimen figured (text-fig. 4a, a') the left prong is longer than the right, but this extra part of the ribbon converges towards the median plane, and it is feasible to suppose that both prongs gave support to the posterior arc of the trocholophe, in the WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 159 manner of crura, and that the additional strip on the left represents the beginnings of a descending branch. A similar asymmetrical growth involving the right prong is seen in another valve 0-75 mm. long (text-fig. Ab). But more often than not, both descending branches developed and fused antero-medianly before the valve attained a length of 1 mm., and this is known to have occurred when the valve was no more than 0-7 mm. long (text-fig. 4J), although suggestions of a suture along the median plane of contact between the two branches probably implies that fusion had not then been completed. By this stage of growth, the loop was already orientated towards the pedicle valve in an TEXT-FIG. 5. A correlation between the growth of the brachidial apparatuses and the growth of brachial valves of Protozyga elongata Cooper. attitude characteristic of adult shells, due to the antero-ventral expansion of the de- scending branches, which met obliquely so that the zone of fusion tended to form a crest to the transverse part of the loop. It is inconceivable, in shells as small as this, that the loop supported any lophophore more complicated than either a trocholophe or an early schizolophe (text-fig. 4c, c'), and it is therefore realistic to assume that the paired genera- tive zones were located about or on the median line of fusion. In subsequent develop- ment the loop expanded anteriorly at about half the rate of shell elongation, although there was considerable variation (text-fig. 5). It also expanded laterally and, although the calcareous ribbon increased in width, especially along the transverse part of the loop, the enlargement must have involved resorption of the inner margins as well as secretion along the outer one by the outer epithelial sheath. Even in the largest adult shells, which are rarely more than 4 mm. long, the loop was the sole brachial support, but it tended to become truncated anteriorly (text-fig. 4c,/) and, exceptionally, from the antero-lateral corners thus formed, a pair of short apophyses grew in an anterior direction (text-fig. 4g, g'). These prolongations are homologous with ones which grew into a pair of arcs or even coils, disposed in a ventro-dorsal plane on either side of the loop, in other species of Protozyga (Cooper 1956, p. 675), and are therefore the beginnings of the calcareous 160 PALAEONTOLOGY, VOLUME 4 spires of the early spiriferoids. Their appearance may therefore be used to identify the transverse part of the loop as the homologue of the spiriferoid jugum. Having recognized the principal elements of the spiriferoid endo-skeleton as they emerge during the development of Protozyga, it is now possible to infer the disposition of the lophophore. The most significant aspect of P. elongata is that it is a loop-bearing stock, and only potentially a spiriferoid in the more orthodox sense. Indeed, were it not for its stratigraphical context, and, less importantly, its impunctate shell, it would be more appropriately classified as a terebratuloid, and, in the circumstances, no one would doubt the persistence of the paired generative zones, responsible for the growth of the lophophore in the median plane of the jugum, throughout the development of living shells. Even the growth of a pair of curved calcareous ribbons from the antero-lateral corners of the loop would not cause much concern, because the antero-lateral lobation of the lophophore to fit around the periphery of each outgrowth would be strictly homo- logous with the side arms of Terebratulina if they were each stiffened by a calcareous ribbon arising from the loop. It was for this reason that the term of deiiterolophe was used by Williams (1956, p. 270) to define a lophophore which extended laterally as a pair of narrowly compressed loops, each supported by a single calcareous ribbon arising from the junction of the jugum with the descending branches of spiriferoid brachiopods (text-fig. 4g'). The fact that in spiriferoids the side ribbons continued to grow into coils arranged in planar or helicoidal spires does not necessitate any important modification of the basic lophophore arrangement, like the migration of the generative zones away from the median plane so as to coincide with the epithelial tips of the calcareous spires. On the contrary, there is sound evidence to suggest that such a migration did not occur. The jugum of athyraceids is prolonged posteriorly as a calcareous process. This jugal stem bifurcates in a number of stocks, e.g. Athyris, to form a pair of arcs (the accessory lamellae) lateral to the first coils of the deiiterolophe, and, in certain unrelated athyra- ceids like the Devonian Kayseria and the Triassic DipIospireUa, the accessory lamellae continued to grow into a pair of spires coextensive with those of the deuterolophe (Wil- liams 1956, p. 270, fig. 5 (9)). If the generative zones moved away from the jugum at all, it is much more likely that they did so posteriorly along the jugal stem and then laterally in association with the accessory spires, and it is these spires which must be homologized with the rhynchonelloid spirolophe, not those giving support to the deuterolophe, which is really equivalent to the side arms of the terebratuloid. The earliest spirebearer, Protozyga, has thus provided some interesting information on the growth of the loop, which is supplementary to that given by Beecher and Clarke (1889) in their classical study of the development of the deuterolophous spires of Zygo- spira subsequent to the formation of the loop. Only a few other growth series have been described, but it is probable that the loop is basic to the growth of all calcareous spires, and its origin may be better understood by comparing the Ordovician spiriferoids with their other articulate contemporaries. It is known that those early spiriferoids were not alone in possessing crura, because Ordovician rhynchonelloids, syntrophiaceids, and some orthoids were equipped with similarly proportioned outgrowths from the hinge- line, which presumably also give support to the posterior part of the lophophore. Development of descending branches, however, was unique to the spiriferoids, and their appearance in very young growth stages of P. elongata emphasizes the coenogenetic nature of the loop. WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 161 This was effectively combined with another important attribute. Sexual maturity is attained quite early on in the life history of living brachiopods. Morse (1873, p. 36) found eggs in individuals of Terebratulim septentrionalis no more than 5 mm. long, which is about one-quarter the size of mature adults, although even at that size the lophophore is likely to be an early plectolophe. Atkins (1958, p. 567) reports sexual TEXT-FIG. 6. Frequency distributions of the longest pedicle valves recorded in the type descriptions of forty-six Ordovician spiriferoid species and 1,113 other contemporary species of articulate brachiopods. In the smaller graph: frequency distributions of the length of the loops (measured from the dorsal umbones to the posterior edges of the transverse bands and juga) relative to the length of the brachial valves of twenty-five terebratuloid and forty-five spiriferoid Silurian and Devonian genera. maturity in specimens of Pumilus aniiquoliis which were slightly more than one-third the size of adults, when the lophophore was in the early schizolophous stage of develop- ment. The sexual precocity of P. anliquatus relative to the lophophore is all the more noticeable, because senile specimens are not more than 5 mm. long, and this size dis- crepancy between, for example, Pumilus and Terebratulina, is also seen when early spiriferoids are compared with other brachiopods of the same age. Text-fig. 6 shows the frequency distribution of the lengths of adult shells (derived from measurements of type specimens) of forty-six Ordovician species, distributed among nine spiriferoid genera, and 1,113 other species, belonging to 185 contemporary non- spiriferoid articulate genera. Both distributions are similar in being positively skewed, so that only a minority of stocks attain a relatively large size, but the modal length of adult 162 PALAEONTOLOGY, VOLUME 4 spiriferoids at 4-5 mm. is less than one-half the modal length of the remainder. The dis- crepancy is even more striking in the earliest known spiriferoid stocks like P. elongata^ adults of which rarely exceed 3 mm., and if sexual maturity occurred at the same relative stage of growth in that species as it does in living brachiopods, then individuals of P. elongata were functional adults about the time when fusion of the descending branches occurred. Protozygci then could well have been derived neotenously from some existing group, preferably impunctate and rostrate in the manner of contemporary rhynchonel- loids. Moreover, the endowment of a new coenogenetic character like the loop with an unspecialized juvenile anatomy, including a trocholophous lophophore, meant that the prospects for full exploitation of this novelty during subsequent radiation were quite good. The origin of the terebratuloids can only be seriously considered in the light of what has already been stated. The oldest representatives of this suborder are the centronel- laceids, Podella, MiitationeUa, and Brachyzyga (Kozlowski 1929, pp. 232-45) from the Upper Silurian of Poland. The development of the loops characteristic of these three genera is unknown, and, of all other centronellaceids, only the young stages of the Devonian Cranaena (Stehli 1956, p. 191) and the Permo-Carboniferous Dielasma (Beecher 1897, p. 1 10) have been described. It is, however, generally and safely assumed that all adult centronellaceid loops were derived, by processes of resorption and differen- tial growth, from a simple lanceolate apparatus, known as the centronelliform loop, which is common to the early stages of both Cranaena and Dielasma, and which per- sisted, with little or no modification, as the adult loop in a number of Devonian stocks. The centronelliform loop is identical with the one found in young Zygospira shells (Beecher 1897, p. Ill) and is strictly homologous with the Protozyga one. It must, therefore, have given support to a trocholophe or an early schizolophe, with the genera- tive zones disposed contiguously about a median lamella whenever that structure developed. Subsequent growth is not difficult to envisage. In adult Rensselandia, Centro- nella, and the majority of MutafioneUa, &c., the fundamental pattern was retained, simply by resorption along the inner margin of the loop and secretion along the outer edge, so that a greatly enlarged trocholophe probably served as the feeding organ of adult shells. A more important and successful modification included resorption of the antero-median part of the loop and the refashioning of the corroded connexion into a transverse, posteriorly curved band making acute angles with the descending branches. Without further modification, except enlargement, this structure constitutes the short loop of Cranaena and Dielasma, and is also anticipated in a minority of adult Mutation- el la (Kozlowski 1929, p. 241). It is also like the terebratulaceid loop and, although the connecting band in this case results from the convergence of the descending branches and not from the modification of a pre-existing centronelliform loop, the independent expansion of the lophophore from a pair of median generative zones in Cranaena and Dielasma could well have given rise to a pair of fleshy appendages hanging free from the antero-lateral corners of the loops, in the manner of the terebratulaceid side arms. A recognizable plectolophe must certainly have existed in Cryptonella (Cloud 1942, pi. 22, figs. 16-20), because in this stock differential antero-lateral growth of the centro- nelliform loop resulted in the development of an apparatus duplicating the arrange- ment of the terebratellaceid long loop. It must also have been present in Cimcinella (Schmidt 1946), the loop of which is essentially like that of Cryptonella, except that the descending and ascending branches are ankylosed to form a pair of ribbons extending WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 163 anteriorly from the junctions of the transverse band with the descending branches. Cinicinel/a is remarkable because its lophophore support is morphologically com- parable with the late growth stages of Protozyga and early post-centronelliform stages of Zygospira, where the calcareous ribbons, which gave support to the deuterolophe, had not quite completed half coils of the first pair of spires. The transverse connecting bands of these early terebratuloids clearly arose in exactly the same way as the jugum of the spiriferoids, and there can be little doubt that those portions of the terebratuloid and spiriferoid apparatuses, lying posteriorly to the band and the jugum respectively, are identical in origin, and presumably give support to similarly disposed lophophores. Even in adult shells the ‘loops’ thus defined by the transverse bands and juga are closely comparable in proportions. Text-fig. 6 shows the length of these loops, measured from the dorsal umbo to the inner edges of the transverse bands and the juga, relative to the lengths of the brachial valves of twenty-five terebratu- loid and forty-five spiriferoid genera of Silurian and Devonian age. In both suborders it is seen that the modal length of the loops was about two-fifths that of the brachial valve. The terebratuloid loop, then, was most feasibly derived from the spiriferoid brachidial skeleton simply by a suppression of the growth of the calcareous spires. Furthermore, since the development of the spires was preceded by the secretion of a loop, it may be assumed that the earliest terebratuloids were small, generalized shells of pre-Ludlow age, distinguishable from the juveniles of contemporary, punctate spiriferoids, from which group they were probably neotenously derived, mainly in physiological differences responsible for the early sexual maturity of the former. Two Devonian loop-bearing genera which do not fit into the scheme of derivation out- lined above are Enantiosphen Whidborne and Tropicloleptus Hall. A number of studies have been made of these two stocks, notably by Holzapfel (1912), Leidhold (1928), and Torley (1934) who concluded, with varying degrees of conviction, that Enantiosphen is a pentameraceid, and by Hall and Clarke (1893) and Schuchert and Cooper (1932) who respectively assigned Tropicioleptiis to the TerebrateUacea and the DahnaneUacea. The descriptions given by these authors were based on dissected specimens and, although the preparations were adequate enough to reveal the general morphology of the loops, no satisfactory illustration of the interiors and no detailed account of the shell structure have yet been given. To remedy this deficiency, a few specimens of both genera were serially sectioned, to obtain cellulose impressions of shell surfaces which had been differentially etched to reveal the details of shell growth. In addition, large-scale models of the shells were reconstructed by fusing together, with a hot needle, successive layers of ‘tenastyle’ wax, each of which had been first cut into an outline coincident with that on an enlarged photograph of the impressions on each cellulose peel. Enantiosphen is an impunctate, rostrate stock with a smooth, or faintly and sporadi- cally costate, exterior and unusually disposed valves. The transversely oval outline, and gently and subequally biconvex profile of some species (like E. tor ley i Holzapfel) are fairly orthodox, but postero-medianly, the edges of the valves are sharply deflected in- wards to define a pair of false ‘interareas’, each lanceolate in outline and situated on either side of the umbones. In E. vicaryi (Davidson) this deflexion affects the entire shell, so that wide margins of both valves are sharply geniculated towards the commissural plane to give the shell a trigonal, wedge-like aspect in profile and outline, and this, as will be seen, is accompanied by a similar ventral deflexion of the loop. 164 PALAEONTOLOGY, VOLUME 4 The morphology of the pedicle valve is typically pentameraceid (text-fig. 7c). The in- curved umbo contains a narrowly triangular delthyrium, partly receiving the ventrally projected dorsal umbo, and covered posteriorly by a slightly convex deltidium. The delti- dium is seen in section (text-fig. 8<7) to be buttressed by secondary shell substances, which must have been secreted by outer epithelial extensions encroaching ventro-anteriorly on to the inner spondylial surface, and, since these extensions could only have existed ventral of the pediculate-outer epithelial junction (Williams 1956, p. 257), the pedicle itself must have atrophied in adult shells at least. The spondylium (text-fig. Sb, c) is TEXT-FIG. 7. The internal morphology of the brachial valve, in ventral (a) and lateral (h) views, and of the pedicle valve, in antero-dorsal view (c), of Enantiosphen vicaryi (Davidson) : together with a stylized reconstruction of the lophophore {d). of a kind which is usually referred to as ‘duplex’, in the sense that the supporting septum is made up of secondary fibrous calcite, incompletely divided into two partitions by a thin median prismatic layer. Prismatic calcite also occurs on and within the spondy- lium itself, and again along the outer edges of the teeth, largely supported by the spondy- lial walls, as a series of wedges and lenses (text-fig. 8c). These are seen to pass laterally into fibrous calcite and, since the definition of each fibre was originally due to its being con- tained within a cytoplasmic sheath-like extension of an outer epithelial cell, it must be concluded that the prismatic patches were extra-cellular secretions by the outer epithe- lium (Williams 1956, p. 250). The primary outer shell layer is also secreted in a similar way, and St. Joseph (1938, p. 244) believed that the median prismatic layer, which is com- monly found embedded in the fibrous calcite of the spondylial septum of pentameroids as well as Enantiosphen, was deposited by the mantle edge. This is impossible, because it implies that the septum originated at the antero-median edge of the pedicle valve, where- as it arises well within the valve margin. Also, the presence of prismatic calcite in the median plane of the septum is not in our view indicative of any difference in the origin I of the septal support to the spondylium duplex as compared with that of the spondylium i WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 165 simplex, which is purported to consist of fibrous calcite alone. The terebratuloid Amphi- genia Hall is also equipped with a spondylium, but this structure is quite unlike the penta- meroid ones, for it is buttressed by a pair of mystrochial plates, and has been shown (Boucot 1959, p. 737) to have developed from discrete dental lamellae as in Rensselaeria Hall. The cardinalia of the brachial valve of Enantiosphen are also pentameraceid in arrange- ment (text-fig. la, b). The rod-like crura, which extend anteriorly for about one-half the TEXT-FIG. 8. Three sections showing the structure of the spondylium in the pedicle valve of Enantio- sphen vicaryi (Davidson) length of the valve, can be traced from the umbo. In this region they are deeply embedded in thick deposits of secondary, fibrous and prismatic calcite, which make up the massive posterior part of the cruralium, but anteriorly their relationship with other elements of the cardinalia are easily seen (text-fig. 9a-e). It is evident that they are intimately asso- ciated with the slightly convergent blade-like inner plates, which are continuous ventro- laterally with the socket ridges, and which form the lateral walls of the cruralium. The essential unity of the inner plates and crura is illustrated by the manner in which they both become discrete from the outer plates at about one-third the length of the valve anterior of the umbo (text-fig. 9d, e). The outer plates, which are really a pair of ridges diverging from a stout septum, form the basal part of the cruralium. They retain their identity for a short distance anterior of their separation from the crura and the more ventrally placed inner plates, but ultimately they, and then the median septum, are no longer found (text-fig. 9/, g). Just anterior to the tips of the crura, the posterior ends of the loop are found at some B 9423 M 166 PALAEONTOLOGY, VOLUME 4 distance dorsal of the extrapolated positions of the crura. The actual connexions be- tween the loop and the crural tips have not been identified, but the gap between the tips and the first traces of the loop is not more than a millimetre or so thick, and it seems safe to assume that the connexions actually swept dorsally away from the crural points, more or less in the same plane as the sectioning in the style illustrated by Leidhold (1928, pi. 5, fig. 3). The brachidial apparatus is unique, for it consists essentially of two broad f g TEXT-FIG. 9. Seven sections showing the structure of the cardinalia and the cruralium and its support- ing median septum in the brachial valve of Eimntiosphen vicaryi (Davidson). plates, composed of fibrous calcite and essentially suboval in outline, but curving along the lateral edges towards the ventral valve and crenulated in transverse section by a series of ridges running more or less concentric with the lateral edges of the blades. Posteriorly, the blades narrow rapidly to form ribbon-like connexions with the crural points. Ante- riorly, they taper more gradually into blunt ends which are either in the same plane, as the rest of the blades, for example, in the gently biconvex E. torleyi (Torley 1934, p. 97, fig. 28), or deflected sharply towards the pedicle valve, as in the bigeniculate E. vicaryi. The two blades are united by a variably developed transverse plate which rises to a sharp ridge ventro-medianly. The transverse plate is also composed of fibrous calcite and appears to be continuous with the lateral blades, but its position relative to them seems to vary considerably, so that in some specimens it connects the postero-median edges of the lateral blades while in others it may occur between the anterior ends. Leidhold (1928, p. 58) maintained that the apparatus was supported by the anterior part of the dorsal median septum. This is not so in the specimen sectioned by us, and Torley makes i WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 167 no mention of such an arrangement in the shells he examined, which suggests that those described by Leidhold had been imperfectly prepared, and indeed, in one specimen figured by him (pi. 5, fig. 2), the arrangement he suggests would have been impossible. The lack of young specimens precludes any precise assessment of the role of the Enantiosphen apparatus in its support of the lophophore, but a number of adult features give some guide to possible relationships. The blades, consisting as they do of fibrous calcite, were secreted by a bilobate envelope of outer epithelium continuous with those extensions from the floor of the brachial valve which ensheath the crura. The ridges, which are roughly aligned with the lateral edges of the blades, probably represent pauses in an erratic antero-lateral expansion of an outer epithelial cover to what was initially a subcircular ribbon of calcite suspended from immature crura. Resorption must have taken place along the postero-median edges of the epithelial envelope to adjust the con- nexions of the apparatus to the divergent forward growth of the crura. But it was so much slower than the secretion along the antero-lateral margins that a pair of blades developed in adult stages of growth. Variation in the rates of resorption and secretion was probably also responsible for the range in width and position of the transverse band from one in- dividual to another. Neither the blades nor the transverse bands thicken consistently in a postero-median direction, which suggests that only the outer edge of the epithelial cover was engaged in the secretion of fibrous calcite in a manner similar to the growth of the campagiform loop of certain terebratellaceids (for example Fallax daUinifonnis Atkins 1960). In these circumstances it is reasonable to assume that the lophophore was inti- mately associated with the secretory zone of the outer epithelium and accordingly was essentially schizolophous in disposition (text-fig. Id). It is not possible to decide whether the median generative zones existed free of the crest along the transverse plate as a pair of spires coiled in a plane normal to the commissure. The proximity of the plate to the floor of the valve, together with its variable position, suggests that if coiling had taken place it must have been towards the ventral valve. In summary, it may be said that Enantiosphen is undoubtedly a pentameraceid brachiopod which is unique in that adult shells were equipped with a bilobate brachidial apparatus. The apparatus probably developed by differential growth and resorption from a simple subcircular loop, presumably surrounding a juvenile trocholophe, and is most reasonably interpreted as having supported a schizolophous-hke lophophore. The structure is not closely comparable with the loops of contemporary centronellaceids, except, of course, that its development likewise imposed certain restrictions on the atti- tude to be adopted by the adult lophophore. Accordingly, the inferred disposition of the lophophore was not necessarily typical of other pentameraceids, the crura of which were more likely to have supported spirolophes like those found in recent rhynchonelloids. Tropidoleptiis carinatus (Conrad) is a costate brachiopod, subquadrate in outline with a concave and medianly sulcate brachial valve, and a convex pedicle valve which is narrowly folded medianly. In other external features, notably the wide hinge-line and the well-developed, orthocline, ventral interarea and the shorter, anacline, dorsal one, and also in the coarsely endopunctate structure of the shell, the genus is undoubtedly a dalmanellaceid. The interior of the pedicle valve is also organized in a dalmanellaceid manner (text- fig. 10/). The delthyrium is not restricted by anydeltidial outgrowth, and, during the life of the animal, was filled by the cardinal process so completely that no functional pedicle 168 PALAEONTOLOGY, VOLUME 4 could have existed in adult shells at least. The teeth are massive, elongated and ridge- like, and exhibit the extremely rare disposition of being completely separated from the hinge-line by a pair of deep, oblique grooves which accommodate the outer walls to the dorsal sockets. They lie in the same plane as, and are supported by, a pair of widely divergent dental lamellae which extend beyond the umbonal cavity only as subdued TEXT-FIG. 10. The internal morphology of the brachial valve, in posterior (a), ventral (h), and lateral (c) .j views, and of the pedicle valve, in antero-dorsal view (/), of Tropidoleptus cariuatus (Conrad) ; together II with stylized reconstructions of the lophophore in ventral (d) and lateral (e) views. traces. The inner surfaces of both the teeth and lamellae are smooth and fit snugly against the undercut lateral edges of the dorsal notothyrial platform (the inner socket walls), whereas the outer postero-lateral surfaces of the teeth are obliquely striated by five or six ridges and grooves which articulate with a complementary set developed on the outer socket walls (text-fig. \\d). A low median ridge, posteriorly indented down the middle, extends along the floor of the pedicle valve for about one-third its length and divides a wide, poorly differentiated muscle scar. The dorsal interior is unique in a number of features (text-fig. \0a-c). The cardinal process stands high above the hinge-line. It consists essentially of a rod of secondary fibrous calcite tapering slightly posteriorly and flattened along its ventral surface where there occurs a pair of deep hollows, elongated with the long axis of the process, and separated from each other by a postero-median ridge (text-fig. llu). The anterior ends WILLIAMS AND WRIGHT; ARTICULATE BRACHIOPODS 169 of the hollows are inserted into the shaft of the process as a pair of short pits directed antero-ventrally, and they must have acted as seats of attachment for the dorsal diductor muscles (text-fig. 11c). The cardinal process is continuous with a well-developed noto- thyrial platform, which passes anteriorly into a low median ridge, and flares laterally to form the inner walls of elongate sockets disposed obliquely to the hinge-line. The striated outer walls of the sockets also stand above the hinge-line medianly, where they are ankylosed to the dorsal surface of the cardinal process to form a gently arched structure, which is rutted by growth-lines and is seen externally more or less occupying TEXT-FIG. 11. Ten sections through the shell of Tropidoleptus cariuatiis (Conrad) to show especially the structure of the cardinalia and the brachidial apparatus of the brachial valve. the delthyrial opening. This structure has previously been referred to as the chihdium, but it is not homologous with that feature as developed in the strophomenoids, because it could only have been deposited by the pediculate-outer epithelial junction; it is thus equivalent to the antigydium, which is also found in other orthoids like Hesperorthis (Williams 1956, p. 258). The notothyrial platform gives support to a pair of subparallel crura, lanceolate in transverse section, with the sharper edges directed ventrally. In adult shells the crura arise slightly antero-medianly of the outer socket walls, but they retain their individuality within the heavy accretion of the notothyrial platform, and can be traced back to the hinge-line, where they become continuous with a pair of slender nodes representing the socket plates of young shells (text-fig. \ld-f). In all three specimens sectioned by us, the crura extend anteriorly for about one-quarter the length of the brachial valve, and then give rise to a pair of short, slightly divergent apophyses (text-fig. llg). Meanwhile, the low ridge on the floor of the valve passes anteriorly into a high median septum, consist- ing of a middle plate of prismatic calcite coated by a thin layer of fibrous calcite (text- 170 PALAEONTOLOGY, VOLUME 4 fig. \\h-j). The septum extends anteriorly for about two-thirds the length of the valve. Posteriorly, it has been appreciably undercut by epithelial resorption to form a posteriorly directed ‘median prong’, which supports a pair of slender outgrowths. These are plate- like in transverse section, with the long axes normal to the plane of the median septum. Hall and Clarke (1894, p. 305) described specimens in which the apophyses from the crura are continuous with the septal outgrowths, and they concluded that this mode of growth revealed the terebratellaceid affinities of the genus. Such a fusion is not found in the three adult specimens on which this description is based. None the less the arrange- ment, whether or not it led to the completion of the loop, is remarkable in that the resultant structure is demonstrably composed of two distinct elements in the terebratel- laceid fashion. The development of the dorsal septum now becomes a crucial matter. Its basic structure, the medianly disposed plate of prismatic calcite, can be traced posteriorly along the floor of adult valves, buried beneath the median ridge and the notothyrial platform, to within 1 mm. of the hinge-line, where it stands about 0-5 mm. above the external surface of the brachial valve. The average depth of the pedicle valve is about one-quarter its length, and, when allowance is made for the height of the septum relative to the convexity of the shell, it is evident that, even in specimens a few milli- metres long, the septum must have stood as high above the dorsal floor as it does in adults, where it almost divides the brachial cavity into two. In this event, the septum would certainly have intervened between the generative tips of an early schizolophe in the same way as it does in recent terebratellaceids. The development of a septum among orthoids is not uncommon; it is known, for example, in Skenidioides, Phragmorthis, Mystrophora, Phragmophora, &c. But there are two fundamental differences. First, the shells of the four genera just named are very much deeper, and the crural counterparts are directed ventrally rather than anteriorly as in Tropidoleptus, so that their lophophore disks may well have been suspended ventro- posteriorly of the septa, and thus may have developed without complications into spiro- lophes. Secondly, and more importantly, the growth of apophyses anteriorly from the crura must have prevented any lateral migration of the first formed coil of the lopho- phore, other than the kind of adjustment which would have normally accompanied the growth and resorption of the calcareous supports. Consequently, it seems reasonable to assume that the apophyses and the posteriorly directed outgrowths from the median septum, which arose in the same way as the descending branches of the terebratellaceids, supported the first formed part of the lophophore, and that this was accordingly dis- posed as an oval broken anteriorly by the septum. In adult shells, however, which attained a width of over 30 mm., proliferation of the lophophore from the paired generative tips almost certainly exceeded the length accommodated by the oval formed of the crural apophyses and the septal outgrowths. Yet the only possible skeletal equiva- lent to the ascending branches (invariably developed in the terebratellaceids in contrast to the descending ones) is the posterior part of the median prong. The height of the prong above the floor of the brachial valve, together with the shallowness but relatively great width of the shell, suggests that the later formed portions of the Tropidoleptus lophophore were arranged in an entirely different way from those of the terebratellaceids. In the initial stages of lophophore development, the generative tips would have been contiguous with the prong and ventral of the outgrowths. But further growth would WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 171 necessarily have resulted in a migration of these coiled ends of the lophophore away from the prong, and the proximity of the pedicle valve would have ensured growth towards the lateral areas (text- fig. \f)d, e). In retrospect, it seems best, despite the unusualness of the dorsal interior, to accept Tropidoleptus as a dalmanellaceid. In respect of the dual origin of the loop, the stock anticipates the development of the descending branches in the brachidial apparatus of the later, unrelated, terebratellaceids, but the disposition of the lophophore in adult Tropidoleptus is most likely to have consisted of an oval-shaped, primary coil, supported by extensions from the crura and the median septum, and a pair of unsupported planar or low helicoidal spires, separated from each other by the high dorsal septum, and lying more or less in the plane of the commissure. REFERENCES ATKINS, D. 1958. 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The Invertebrates: smaller Coelomate Groups, 5, 1-783. New York; McGraw-Hill. KOZLOWSKi, R. 1929. Les Brachiopodes gothlandiens de la Podolie polonaise. Palaeont. polon. 1, 1-254, pi. 1-12. LEiDHOLD, c. 1928. Bcitrag zur Kenntnis der Fauna des rheinischen Stringocephalenkalkes, insbeson- dere seiner Brachiopodenfauna. Abh. Preiissischen Geol. Landesanstalt. 109, 1, 58-60, pi. 4-5. MORSE, E. s. 1871. Embryology of Terebratiilina. Mem. Boston Soc. Nat. Hist. 2, 249-64, pi. 8-9. 1873. On the early stages of Terebratiilina septentrionalis (Couthouy). Ibid. 2, 29-39, pi. 1-2. MUIR-WOOD, H. M. 1959. Report on the Brachiopoda of the John Murray Expedition. Brit. Mus. {Nat. Hist.), 10, 6, 283-317, pi. 1-5. 172 PALAEONTOLOGY, VOLUME 4 PERCiVAL, E. 1944. A contribution to the life-history of the brachiopod, TerebrateUa incouspiciia Sowerby. Trans. Roy. Soc. N.Z. 74, 1-23. ST. JOSEPH, j. K. s. 1938. The Pentameracea of the Oslo Region. Norsk, geologisk. Tidsskrift. 17, 225- 335, pi. 1-8. SCHMIDT, H. 1946. Die Terebratulidae des Wetteldorfer Richtschnittes. Senckenbergiana, 27, 67-75. SCHUCHERT, c. and COOPER, G. A. 1932. Brachiopod genera of the suborders Orthoidea and Penta- meroidea. Mem. Peabody Mas. Nat. Hist. 4, 1-270, pi. 1-29. STEHLi, F. G. 1956. Evolution of the loop and lophophore in terebratuloid brachiopods. Evolution, 10, 2, 187-200. TORLEY, K. 1934. Die Brachiopoden des Massenkalkes der oberen Givet-Stufe von Bilveringsen bei Iserlohn. Abh. Senckenbergischen natiirf. Ges. 43, 3, 69-148, pi. 1-9. WILLIAMS, A. 1956. The calcareous shell of the Brachiopoda and its importance to their classification. Biol. Rev. 31, 243-87. YATSU, N. 1902. On the development of Lingula anatina. J. Coll. Sci. Tokyo, 17, 4, 1-1 12, pi. 1-8. ALWYN WILLIAMS and A. D. WRIGHT Department of Geology, The Queen’s University, Manuscript received 20 April 1960 Belfast. ADDENDUM Filter feeding in spire-bearing brachiopods. Since the submission of this paper, Dr. M. J. S. Rudwick (1960n) has published an interpretation of the feeding mechanism in spire- 1 1 bearing brachiopods, which involves a refutation of the opinion expressed here to the - 1 effect that calcareous spires were equipped with a doubled lophophore, the deuterolophe. ' i Put very briefly, Rudwick is concerned with the efficiency of the brachiopod filter feeding ' system in separating filtered, exhalant water from unfiltered, inhalant currents, with the . filaments, through which water passes from the frontal surfaces — those facing the lip — to the abfrontal ones, acting in concert like a straining valve (text-fig. 12). The flow of water in an abfrontal direction is normally irreversible except in Argyrolheca (Atkins 1960), which anomaly only effects Rudwick’s conclusions in so far as the atrypid and j spiriferid current systems may have been interchangeable. Using an irreversible model, „ Rudwick finds that efficient filter systems can be reconstructed for the spire-bearing i, brachiopods by assuming that the skeleton bore a single series of filaments, which could " only have come about if the generative tips of the lophophore migrated away from their : median juxtaposition in the trocholophous stage of development, and were, during sub- jj sequent growth, coincident with the ends of the epithelial sheaths to the primary spires, f This assumption leaves open the function of the jugum and its elaboration into spinose ■ platforms, stems, and coextensive whorls (except possibly as subsidiary supports to the s lophophore occupying the primary spires). Rudwick cites the facts that the lophophore || and the internal skeleton grow independently of each other and are differently disposed i! in Recent terebratuloids, to support his behef that the jugum was not important to the attitude of the lophophore. But terebratuloids are not good examples to quote, because, ^ when a median septum and/or a transverse band develop, they do in fact support the generative zones of the lophophore, which may coil in the median plane but never mi- ^ grate laterally in the manner described by him. Rudwick has also stated that the best interpretation is one which explains the greatest number of facts (1960/6, p. 518). Without being prejudicial to his conclusions, there is WILLIAMS AND WRIGHT: ARTICULATE BRACHIOPODS 173 but one fact relevant to this discussion, and that is the existence and persistence of a jugum. Certainly, judging from Recent brachiopods, it is highly likely that the spire- bearers fed by filter systems, which must have worked competently enough to ensure group survival for over 300 million years, although they need not have been as efficient as Rudwick would wish. Further observations of his, like the ‘moulding’ of the spiralia to the ‘form of the mantle cavity’ (p. 380), and the ‘anterior flaring’ of the brachidium to accommodate a ‘median exhalant current’ (p. 380), are either generalizations or hypotheses and could be used with equal conviction in other reconstructions. In effect, his rejection of the deuterolophe does not spring from a demonstration that its jugal TEXT-FIG. 12. Transverse sections through the spirolophe of Tegiilorliynchia (a) and the side arm of Terebratulina (b) and the inferred deuterolophe of spiriferoids (c), (d), with accessory calcareous spires {e) : — f. hlament, 1 — brachial lip, m — direction of movement of food particles, o — outer epithelium, s — supporting calcareous ribbon, u — unfiltered, inhalant current, c — filtered, exhalant current. connexions could not have supported the generative parts of the lophophore, but from an opinion that it could not have functioned as a filter system. In an exchange of letters about the article, the homology between the plectolophe and the deuterolophe was taken so literally as to envisage each spirally coiled, doubled lopho- phore acting as a ‘filter tube’ (comparable with that formed by the contiguous generative zones of the terebratuloids) which was fed by unfiltered water entering ventro-medianly, and separated from the filtered water, within and outside the cones, by the lateral fila- ments of the jugum restiug on the ventral walls of the first coils and by the shorter median filaments deflected antero-ventrally (Williams, p. 516). The system was admittedly ‘cum- bersome’ (p. 516), and Rudwick considered it to be hydrodynamically weak (p. 517). At the same time, it was suggested that, if a median exhalant current operated in the spiriferids in the style favoured by Rudwick, only filtered water would have been supplied to the mouth section of the lophophore subtended between the crura. Rudwick coun- tered with the opinion that the filaments would have arched over the lip of this segment to touch the dorsal surface of the inner epithelium, and described the structure as the reverse of the arrangement around the mouth of living rhynchonellids. This is still diffi- cult to visualize, because the rhynchonellid exhalant canal is dorsal of a series of posteriorly deflected filaments belonging to both the mouth segment and the posterior part of the basal coils, which are in the same plane. In Rudwick’s spiriferid pattern. 174 PALAEONTOLOGY, VOLUME 4 however, filaments of the posterior part of the basal coils would have been deflected posteriorly to receive an inhalant current, while those of the mouth segment would have incurved anteriorly, and in this attitude could only have presented a pair of cir- cular openings to the lateral inhalant streams when the filaments of the posterior part of the second coils were deflected medianly, so that several of them touched the most lateral filaments at either end of the mouth segment. The canalization of the exhalant current in the mouth segment of rhynchonellids does, however, provide an important model for possible attitudes adopted by a deuterolophe, and, in conjunction with modifications in the performance of the ‘filter tube’, may be used to demonstrate efficient filter systems of feeding by any type of deuterolophe. Thus, posteriorly deflected filaments of the mouth segment and antero-dorsally deflected fila- ments of the generative ends of the lophophore situated on the jugum would have touched either the inner epithelium bounding the mantle cavity or connective membranes, known to drape the loop of modern terebratuloids and feasibly inferred to have existed about the jugum of the spire-bearers. In this manner, two streams of filtered water, flowing dorso-laterally, would have been effectively separated from a median, inhalant current. Add to this segregation the possibility of inducing currents to pass from within a cone or from outside it simply by the reversal of oppositely directed filaments on the deuterolophe — text-fig. 12, (c), {d) — and the basic pattern of current systems could have been the same in all spiriferoid brachiopods irrespective of the attitude of the spires. Rudwick effectively used the presence of spinose outgrowths to determine the position of the lophophore on the calcareous, spiral ribbons, but this procedure is not necessary if the attitudes of the spires are considered relative to the axis of the mouth segment lying between the ends of the crura, where the lip must face ventrally. By this means, all pos- sible attitudes taken up by the lophophore of spire-bearers may be referred to one of five fundamental positions which have been illustrated in text-fig. 13. In the atrypid type, with dorsal directed spires, it is assumed that the inhalant current entered ventro- medianly and passed into the cones while the exhalant canals from the mouth region and the jugum fed dorso-laterally into the exhalant chamber containing the cones. In the spiriferid type a median, inhalant current diverged to pass laterally into the cones, and the exhalant canals from the mouth segment and the jugum entered the separated, exhalant chambers peripheral to the cones. In the protozygid type the piano-spiral deuterolophe effectively sealed off a median, inhalant chamber from a pair of lateral, exhalant ones, each of which was joined dorso-laterally by the exhalant canals of the mouth segment and jugum. The zygospirid arrangement is essentially the same as the protozygid one except that the apices of the cones are directed inwardly, and the median inhalant cur- rent became filtered during the passage of water into the cones. Finally, for the cyrtinid type with ventrally directed cones, it is assumed that a median inhalant current passed into the cones through a gape, which was created by the inner series of filaments on the anterior part of the basal coils curhng outwards to touch the antero-median part of the ventral commissure. The inner filaments of the posterior arcs of the basal coils would then have been outwardly deflected to rest on the dorsal inner epithehum and, together with the exhalant canals of the mouth segment and jugum, would have ejected filtered water postero-laterally; while those along the median parts of the basal coils would have been deflected towards the ventral median septum to form an arch, which would have separated the exhalant chambers containing the cones from the median incoming stream. around the mouth segment (right-hand drawings) in five different attitudes of the spiriferoid deutero- lophe: a — stylized mouth segment for orientation of the feeding apparatus, c — calcareous ribbon of spiralia, g — generative zone, i — inner epithelium, 1 — brachial lip, m — mouth, s — shell, e — exhalant current, f — filtered water, u — unfiltered, inhalant water. 176 PALAEONTOLOGY, VOLUME 4 Escape from the exhalant chambers formed in this way would also have oceurred postero-laterally. All these systems are, hydrodynamically, at least as efficient as any described by Rud- wick, and, with two series of filaments on each coil setting up a current flow in the same direction, they could have acted as more powerful pumps. Moreover, novel reorientations of the spires would not require a concomitant change in the direction of the inhalant current, which, according to the interpretation given here, was always a median one, as it most probably was in the young stage of all spire-bearers. Indeed, it might well be argued that the variety of attitudes assumed by the spires in this group of brachiopods was functionally possible because the calcareous ribbons bore, not a simple spirolophe, but a deuterolophe, which, irrespective of its disposition, effectively filtered an invariably : median, inhalant current. In this respect, it may be significant that in all but the zygo- spirid system, unfiltered water passed into conical or planar filamentous screens and that the exceptional stocks, in which filtered water occupied the cones, were short-lived, un- important members of the group. Rudwick (pp. 377, 517) has remarked adversely on the wealth of filaments and the crowding of filter tubes in a deuterolophe, but these can- ' not be more than minor objections. Reference has been made, in the main article, to the decrease in the number of filaments per unit length of the terebratuloid side arms relative to their incidence near the generative zones, due to the proliferation of non-filamentous tissue. Spiralia, which are known to have been up to ten times as long as the side arms, can be expected to have borne two series of filaments so widely spaced that each set on one whorl would have alternated with sets on adjacent whorls. Nor can crowding be- tween the spiral ribbons be seriously considered as detrimental to the efficient operation of the deuterolophe. Each succeeding whorl must necessarily have a shorter perimeter than the one before, so that whorls of filter tubes mainly occurred within one another from base to apex: and from the example afforded by the Terebralulina side arm, where one common canal supported a doubled lip and two filament series — text-fig. 12 {b) — it can be safely inferred that the deuterolophous segments supported by the spires need only be slightly wider than the simple lophophore proposed by Rudwick. In fact, if the accessory spires of stocks like Diplospirella supported lophophorous segments which had diverged from the median zone of the jugum, room could even be found for them in the manner illustrated in text-fig. 12 {e). REFERENCES ATKINS, D. 1960. The cilary feeding mechanism of the Megathyridae (Brachiopoda), and the growth stages of the lophophore. J. Mar. Biol. Ass. U.K. 39, 459-79. RUDWICK, M. j. s. 1960n. The Feeding Mechanisms of Spire-bearing Fossil Brachiopods. Geol. Mag. 97 (5), 369-83. 19606. Correspondence. Ibid., 97 (6), 516-18. WILLIAMS, A. 1960. Correspondence. Ibid., 97 (6), 514-16. UPPER LLANDEILO BRACHIOPODS FROM THE BERWYN HILLS, NORTH WALES by A. R. MACGREGOR j Abstract. Twenty-one species are described and figured, including the following new species, Corineorlhis bicon- \ vexa, McEwanella berwyneitsis, Glyptorthis niinor, Atelelasnia anatolica, Horderleyella subcan'iuita, Oxoplecia nantensis, Parastrophinella parva, Parastrophinella costata, and Rafinesquina simplex. Macrocoelia llandeiloensis (Davidson) is redescribed from topotype material as Davidson's original material appears to be lost. ' The fauna described was collected from three small inliers of Llandeilo rocks in the Berwyn Dome, North Wales. The fauna is composed of two elements, an indigenous element whose ancestors are to be seen in older rocks in the Anglo-Welsh Province and an exotic element. Within the exotic element various species appear to be migrants from the Scotto-Appalachian Province, the Baltic Province, and the Bohemian Province. One [ species must at present be regarded as cryptogenetic. This paper is a systematic (description of the brachiopod fauna found in the three in- liers of Llandeilo rocks in the Berwyn Hills, together with a discussion of that fauna. The Llandeilo rocks, in which the fossils occur, are divided into three units on the basis of their lithology. At the base, resting on rocks of unknown age beneath, is a Calcareous Ash 200 feet thick, followed by sandy and muddy Limestones 150 to 350 feet thick and then Shales 400 to 1,000 feet thick and calcareous in all but the topmost 100 feet. Only the zone of MorroUthiis favus of the Upper Llandeilo has certainly been identified, but the lowest beds may extend down into the Middle Llandeilo. The placing of this fauna in the Upper Llandeilo is based, not so much on the brachio- pods themselves, as on the accompanying trilobite fauna and the stratigraphical relation- ships of the rocks in which the fossils were found. Both the trilobites and the rocks of the area will be described shortly in forthcoming papers. The material was collected by the writer during the course of a study of the Lower Palaeozoic rocks of the area and of the Llandeilo rocks in particular. The writer wishes to thank Professor Bulman and Professor W. B. R. King for their guidance throughout the work, and Dr. Stubblefield and Professor Williams for helpful discussions. The work was carried out during the tenure of a Carnegie Research Scholarship and the field expenses were met by grants from the Cross Trust, and for these the writer extends his grateful thanks. The writer is also grateful for permission to examine specimens in the Geological Survey Museum, the Sedgwick Museum, and the British Museum (Natural History). All the figured material has been presented to the Sedgwick Museum, Cambridge, except the specimens of Macrocoelia llandeiloensis from the Geological Survey Museum, London. The writer is also in- debted to the Carnegie Trust for the Scottish Universities for a grant towards the cost of the plates. The brachiopod fauna. This consists of Corineorlhis biconvexa sp. nov., McEwanella berwynensis sp. nov., Platystrophia cf. precedens major Whittington and Williams 1955, ?Skenidioides sp., ?CyrtonoteIIa sp., Glyptorthis minor sp. noy., Atelelasma anatolica sp. nov., ?Atelelasma sp., Dahnanella parva Williams 1949, D. cf. lepta (Bancroft) 1945, Paucicrura immatura (Williams) 1949, Horderleyella subcarinata sp. nov., Salopia cf. salteri (Davidson) 1871, Oxoplecia nantensis sp. nov., Parastrophinella parva sp. nov., P. costata sp. nov., Rostricellida triangularis Williams 1949, Sowerbyella antiqua Jones 1928, ?Dactylogonia sp., Rafinesquina. simplex sp. nov., Macrocoelia llandeiloensis (Davidson) 1871. {Palaeontology, Vol. 4, Part 2, 1961, pp. 177-209, pis. 19-23.] 178 PALAEONTOLOGY, VOLUME 4 Much of it is indigenous in the sense that the genera were already present in the Anglo-Welsh Province; the rest of it is exotic and various genera make their first appearance in the province at this time. Various species occurring in the Lower Llandeilo of Llandeilo reappear in the Upper Llandeilo of the Berwyns. Much of this can be explained on the basis of facies control, since the sediments of the Upper Llandeilo of the Berwyns resemble the sediments of the Lower Llandeilo of Llandeilo and not the sediments of the Upper Llandeilo of Llandeilo. This faeies control has led, up till now, to a false impression of the range of many of the Lower Llandeilo species of the type area, since many of these reappear in the Upper Llandeilo of the Berwyn Hills. The following can all be regarded as indigenous to the Anglo-Welsh Province: Corineorthis biconvexa, ? Skenidioides sp., Glyptorthis minor, Dalmanella parva, D. cf. lepta, Paudcnira immatwa, Horderleyella subcarinata, Oxoplecia nantensis, Rostricellida triangularis, Sowerbyella antiqua, Macrocoelia Ikmdeiloensis. Corineorthis is not at present known in rocks of other than Llandeilo age or outside England and Wales, with one possible exception in Brittany and there it may be regarded as an immigrant from the north. Skenidioides is known in a lower part of the Llandeilo of Llandeilo. Schuchert and Cooper (1932) were of the opinion that the Skenidiidae were deseended from the Fink- elnburgiidae, which is an essentially North American family apart from the occurrence of Orusia in the Baltic Province. These early representatives of Skenidioides may be looked upon as immigrants from North America or, just possibly, from the Baltic. They are contemporary with the first appearance of the genus in North America (Kay 1958). In the Anglo-Welsh Province the earliest specimens of Glyptorthis previously recorded have been from the Caradocian and have usually been attributed to G. crispa (M‘Coy) on the basis of the ornament which, however, is characteristic of the whole family. The Glyptorthidae first appear in the Marmor stage in North America, where they are very abundant ; they range on into the Silurian. The range is similar in Britain, an as yet un- described species having recently been obtained from the base of the Llandeilo in Pem- broke. G. minor from the Upper Llandeilo of the Berwyns may therefore be regarded as indigenous. Dalmanella parva and Paucicrura immatura persist from the Lower Llandeilo Dal- manellidae, although in the latter species some minor changes are noticeable. The Dalmanella cf. lepta is rare, but may be regarded as anticipatory of the great increase in genera and species within the Dalmanellidae in the succeeding Caradocian. Horderleyella appears in the Llanvirn at Llandeilo (Williams 1949) and H. subcarinata is a species intermediate in its features between the Llanvirn-Lower Llandeilo species of Llandeilo and the Caradocian species of the Welsh Borders. Oxoplecia nantensis may be a reappearance of the genus already seen in the Lower Llandeilo of Llandeilo where Cliftonia is recorded by Williams (1953). Rostricellida triangularis after being common in the Lower Llandeilo at Llandeilo is rare in the Upper Llandeilo of the Berwyns. The genus is known from contemporary and even earlier rocks in North America. Sowerbyella makes its appearance in the Upper Llanvirn of Llandeilo, appearing also in the contemporary Pogonip Limestone of Nevada and Mystic Conglomerate of Quebec (Whittington and Williams 1955). Recent work by Spjeldnaes (1957) shows that A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 179 the closely allied genus Alwynella appears in the Llanvirn of the Oslo district and Leptel- loidea and Chonetoidea in the Llandeilo rocks there. Chonetoidea also appears in the Middle Llandeilo of Bohemia (Havlicek 1950). The Sowerbyellidae must have spread with great rapidity into many provinces upon their appearance. At present they appear to be cryptogenetic, though Cooper (1956) thought that Pelonomia might be ancestral to the sowerbyellids. Macrocoelia llandedoensis occurs as early as the Upper Llanvirn at Llandeilo (Wil- liams 1953) and can be looked upon as indigenous therefore. This Llanvirn occurrence is contemporary with the first North American appearance of the genus. The remainder of the fauna is exotic in origin, but with two exceptions can be attributed to two sources — the Baltic Province and the Scotto-Appalachian Province of Whitting- ton and Williams (1955). In the absence in Scotland of fossiliferous shelly strata of this period and of the immediately preceding Lower Llandeilo, the latter is in effect the Appalachian Province. ?Dactylogonia sp., Paraslrophinella parva, and P. cost at a are from the Appalachian Province. ?DactyIogonia is the first appearance of the Leptaenidae in the Anglo-Welsh Province, although it is followed by the much commoner Leptaena in the Caradocian. Previously Dactylogonia was unknown outside eastern North America and Oklahoma. The Parastrophinidae seem to take their origin, according to St. Joseph (1941), in the Camerellidae, which Cooper (1956) says reach their zenith between the Whiterock and Wilderness stages. In the Camerellidae the cruralium duplex is normally seen, and only the rare Brevicamerellidae attain the sessile cruralium of the Parastrophinidae. Pre- viously the Parastrophinidae were unknown before the Caradocian of Britain and North America, and they remain uncommon until the Ashgillian and Llandovery. The occur- rence of two species of Parastroplunella, one of them in abundance, in the Anglo-Welsh Province in the Upper Llandeilo is all the more remarkable. The occurrence of these two genera in the Llandeilo and Macrocoelia in the Llanvirn, brings forward the first appearance of members of the Scotto-Appalachian fauna in the Anglo-Welsh Province. Whittington and Williams (1955) have pointed out that the Derfel Limestone contains little or nothing of the Scotto-Appalachian fauna ; it seems that the early immigrants of the Llandeilo did not persist for long. The remainder of the brachiopod fauna is, with the exception of Salopia and Rafines- qidna, probably of Baltic origin: McEwanella benvyneiisis, Platystrophia cf. precedens major, ?Cyrtonotella sp., Atelelasma anatolica, and ?Atelelasma sp. The Platystrophiinae consist of only two genera within the Plectorthidae, regarded by Schuchert and Cooper (1932) as derived from the Finkelnburgiidae. The genus Platys- trophia first appears in the Baltic Province, where it is recorded in the Uhaku Shales by Opik (1930). From there it spread westwards, reaching Britain in the Upper Llandeilo and North America by Porterfield times. P. precedens is an American species erected by McEwan (1919), but this material like that of Whittington and Williams is very much earlier. Only P. dentata (Pander) seems a possible ancestor to the Welsh variety, the other species from the Uhaku Shales P. biforata having too advanced ribbing. The allied genus McEwanella is problematic on account of its very patchy distribution and rarity. Only three species are known, M. berwynensis and two North American species from the Upper Ordovician. It is only on the Baltic origin of the Platystrophiinae that it is possible to suggest a Baltic origin for McEwanella. 180 PALAEONTOLOGY, VOLUME 4 AteJelasma anatolica is the first clitambonitid in the Anglo-Welsh Province, and in this respect it precedes, by a short time, the arrival of Kullervo, with the KuUervo-Palaeo- strophomena-Nicolella association of Whittington and Williams, in the Derfel Limestone. This too appears to represent a stock migrating westwards from the Baltic to America. Although Atele/asma first appears in America, it is believed to be related to the older Baltic genus Apomatella. Little comment can be offered on the ?CyrtonoteIla since only a single specimen was collected. Although a Baltic stock, a species of Cyrtonotella was also collected from the contemporaneous rocks of Brittany. Only two genera remain, Salopia and Rafinesquina. Salopia was discussed by Whitting- ton and Williams (1955), who placed it in the Linoporellidae, although they had some doubts as to its affinities with the Draboviinae, a Bohemian subfamily within the Schizo- phoriidae. A comparison of Salopia with various genera within the Draboviinae shows considerable resemblances and the Bohemian Skiddavian genus Noctuniellia Havlicek 1950 seems a possible ancestor. If this ancestry is accepted then this is the only genus in the fauna that has immediate Bohemian ancestry. The origin of the Rafinesquina is uncertain. The genus is unknown in North America before Wilderness times and this seems to be the first certain record in Britain. It is un- known before the Caradoc in either the Oslo district or in the Baltic. Salmon (1942) expressed the view that Kirkina from the Llanvirn equivalent Pogonip Limestone of Utah might be ancestral to both Rafinesquina and Oepikina. Maeroeoelia, occurring in the Llanvirn, must also be one of the earliest genera of the Strophomenidae and may be another possible ancestor to Rafinesquina. SYSTEMATIC DESCRIPTIONS Superfamily orthacea Walcott and Schuchert 1908 Family plectorthidae Schuchert and Cooper 1930 Genus corineorthis Stubblefield 1939 sens nov. Remarks. When the genus was erected by Stubblefield, C. deeipiens Stubblefield 1939 was the only known species. It has a concave ventral valve. C. pustula Williams 1949 has a ventral valve that is convex in its earlier part before taking on a concave form. C. bieonvexa sp. nov., otherwise answering closely to the genus, has a ventral valve that is gently convex throughout its length. It is proposed therefore to revise the generic diag- nosis slightly to include forms with plane or gently convex ventral valves. Revised diagnosis. Orthoid with convexo-concave, convexo-plane, or dorsiconvex valves, dental plates divergent, cardinal process with elongated shaft, brachiophore supporting plates convergent to form a cruralium, ornament multicostellate-fascicocostellate, ? coarsely exopunctate. Corineorthis bieonvexa sp. nov. Plate 19, figs. 1-6 1929 Orthis (Dalmaiiella) rank ini, Davidson, Wedd et alia, p. 32. Derivation of name. Biconvex, having both valves convex. A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 181 Length (mm.) Breadth (mm.) Depth (mm.) Holotype. A 46841, P). 19, figs. 1-3. Internal mould of dorsal valve ........ 13 + 17 5 Paratypes. 1. A 46842, PI. 19, fig. 6. External mould of ventral valve . ....... 16 24 3-5 2. A 46843, PI. 19, figs. 4, 5. Internal mould of ventral valve . ....... 15 16 4 Material. Internal and external moulds of dorsal and ventral valves, 1 50 specimens. Type locality. SJ 11602860, 60 yards south of Carnedd-y-forwyn, 2 miles north of Llanrhaiadr-ym- Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Ash. Diagnosis. Both valves convex, the brachiophores long and slender rising sharply above the notothyrial platform. Description. Exterior; typically orthid outline, wider than long with maximum width anterior to the hinge-line. Dorsal valve strongly convex with well marked median sulcus widening to the anterior; interarea anacline near orthocline. Ventral valve convex, less so than the dorsal valve, umbo slightly incurved, interarea apsacline. Multicostellate with very fine concentric ridges between the ribs. Seventy to ninety ribs round the circum- ference at half an inch from the umbo. Dorsal interior: notothyrial platform small with simple cardinal process running for- ward on to the median septum as a fine ridge. Bounded laterally by moderately long brachiophores rising steeply above the dental sockets and the notothyrial platform; they are divergent but not strongly so. In larger specimens the brachiophores are more massive as is the cardinal process at its posterior end. Sockets deep and bounded by fulcral plates. Supporting plates converge on to the median septum which is quite strong and runs forward for one-third to half the length of the valve. Muscle scars sometimes well developed, when they are seen to be subtriangular in outline, running almost exactly half-way to the anterior margin in the holotype. The large posterior adductors are separated from the quadrangular anterior adductors by a transverse ridge. Ribbing is impressed over the interior of both valves. Ventral interior: delthyrium open, deep, teeth rising slightly above the straight hinge- line, and with well developed dental sockets. Dental plates bounding the posterior part of the ventral muscle scars. These consist of narrow adductor scars bounded laterally by diductors with muscle tracks and weak longitudinal ridges. In the postero-lateral corners of the valve are the pustules of the genital markings, and these extend over a small area only. Remarks. This material resembles C. pustiiJa Williams 1949, but before considering this it is necessary to mention some discrepancies in Williams’s description. His text-figure of the interior of the dorsal valve is misleading since the brachiophores are much larger than he shows (see PI. 19, figs. 7, 8); further, the notothyrial platform is not recessed, as would appear in his text-figure 3, where it contains the cardinal process, and in fact it continues without a break on to the median septum. In the interior of the ventral valve he only figures the internal mould. By doing this he failed to show the crural fossettes B 9425 N 182 PALAEONTOLOGY, VOLUME 4 that are present on the teeth. These additional features became apparent when poly- vinyl-chloride moulds of the type material in the Sedgwick Museum were taken from specimens A 16680, A 25321, and A 25323. The Berwyn material differs from C. pustida in the following respects: the ventral valve is moderately convex throughout its length while in C. pustula it is flat to concave anteriorly. The brachiophores are not as massive as they are in C. pustula but they are longer, standing considerably higher above the floor of the notothyrial platform (PI. 19, figs. 2, 3). There is some variation in the brachiophores, but in none of the material are they so massive as in C. pustula. Williams’s species was restricted to one horizon in the Lower Llandeilo, but this material was obtained abundantly in the Llandeilo of the Berwyn Hills, although re- stricted to the Calcareous Ash division there. There is little resemblance to C. decipiens Stubblefield, which has a concave ventral valve, or to C. globosa Williams. In the dis- cussion of this last species Williams (1949) pointed out that there was a considerable resemblance to Orthis salteri Davidson and that that species might have to be put into a new genus. Since then Whittington and Williams (1955) have set up the genus Salopia with O. salteri as the type species. A comparison of ‘ C\ globosa with that genus shows many similarities, indeed more than there are between that genus and other species of Corineorthis. It is therefore considered that Corineorthis globosa is probably Salopia globosa as suggested by Williams, but the determining factor is the presence or absence of punctae which have never been demonstrated in ‘ Salopia ’ globosa. Since this is the third species of Corineorthis to be described from the Llandeilo it seems possible that the genus may be limited to strata of Llandeilo age. It has not been recorded from any other formation. EXPLANATION OF PLATE 19 The photographs are of natural external and internal moulds and of plastic moulds made from these. They are unretouched, but the specimens were lightly coated with ammonium chloride before being photographed. Figs. 1-6. Corineorthis biconvexa sp. nov. 60 yards south of Carnedd-y-forwyn, 2 miles north of Llanrhaiadr-ym-Mochnant. 1, A 46841, holotype, internal mould of dorsal valve, X 2. 2, 3, Normal and posterior views of plastic mould of holotype, X 2, posterior view to show form of brachiophores. 4, A 46843, paratype 2, internal mould of ventral valve, X 2. 5, Plastic mould of paratype 2, X 2. 6, Plastic mould of A 46842, paratype 1, external mould of ventral valve, X2. Figs. 7-8. Corineorthis pustula Williams. Craig-y-beri, Llanarmon, Carmarthenshire. 8, 7, Normal and posterior views of plastic mould of A 16680, syntype 2, internal mould of dorsal valve, xl-5, posterior view to show form of brachiophores. (For comparison with figures of Corineorthis biconvexa.) Figs. 9-15. McEwanella berwynensis sp. nov. 9-12 from 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 9, A 46844 b, holotype, external mould of dorsal valve, x2. 10, Plastic mould of holotype, X 2. 11, 12, Normal and posterior views of A 46844 n, paratype 1, internal mould of dorsal valve, x2. 13, 14, 15, From 80 yards north-north-east of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 13, A 46920 6, paratype 3, internal mould of ventral valve, x 3. 15, A 46920 a, paratype 2, external mould of ventral valve, X 3. 14, Plastic mould of paratype 2, X 2. Figs. 16-20. Glyptorthis minor sp. nov. 16-18 from 35 yards north of Nant, 1 mile north of Llanrhaiadr- ym-Mochnant. 16, A 46848, paratype 1, external mould of dorsal valve, x3. 17, A 46921, holotype, internal mould of dorsal valve, x3. 18, Plastic mould of holotype, x3. 19, 20, From 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 19, A 46849 b, paratype 3, external mould of ventral valve, X 3. 20, A 46849 a, paratype 2, internal mould of ventral valve. Palaeontology, Vol. 4. PLATE 19 Eci-a'i tli 3 X 2 6 X 1-5 12 X 2 7 X 15 MacGREGOR, Llandeilo brachiopods A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 183 Subfamily platystrophiinae Schucliert 1929 Genus mcewanella Foerste 1920 Diagnosis. Platystrophiinae with the whole surface multicostellate, the costellae covering the coarse costae. Internally like Platystrophia with very little adventitious shell deposi- tion. McEwanella berwynensis sp. nov. Plate 19, figs. 9-15 Derivation of name. Latin, berwynensis, belonging to the Berwyns or Berwyn Hills. Length {mm.) Breadth {mm.) Depth {mm.) Holotype. A 468446, PI. 19, figs. 9, 10. External mould of the dorsal valve ....... 18 19 5 Paratypes. 1. A 46844u, PI. 19, figs. 11, 12. Internal mould of the dorsal valve ....... 14 18 6 2. A46920u, PI. 19, figs. 14, 15. External mould of the ventral valve ....... 9 4 3. A 469206, PI. 19, fig. 13. Internal mould of the ven- tral valve ....... 9 1j Laterally com- pressed 4 Material. One dorsal valve external and internal mould and one fragment, one ventral valve external and internal mould. Type localities. Holotype and paratype 1 from SJ 12262802, 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Paratypes 2 and 3 from SJ 12272807, 80 yards north- north-east of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Diagnosis. Only some ten plications, and with a fold in the ventral valve. Description. Exterior; strongly biconvex, a weak fold in the ventral valve and a weak sulcus in the dorsal valve, ten strong plications in the dorsal valve and nine in the ventral, the two central ones in the dorsal valve being stronger than the others. The plications do not extend as far round the edge of the shell as the hinge-line. Greatest breadth at the hinge-line which is straight. External surface covered by costellae both on the costae and in the grooves between. There are approximately four costellae in 2 mm. Concentric growth-lines are present at irregular intervals. Dorsal interarea anachne near orthochne, curved over the hinge-line; ventral interarea apsacline also curved over the hinge-hne. Dorsal interior: this is of the normal platystrophid type; there is a simple linear cardinal process, strongly divergent brachiophores with the supporting plates converging to unite with the floor of the valve beneath the cardinal process. Sockets small with ful- cral plates. Narrow deep crural pits beneath the brachiophores. Cardinal process con- tinued forward for a short distance on the crest of the median plication, seen on the interior of the valve as a fold. Muscle scars rather obscure, small, triangular, and lying anterior to the crural pits, each having its base parallel to the midline and its apex point- ing laterally, about T5 mm. long and TO mm. wide. 184 PALAEONTOLOGY, VOLUME 4 Ventral interior: delthyrium open, deep; teeth with divergent supporting plates which pass forward into ridges on the floor of the valve bounding the muscle scar which | is quarter the length of the valve, the ridges become parallel and then converge, decreas- ing in height so that they are almost imperceptible where they join anteriorly. It is not possible to diflerentiate the different parts of the muscle. In paratype 3 it is partly obscured by a shell fragment lying in the posterior part of the scar. Scar is crossed by the five median costae, and is approximately diamond shaped with the anterior acute angle truncated a short distance from its apex. Marginally the costellae can be seen on the interior surface and posterolaterally concentric corrugations occur. Remarks. M. raymondi Foerste, the genotype, has a prominent median fold in the dorsal , valve, the two median plications being only 3 mm. apart in a valve 25 mm. wide, a condi- ! tion quite different from this species. In M. lineolata Savage there are thirty costae and these often die out before reaching the anterior margin of the shell. The Welsh material is quite distinct from either and is therefore placed in a new species. It is also the earliest . occurrence of the genus anywhere, the other two species being North American from the )| Caradocian and Ashgillian respectively. The distribution of the genus is sporadic in time j and space, and is at present problematical. « Genus platystrophia King 1850 :j Platystrophia cf. precedens major Whittington and Williams :| Plate 20, figs. 1-4 | 1955 Platystrophia precedens major, Whittington and Williams, p. 402, pi. 38, figs. 24-29. i Material. Dorsal internal and external moulds and ventral internal mould, total nine specimens. EXPLANATION OF PLATE 20 The photographs are of natural external and internal moulds and of plastic moulds made from these. They are unretouched, but the specimens were lightly coated with ammonium chloride before being photographed. Figs. IM. Platystrophia cf. precedens major Whittington and Williams. 100 yards north-north-east of Llwyn-Onn, 3 miles west of Llanrhaiadr-ym-Mochnant. 1, A 46845 a, internal mould of dorsal valve, X 3. 2, Plastic mould of dorsal interior, x 3. 3, Plastic mould of A 46845 b, external mould of dorsal valve, x 3. 4, A 46846, internal mould of ventral valve, X 3. Figs. 5-7. lAtelelasma sp. 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 5, A 46851 b, external mould of dorsal valve, x L5. 6, A 46851 a, internal mould of dorsal valve, X 1-5. 7, Plastic mould of A 46851 a, X 1-5. Figs. 8-14. Ateielasma anatolica sp. nov. 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym- Mochnant. 8-10, A 35413, paratype 1, side, anterior, and posterior views of internal mould of ventral valve, x 3. 1 1, A 35414, paratype 2, external mould of ventral valve, X 4. 12, 13, Normal and posterior views of plastic mould of paratype 2, x4. 14, A 35412, holotype, internal mould of dorsal valve, X 2. Figs. 15-19. Oxopiecia nantensis sp. nov. 15-17, From 930 yards north-west of Plas-yn-glyn, 1 mile north-north-east of Llanrhaiadr-ym-Mochnant. 15, A 46867, paratype 1, internal mould of ventral valve, x2-5. 16, Plastic mould of paratype 1, x2-5. 17, A 46869, paratype 3, posterior view of internal mould of dorsal valve, X 3. 18, From 200 yards north-north- west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, A 46922, holotype, internal mould of dorsal valve, X3. 19, From 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, plastic mould of A 46868, para- type 2, external mould of ventral valve, x 2-5. Palaeontology, Vol. 4. PLATE 20 8x3 17 X 3 18 X 3 9 X 3 10 X 3 15 X 2-5 16 X 2-5 19 X 2-5 Mac GREG OR, Llandeilo brachiopods 'A ( A A. R. MACGREGOR; UPPER LLANDEILO BRACHIOPODS 185 Locality. SJ 07292634, 100 yards north-north-east of Llwyn-Onn, 3 miles west of Llanrhaiadr-ym- Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Limestone. Description. Exterior: semicircular, strongly biconvex, with deep sulcus in the ventral valve of about 25 per cent, of the breadth of the valve and a high fold in the dorsal valve of about 30 per cent, of the breadth of the valve. Cardinal angles rectangular to slightly obtuse. Ventral interarea orthocline to slightly apsacline, dorsal interarea anacline. Notothyrium and delthyrium open. Ornament of strong costae, three on the dorsal fold with five on either side, ventral valve with two in the sulcus and five on either side. Dorsal interior : cardinal process consists of a simple plate running the whole length of the notothyrial platform, brachiophores straight and divergent at 90° to each other, with fulcral and supporting plates, the latter converging rapidly to meet at the anterior end of the cardinal process. Sockets small. Posterior pair of adductor scars oval on either side of the median ridge ; anterior pair quadrate to triangular narrowing anteriorly, separated by the median ridge, and from the posterior pair by a pair of transverse ridges set at about 70° to the median ridge. Ventral interior: teeth simple, small, supported by short parallel dental plates which are continuous with the ridge round the muscle scars, these being approximately U-shaped but pointed towards the anterior. Muscle scar about one-fifth of the length of the valve, poorly differentiated, but with two longitudinal ridges (?) containing the median adductor scars. The diductor scars (?) pass on to the dental plates postero- laterally. Remarks. This material is externally like P. precedens McEwan, but on account of its size it is more like its variety P. precedens major Whittington and Williams. Erom that variety it differs in the following respects: externally the fold and sulcus are much nar- rower, 25-30 per cent, of the breadth compared with an average of 48 per cent. None of the tubercular ornament of Whittington and Williams material has been seen in this material. Internally in the ventral valve the supporting plates are parallel and not just sub-parallel; the muscle scar is smaller being only one-fifth of the length of the valve compared with two-fifths in P. precedens major, the shape of the anterior end of the scar is also more pointed instead of rounded. In the dorsal valve only the shape and size of the muscle scars differ. Opik (1930) recorded P. biforata and P. dentata from the Uhaku Shales of Estonia ; of these the former is too advanced in ribbing to be related to this species. The latter has eight or nine ribs lateral to the fold and sulcus compared to the five or six in this material but is otherwise similar. The species is a member of the bicostate group and sub-group A of McEwan (1919), i.e. with two plications in the sulcus and three on the fold. Neither the bifurcation nor the intercalation can be seen in this material. Family skenidiidae Kozlowski 1929 Genus skenidioides Schuchert and Cooper 1931 ? Skenidioides sp. Plate 22, fig. 17 Material. One dorsal valve internal mould. 186 PALAEONTOLOGY, VOLUME 4 Locality. SJ 12272807, 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Mont- gomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Description. Exterior: dorsal valve only; small semi-elliptical to sub-triangular, hinge- line straight, cardinal extremities rounded, obtuse, near 90°. Convex, anterior commissure sulcate, sulcus fairly broad and rounded. Interarea anacHne, notothyrium open. Surface multicostellate. Dorsal interior: notothyrial cavity moderately shallow, brachiophores with fulcral and supporting plates, former partly cutting off the sockets ; latter quite strongly con- vergent to join the median ridge and forming a low, almost sessile cruralium. Cardinal process runs the length of the crurahum-notothyrium and passes anteriorly on to the median ridge which runs about three-quarters of the length of the valve. Remarks. This valve can only be placed in Skenidioides with some hesitation on account of the following points: it is unlike contemporary species in being multicostellate instead of costate; the median septum is weakly developed anterior to the cruralium; the cardi- nalia are smaller than usual. Family orthidae Woodward 1852, emended Schuchert and Cooper 1932 Subfamily orthinae Schuchert and Cooper 1931 Genus cyrtonotella Schuchert and Cooper 1931 ? Cyrtonotella sp. Plate 23, fig. 18 Material. One external mould of the ventral valve. Locality. SJ 12262802, 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Mont- gomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Description. Exterior: ventral valve only; strongly convex, anterior margin rounded, lateral margins slightly convex almost straight. Cardinal angles approximately 90°. Interarea anacline and curved. Anterior commissure weakly uniplicate. Delthyrium unknown. Ornament multicostellate. Remarks. There is some resemblance to the genus in the strongly convex ventral valve and the multicostellate ornament. Subfamily glyptorthinae Schuchert and Cooper 1931 Genus glyptorthis Foerste 1914 Diagnosis. With typical glyptorthid lamellose exterior, sulcus in the dorsal valve and internally typical orthid cardinalia. Glyptorthis minor sp. nov. Plate 19, figs. 16-20 Derivation of name. Latin, minor, small or inferior, on account of the small size of this species. A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 187 Length (min.) Breadth (mm.) Depth (mm.) Holotype. A 46921, PI. 19, figs. 17, 18. Internal mould of the dor- sal valve ........ 4 5 1 Paratypes. 1. A 46848, PI. 19, fig. 16. External mould of the dor- sal valve ........ 3-5 5 1 app. 2. A 46849a, PI. 19, fig. 20. Internal mould of the ven- tral valve. ....... 5 6 2-5 3. A 468496, PI. 19, fig. 19. External mould of the ventral valve ....... 5 6 2-5 Material. External and internal moulds of both valves, thirteen specimens in all. Type localities. Holotype and paratype 1 from SJ 12262802, 35 yards north of Nant; paratypes 2 and 3 from SJ 12172815, 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Diagnosis. Strongly convex ventral valve with almost orthocline interarea, gently con- vex dorsal valve with long, strong, median ridge internally. Description. Exterior: lateral profile biconvex with strongly convex ventral valve and weakly convex dorsal valve. Outline subquadrate to subcircular, hinge-line less than greatest breadth which is half to two-thirds the way forward. Cardinal extremities rounded to obtuse, about 1 10°, anterior margin rounded, anterior commissure weakly uniplicate. Ventral fold broad and gentle, dorsal sulcus narrow and sharp posteriorly, becoming broader and shallower anteriorly. Ventral interarea slightly apsacline, almost orthocline, dorsal interarea smaller than ventral, anacline. Ornament of bifurcating costae crossed by strong concentric lamellae. Dorsal interior: notothyrial cavity moderately shallow, cardinal process stout and raised anteriorly before flattening out near the front of the notothyrial platform, tapers sharply posteriorly. Brachiophores large and blunt, bounding the notothyrial cavity, supported by considerable adventitious shell which joins the strong median ridge in front of the notothyrial platform. The median ridge runs forward for three-quarters of the length of the valve. On either side of the median ridge and beneath the brachiophores are well developed adductor pits. Adductor impressions ill defined — ? semicircular on either side of median ridge in front of the brachiophores. Sockets fairly small with well defined fulcral plates. Ribbing promment over the whole of the inside of the valve. Slight concentric ridge on the floor of the valve about three-quarters of the way to the periphery. Ventral interior: deep delthyrial cavity, teeth with gently convergent dental plates which join the large muscle platform. Muscle platform about half the length of the valve, tapering posteriorly, with the edge raised laterally and anteriorly; a short median ridge runs forward from the front of the muscle platform. Muscle scar with two longitu- dinal ridges at the anterior and a slight median ridge in line with the median anterior prolongation. At the posterior end of the muscle scar there is a small raised area with prominent lateral ridges making up a pedicle callyst. In front of and lateral to the muscle scar is a gentle rounded concentric hollow. Remarks. Three species of Glyptorthis are known in North America from rocks of 188 PALAEONTOLOGY, VOLUME 4 Llandeilo equivalent age. They differ from this material in the following respects; G. sulcata Cooper has both valves strongly convex; G. transversa Cooper though similar in size has a much less convex ventral valve; G. sp. 4 Cooper has a weakly convex ventral valve. In Britain G. baJcIatchiemis (Davidson) has a less convex ventral valve and a different ventral muscle scar. G. crispa (M‘Coy) has a strongly convex dorsal valve without sulcus. Superfamily clitambonacea Schuchert 1929, emended Schuchert and Cooper 1932 Family clitambonitidae Winchell and Schuchert 1 893 Subfamily atelelasmatinae Cooper 1956 Genus atelelasma Cooper 1956 Atelelasma anatolica sp. nov. Plate 20, figs. 8-14 Derivation of name. Greek, anatole, of the east, or eastern, this being the most easterly species de- i scribed so far. I Length (mm.) Breadth {mm.) Depth {mm.) Holotype. A 35412, PI. 20, fig. 14. Internal mould of dorsal valve 9 13-5 1 app. Paratypes. 1. A 35413, PI. 20, figs. 8-10. Internal mould of ven- tral valve ....... 5 13 5 2. A 35414, PI. 20, figs. 11-13. External mould of ventral valve ....... 3-5 7-5 2-5 Material. External and internal moulds of dorsal and ventral valves, total 5 specimens. Type locality. SJ 12262802, 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Ash. Diagnosis. Plano-convex, wide, slightly auriculate, costellate, short median septum in " deep ventral valve. i' ji Description. Exterior: plano-convex to slightly concavo-convex with straight hinge-line : equal to greatest width, semicircular, slightly auriculate, cardinal extremities just acute, ; near 90°. Anterior commissure rectimarginate. Ventral interarea long, strongly apsacline ; to catacline, curving gently over the hinge-line. Dorsal interarea anacline. Delthyrium f open, but with lateral plates characteristic of the genus on either side slightly modifying | the shape. Notothyrium filled by well developed chilidium with growth-lines. Surface | costellate. Shallow fold in dorsal valve broadening anteriorly until it has virtually dis- appeared at the anterior margin. Weak sulcus in ventral valve with gentle fold on either side. Ventral valve strongly convex from side to side, only moderately so from front to back. Dorsal interior: cardinal process a simple, short plate abutting against the chilidium. Notothyrial platform well developed, passing forward into a wide median ridge which fades out anteriorly. Brachiophores diverge at 30° from the hinge-line rising quite sharply and with a short groove on their lateral faces near their ends. Sockets well defined and slightly indenting the hinge-line. Adductor scars forming pits in front of the A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 189 notothyrial platform and on either side of the median ridge ; the limit of the scars not seen either laterally or anteriorly. Broad shallow concentric ridges are developed on the interior of the valve and the ribbing is also seen over the inner surface, although most strongly marked peripherally. There is a slight, low, subperipheral ridge. Ventral interior: teeth simple so far as can be seen. Spondylium about one-third of the length of the valve with transverse ridging posteriorly and longitudinal ridging further forward; situated above the floor of the valve, about half the length of the del- thyrium and supported for half its length on a short median septum before being free from the floor of the valve and some distance above it. Internal surface shows ribbing and concentric corrugations, the ribs being most strongly marked peripherally. Remarks. This species of a genus not hitherto recorded in Europe resembles its con- temporaries in North America, though differing in detail from all of them. A. decortica- tum has the ventral valve markedly curved over the hinge-line; A. obscunim has larger lateral plates in the delthyrium and coaiser ribbing; A. platys is half the size, has coarser ribbing and has a convex dorsal valve; A. sulcatum has a sulcate and moderately convex dorsal valve; A. variabile is much smaller, has too convex a dorsal valve while having an almost square outline. Atelelasma makes its first known appearance in the Lenoir of Tennessee, equivalent to the Llanvirn of Britain, before becoming widespread in the Llandeilo equivalent Chazy rocks of North America, contemporary with this species. The allied genus Apomatella lacks the well developed lateral plates of Atelelasma and the only species known, A. ingrica, is markedly procline. Cooper (1956) remarks on the close relationship of these two genera, Apomatella appearing to be more primitive and known only from the Walchow, Arenig equivalent, of the Leningrad district. As a simpler but similar form it may be ancestral to Atelelasma. ? Atelelasma sp. Plate 20, figs. 5-7 Remarks. A single clitambonitid dorsal valve from the same locality as A. anatolica was also collected. It differs from that species in a number of respects and may possibly be- long to a different genus. The differences are listed below. Externally the ribbing is multicostellate and the con- centric ridges on the shell are much sharper and more pronounced. Internally the cardi- nalia are smaller; the notothyrial platform is smaller, while the cardinal process and the median ridge are shorter, the latter ending abruptly anteriorly at about one-sixth of the length of the valve. The braehiophores are inclined at about 45° to the hinge-hne. Without ventral valves to examine it is not possible to give a more precise identifica- tion. Superfamily dalmanellacea Schuchert and Cooper 1931 Eamily dalmanellidae Schuchert and Le Vene 1929 = wattsellidae Schuchert and Cooper 1931 Genus dalmanella Hall and Clarke 1892 Dalmanella parva Wilhams Plate 21, figs. 18-21 1949 Dalmanella parva, Williams, p. 169, pi. 8, figs. 11-14. 190 PALAEONTOLOGY, VOLUME 4 Lectotype (here selected). Geological Survey Museum, London, GSM 75251, internal mould of a dorsal valve, Williams 1949, pi. 8, fig. 11. Material. Dorsal and ventral external and internal moulds, some 350 in all. Localities. Almost all exposures of the Upper Llandeilo in the Iwrch Valley, Rhaiadr Valley, and Llangynog Inliers, lying north, north-west, and west of Llanrhaiadr-ym-Mochnant, Montgomery- shire. Horizon. Upper Llandeilo, Calcareous Ash, Limestone, and especially Calcareous Shales. Description. Exterior : subcircular, typically orthoid, with maximum width anterior to a straight hinge-line. Dorsal valve gently convex, especially posteriorly where the shell is raised with two shoulders, one on either side of a distinct median sulcus. Ventral valve sharply convex medianly, umbonal region moderately pronounced, ornamentation of concentric growth-lines and multicostellate primitive ribbing. Dorsal interior: notothyrial platform with subparallel sides, extending anteriorly to form a median ridge and supporting a styliform cardinal process and a pair of brachio- phores. The latter consist of very abbreviated widely divergent fulcral plates and a pair of larger subparallel supporting plates. Dental sockets strongly divergent anteriorly. EXPLANATION OF PLATE 21 The photographs are of natural external and internal moulds and of plastic moulds made from these. They are unretouched, but the specimens were lightly coated with ammonium chloride before being photographed. Figs. 1-5. Paiicicrura inmiatura (Williams). 1, From 930 yards north-west of Plas-yn-glyn, 1 mile north-north-east of Llanrhaiadr-ym-Mochnant, A 46861, internal mould of ventral valve, X 2. 2, From 1 30 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, plastic mould of A 46862, internal mould of ventral valve, X 2. 3, 4, 5, From 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 3, Plastic mould of A 46859 b, external mould of dorsal valve, x2. 4, A 46859 a, internal mould of dorsal valve, X 2. 5, Plastic mould of A 46860, internal mould of dorsal valve, X 2. Figs. 6-10. Horderleyella snbcarinata sp. nov. 6, 9, From 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 6, Plastic mould of A 46864, paratype 1, internal mould of dorsal valve, X 2. 9, A 46866, paratype 4, internal mould of ventral valve, X 4. 7, 8, From 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 7, A 46863 a, holotype, internal mould of dorsal valve, X 2. 8, A 46863 b, paratype 2, external mould of dorsal valve, X 2. 10, From 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, A 46865, paratype 3, internal mould of ventral valve, X 3. Figs. 11-15. Parastrophinella costata sp. nov. 11, 12, From 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 12, 11, Normal and posterior views of A 35415, paratype 3, internal mould of dorsal valve, x4. 13, 14, From 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym- Mochnant. 13, A 46876, paratype 1, internal mould of ventral valve dissected to show form of the spondylium, x 4. 14, A 46877, holotype, internal mould of ventral valve, x4. 15, From 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, A 46875 a, paratype 2, in- ternal mould of dorsal valve, X 4. Figs. 16, 17. Rostricellida triangularis Williams. 80 yards north of Nant, 1 mile north of Llanrhaiadr- ym-Mochnant. 1 6, A 46878, internal mould of dorsal valve, X 4. 17, Plastic mould of dorsal valve, x4. Figs. 18-21. Dalnianella parva Williams. 200 yards north-north-west of Nant, 1 mile north of Llan- rhaiadr-ym-Mochnant. 18, A 46856, internal mould of ventral valve, X 6. 19, A 46854 a, external mould of dorsal valve, X4. 20, A 46854 internal mould of dorsal valve, x4. 21, Plastic mould of dorsal valve, x4. PLATE 21 Palacoiilology, Vol. 4. 9x4 11x4 13 X 4 14 X 4 Mac GREG OR, Llandeilo brachiopods A. R. MACGREGOR; UPPER LLANDEILO BRACHIOPODS 191 well defined. Adductor impressions only faintly impressed in gerontic specimens. Rib- bing deeply impressed on internal moulds of both valves. Ventral interior: umbonal region deep with dental lamellae well marked, diverging moderately anteriorly. Diductor scars generally obscure, occasionally seen as sub- cordate scars not enclosing the adductors. Remarks. At Llandeilo this species is abundant in the rocks of the Upper Llanvirn and Lower Llandeilo as high as the Transition Sub-zone of Williams (1953). In the Berwyns it is abundant throughout the Upper Llandeilo. It is easily recognized on account of its constant small size. There do not appear to be any differences between the Berwyn and the Llandeilo area specimens. Dalmanella cf. Jepta (Bancroft) Plate 22, figs. 18, 19 1945 Wattsella lepta, Bancroft, p. 193, pi. 22, figs. 4—7, pi. 23, fig. 4. Material. Four moulds of the interior and one of the exterior of the dorsal valve. Locality. SJ 12272807, 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Mont- gomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Description. Exterior: wider than long, semi-elliptical with long hinge-line, greatest width anterior to hinge-line, dorsal valve gently convex with shallow median sulcus, interarea low, apsacline, notothyrium open. Ribbing not fully known, but with strong development of internals. Ventral valve unknown. Dorsal interior: notothyrial platform small with bilobed cardinal process and shaft, also small. Brachiophores lobe-shaped with well developed supporting plates which show as strongly convergent pre-socket lines in internal moulds. Sockets small with fulcral plates. A broad median ridge passes a short distance forward from the noto- thyrial platform before dying out on the median sulcus. It is about one-quarter of the length of the valve. Adductor scars faintly impressed on either side of the median ridge. Ribbing strongly impressed peripherally and gradually becoming fainter towards the cardinalia. Ventral interior: unknown. Remarks. A small number of specimens from the Berwyns resemble this species of Bancroft’s rather than the much commoner D. parva and P. immatiira. Internally the dorsal valve shows Bancroft’s ‘wattsellid’ organization. The horizon of D. lepta is much higher. Lower Longvillian in the Caradoc, so that this material is rather problematical. Genus paucicrura Cooper 1956 Paiicicrura immatiira (Williams) Plate 21, figs. 1-5 1949 Resserella iimnatiira, Williams, p. 165, pi. 8, figs. 1-4, text-figs. 1 a, b. Lectotype (here selected). Geological Survey Museum, London, GSM 75233, internal mould of dorsal valve, Williams, 1949, pi. 8, fig. 1. 192 PALAEONTOLOGY, VOLUME 4 1 Material. Internal and external moulds of dorsal and ventral valves, eighty-five specimens in all. || Localities. Most exposures in the Iwrch Valley and Llangynog Inliers, especially at Quarry, SJ |l 1 2582848, 960 yards north-west of Plas-yn-glyn, 1 mile north-north-east of Llanrhaiadr-ym-Mochnant, ;■ Montgomeryshire. ! Horizon. Upper Llandeilo, Calcareous Ash, Limestone, and Calcareous Shales. Description. Exterior; transverse, subrectangular with some specimens rather longer. Hinge-line straight, greatest width anterior to the hinge-hne. Moderately biconvex, the j ventral valve more so, the dorsal valve with a weak median sulcus. Delthyrium and noto- | thyrium open, the latter partly or wholly filled by the cardinal process. Interareas low ‘ with the ventral greater than the dorsal. Ribbing fine, multicostate, sector III greater than sectors I and II. Concentric growth-lines present but usually well spaced out. (The I small exopunctae of Williams’s material were not seen, but this may be due to preserva- tion.) Dorsal interior : notothyrial platform small with cardinal process consisting of myo- phore and shaft, the former in large specimens being bilobed (PI. 21, fig. 4), otherwise simple but thickened in more mature individuals. Bounded laterally by small diverging brachiophores with crural pits that are filled in in more mature individuals. Fulcral ^ plates with small, quite deep sockets. Supporting plates small, rapidly convergent to join the median ridge. Notothyrial platform continued forward by a median ridge for one- : third to half the length of the shell. Adductor scars moderately deeply impressed : posteriorly and terminating sharply anteriorly, but vaguely laterally. Ribbing prominent at the periphery and continued more faintly to the muscle scars. EXPLANATION OF PLATE 22 The photographs are of natural external and internal moulds and of plastic moulds made from these. They are unretouched, but the specimens were lightly coated with ammonium chloride before being photographed. Figs. 1-4. Salopia cf. salteri (Davidson). 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym- Mochnant. 1, 2, A 46857 a, normal and posterior views of internal mould of dorsal valve, x3. 3, A 46857 b, external mould of dorsal valve, X 3. 4, A 46858 a, internal mould of ventral valve, X 3. Figs. 5-10. Parastrophinella parva sp. nov. 5, 6, 9, 10, From 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 5, A 46874, paratype 4, internal mould of dorsal valve, X 3. 6, A 46870, holotype, internal mould of ventral valve, X 3. 9, Plastic mould of A 46872, paratype 2, internal mould of ventral valve, X4. 10, Plastic mould of A 46873, paratype 3, external mould of ventral valve, X 3. 7, 8, From 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, A 46871, oblique and normal view of paratype 1, internal mould of ventral valve, dissected to show spondylium and median septum, X 3. Figs. 11-16. Rafinesqitina simplex sp. nov. 11, 14, 15, From 400 yards north-north-east of Siambr, 3 miles west of Llanrhaiadr-ym-Mochnant. 11, A 46885, paratype 1, internal mould of ventral valve, X 1. 14, Plastic mould of A 46884, paratype 2, internal mould of dorsal valve, X 1-3. 15, Plastic mould of A 46886, paratype 3, internal mould of ventral valve, X 1. 12, 13, From 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, plastic moulds of A 46887 a, b, holotype, external and internal moulds of incomplete ventral valve, X 1. 16, From 960 yards north- west of Plas-yn-glyn, 1 mile north-north-east of Llanrhaiadr-ym-Mochnant, A 35416, paratype 4, external mould of ventral valve, x 1-5. Fig. \1 .‘ISkenidioides sp. 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, A 46847, internal mould of dorsal valve, X 3. Figs. 18, 19. Dalmanella cf. lepta (Bancroft). 80 yards north of Nant, 1 mile north of Lanrhaiadr-ym- Mochnant. 18, Plastic mould of A 46852, external mould of dorsal valve, X 4. 19, Plastic mould of A 46853, internal mould of dorsal valve, x4. Palaeontology , Vol. 4. PLATE 22 4x3 II X I 9x4 8x3 MacGREGOR, Llandeilo brachiopcds A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 193 Ventral interior : delthyrium moderately deep ; hinge-line with teeth with weak crural fossettes and supported by slightly divergent dental lamellae which are continued for- ward as boundaries to the muscle scars. Apex of delthyrium thickened by a pedicle callyst (PI. 21, fig. 1). Muscle scars well defined, narrow adductors with ? a median ridge, bounded by the elongate, flabellate diductors extending beyond and enclosing the adductors, and having muscle tracks anteriorly. Ribbing marked at the periphery and less marked up to the muscle scars. Remarks. This material is not identical with P. immatiira from Llandeilo, but differs in minor respects only. Exteriorly the ribbing agrees with the Llandeilo material in having sector III greater than I and II. As has been pointed out by Williams (1949) the reverse is the case in the Caradocian species. Internally the brachiophores are less slender than in Williams’s material while in mature material they are much thicker. Along with this thickening the crural pits become lost although still present in juvenile specimens. The dorsal muscle scars are still not well defined, but the ventral scars are well developed as is the pedicle callyst. The pre-socket line in dorsal interior moulds reflects the presence or absence of the crural pits, being sinuous where these are present and straight where absent in the mature individuals. The Berwyn material shows advances from the Lower Llandeilo stage of development towards that of Caradocian species. Lamily heterorthidae Schuchert and Cooper 1931, emended Bancroft 1945 Subfamily harknessellinae Bancroft 1928 Genus horderleyella Bancroft 1928 Horderleyella subcar iimt a sp. nov, Plate 21, figs. 6-10 Derivation of name. Latin, sub-, near, carinatus, a keel, from the prominent median ridge in the ventral valve. Length (mm.) Breadth (mm.) Depth (mm.) Holotype. A 46863n, PI. 21, fig. 7. Internal mould of dorsal valve. 18 16 3-5 Paratypes. 1 . A 46864, PI. 21, fig. 6. Internal mould of dorsal valve 13 19 4 2. A 46863^, PI. 21, fig. 8. External mould of dorsal valve ........ 16 4 3. A 46865, PI. 21, fig. 10. Internal mould of ventral valve ........ 9 12-5 2-5 4. A 46866, PI. 21, fig. 9. Internal mould of ventral valve ........ 5 6 1-5 Material. Dorsal and ventral external and internal moulds, twenty-four specimens. Type Localities. Holotype and paratype 2, SJ 12172815, 200 yards north-north-west of Nant; para- types 1 and 4 from SJ 12272807, 80 yards north-north-west of Nant; paratype 3 from SJ 12262802, 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Diagnosis. Has a delicate cardinal process and deheate fuleral plates in the dorsal valve. In the ventral valve there is a sharp fold and internally a subpentagonal muscle scar. 194 PALAEONTOLOGY, VOLUME 4 Description. Exterior: shape weakly harknesselloid without prominent ears, cardinal angles obtuse and close to 90° with a few specimens acute and close to 90°. Biconvex, hinge-line straight. Dorsal valve with well developed median sulcus bordered by rounded folds narrowing posteriorly; ventral valve with a median fold, often quite sharp, with small sulci and then folds outside these. There is a regular development of intercostellate pores. Ribbing: a strong development of sector III is present in the dorsal valve and is much greater than sectors I and II together. Branching is more internal than external. Dorsal interior : elevated notothyrial platform passing anteriorly into a broad median septum. Cardinal process of a slender myophore and shaft, almost a simple plate and extending most of the length of the notothyrial platform. Stout brachiophores make an angle of about 60° bisected by the cardinal process, with well developed inner supporting plates and very delicate fulcral plates. These are separated by narrow deep crural pits. Dental sockets fairly short and quite deep. Deep adductor pits on either side of the median septum; weak ridges outside the adductor muscle scars may be extensions of the supporting plates. This feature is well seen in internal moulds. Anterior limit of the adductor scars ill defined. Ventral interior: delthyrium deep; divergent dental plates with a low ridge extending beyond and bounding the muscle scars which are subpentagonal in outline with only a very slight tendency towards bilobation. Parallel-sided adductor scar bounded on either side by triangular diductors, both (?) being ridged by ribbing. The inside of both valves shows ribbing right up to the cardinalia. Remarks. Differs from H. convexa Williams 1949 which has a weak ventral carina, a ‘stout’ cardinal process, fairly massive fulcral plates, and impressions of the ribbing limited to the periphery of both valves internally. H. plicala Bancroft 1928 has the valves considerably less convex, the ventral carina less well developed and the cardinal process more massive, but otherwise is not unlike this species. H. corrugata Bancroft 1945 may not have the median and lateral folds in some specimens, and the myophore and shaft are resorbed into a single massive body practically filling the space between the brachio- phores. Crural pits are very fine or absent at maturity and the ventral muscle scar is subtrigonal. H. lata Williams 1949 is consistently rather wider, length/'breadth ratio 0-58 compared with 0-70 for this species, and the fulcral plates are quite robust. It does, however, have the same fine cardinal process, and the form of the shell is similar while the ribbing is impressed over most of the interior of the dorsal valve at least. A single interior of a ventral valve of Horderleyella from the Derfel Limestone (Whittington and Williams 1955) does resemble this species but the anterior of the muscle scar is curved forward rather than having a re-entrant as in this species. This species falls rather precisely between the Llanvirn species H. lata and the Caradoc species H. plicata, having the fine cardinal process of the former and, apart from the cardinal process and the ventral carina, being otherwise similar to the latter. The ribbing is more like H. lata, having a greater development of internal rather than external branching. Family linoporellidae Schuchert and Cooper 1931 Genus salopia Whittington and Williams 1955 Remarks. Whittington and Williams (1955) consider that Salopia may be descended from A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 195 the Draboviinae of Bohemia, a subfamily appearing in the Arenig and becoming abun- dant in the Llandeilo and Caradoc. In the absence of the demonstration of punctation in the subfamily they prefer to put Salopia in the Linoporellidae on the basis of the puncta- tion and the cruralium in the dorsal valve. Since then Cooper (1956) has described the genus Laticrura from the Caradocian of North America, and it seems to be a similar but more specialized genus; in particular in the brachiophores which have an S-shaped cross-section. Whittington and Williams remark on the absence of convergent supporting plates beneath the brachiophores of the Draboviinae with the exception of GiraldieUa. They then demonstrate that GiraldieUa cannot be retained in the subfamily since it is im- punctate. However, Drabovinella idrichi Havlicek 1950 has, as can be clearly seen in his plate 12, fig. 14, markedly convergent supporting plates for the brachiophores, so much so that they join the median septum and in efifect form a cruralium comparable to the structure seen in Salopia. The development of a cruralium from the more usual state of organization seen in the Draboviinae seems to be simply a matter of degree of convergence of the supporting plates beneath the brachiophores, and the species of Drabovinella referred to above lies in an intermediate position between the more usual Drabovinella condition and the condition seen in Salopia where the cruralium is well developed. If one can accept that the Draboviinae are to be included in the Schizophoriidae, which must be governed by the demonstration of punctae in the Draboviinae, then the descent of Salopia from the Draboviinae seems quite possible. Similarly Laticrura may also be descended from this Bohemian stock. The Upper Llandeilo occurrence of Drabovinella and now of Salopia would not disagree with this, while Laticrura is first known in the Lower Caradoc. It is possible that Salopia might be ancestral to Laticrura. Salopia cf. salteri (Davidson) Plate 22, figs. 1-4 1871 Orthis salteri, Davidson, p. 255, pi. 36, figs. 31-34. 1955 Salopia salteri (Davidson), Whittington and Williams, p. 409, pi. 38, figs. 43-46. Lectotype (here selected). Geological Survey Museum, London, GSM 11228, internal mould of the dorsal valve; Davidson 1871, pi. 36, figs. 33, 33n. Material. Dorsal and ventral external and internal moulds, one of each. Since these lie only 2 inches apart on the same bedding plane they may have been the valves of the same individual. Locality. SJ 12262802, 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Mont- gomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Description. Exterior: wider than long, strongly biconvex with the greater convexity in the ventral valve, finely multicostellate, dorsal valve with sulcus and ventral with weak fold anteriorly. Very long interarea in ventral valve, (?) delthyrium and notothyrium open. Anterior margin gently uniplicate. Dorsal interior: cardinal process not preserved, but median ridge extending anteriorly from its position is present and this is continued beyond the cruralium by a strong median ridge running three-quarters the way to the anterior margin. Brachiophores fairly 196 PALAEONTOLOGY, VOLUME 4 large, supported laterally by the fulcral plates which separate deep sockets, and ante- riorly by long supporting plates converging to form a large crurahum which is supported anteriorly by the median septum or ridge mentioned above. Large adductor scars on either side of the median septum. Ribbing present peripherally. Ventral interior (incomplete): delthyrium large, teeth simple with large dental plates descending to the floor of the valve, but not running far to the anterior. Muscle area \ about one-fifth the width of the valve, but not clearly seen owing to poor preservation. Ribbing faintly marked peripherally. Remarks. The main difference observed between this material and the type of the species is the absence of the fold in the anterior margin of the dorsal valve. Since, however, the Berwyn material is little more than one- third of the size of Davidson ’s material it seems possible that it was still too small to have developed an anterior fold. It possesses the dorsal sulcus seen in the more posterior parts of the type material. In all other respects the Berwyn material answers closely to this species as far as can be observed. Superfamily triplesiacea Cooper 1944 Family triplesiidae Opik 1932 Genus oxoplecia Wilson 1913 111 Diagnosis. Surface covered with plications or striae, with increase by interpolation and bifurcation; large, triangular, slightly concave cardinal area in the ventral valve; broad, i usually flat deltidium; cardinal process shorter than in Triplesia; long beak in the ventral valve. Type species O. calhouni Wilson 1913. Remarks. The genus was set up by Wilson for ribbed Triplesia with fold and sulcus, but it appears to have been overlooked and species that clearly should belong to this genus have been placed in Foerste’s genus Clift onia. Cliftonia Foerste 1909 was also set up for ribbed Triplesia but which were externally with ‘the appearance of a small Atrypa\ An | example of this is Cliftonia andersoni Reed 1917 which has a marked fold and sulcus. It clearly should be assigned to the genus Oxoplecia. Oxoplecia nantensis sp. nov. Plate 20, figs. 15-19 Derivation of name. Latin termination -ensis, from Nant, the farm adjacent to the locality of the holo- type. Length {mm.) Breadth {mm.) Depth {mm.) Holotype. A 46922, PI. 20, fig. 18. Internal mould of dorsal valve 5 9 3 Paratypes. 1. A 46867, PI. 20, figs. 15, 16. Internal mould of ven- tral valve ....... 11 13 3 2. A 46868, PI. 20, fig. 19. External mould of ventral valve ........ 10 11 3-5 3. A 46869, PI. 20, fig. 17. Internal mould of dorsal valve ........ 9 17 6 Material. Internal and external moulds of dorsal and ventral valves, fifty-eight specimens in all. A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 197 Type localities. Holotype from SJ 12172815, 200 yards north-north-west of Nant; paratype 2 from SJ 1 2272807, 80 yards north of Nant ; 1 mile north of Llanrhaiadr-ym-Mochnant ; paratypes 1 and 3 from SJ 12852846, 930 yards north-west of Plas-yn-glyn, 1 mile north-north-east of Llanrhaiadr-ym- Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Ash, Limestone, and Calcareous Shale divisions. Diagnosis. Oxoplecia with sharp plication in the dorsal valve, sulcus in the ventral valve to give a paraplicate anterior commissure ; well developed costate and imbricate orna- ment, divergent dental plates in ventral valve. Description. Exterior; shell transversely elliptical to subquadrate, biconvex, the dorsal valve more strongly convex than the ventral, hinge-line less than width of the shell, cardinal angles obtuse to rounded. Ventral valve with a strong median sulcus with a flat floor and steep sides increasing in width anteriorly and ending in a tongue fitting into the fold in the dorsal valve. Interarea triangular, high and curved over the hinge- line. Dorsal valve with a sharp fold, more swollen than the ventral valve, with the umbo curved over the hinge-line. Interarea small, steeply inclined and triangular; lateral lobes of the valve somewhat swollen. Ribbing: 7-9 ribs in the ventral sulcus and 13-16 on either side, 3-5 ribs on the dorsal fold and 12-14 laterally. The surface is covered by a fine concentric ornament of closely packed imbricate lines or ridges. Dorsal interior: stout cardinal process forking (base only seen), short divergent rod- like brachiophores ; anterior and posterior adductor scars rounded and separated by low, short, transverse ridges, the scars lie on either side of the median ridge. Ventral interior: delthyrium open except for a small, strongly curved deltidium at the apex. Teeth small with divergent dental plates descending to the floor of the valve, and extending for a very short distance forward. Muscle scars not seen on floor of the valve. Remarks. This species most closely resembles Oxoplecia andersoni (Reed 1917) but that species differs in the following respects : the ventral valve is more inflated and has a much longer tongue in the anterior commissure, it has fewer ribs and a higher ventral in- terarea. O. plicata Cooper 1 956 is also similar, but has only four ribs in the sulcus and has eighteen laterally, the sulcus is also wider at the anterior margin, being about half the total width in adult shells. In the dorsal valve the fold does not originate until about one-third of the length of the valve. O. nmtabilis Whittington and Williams 1955 from the Derfel Limestone is less transverse and has a wider fold with more ribs in the dorsal valve. This is possibly the earliest record of Oxoplecia so far described in this country, but Williams (1953) records 'Cliftonia' sp. from the Lower Llandeilo and Upper Llanvirn of the Llandeilo district. The genus makes its first appearance in North America in beds of Upper Llandeilo age, the Whistle Creek and Lincolnshire Limestone formations in Virginia (Cooper 1956, pp. 169, 170). Superfamily syntrophiacea Ulrich and Cooper 1936 Family parastrophinidae Ulrich and Cooper 1938, emended St. Joseph 1941 Genus parastrophinella Schuchert and Cooper 1931 Parastrophinella parva sp. nov. Plate 22, figs. 5-10 Derivation of name. Latin parva, small, on account of the very small size of this species. O B 9425 198 PALAEONTOLOGY, VOLUME 4 Length (mm.) Breadth (mm.) Depth (mm.) Holotype. A 46870, PI. 22, fig. 6. Internal mould of ventral valve 8 6-5 1-5 Paratypes. 1. A 46871, PI. 22, figs. 7, 8. Dissected internal mould of ventral valve ....... 7 8 L5 2. A 46872, PL 22, fig. 9. Internal mould of ventral valve ......... 8-5 9-5 2 3. A 46873, PI. 22, fig. 10. External mould of ventral valve ......... 6-5 7-5 1-5 4. A 46874, PI. 22, fig. 5. Internal mould of dorsal valve ........ 5-5 5 1-5 Material. Dorsal and ventral internal and external moulds, total 54 specimens. ''j Type localities. Holotype and paratypes 2, 3, and 4, SJ 12172815, 200 yards north-north-west of Nant; j paratype 1, SJ 12272807, 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Mont- j gomeryshire. Horizon. Upper Llandeilo, Calcareous Shales. Diagnosis. Two to eight coarse costae at the anterior margin; ventral interior with well ! developed median septum, and dorsal interior with long, slightly divergent outer plates, j Description. Exterior: both valves strongly convex, narrow hinge-line with greatest i width two-thirds the way forward, the anterior rounded and the posterior almost pointed. Anterior commissure multiplicate. Ventral interarea apsacline towards orthocline and curved over hinge-line; dorsal interarea anacline towards orthocline, also curved; flat- tened areas present. Surface almost smooth with a few concentric corrugations; ante- ; riorly there are two to eight coarse costae or plications. Dorsal interior: deep notothyrial cavity with slight secondary thickening on the floor ^ especially towards the posterior. This appears to constitute a sessile cruralium. Brachial supports or outer plates long, vertical and diverging very slightly forwards, about a quarter to one-fifth the length of the valve. The anterior ending of these above the floor of the valve is unknown. Very small and short inner plates are present. Sockets ; small; fulcral plates unknown. No cardinal process seen. Muscle scars seen at the i anterior end of the outer plates, and divided into two, each consisting of a long i narrow scar diverging beyond the plates and outside that there may be a short feathered | scar, j Ventral interior: teeth (?) small, supporting plates convergent to form a spondylium ' which is sessile at the posterior, but which rises forwards on a median septum eventually being sharply upturned at its anterior end. The median septum continues forward for a j short distance beyond the end of the spondylium. Length of the spondylium one-quarter to one-fifth the length of the valve. Faint muscle scars are present as striations along the length of the spondylium. Remarks. The presence of what appears to be a sessile cruralium distinguishes this material from Camerella which has a cruralium duplex. A difficulty about placing this species in the Parastrophinidae is the absence of a fold and sulcus. All the other evidence, however, suggests placing the species in ParastrophineUa. It clearly does not belong in Branconia which has a strong septum in both valves. The ribbing is quite dififerent from A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 199 Anastrophia although the form of the spondylium agrees. In the dorsal interior it is not known whether the sockets are deep as in that genus, or whether there are wing-like processes on the outside of the outer plates. A low ridge is not present between the outer plates as in Anastrophia, but the adductor muscle scars agree. From Parastrophina, this material differs in not having a strong median septum in the dorsal interior, and in having the spondyUum sessile for part of its length in the ventral interior. Within Parastrophinella, P. lenticularis (E. Billings 1866) is less globose but has a spondylium, sessile for most of its length and sometimes raised on a septum anteriorly. The cardinalia are strongly alate with long slightly convergent outer plates forming a sessile cruralium. This is a condition not unlike the Welsh material but differing in the convergent outer plates among other points. P. latiplicata (Hall and Clarke 1894) is externally similar, but has a septum in the dorsal interior; this condition is also seen in P. multiplicata (Hall and Clarke 1894); while 'mP. divergens (Hall and Clarke 1894) the outer plates are convergent and the shell is more transverse. P. ops (Bilhngs 1865) is thought by St. Joseph (1941) to be a synonym of P. reversa (Billings 1857) which is costate with the costae reaching a considerable distance back on the shell. There is also a prominent fold and sulcus with a deep anterior plication and internally there are also several differences. This material appears to resemble to some extent the new genus Parallelasma Cooper (1956) from the Pratt Ferry Formation, Alabama. That it should do so is interesting indeed since it is the earliest known genus of the Pentameridae (Cooper 1956). Points of resemblance are: the paucicostate exterior and the multiplicate anterior commissure, though there is no evidence in the Welsh material for the elaboration of the anterior commissure seen in Cooper’s genus. In the dorsal interior of the Welsh material the cruralium is almost vestigial and in this resembles the appearance of Parallelasma with its long slender brachiophore plates. Points of difference are: the long deep sockets and large fulcral plates of Parallelasma and, of course, the unique anterior commissure. Although uncertain. Cooper believes the muscle scars of the dorsal valve of Parallelasma to lie within the notothyrial cavity. This is a point of great importance in the distinction between the pentamerid and syntro- phid organization. Whether this material could be regarded in any sense as ancestral to the Parallelasma- tidae is open to considerable doubt, especially when the two occur so far apart geo- graphically. The resemblance is there and in time Parastrophinella parva occurs a short time before Parallelasma petagonwn Cooper (1956), the only known species. In 1932 Schuchert and Cooper suggested that the Pentameracea might be derived from the Camerelhdae, which have since had the Parastrophinidae split off from them by Ulrich and Cooper (1936 and 1938). It may be suggested that the Parastrophinidae and in particular the genus Parastrophinella might be ancestral to the Parallelasmatidae. Parastrophinella costata sp. nov. Plate 21, figs. 1 1-15 Derivation of name. Latin, costata, having many lines of rib-like ridges; on account of the many ribs in this species. 200 PALAEONTOLOGY, VOLUME 4 Length (mm.) Breadth (mm.) Depth (mm.) Holotype. A 46877, PI. 21, fig. 14. Internal mould of ventral valve ........ 4-5 7 2 Paratypes. 1. A 46876, PI. 21, fig. 13. Dissected internal mould of ventral valve ...... 6 7 2 2. A 46875a, PI. 21, fig. 15. Internal mould of dorsal valve ........ 5 6 2 3. A 35415, PI. 21, figs. 11, 12. Internal mould of dorsal valve ....... 5 6 2 Material. Dorsal and ventral internal moulds, and dorsal external mould, 1 1 specimens in all. Type localities. Holotype and paratype 1 from SJ 12262802, 35 yards north of Nant; paratype 2, SJ 12172815, 200 yards north-north-west of Nant; paratype 3, SJ 12272807, 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Diagnosis. Very small size, large number of ribs, 13-22, spondylium mainly sessile but with very short median septum anteriorly. Description. Exterior: both valves strongly convex, hinge-line narrow, greatest breadth half to two-thirds the way forward. Anterior slightly convex almost straight, sides convex at first then tapering almost straight to the umbones. Anterior commissure uniplicate, sulcus in the ventral valve and weak fold in the dorsal. Ventral interarea apsacline to- wards orthocline ; dorsal interarea curved, anacline towards orthocline. Surface smooth posteriorly except for a small number of concentric corrugations. Anteriorly 13-22 costae which extend about one- third the way to the umbo. Dorsal interior: notothyrial cavity deep and without a cardinal process, with little or no secondary thickening on the floor, making the presence or absence of a cruralium almost impossible to detect. Two long outer plates are parallel or very slightly divergent and are about one-third the length of the valve. They have external alae but are otherwise not known above the floor of the valve. Crura (?) short, sockets fairly large, no fulcral plates. Muscle scars not known. Ribbing seen on the peripheral one-third anteriorly. Ventral interior: teeth small with strong dental plates which form a large spondylium, sessile for most of its length, but rising anteriorly where there is a very short median septum. The spondylium extends for almost half the length of the valve but does not rise far above the floor at the anterior. Muscle scars not seen. Ribbing is strongly marked at the anterior. Remarks. The almost completely sessile nature of the spondylium precludes this species being placed in either Parastrophina or Anastrophia. Apart from being much more con- vex in both valves this material is quite similar to P. lenticiilaris (Billings 1866); points of similarity include the spondylium, sessile for most of its length, alate cardinalia, and not too prominent fold and sulcus. Superfamily rhynchonellacea Schuchert 1896 Family camarotoeceiidae Schuchert and Le Vene 1929 Genus rostricellula Ulrich and Cooper 1942 A. R. MACGREGOR; UPPER LLANDEILO BRACHIOPODS 201 RostricelhiJa triangularis Williams Plate 21, figs. 16, 17 1949 Rostricellula triangularis, Williams, p. 235, pi. 11, figs. 15-18, text-fig. 5. Lectotype (here selected). Geological Survey Museum, London, GSM 75229, internal mould of dorsal and ventral valves interlocked. Williams, 1949, p. 235, text-fig. 5. Material. Three dorsal internal and one dorsal external moulds. Locality. SJ 12272807, 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, Mont- gomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Description. Exterior; about as wide as long, dorsal valve strongly convex with a gentle fold. Surface ornament of twelve strong radiating plications. Dorsal interior: hinge-line short and curved; a median septum passes forwards on to one of the plications. Posteriorly the septum splits to pass round a very small septalium which does not contain a cardinal process. The sides of the septalium pass up into the crural bases. Outside these are very tiny sockets. The inside of the valve is heavily im- pressed by the ribbing. Ventral valve not known. Remarks. Apart from being even smaller than the Llandeilo district material there do not appear to be any differences. Length Breadth (mm.) (mm.) Llandeilo material ...... 8-5 10 Berwyn material ....... 4 3 Superfamily plectambonitacea Cooper and Williams 1952 Family plectambonitidae Kozlowski 1929 Subfamily sowerbyellinae Opik 1930 Genus sowerbyella Jones 1928 Sowerbyella antiqiia Jones Plate 23, figs. 1 1-15 1928 Sowerbyella antiqua, Jones, p. 419, pi. 21, figs. 7-11. Lectotvpe (selected by Spjeldnaes 1957). Geological Survey Museum, London, GSM ZllSlb, Jones 1928, pi. 21, fig. 11. Material. Dorsal and ventral internal and external moulds, total about 800 specimens. Localities. Almost every exposure of the Llandeilo in the Iwrch Valley, Rhaiadr Valley, and Llangynog Inliers. Horizon. Upper Llandeilo, Calcareous Ash, Limestone and Calcareous Shale. Description. After Jones 1928. Exterior: shell small, outline semicircular, the posterior margin slightly curved. The ventral valve moderately convex, the dorsal valve weakly concave, the umbo small and erect. Surface covered by rounded threads, five or six in 202 PALAEONTOLOGY, VOLUME 4 1 mm. ; every second or third slightly more prominent than its neighbour, but no clear differentiation into sets. Dorsal interior: the muscle area is slightly raised above the level of the rest of the interior, especially at its anterior margin. The crural bases are very short; the median septum does not extend to the cardinal process ; the submedian septa are well defined, but the transverse septa are absent. Each muscle impression is clearly divided by a longitudinal ridge. The whole muscle area is traversed also by coarse longitudinal ridges and furrows which are less prominent than the characteristic septa. Ventral interior: there are two very short diverging muscle impressions, each divided by a faint longitudinal groove. The adductor impressions cannot be distinguished. Obscure papillae occur over most of the interior. Ventral valve (nmi.) Ventral valve (mm.) Dorsal valve (mm.) Width 8-9 10-8 8-9 Length ...... 4-5 7-0 5-1 Width/length ..... 0-50 0-65 0-56 (Figures after Jones 1928, p. 419.) Remarks. WilHams (1949) set up the variety S. antiqiia llandeiloensis and the following differences from S. antiqua were cited: externally the ribbing is finer with primaries developed, seven to eight ribs/mm. with every fourth or fifth accentuated. The outline is EXPLANATION OF PLATE 23 The photographs except fig. 1 1 are of natural external and internal moulds and of plastic moulds made from these. They are unretouched, but the specimens were lightly coated with ammonium chloride before being photographed. Figs. 1-10. Macrocoelia llandeiloensis (Davidson). 1-7, From Quarry, 125 yards south-east of Bryn- glas, 450 yards east of Llan Mill, 1 mile west of Lampeter Velfrey, Pembroke. 1, 2, GSM 87336 b, internal mould of ventral valve and plastic mould, x 1-4. 5, GSM 87336 a, internal mould of dorsal valve, X 1-5. 3, 4, Normal and posterior views of plastic mould of dorsal valve, showing cardinal process and chilidium, X 1-5. 6, GSM 87336 c, external mould of dorsal valve, X T5. 7, GSM 87336 D, external mould of ventral valve, x2. 8, 10, From 400 yards east-north-east by north of Carnedd-y-forwyn, 2 miles north of Llanrhaiadr-ym-Mochnant. 8, A 46892, internal mould of ventral valve, X 1-5. 10, Plastic mould of A 46889, internal mould of dorsal valve of gerontic individual, X T5. 9, From 100 yards south-west of Tyn-y-llwyn, 2| miles north-west of Llanrhaiadr-ym- Mochnant, A 46890, fragmentary internal mould of dorsal valve, X T5. Figs. 11-15. Sowerbyella antiqua Jones. 11, From 100 yards south-south-west of Tyn-y-llwyn, 2|- miles north-west of Llanrhaiadr-ym-Mochnant, A 46883, exterior of ventral valve, x3. 12, From 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, A 46880, internal mould of ventral valve, x3. 13-15, From 80 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant. 13, Plastic mould of A 46881, internal mould of ventral valve, X 3. 15, 14, A 46882, internal mould and plastic mould of dorsal valve, x 3. Figs. 16, 17. IDactylogonia sp. 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym- Mochnant. 16, 17, Normal and side views of plastic mould of A 46888, internal mould of dorsal valve, X 2. Fig. 18. ICyrtonotella sp. 35 yards north of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant, normal and side view of plastic mould of A 46850, external mould of ventral valve, x 3. Palaeontology , Vol. 4. PLATE 23 MacGREGOR, Llandeilo brachiopods A. R. MACGREGOR; UPPER LLANDEILO BRACHIOPODS 203 semi-oval and the hinge-line is winged. The size is considerably greater. Internally all characters are emphasized with reference to 5". antiqua, e.g. the umbonal region of the ventral valve is deeper, the elevation of the muscle area in the dorsal valve is greater and the pustules are larger. Dimensions of S. antiqua Ikmdeiloensis Williams (after Williams 1949, p. 234): Ventral Ext. Own.) Dorsal Ext. Own.) Ventral hit. Own.) Dorsal hit. Own.) Length .... 80 70 80 70 Width .... 15-5 140 170 140 Length/width 0-47 0-50 0-51 0-50 S. antiqua llandeiloensis is very abundant in the Llandeilo district where it marks a definite horizon in the Lower Llandeilo. In the Llandeilo of the Berwyn Hills, S. antiqua is an abundant species and the size ranges from that given by Jones to that given by Williams. Recently Spjeldnaes (1957) has stated that S. antiqua llandeiloensis Williams is a distinct species which he calls S. llandeiloensis. Since this is in disagreement with the findings of the present work, a re-examination of Sowerbyella antiqua Jones and Sowerbyella antiqua llandeiloensis Williams has been made. The results are given below. They are based on an examination of the type material of both the species and its variety from the Geological Survey Museum, London, topotype material of both and some 800 specimens at present attributed to ‘5. antiqua' from the Berwyn Hills, North Wales. External characters: Williams states that the variety has a semi-oval outline while Jones states that the species has a semicircular outline. Williams’s dorsal interior GSM 75269 is distinctly semicircular nevertheless. There is a considerable degree of variation in his material and in that of Jones, and also in the topotype material of both; both con- tain semicircular and semi-oval specimens. The ribbing in Jones’s material answers to his description, but the more prominent ribs are more persistent towards the umbo than is apparent from his description. The ribbing is not dissimilar to that described by Williams. The material from the Berwyn Hills suggests that there is a complete range of variation from that described by Jones to that described by Williams. Ventral interior: Williams states that the septal groove dividing the adductor impres- sions is more prominent in his variety than it is in the species described by Jones. Jones states that the adductor scars cannot be distinguished. It seems likely that Williams meant the septal groove dividing the diductor scars and not the adductor scars. On the interior of the shell this is a slight ridge lying between two shallow grooves. It is not always present though it does occur on both type specimens. The slightly divergent dental lamellae occur in both forms. Dorsal interior: the muscle scar is essentially the same in both the species and the variety even in considerable detail apart from the slightly raised anterior mentioned by Williams. Again the Berwyn material suggests that there is a range between the two. Spjeldnaes (1957) points out that there are oval smooth ridges not composed of pseudopunctae in S. antiqua Jones. Examination of Jones’s material shows that these do not extend to the anterior of the muscle scar, but are seen only laterally. A weak ridge 204 PALAEONTOLOGY, VOLUME 4 extends from the anterior of this ridge backwards and inwards towards the cardinal process. This would appear to be the oval area referred to by Spjeldnaes, but exactly the same two ridges are to be seen on the muscle scar in Williams’s variety. The anterior of the muscle scar in both the species and the variety is coarsely pseudo-punctate. A strong median septum is present in both, and is, in both, bordered by two submedian septa almost immediately adjacent to it. Conclusion. The two should be united as a single species containing within it the variation from Jones’s original material to that subsequently described by Williams, since the two seem to merge without any hard and fast distinction being possible. Superfamily strophomenacea Schuchert 1896 Family leptaenidae Cooper 1956 Genus dactylogonia Ulrich and Cooper 1942 Remarks. Spjeldnaes (1957) regards the genus as synonymous with Oepikina, but the following differences may be noted : Dactylogonia has a more strongly pustulose interior, a smaller ventral muscle scar and is more strongly geniculate. ? Dactylogonia sp. Plate 23, figs. 16, 17 Material. Internal and external moulds of one dorsal valve. Locality. SJ 12172815, 200 yards north-north-west ofNant, 1 mile north of Llanrhaiadr-ym-Mochnant, Montgomeryshire. Horizon. Upper Llandeilo, Calcareous Shale. Description. Exterior; dorsal valve only. Gently concave and strongly geniculate, rather wider than long with the greatest width at about half-way forward. Geniculation at about three-fifths way forward, greatest depth at about half-way forward. Anterior profile gently concave until the geniculation, then steeply bent towards the dorsal valve. Cardinal angles obtuse, interarea not known. Costellate with every third or fourth rib accentuated. Dorsal interior: cardinal process bifid, standing sharply above the floor of the valve, cleft to its base, the two parts being some distance apart. Lateral ridges not prominent, extending forwards from the small brachiophores as ridges round the posterior part of the adductor scars. Muscle scar raised slightly anteriorly, radially fluted with two pairs of radial ridges moderately well developed, the more median pair being rather weaker ; scar about three-eighths the length to the geniculation. There is a slight pit at the pos- terior end of each of the adductor scars on either side of the weak median ridge and immediately anterior to the lobes of the cardinal process. The anterior and pos- terior adductor scars are not separable; the scar is frilled anteriorly and laterally. The remainder of the interior of the valve is strongly pustulose as far as the geniculation, beyond there it is less densely pustulose. At the geniculation there is a submarginal thickening and this is radially fluted. Remarks. There is a considerable resemblance to D. obtiisa Cooper and the differences seem quite small so far as the dorsal valve goes. The American species has the cardinal A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 205 process smaller and has more strongly developed adductor ridges. In almost all other respects the two dorsal valves are similar. Without further material nothing more can be said about resemblances. The genus has not previously been recorded outside North America where it is quite widely dis- tributed in rocks of this and slightly later age. Family strophomenidae King 1846 Subfamily strophomeninae Williams 1953 Genus rafinesquina Hall and Clarke 1892 Rafinesquina simplex sp. nov. Plate 22, figs. 11-16 Derivation of name. Latin simplex, simple or plain. Length (mm.) Breadth (mm.) Depth (mm.) Holotype. A 46887 a, b, PI. 22, figs. 12, 1 3. Incomplete external and internal mould of ventral valve . 17+ 40 3 Paratypes. 1. A 46885, PI. 22, fig. 11. Internal mould of ventral valve ........ 32 38 5 2. A 46884, PI. 22, fig. 14. Internal mould of dorsal valve ........ 23 30 1 3. A 46886, PI. 22, fig. 15. Internal mould of ventral valve ........ 32 30 3 4. A 35416, PI. 22, fig. 16. External mould of ventral valve ........ 30 24 3 Type localities. Holotype from SJ 12172815, 200 yards north-north-west of Nant, 1 mile north of Llanrhaiadr-ym-Mochnant; paratypes 1, 2, and 3 from SJ 07762642, 400 yards north-north-east of Siambr, 3 miles west of Llanrhaiadr-ym-Mochnant, Montgomeryshire, paratype 4 from SJ 12582848, 960 yards north-west of Plas-yn-glyn, 1 mile north-north-east of Llanrhaiadr-ym-Mochnant, Mont- gomeryshire. Material. Internal and external moulds of dorsal and, much more commonly, ventral valves, sixty specimens in all. Horizon. Upper Llandeilo mainly in Calcareous Ash, less commonly in Limestone and Calcareous Shale divisions. Diagnosis. Typical of the genus, with weakly ridged ventral muscle scar, broad shallow peripheral ridge in both valves, greatest width at the hinge-line and with a small pseudo- deltidium. Description. Exterior: wider than long, almost semicircular in appearance, greatest width at the hinge-line with cardinal angles 70°-90°, sides and anterior rounded. Plano- or slightly concavo-convex, the ventral valve gently and uniformly convex. Ornament of fine costellae, increasing by splitting; the primary costellae cease to be prominent after about 1 5 mm. from the umbo and the costellae are then almost equal in size. At 15 mm. from the umbo five to seven secondaries occur between the primary costellae. Con- centric wrinkles on the shell absent, but extremely fine concentric ornament of the shell can be seen in well preserved material. Ventral interarea apsacline, becoming almost 206 PALAEONTOLOGY, VOLUME 4 catacline laterally, about 2 mm. high with well developed growth-lines. Wide delthy- 'i rium with small arched apical pseudo-deltidium. Dorsal interarea low, anacline, chili- ) dium present. ! Dorsal interior ; cardinal process bifid on a very slightly elevated notothyrial platform. Brachiophores short, narrow and small, lying very close to the cardinal process and | with very small sockets lateral to them. Passing antero-laterally from the brachiophores j are two low ridges, one on either side, and these join posteriorly with a low median ridge j in front of the cardinal process to give the anchor-shaped mass characteristic of the < rafinesquinids. There is a suggestion of a second pair of lateral ridges anterior to the first pair and nearer the mid-line. Adductor scars present as vague depressions on either , side of the median ridge. They appear to be separated into anterior and posterior scars by ill defined transverse ridges. There is, round the periphery, a faint thickening of the shell, and also peripherally a faint impression of the ribbing. i Ventral interior: teeth large with short divergent dental plates, continued for a short distance anteriorly as boundaries to the deeply impressed muscle scar which consists of two subtriangular diductor scars bounding laterally a narrow adductor scar, divided down the middle and broadening slightly anteriorly. The anterior of the muscle scars slightly frilled and the surface of the scars with radial ridges. Scar about two-fifths the length of the valve. The inner surface of some specimens shows the ribbing weakly; in others there is a coarse pustulose surface especially near the periphery where the pus- ’ tules show a radial arrangement. Abroad gentle sub-peripheral ridge is present. Vascular sinuses not seen. Remarks. The material most closely resembles R. expansa (Sowerby) which can, how- ever, be distinguished from this species on the following grounds: the ventral muscle i scar is prominently ridged; the vascular sinuses are prominent on the ventral interior; ! there is no sub-peripheral thickening on either valve; the greatest width is one-third to half-way forward from the hinge-line; the delthyrium appears to be open and a pedicle callyst is present posterior to the muscle scar. The contemporary MacrocoeJia llandeiloensis (Davidson) can at once be distinguished by the much larger ventral muscle scar and the adductor ridges in the dorsal valve. This is an early species of Rafinesquina coming before the common occurrence of the genus in the Caradoc. The genus is said to occur at various areas of Llandeilo outcrop li but nothing is known of these occurrences at present. | Genus macrocoelia Cooper 1956 j: Macrocoelia llandeiloensis (Davidson) l;| Plate 23, figs. 8-10 | 1871 Strophomena compressa var. (?) llandeiloensis, Davidson, p. 316, pi. 46, figs. 11-14. | Material. Sixty-four specimens, mainly ventral valves, both external and internal moulds. Localities. SJ 11952879, 400 yards east-north-east by north of Camedd-y-forwyn, li miles north of Llanrhaiadr-ym-Mochnant, Montgomeryshire; SJ 07762642, 400 yards north-north-east of Siambr, 3 miles west of Llanrhaiadr-ym-Mochnant, and many other outcrops in all three inliers of Llandeilo rocks. t Horizon. Upper Llandeilo, Calcareous Ash division only. ! A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 207 Remarks. The material collected in the Berwyns Llandeilo corresponds closely with the topotype material of this species, described in the Appendix. The following differences were noted. The Berwyn material has the ribbing slightly more marked on the interior of the valves; the adductor ridges are rather more prominent in the dorsal valve, this being a greatly accentuated feature in thickened, old specimens ; the sub-peripheral ridge is slightly more prominent, another feature that is accentuated in old thick specimens. The species is a long ranged one, first appearing in Upper Llanvirn rocks in the Llan- deilo District (Williams 1953) and persisting little changed as far as the Upper Llandeilo of the Berwyns. It is also recorded by Whittard (1931) from the Welsh Borders. APPENDIX Description of Macrocoelia Ilandeiloensis (Davidson) based on topotype material in the collections of the Geological Survey, London, specimen GSM 87336 A, b, c, d. It has not been possible to trace the specimens on which Davidson’s description was based. Macrocoelia Ilandeiloensis (Davidson) Plate 23, figs. 1-7 1871. Strophomena compressa var. (?) Ilandeiloensis, Davidson, p. 316, pi. 46, figs. 11-14. Material. Length (mm.) Breadth (mm.) Depth (mm.) PI. 23, figs. 3-5, GSM 87336a. Internal mould of dorsal valve . 22 26-5 1-5 PI. 23, figs. 1, 2, GSM 87336b. Internal mould of ventral valve . 25-5 29 3 PI. 23, fig. 6, GSM 87336c. External mould of dorsal valve 16 20 1 PI. 23, fig. 7, GSM 87336d. External mould of ventral valve 12 16 1-5 Locality. SN 14501413, quarry, 125 yards south-east of Bryn-glas, 450 yards east of Llan Mill, 1 mile west of Lampeter Velfrey, Pembroke. Horizon. About 30 feet above the base of the Llandeilo of this area. Diagnosis. As for the genus, but with very fine adductor ridges in the dorsal valve, a small pedicle callyst in the ventral valve; weakly concavo-convex with neither valve strongly curved. Description. Exterior: about medium size for the genus, weakly concavo-convex, almost plano-convex. Hinge-line straight, cardinal angles 100° ±10°, sides and anterior curved with greatest width about a third of the way forward from the hinge-line; width/length: 6/5. Ventral valve most strongly convex near the umbo and only gently so anteriorly and laterally, interarea low apsacline. Dorsal valve most strongly concave near the umbo, almost plane anteriorly and laterally; interarea low anacline, almost as large as that in the ventral valve ; ornament of fine costellae without marked differentiation into primary and secondary ; concentric ornament practically absent, little more than weak growth-lines. Dorsal interior: cardinal process bifid, tapering posteriorly, on a raised notothyrial platform, and abutting against the arched chilidium. Brachiophores very small, defining 208 PALAEONTOLOGY, VOLUME 4 moderate-sized sockets outside them. Low ridges extend for a short distance antero- laterally from the brachiophores and also form part of the notothyrial platform. The median ridge of the notothyrial platform is extended anteriorly as a very low, wide, gentle ridge for about one-quarter length of the valve. Two radial dorsal lateral ridges are present on either side of a weak median ridge which lies between one-quarter and half-way towards the anterior margin. A more lateral pair of ridges lie about one-quarter of the way to the antero-lateral margin and are inclined at about 30° to the mid-line. The boundary of the adductor scars is ill defined but probably lies along the slightly elevated area on which the radial dorsal lateral ridges occur. These ridges though distinct are not prominent in this material. A subperipheral ridge is present and this is weakly fluted radially. It is less well developed in the dorsal valve than in the ventral. Posteriorly it swings towards the mid-fine before merging with the hinge-line just lateral to the sockets. Ventral interior: delthyrium open, teeth large with small, strongly divergent, dental plates which pass forward into weak ridges bounding the posterior margin of the very large muscle scar. The muscle scar extends for about half the length and two-thirds of the breadth of the valve. It consists of two large radially ridged diductor scars bounding the long narrow adductor scars which posteriorly are divided by a low median ridge that becomes finer anteriorly before splitting into a double ridge which persists for the rest of the length of the scar. At the posterior of the muscle scar is a small pedicle callyst. Peripherally there is a ridge of shell material. This is radially fluted and beyond it the i ribbing of the shell is well marked. The ribbing cannot be made out inside this ridge though weak radial ridges similar to those on the muscle scar do occur. Fine pseudo- punctae can be seen on the inner surface of the shell; they are not arranged in any regular pattern and form a dense mat. Traces of the vascular system can be seen in the postero- lateral corners of the ventral valve. Remarks. The genus Macrocoelia is very similar to Oepikina Salmon, but the presence of weak adductor ridges in the dorsal valve, together with the ridge in the adductor scar and the open delthyrium in the ventral valve serve to place this species in the former genus. The genus is known from the contemporary rocks in the Appalachian region as is Oepikina which also occurs in the contemporary beds in Estonia. REFERENCES BANCROFT, B. B. 1928. The Harknessellinae. Mem. Manchr. lit. phil. Soc. 72, 173-96, pi. 1, 2. 1945. The brachiopod zonal indices of the Stages Costonian to Onnian in Britain. /. Paleont. 19, 181-252, pi. 22-38. COOPER, G. A. 1956. Chazyan and related brachiopods. Smithsonian Misc. Coll. 127, 1-1245, pi. 1-269. DAVIDSON, T. 1871. British Fossil Brachiopoda. 3, Devonian and Silurian Species, Pt. 7. Palaeont. Soc. 24, 249-397, pi. 38-50. FOERSTE, A. G. 1909. Fossils from the Silurian Formations of Tennessee, Indiana and Kentucky. Bulk sci. Labs. Denison Univ. 14, 61-116, pi. 1-4. 1914. Notes on the Lorraine Faunas of New York and the Province of Quebec. Ibid. 19, 247- 339, pi. 1-5. 1920. The Kimmswick and Plattin Limestones of northeastern Missouri. Ibid. 19, 175-224, pi. 1-3. HAVLiCEK, V. 1950. The Ordovician Brachiopoda from Bohemia. Rozpr. Ustr. Ust. Geol. Praha. 13, 1-133, pi. 1-13. A. R. MACGREGOR: UPPER LLANDEILO BRACHIOPODS 209 JONES, o. T. 1928. Plectambonites and some allied Genera. Mem. Geol. Siirv. Palaeont. 1, 367-527, pi. 21-25. KAY, M. 1958. Ordovician Highgate Springs sequence of Vermont and Quebec and Ordovician Classifi- cation. Amer. J. Sci. 256, 65-96. MCEWAN, E. D. 1919. A Study of the brachiopod genus Platystrophia. Proc. U.S. nat. Mas. 56, 383-448, pi. 42-52. ■OPiK, A. 1930. Brachiopoda Protremata der Estlandischen Ordovizischen Kukruse-Stufe. Acta Univ. ciorpat. (tartu.). 17, 1-262, pi. 1-26. REED, F. R. c. 1917. The Ordovician and Silurian Brachiopoda of the Girvan District. Trans, roy. Soc. Edinb. 51, 795-998, pi. 1-24. SAiNT-JOSEPH, J. K. 1941. The brachiopod family Parastrophinidae. Geol. Mag. 78, 371-401. SALMON, E. s. 1942. Mohawkian Rafinesquinae. Jour. Paleont. 16, 564-603, pi. 85-87. SCHUCHERT, c. and COOPER, G. A. 1932. Brachiopod Genera of the Suborders Orthoidea and Penta- meroidea. Mem. Peabody Mas. Yale. 4, 1-270, pi. 1-29. SPJELDNAES, N. 1957. The Middle Ordovician of the Oslo Region, Norway. 8, Brachiopods of the Suborder Strophomenida. Norsk, geol. Tidsskr. 37, 1-214, pi. 1-14. STUBBLEFIELD, c. J. 1939. Somc Devonian and supposed Ordovician fossils from southwest Cornwall. Bull. Geol. Surv. 2, 63-71, pi. 4. ULRICH, E. o. and cooper, g. a. 1936. New Genera and Species of Ozarkian and Canadian brachiopods. J. Paleont. 10, 616-31. 1938. Ozarkian and Canadian Brachiopoda. Spec. Pap. geol. Soc. Amer. 13, 1-323, pi. 1-57. WEDD, c. B., SMITH, B., KING, w. B. R. and WRAY, D. A. 1929. Explanation of Sheet 137. The Country around Oswestry. Mem. Geol. Surv. 1-234. whittard, w. f. 1931. The geology of the Ordovician and Valentian rocks of the Shelve Country, Shropshire. Proc. Geol. Ass. 42, 322-39, pi. 10, 11. WHITTINGTON, H. B. and WILLIAMS, A. 1955. The fauna of the Derfel Limestone of the Arenig District, North Wales. Phil. Trans, roy. Soc. Ser. B, 238, 397-430, pi. 38^0. WILLIAMS, A. 1949. New Lower Ordovician brachiopods from the Llandeilo-Llangadock District. Geol. Mag. 86, 161-74, 226-38, pi. 8, 1 1. 1953. Geology of the Llandeilo District, Carmarthenshire. Quart. J. Geol. Soc. London, 108, 177-208, pi. 9. WILSON, A. E. 1913. A new brachiopod from the base of the Utica. Bull. Victoria Mem. Mus. 1, 81-86, pi. 8. A. ROY MACGREGOR Department of Geology, The University, St. Andrews, Fife. Manuscript received 20 May 1960 SOME ADDITIONS TO OUR KNOWLEDGE OF ANTIARCHS by D. M. S. WATSON Abstract. The author has in his collection some uncrushed antiarch material which is very beautifully pre- served. This has enabled him to determine the shape of Bothriolepis with real certainty, and to describe the | muscle insertions on the helmet process, and thus interpret their function. The material also shows the oper- cular plate, and its relation to the branchial cavity, thus suggesting the probable nature of the gill arches, and enabling them to be compared with those of other groups. The remarkable group of Old Red Sandstone ‘fish’, the Antiarehi, of which the oldest , known member is Pterichthyodes, has now been very completely described and analysed by a succession of authors, from Agassiz who named Pterichthyodes [Pterichthys], and , Eichwald who named Asterolepis and Bothriolepis, to Stensio. Traquair (1894) made out the external structure of the limb in many forms; Gross (1931) gave an admirable account of the structure and mechanics of the limb in Asterolepis', Stensio (1948, 1959) has given a full and detailed account of the Canadian Bothriolepis canadensis; but some | material in my own collection, from Russia and Scotland, seems to add a little to our ; knowledge, especially of the musculature of the limb, and the shape of the body. SHAPE OF BODY Bothriolepis panderi Lahus (P. 533) from the D3 Shelon Beds, Syas River, Stolbovo, U.S.S.R., given me by Professor Obruchev, is remarkable because it is very little crushed i or distorted (text-fig. 1). Although its right side has suffered a httle depression it still, ^ taken as a whole, shows the real shape of the head and anterior part of the body more j clearly than any other individual known to me. Furthermore, it is a very small (i.e. | young?) individual, the total width across the head shield being of the order of 4 cm., in i contrast to some 6-5 cm. in a rather small B. canadensis. It is of markedly pentagonal section across the body; the ventral surface, which rounds into the lateral surfaces, is essentially flat, the side walls pass upwards and outwards, and there is a distinct median , ridge along the anterior median dorsal plate, continued eventually on the incomplete posterior median plate. Gross’s reconstruction of Asterolepis (1931) is an admirable illustration of the shape of this form, which is somewhat deeper, and is confirmed by the evidence of a small specimen from Nairn of A. maxima (P. 67) also complete and un- distorted. PECTORAL FIN Specimen P. 533 has the beautifully preserved proximal part of each arm in articula- tion with its helmet process (Stensio ’s processus brachialis). The arms lie closely along the sides of the body in an extreme backward position, and slope down towards the bottom. The denticulated hinder border of the arm plate for most of its length is separ- | ated from the ventrolateral plate by a small space of the order of a millimetre, the arm becoming progressively flattened as it approaches the elbow. The helmet process of the [Palaeontology, Vol. 4, Part 2, 1961, pp. 210-20.] D. M. S. WATSON; SOME ADDITIONS TO ANTIARCHS 211 River, Stolbovo, U.S.S.R., collected by Professor D. Obruchev; natural size. The anterior end of a small individual, essentially uncrushed, which shows the shape of the animal better than any other I have seen; A, left lateral, B, right lateral, C, anterior, D, posterior aspects. The gill chamber is here uniquely preserved; the left operculum is present, a little misplaced dorsally and posteriorly, the right is absent, exposing the posterior wall of the gill chamber which is carried on the anterior ventro-lateral. The rounded process of the lateral plate which fits into the opercular notch is well shown on the right side; it is partly hidden on the left by the inturned anterior projection of the opercular. Both pectoral appendages are in natural articulation, brought as close to the body as pos- sible. The left shows the presence in section of a hollow structure (End.), which is D-shaped, and appears to represent a cartilaginous axis with a superficial investment by bone. Between this axis and the super- ficial bone the upper half of the cavity is completely filled with a white calcareous mass, obviously deposited from solution in an empty space. The lower part of the cavity, including that within the axis, is filled by red mud. The right arm is cut across farther along its length, but contains two quad- rangular pieces of the white calcareous infilling described above, embedded in a normal red mud in- filling. The helmet process, obscured by matrix on the left side, is welt seen on the right, where the wide space between the articular parts of the two proximal arm plates shows how considerable was the freedom of motion up and down, and presumably rotationally, of the arm. Adi, anterior dorso-lateral; Adm., anterior median dorsal; Ard., dorsal articular; Arv., ventral articular; AvL, anterior ventro- lateral; Calc., calcite infilling in arm; End., axial skeleton of arm; Eac. Art. Proc., seating for the articu- lar process of the opercular; Helm. Proc., helmet process; Ifg., infraorbital sensory canal groove; Lmp., lateral marginal; Ep., lateral; Mv., median ventral; NL, lateral nuchal; Nm., median nuchal; OpL, opercular; PdL, posterior dorso-lateral; Pdm., posterior median dorsal; Pnn., premedian; Proc., the rounded process of the lateral plate which fits into the notch of the opercular; Ptm., post median; PvL, posterior ventro-lateral; SL, sufflaminal. 212 PALAEONTOLOGY, VOLUME 4 TEXT-FIG. 2. Five fragments of Bothriolepis, Upper Old Red Sandstone, Moray, Scotland, natural »| size. 1 1 A, Bothriolepis sp., P. 111a, ? Scaat Craig, left helmet process seen from the side. B, outline of the J ; same, with the muscle insertions shown in plan, and the proximal end of the ventral arm plate belonging • j to it (P. 777b) in place, broken through an internal muscle insertion; the extent of the funnel pit is , | shown by a dotted line; an arrow shows the position of the thin anterior end of the pedicel (Stensio’s U pars pedalis) and the triangular muscle insertion distal to it. C, Bothriolepis sp., P. 779, ? Scaat Craig, i; I right helmet process (orientated to show up surface modelling and the muscle insertions). D and E, ^ Bothriolepis major, P. 625, Scaat Craig, exceptionally large left anterior ventro-lateral plate showing j D. M. S. WATSON: SOME ADDITIONS TO ANTIARCHS 213 right arm is widely exposed through the large notch between the dorsal and ventral proximal arm plates, which are rigidly attached to one another. The ventral arm plate is in contact with the thin anterior end of the pedicel (Stensio’s pars pedalis) of the helmet process, and in this position the outer border of the arm is so far downturned that it alone — if resting on a hard surface — can touch the lake bottom. But, as I shall shortly show, the dorsal arm plate could equally well be in similar contact with the pedicel, thus indicating that the arms were capable of twisting round on their own axes on the helmet process through an angle which may be some 30 degrees; in which case the broad plane of the arm may have stood almost vertically, nearly parallel to the principal plane of the body. In this position the swimming stroke would be effective, whilst in the other extreme position the limb could be brought forward with the least possible resistance from the water. Articulation. The general position of the helmet process in relation to the animal as a whole, which has long been known, and its implications in the determination of the plane of movement of the limb understood, is exceedingly well shown by Stensid (1931, figs. 40-42), and it is evident that there is an extraordinarily accurate fit of the proximal arm plates on the helmet process. Furthermore, Gross (1931) has determined the possible movements of the pectoral fin on the helmet process. I have, however, a beautifully preserved specimen of Bothriolepis (P. 111a and b), from ? Scaat Craig, the famous Upper Old Red Sandstone locality in Moray, Scotland, which shows the fit of the arm plates on the helmet process unusually well. It consists of a helmet process broken off from its pedicel, and one of the arm plates which clasped it, separated and entirely free from matrix, and in consequence shows by trial the extremely accurate way in which the arm plate slides round the process, maintaining contact despite the lack of soft parts (text-fig. 2, A and B). Its range of sliding movement is through about 90 degrees, agreeing with that assumed from the evidence of complete specimens with arms in articulation. At the same time it shows that there is some possibility of rotational movement, for the pedicel is narrow anteriorly, and broadens towards the inturned posterior surface, so that it is wedge-shaped in section. This is particularly well shown in P. 625, a magni- the helmet process somewhat damaged, collected by Professor S. P. Welles; D, from behind and slightly below, showing the unusual auxiliary articular facet; E, from above, showing the floor of the branchial chamber, and the anterior wall of the body cavity. F, Bothriolepis sp., P. 778, ? Scaat Craig, helmet process split through the length of the funnel pit, which received the skeletal axis of the pectoral fin, showing the ossified base (Os. ).G, and H, Bothriolepis sp., P. 783, ? Scaat Craig, proximal end of right ventral arm plate G, outer, H, inner face showing the surface for articulation with the helmet pro- cess. Ant. Inf., antero-inferior muscle insertion; Ant. Sup., antero-superior muscle insertion; Art. Lmp., articular surface for lateral median plate; Art. Bed., articular surface on pedicel; Arv., ventral articular plate of arm (reference line ending in a thickening which is a muscle insertion); Aux. Art. Fac., auxiliary articular facet; B. Ves., blood-vessel; Body Cav., base of partition separating the gill cham- ber from the body cavity; Br. Cav., branchial cavity; Ext. Art., articular surface of proximal arm plate for the outer side of the groove around helmet process ; F. Art. D., upper sliding surface for articu- lation of fin; F. Art. V., lower sliding surface for articulation of fin; F. P., funnel pit; Int. Art. Proc., internal articulation on sliding surface of helmet process; Op., facet for free margin of operculum; Os., ossification at base of funnel pit; Ped. Ant., anterior and outer (thin) end of pedicel; Ped. Post., posterior and inner (thick) end of pedicel; Post. Inf., postero-inferior muscle insertion; Post. Sup., postero-superior muscle insertion. B 9425 P 214 PALAEONTOLOGY, VOLUME 4 ficent helmet process still attached to part of the anterior ventro-lateral plate, completely free from matrix, which Professor S. P. Welles found during the vertebrate palaeontology excursion associated with the International Geological Congress of 1948, and very generously gave to me (text-fig. 2, D and E). In this specimen the pedicel widens from 3-3 mm. at its anterior and outer end to 12-0 mm. posteriorly, 20 mm. separating these points. The bearing surfaces on the pedicel for the arm plates (text-fig. 3, Art. Fed.) form segments of circles, and are quite flat, the helmet process swelling out distal to them, so that the arm was held in place by the contact between the opposed spheroidal surfaces of the helmet process and the inner sides of the two arm plates. These spheroidal sur- faces are unequal in size, the upper being noticeably wider and longer than the lower, as shown in all available specimens. The ‘slot’ between the arm plates for the helmet process is not parallel sided, nor tight fitting, a condition shown by Traquair (1904, figs. 60-61), and confirmed by Gross (1931, pi. 6, figs. 1-2). Thus it is evident that the arm plates embrace the helmet process by concave surfaces allowing sliding movement in one plane of up to 90 degrees, and also rotational move- ment in directions limited by the wedge-shaped pedicel, which, even at its widest, is less than the widest part of the ‘slot’. In the fully advanced position of the arm, when it stands out at right angles to the body, the ‘slot’ would be held on the thick end of the pedicel, and the arm would be incapable of rotation (and probably of up and down movement). But when it was drawn back nearly parallel to the body, its ‘slot’ would surround the thin end of the pedicel, which would provide the conditions necessary for the small rotation of the arm on its axis, perhaps altering the direction of the fin through a small arc. This movement, of course, would have the effect of elevating or depressing the anterior border of the fin, enabling the animal to rise or fall in the water. The tail was obviously capable of enabling the animal to travel forward without the assistance of its pectoral fins, and such was presumably its normal method of progress from place to place. The small size of the mouth parts, described by Stensio (1931, fig. 74) in B. canadensis, implies that it ate food particles, and the essentially uncrushed P. 533 makes it clear that the mouth must lie immediately behind the anterior border of the head shield and face directly downward, so that the animal was a bottom feeder, browsing, as it were, on the floor of the lake or river in which it was living. Auxiliary articular surface. One very curious feature of P. 625, less well shown in P. 780 (a fragment), is the presence on the anterior ventro-lateral, immediately above the highest point of the bearing surface for the upper arm plate, of a smooth apparently articular surface, agreeing exactly in character with that of the helmet process, called by Gross (1931, p. 16) ‘siebknocken’, and described by him as characteristic of movable joints. This area (text-fig. 2, D) lies as a low boss projecting from the floor of a semi- circular depression, which dorsally passes abruptly to the outer surface of the bone, ? whilst anteriorly it grades into it over a rounded surface. The implication is that, when l raised to its highest position, the outer surface of the upper arm plate actually came to | bear upon it, though it is difficult from articulated specimens (e.g. P. 533) to understand 3 how this could have come about. Museulature. The general nature of the anterior ventro-lateral plate is well known and may be understood from Stensio’s account (1931). It should be noted that the large open- D. M. S. WATSON: SOME ADDITIONS TO ANTIARCHS 215 ing {F.Ax.) behind the helmet process, shown by Stensio (1931, fig. 40), is peculiar to Bothriolepis, and is represented as a very much smaller opening in Pterichthyodes where, in an individual whose body carapace is 80 mm. long (C. 44, U.C.L. Coll.) it measures 3-2 mm. by a maximum of 2-5 mm. ; in another specimen (C. 88), in which the carapace IS 91 mm. long, the opening is 5-5 mm. by 2-1 mm. Such foramina are appropriate to house the artery and vein passing out into the limb, but are quite unsuitable in both size 1 TEXT-FIG. 3. Bothriolepis major, P. 625, Scaat Craig. Diagrammatic drawings of a left anterior ventro- lateral plate to illustrate the articulation of the arm with the helmet process, natural size. A, seen postero-laterally, the position of the articular surfaces of the pedicel is shown by broken lines; B, section approximately through X-Y, the ossification in the funnel pit restored from P. 778, the proximal arm plates restored from other specimens; the arm is in its most forward position. Ard., dorsal articular plate of arm; Art. Bed., articular surface on the pedicel; Arv., ventral articular plate of arm; Aux. Art. Fac., auxiliary articular facet; AvL, anterior ventro-lateral plate; Body Cav., a line of dots showing the thickness of the bone, and the extent of the body cavity; Br. Cav., branchial cavity; End., axial skeleton of arm; F. Art. D., upper sliding surface for articulation of fin; F. Art. V., lower sliding surface for articulation of fin; F.Ax., foramen axilare; F.P., funnel pit; For., foramen; Helm. Proc., helmet process; Op., facet for free margin of operculum; Os., ossification at base of funnel pit; Per/., pedicel. and character to permit of the passage of a muscle as well. It seems, therefore, that the whole musculature of the pectoral fin must be internal, lying within the cavity of the fin and in general distal to the helmet process. Of the six helmet processes of Bothriolepis in my collection, one was collected at Scaat Craig, and the others in all probability came from that locality; they represent, in fact, individuals which lived effectively together. The only other helmet process I possess is one of Asterolepis (P. 177) from Livonia, which affords a little confirmatory evidence. The detailed shape of the helmet process may be seen in text-fig. 2, A-D, which supple- ment various published figures, of which perhaps the best are those by Stensio (1931) and Gross (1931, pi. 7), and show the nature of most of the muscle attachments. The surface facing into the cavity of the arm is finished with a thin layer of hard, smooth bone on which muscle insertions take the form of deep, sharply defined pits with a striated or otherwise roughened attachment surface, presumably for ligaments. It is cut off by the 216 PALAEONTOLOGY, VOLUME 4 spheroidal sliding surfaces (F. Art. D. and F. Art. V.) for the proximal arm plates, which bear a characteristic ornament of very delicate, abruptly truncated grooves (‘siebknocken’) identical with the surfaces of the arm plates which shde on them. I do not know anything in modern vertebrates exactly comparable with these articular surfaces, and it is not at all easy to suggest how they arose. The central funnel pit in my specimens is rather more than 6 mm. in diameter, and not always accurately circular; but its irregularities are not consistent, sometimes the hole is asymmetrical in shape, as in the original of text-fig. 2, D, sometimes effectively circular, as in text-fig. 2, A and C. The pit passes down between the sliding surfaces, is conical in section, and in the one case in which its proximal end is well shown (P. 778, text-fig. 2, F) bears a small, firmly attached, upstanding cylinder of bone, rising free for about a millimetre and separated from the walls of the pit by an annular space less than half a millimetre in width. The implication is that this pit housed a cartilaginous axial rod continuing into the arm, as we know from the occasional occurrence of a bony skin coating it, shown in text-fig. 1, D, and by Stensio (1931, fig. 55), and confirmed by the presence in P. 176 of a very thin-walled cylinder of bone, which at its maximum is a little under 3 mm. high, in an arm of about 28 mm. across. How far it extended, and how far it served muscle attachments is unknown. There are five muscle insertions on the helmet process, four of which, on its distal surface, are shown in text-fig. 2, A-D. The fifth is on its anterior face immediately distal to the anterior part of the pedicel, and lies just within the cavity included by the arm plates. Of the insertions on the distal surface the most pronounced are the antero-superior and antero-inferior, which lie respectively above and below the funnel pit, near the front end where the distal surface is widest. These, which are seen on all the available material of Bothriolepis, are each divided into two parts, having a deep insertion, from which a slope passes forward reaching the surface of the helmet process abruptly. The postero-superior muscle insertion is well marked in all the individuals of my series. It is a single attachment, often deeply incised, and lying well back towards the opening of the foramen axillare. The postero-inferior insertion varies somewhat in appearance; in all cases it extends over a considerable distance, and is often divided into three parts. A foramen, or a small group of foramina, evidently for blood-vessels, lies between the insertion of the antero- and postero-superior muscle insertions. The muscle attachment on the anterior face of the helmet process, well shown in Asterolepis by Pander (1857, pi. 6, fig. 2; pi. B, figs. 8a and b), occupies part of an equilateral triangle, lying between the sliding surfaces of the proximal arm plates, the anterior edge of the pedicel which separates them, and the thin, effectively straight, anterior edge of the distal surface of the helmet process. About half-way, or rather more, down the triangular area is a depressed region which is evidently the base of the muscle attachment; its surface is not very different in character, but the foramina which open into it seem to be a little larger than elsewhere, suggesting an increased provision of blood. This area is visible in all the helmet processes available, though it varies slightly, and is best shown in P. 111a and P. 779. Its relation to the arm as a whole is well shown on the right side of P. 533, though it is partly obscured by the lower proximal arm plate. My three proximal arm plates of Bothriolepis from ? Scaat Craig show something of the inner surface and muscle attachments. One, P. 111b, a left, was found in position on D. M. S. WATSON: SOME ADDITIONS TO ANTIARCHS 217 its helmet process, is thus known to be a ventral plate, and agrees well with Gross’s figure of Asterolepis. Towards the posterior edge it shows a muscle insertion in the form of a flat-topped, sand-eroded thickening, arising rather abruptly from the inner surface just distal to the articular part of the bone lying, in fact, within about 3 mm. of the outer surface of the helmet process (text-flg. 2, B). A deep groove proximal to the muscle insertion, and distal to the articulation with the helmet process, has the appearance of housing a blood-vessel. P. 783, a right arm plate (text-fig. 2, G and H), is shown by com- parison with Stensio’s photograph of Asterolepis (1931, fig. 60, B) also to be a ventral plate, and agrees with P. 111b in the general character of its articular surface. But the comparable muscle insertion is not eroded and faces inwards and distally, and it may be noted that the groove just above the reference line Mus. is much deeper than in P. 111. P. 799 is a fragment of a proximal arm plate broken along its length, is probably a ventral, and if so is of the left side. It shows, just distal to the articular surface for the helmet process, a very definite, well preserved muscle insertion forming an irregular bony projection rising abruptly from the inner surface of the plate and facing mesially and distally, thus confirming the condition in P. 783. Stensio’s figures of the dorsal articular plates of Asterolepis (1931) show a possible muscle insertion lying on the inner surface just below the articular extremity on the admesian side; nothing similar is shown in his figure of ventral plates. Gross (1931, pi. 6, fig. 12) shows a muscle insertion labelled "a\ which lies on the inner side of the dorsal plate just distal to its articulation with the helmet process. It seems quite certain that the antero-superior and antero-inferior muscle insertions on the helmet process imply the presence of a dorsal muscle and a ventral one, which must be attached to the inner surface of the arm. The character of these insertions, with their deep basal part and sloping anterior surface, implies that the muscles were directed somewhat laterally, and would thus be attached to dorsal and ventral proximal arm plates respectively, not far from the sliding surfaces. Their joint shortening must pull the arm as a whole forwards, sliding the proximal part of the arm plate backwards round the helmet process, and the action of one alone could rotate the arm slightly on its own axis, a function obviously necessary if the arm is to be used as an oar. The corresponding posterior pair of insertions gives no similar indication of the direction in which the muscles attached to them came out, but the muscles must have passed into the cavity of the arm, and on contraction have had the effect of sliding the arm plate round so that the arm was pulled backward to lie alongside the body. It will be seen from text-fig. 2, B that the muscle insertions on the distal surface of the helmet process only form part of a circle round the funnel pit, and lie in the main behind its centre. It is evident on mechanical grounds that some musculature must be provided to occupy the other half of the circle, and this, presumably, is the function of the muscle which arises from the triangular depression on the front face of the helmet process, immediately lateral to the thin end of its pedicel. The presence of the abrupt edge of the depressed area, and the pitch of the definite roughenings within it, show that a muscle arising from it must have passed outwards over the anterior border of the distal face of the helmet process to be attached to the inner surface of the proximal plates of the arm, and it must be the contraction of this muscle which draws the whole arm forwards without tending to twist it round on its axis. When the lower proximal arm plate P. 111b is rearticulated with its helmet process, it 218 PALAEONTOLOGY, VOLUME 4 is dear that the musde suggested by the insertion on it cannot have arisen from the helmet process. As the attachment area is large, it is natural to assume that the muscle also was important, and it may possibly have accommodated some of the muscles which ' moved the distal part of the limb ; but only examination of a series of well-preserved arm plates can make clear the nature of this musculature. | The right appendage of P. 533 shows beautifully that at its articulation the whole | structure is very nearly circular ; by the end of the anterior ventro-lateral plate it is 1 1 -0 | mm. wide but has already decreased to a depth of 4-6 mm., whilst the arm of the other side, 14-0 mm. from its articulation, is 110 mm. wide and 6-0 mm. in depth, thus show- ing the rapid flattening. The most striking fact which arises from the whole discussion is the conclusion that the resemblance of the Bothriolepis arm to an arthropod limb really implies a similar mus- culature, of a kind not found in any other group of vertebrates; this is interesting as emphasizing the extreme versatility of chordate anatomy. OPERCULAR Bothriolepis panderi. In median section from hinder edge to front the head of P. 533 is almost a quadrant of a circle ; the lateral border stands vertically, the opercular (extra lateral of Traquair, 1904, fig. 34) being attached to its lower edge. The opercular of the left side is displaced outwards and backwards by being squeezed down on to the for- ward part of the anterior ventro-lateral and the arm plate; it is evidently complete, except for a fragment some 3 mm. in length which is stripped off the posterior end, leaving behind it an impression in the matrix. The outer surface of the anterior end of : the opercular turns inwards almost through a quadrant of a circle, forming a nearly straight border. From this anterior region a very definite process passes upwards and I inwards, and there is a matching facet on the lower border of the lateral plate of the head ! to accommodate it (text-fig. 1, C, Fac. Art.Proc.). The process is marked off from the rest i of the plate by a distinct unornamented groove, clearly recessed below the outer surface : of the bone by at least half a millimetre, and passes into the body of the bone without | any change in the character of its ornamented surface. Behind this is the rounded notch ; shown in text-fig. 1, C, which has a cylindrical surface more than 2 mm. in width. It | does not look like an articular surface, and seems in every way fitted to be filled with the j projection Proc. (best seen on the right side) which lies quite laterally on the lateral plate ; ] the rest of the dorsal border of the opercular fits exactly under the remaining ventral margin of the lateral plate. The implication is, therefore, that this plate was indeed a genuine opercular, hinged anteriorly but merely fitting against the hinder part of the lateral margin of the head shield. The upper border of the bone is comparatively thick, its lower border, very thin; it is clearly adapted to fit snugly down against the , anterior ventro-lateral, thus making a watertight gill chamber. Stensio (1947, fig. 13) shows this opercular plate with an opening called ‘spiracle’, which is presumably the notch into which the lower projection of the lateral plate fits. It does not seem to me in the least likely that it is actually a spiracle : indeed to anyone handling my material such an idea would not occur at all. The spiracle in those fish in j which it does occur lies anteriorly and dorsally, and does not form part of the border with which the opercular articulates. Stensio’s ‘ prelateral plate’ (fig. 14) I have never D. M. S. WATSON: SOME ADDITIONS TO ANTIARCHS 219 seen: I strongly suspect it is, in fact, merely that part of the opercular which lies below the inwardly directed process by which the bone articulates with the head shield. The opercular is absent on the right side, thus exposing some part of the almost flat floor, and the incomplete hinder surface of the gill chamber, which is carried entirely on the anterior ventro-lateral plate, and lies immediately in front of the helmet process. P. 625 shows very well the lower surface of part of the gill chamber, and the boss of bone containing the helmet process which is its vertical hinder wall (text-flg. 2, E). A pro- nounced ridge runs forwards and inwards from the boss, and represents the base of the median part of the hinder wall of the gill chamber on to whose posterior surface the trunk musculature was inserted. Bothriolepis canadensis. The opercular of B. canadensis, shown in P. 101, agrees entirely in nature and relative size with that just described in the small Russian form. It shows the internal process, broken and incompletely exposed, behind which is an almost hemispherical notch of small size. The anterior part of its lower border is incomplete, but half-way along it is seen to be thin and very slightly rounded, tapering off until at the hinder end it is a feather edge. Ptericlithyodes. It is interesting to compare the character of the opercular of Bothrio- lepis with that of Ptericlithyodes, which is represented in my collection by P. 339, a nodule from Tynet Burn, Nairn, showing a perfect mould of the visceral surface of the head, and the visceral surface and dorsal margin of the opercular, casts from which show all the details of its structure. The opercular diflfers noticeably from that of Both- riolepis because it has a long, straight dorsal border which was attached to the lateral border of the head shield, and is relatively longer and wider. Towards its hinder end, the thickened dorsal edge of the opercular bears a conical pit extending into its substance, which ends blindly, and is evidently related to some attachment to the head shield. C. 85 (U.C.L. collection), a similar specimen from Lethen Bar, Nairn, which has also been converted into a mould, is less well preserved but confirms the structure described above, though it adds nothing to it. Asterolepis. In Asterolepis (P. 187) the head shield is narrow, and the eyes large and far forward. According to Gross (1931, pi. 12, fig. 7) the opercular is relatively even longer than in Ptericlithyodes and is attached to the whole lateral border of the head shield ; this conception is supported by the appearance of a rather badly preserved, very small speci- men from Nairn (P. 67), probably the most complete Asterolepis known. It may be noted that Gross’s figure shows a notch in the middle of the long upper border of the oper- cular which corresponds with the similar notch (the conical pit) in the upper border of the opercular of Ptericlithyodes. As I have shown above, it seems evident that the opercular bone of Bothriolepis was movable; indeed it may well have had considerable freedom, pivoting round the process from its anterior end which fits into the corresponding pit on the head shield. Its exis- tence and character imply a fish-like set of respiratory movements. In other words the branchial arches must have been provided with a musculature capable of bringing about such rhythmical movements, alternately taking in and discharging water from the branchial region. This branchial region, evidently very short, is wide from side to side, and may well have been quite capacious because the whole head is broad. The brain case of the antiarchs is practically unknown : Gross ’s figure of the dermal 220 PALAEONTOLOGY, VOLUME 4 part of the head of Asterolepis (1931, pi. 12, fig. 7) shows in effect all that is known of it. ' The median nuchal plates of Asterolepis and Bothriolepis (Stensio 1931, figs. 14-18), ■' showing what appears to be the summit of a foramen magnum, suggests that it may have | been comparatively large, and the visceral surface of the Pterichthyodes head shield ' represented by P. 339 bears this out. The brain must, however, have been a remarkable : shape, for the confluence of the orbits above it suggests that it lay well down towards the , roof of the mouth, of whose character we know nothing. In Pterichthyodes, at any rate, j the bone forming the roof of the head is shown by the mould in P. 339 to have been i extremely thick, a maximum in front of the orbits of 4 mm., in a head 30 mm. long. The head of the antiarchs is thus known to some extent in a variety of forms of preser- vation. The position of the branchial arches in Bothriolepis is evident and any spiracular ! opening which existed could be expected to come out, either through a special opening in the head shield, or a notch in its border, which should, in the perfectly preserved | material available, make some definite showing. In fact, in no such material is anything of the kind visible, and the obvious reading is that the first gill slit was of full size, and not reduced to its dorsal end alone. It would agree with the conditions which I believe exist in the Acanthodians, an association which is perfectly reasonable, for although there is little reflection of acanthodian structure elsewhere, there is evidently no counter- vaihng resemblance to fish. My thanks are due to Professor P. B. Medawar, F.R.S., for the hospitality of his department, and to the Royal Society for the long-continued grant which has enabled Miss Townend to work with me. REFERENCES DENISON, R. H. 1958. Early Devonian fishes from Utah, part III, Arthrodira. Fieldiana: Geologv, 11,9, 461-551. GROSS, w. 1931. Asterolepis oniata Eichw. und das Antiarchiproblem. Palaeontographica, 75, 1-62, pi. 1-12. 1941. Die Bothriolepis-arten der Cellulosa-mergel Lettlands. Kungl. svenska Vetensk. Hamit. 3rd series, 19, 5, 3-79, pi. 1-29. PANDER, c. H. 1857. liber die Placodermen des Devonischen Systems. Kaiserliche Akademie der tViss., St. Petersburg, 1-106, pi. 1-8 and B. PATTEN, w. 1904. New facts concerning Bothriolepis. Biot. Bull. 7, 2, 113-24. STENSIO, E. A. 1931. Upper Devonian vertebrates from East Greenland. Medd. om Gronlaud, 86, 1, 8-212, pi. 1-36. 1942. On the snout of Arthrodires. Kungl. svensk. Vetensk. Handl. 3rd series, 20, 3, 3-32. 1945. On the heads of certain Arthrodires. II. On the cranium and cervical joint of the Doli- chothoraci (Acanthaspida). Ibid., 22, 1, 3-70. 1947. The sensory lines and dermal bones of the cheek in fishes and amphibians. Ibid., 24, 3, 4-195. 1948. On the Placoderms of the Upper Devonian of East Greenland. II. Antiarchi: Subfamily Bothriolepinae. Palaeozool. Groenlandica, Kobenhavn, 2, 622 pp., 75 pi. 1959. On the pectoral fin and shoulder girdle of the arthrodires. Kungl. svensk. Vetensk. Handl., 8, 1, 5-229, pi. 1-25. TRAQUAiR, R. H. 1894-1913. The fishes of the Old Red Sandstone of Britain. Part II — the Asterole- pidae. Mon. Palaeont. Soc., 63-134, pi. 15-31. WATSON, D. M. s. 1937. The Acanthodian fishes. Phil. Trans. Roy. Soc., B, 228, 49-146, pi. 5-14. Manuscript received 28 June 1960 D. M. S. WATSON University College, Eondon. TYPE SPECIMENS OF THE GENUS FENESTELLA FROM THE LOWER CARBONIFEROUS OF GREAT BRITAIN by T. G. MILLER Abstract. The morphology and systematic position of the bryozoan genus Fenestella Lonsdale are briefly dis- cussed. Phillips’s species of the genus are referred to a variety of genera or declared nomina dubia\ M’Coy’s species are redescribed and a new genus Parafenestella erected to contain one of them; two of R. Etheridge junior’s species are redescribed, and figured for the first time. In recent years extensive work on the fenestrate bryozoan faunas of the Russian and North American Upper Palaeozoic successions has indicated the desirability of dis- tinguishing, in the light of modern techniques, the type specimens on which early specific descriptions were based. The original authors gave, in many cases, only brief descriptions of their material, with inadequate and often inaccurate drawings, or even composite reconstructions. The more commonly occurring British Carboniferous fene- stellid species have therefore been difficult to identify with precision, and incomplete knowledge has led not only to misidentifications but to the development of two almost separate lists of names (Russian and North American), while no valid redescriptions of British types have been available as a common comparative standard. The situation has been made worse by the nature of the fossil remains themselves, since fragments of reticulate fronds tend to have a close superficial resemblance. An attempt was made towards the end of the last century by Shrubsole (1879, 1881) to regularize the position as it then stood, by lumping together many of Phillips’s and M‘Coy’s species and allowing only five ‘good’ species to persist, but it is not possible to agree with many of Shrubsole’s somewhat sweeping conclusions. Most British workers meanwhile solved the problem of naming fenestellid fronds either by applying one or other of Phillips’s or M‘Coy’s names more or less at random, or by recording all remains indiscriminately as Fenestella sp., or by ignoring them altogether. The main effect of these methods has been to render useless, from the systematic stratigraphic point of view, almost all references to species of Fenestella in British literature (with the notable exception of Oakley (1948) referring to Malayan material). But the practice led also, though indirectly, to the recognition of Fenestella plebeia M‘Coy, a wide-ranging form, as the ‘accepted type’ of the genus Fenestella (see, for an example of this usage, Ulrich 1890). The lack of a definitely described and well-understood type species for the genus, and additional taxonomic difficulties relating to the use of the name Fenestella, led Bassler (1935) to re-introduce the genus Fenestrellina d’Orbigny 1849, while retaining as the ‘ac- cepted genotype" F. plebeia (M‘Coy). This departure was challenged by Condra and Elias (1941), who applied to the International Commission for Zoological Nomenclature for a suspension of the Rules of Priority in order to retain the name Fenestella for the bryo- zoan genus. A discussion of the position regarding the real type species of the genus has [Palaeontology, Vol. 4, Part 2, 1961, pp. 221-42, pis. 24-27.] 222 PALAEONTOLOGY, VOLUME 4 been published by Elias (1956), in relation to Fenestella subantiqua d’Orbigny, and this has been criticized by Spjeldnaes (1957). As the matter remains sub judice it will be con- venient here simply to redescribe the available type material. A summary of the taxo- nomy of Fenestella Lonsdale is contained in Condra and Elias (1944), and an attempt has been made by the same workers (Elias and Condra, 1957) to subdivide and group the known North American Carboniferous species. MORPHOLOGY OF FENESTELLA The structure of the reticulate fronds of Fenestella was hrst described in detail by Ulrich (1890), and since then many Russian workers (Nekhoroshev, Shulga-Nesterenko, Nikiforova, and others) and Americans, notably Cumings, Condra, and Ehas, have con- tributed to an understanding of the morphological variations within the family. The microstructure is well summarized by Ehas (1956, p. 323). Different workers have naturally placed different amounts of emphasis on the various skeletal elements in the process of recognizing and defining species, subspecies, and varieties. Some palaeonto- logists (e.g. Nekhoroshev 1932; Shulga-Nesterenko 1949^) have used the microstructure of the branches and dissepiments as a basis for intra- and inter-specific determinations. However, apart from the shape of the zooecial chambers, this refinement is not con- sidered useful here (cf. Ehas and Condra 1957, p. 59). The desirability of employing a standard biometric usage in measuring mesh dimen- sions has been stressed by Condra and Ehas (1944, p. 54), and it is the counting method used by these authors that should be employed in all descriptions of bryozoan meshes or other similar repetitive structures. This method, the simplest possible, is applicable to all the counts normally needed (of branches, dissepiments, zooecial apertures, and carinal nodes per unit length) and merely requires the count to begin at zero and to start and finish at similar structural feature-points. It must be appreciated, however, that the simple record of such a so-called ‘micrometric formula’ can lead to the confusing of widely differing meshes, if the immediately visible amount of biometric information falls below the minimum required for accurate unambiguous specific determination. Text-fig. 1 shows two obviously different meshes having the same ‘micrometric formula’. Because the organism originated effectively in a point, from which branches radiate (Cumings 1905), no fenestellid mesh retains constant dimensions or proportions over the whole zoarial surface, and the departure from a mean value in any direction is naturally greatest at the base, nearest to the point of origin, in the region of the earhest, immature, most rapidly developing part of the structure. However, variation does occur within the mature or adult mesh region, and it is probable that study of complete speci- mens would show that the amount of variability itself varies systematically between species or species groups. It might seem necessary, therefore, in descriptive work on the Fenestellidae, to obtain as close an approximation as possible to the real range of mesh variation. Condra and Elias (1944), working primarily on the large, well-preserved fenes- telloid fronds of Archimedes, indicate the position on the zoarial expansion at which each set of measurements was taken. It has not been possible to do this with the material available, which does not include complete or even nearly complete zoaria. Further- more, in most fenestellid fronds, major variation in mesh dimensions only occurs where several branches divide within a small area, or where the zoarial surface departs widely from a plane, as for example where a fold or wrinkle is developed, especially near the T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 223 outer edge. Small fragments of zoaria in clastic limestones or shales are nearly always planar, and it is usually possible to avoid, in making mesh counts, regions of abnormally concentrated mesh division. Finally, if total-variation ranges are used when comparing specimens in specific identification, the overlap in range makes it difficult to make satis- factorily objective determinations. It is only by using the narrower variation-range of the mature (or ‘stabilized’) undistorted mesh that ‘good’ differentiations can be made. There remains also a possible source of error in the structural distortions imposed by secondary processes working within the rock-matrix. In such cases the mesh may be stretched or compressed in some preferred direction, or the skeletal elements may be thickened by secondarily deposited material or by recrystallization. TEXT-FIG. 1. Fenestellid meshes with similar ‘micrometric formulae’ but different gross characters. Notional magnification X 75. Whatever measurements are made, their value in taxonomy differs according to their relevance to the dimensions of the colony or the dimensions of the individual zooecial chamber. The counts of branches and dissepiments refer to the size and variability of the whole zoarium, while those of zooecial chambers and carinal nodes refer to the dis- tribution-density of the zooids themselves, or related structures. The distribution of the carinal nodes, structures possibly homologous with the acanthopores of the Trepo- stomata, has in the past often been ignored in published descriptions, but is here con- sidered to be of great systematic importance. In this connexion Elias and Condra state (1957, p. 19): ‘Likharev’s observation that the carinal spines have the same microstructure as the inner skeleton around the zooecia and as that of the dissepiments is in harmony with the conclusion of Cumings that the carinal spines are part of the primary skeleton or colonial plexus. . . . ’ As might be expected, counts of the morphological elements on or in the branches 224 PALAEONTOLOGY, VOLUME 4 show a much greater stability than the gross zoarial characters, which are more easily affected by simple mechanical distortion, whether this occurs during life or after burial. It is, however, unfortunate that the carinal nodes are easily removed by erosion, and this may account for the absence of reference to carinal nodes in many published diagnoses. Genuine cases of nodeless keels in fenestelhd fronds are thought to be rather rare, and any departure from the ‘normal’ carinal condition, with a single regular row of nodes, is considered to be of primary taxonomic significance. Thus the appearance of a double row of alternating nodes, and the appearance of dissepimental nodes, should be re- garded as of generic discriminatory value. This has already been recognized by Crock- ford (1944, p. 172) in establishing the genus Minilya (Mimlia of Elias and Condra, 1957) for fenestelhds with two rows of carinal nodes, and I erect the genus Parafenestella for the case with dissepimental nodes. Comparison of fenestellid material. The very large number of described species of Fene- stella — over 400, according to Elias and Condra — and the superficial similarity of mesh structure shown by them all, make it useful to devise some way of guarding against the kind of overlap in identification that has clearly operated in the past to proliferate specific names. The meshwork ‘micrometric formula’ of species of Fenestella allows a preliminary sifting of possible correlatives, so that the element of subjective evaluation operates over an initially restricted field. Thus, in identifying a specimen, comparisons are made only with those species known to have a similar micrometric formula, and the final assignment is made by reference to characters like branch thickness, zooecial base- shape, surface ornamentation, and so on. It has been found that this preliminary sifting can best be done by using a simple punched-card system to record the micrometric formulae of adequately described species. The formula for the specimen to be identified is ‘fed-in’ to the card-pack, and the eventual ‘fall-out’ contains all the species with comparable mesh dimensions. Thus, for example, the punched-card system using the micrometric formula with the con- ventional arrangement of counts produces the following information. Branches Dissepiments Zooecia Carinal nodes in 10 nim. in 10 nun. in 5 mm. in 5 mm. Species studied. . . . . . 12-18 9-10 17-18 19-22 Fall-out of punched cards for comparison: F. lahuseni Stuck ..... 15-16 9-10 17-18 19-22 F. plebeia M‘Coy . . . . . 15-23 9-10 17-20 10-20 F. oculata M‘Coy . . . . . 12-18 8-12 15-17 18-24 The field for comparison is reduced by this method to a size in which the application of more subjective tests can proceed without the danger of missing a known form within the observed mesh dimensions. SYSTEMATIC DESCRIPTIONS The material described is in three collections, the National Museum of Ireland, Dublin (specimens labelled NMD), the Geological Survey of Great Britain (speci- mens labelled GS), and the Sedgwick Museum, Cambridge (specimens labelled SM). T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 225 Preliminary note on Phillips’’ s speeies of Retepora. The following have commonly been referred to in the literature under Fenestella : Retepora {'Fenestella') rnembranacea Phillips 1836 Retepora Fenestella') laxa Phillips 1836 Retepora {'Fenestella') plunia Phillips 1836 Retepora {' Fenestella') flabellata Phillips 1836 Retepora {'Fenestella') temiifila Phillips 1836 Retepora {'Fenestella') imdiilata Phillips 1836 Retepora {'Fenestella') nodiilosa Phillips 1836 Retepora {'Fenestella') fliistriformis Phillips 1836 Retepora {'Fenestella') irregularis Phillips 1836 Diseussion. All these species were assigned by Phillips to the genus Retepora. Some of the names have been quoted uncritically as members of the genus Fenestella by later authors, beginning with Portlock ( 1 843), so that certain of them have become embedded in the literature. So far as I know, none of Phillips’s material now exists, and to be cer- tain of the validity of some of M‘Coy’s 1844 species it is necessary to decide whether Phillips’s descriptions and illustrations are complete and accurate enough to serve as bases for practically useful diagnoses. So far as concerns the species variously referred during the last hundred years to Fenestella Lonsdale, as listed above, Phillips’s descrip- tions are almost useless, since they give almost no structural dimensions, and only a few numerical quantities (such as the number of zooecial apertures to a fenestrule) can be extracted reliably from the figures. In only one case, that of Fenestella polyporata (Phillips), discussed below, are the zoarial characters distinctive enough to make it clear which of the known species of Fenestella Phillips was dealing with. Phillips’s remaining fenestellid species are therefore assigned as follows: Retepora rnembranacea: almost certainly not a species of Fenestella’, probably referable to either Semicoscinium Prout, or Isotrypa Hall. Retepora laxa: should be referred to Polypora M‘Coy. Retepora plunia: should be referred to Penniretepora d’Orbigny, and has, in fact, been designated by Bassler (1953) as the type species of that genus. Retepora flabellata, R. tenuifila, R. undulata, R. nodulosa, R. fliistriformis, and R. irregu- laris: although probably referable to Fenestella, and discussed twice in this sense by Shrubsole (1879, 1881), these must be discarded as incompletely described. Unless and until the type material is found they are therefore declared nomina dubia. This setting aside of R. irregularis Phillips, subsequently referred to by various authors as Fene- stella irregularis (Phillips), as of uncertain systematic position, validates F. irregularis Nekhoroshev 1932, which in turn has priority over F. irregularis McNair 1942. Order cryptostomata Shrubsole and Vine 1882 Family fenestellidae King 1850 Genus fenestella Lonsdale 1839 Fenestella plebeia M‘Coy 1844 Plate 24, figs. 1-3 226 PALAEONTOLOGY, VOLUME 4 Feiiestella plebeia M‘Coy 1844, p. 203. Fenestella ejimcida M‘Coy 1844, p. 201. Feiiestella plebeia M‘Coy; d’Orbigny 1850, p. 152. Fenestella plebeia M‘Coy; Meek 1872, p. 153. Fenestella plebeia M‘Coy; de Koninck 1876, p. 171. Fenestella plebeia M‘Coy; Shrubsole 1879, p. 278. Fenestella plebeia M‘Coy; Shrubsole 1881, p. 179. Fenestella plebeia M‘Coy; Stuckenberg 1888, p. 52. Fenestella plebeia M‘Coy; Stuckenberg 1895, p. 138. Fenestella plebeja M‘Coy; Nikiforova 19336, p. 10. Fenestella plebeja M'Coy; Prantl 1934, p. 4. Fenestella aff. plebeia M‘Coy; Oakley 1948, p. 89. M‘Coy’s description: ‘Flat, expanded, fan-shaped; interstices thick; fenestrules equal, rectangular, from two to three times as long as wide; width equal to that ofthe interstices; dissepiments thin, regular; pores four or five to the length of a fenestrule; reverse minutely granulated, and very coarsely sulcated longitudinally.’ Material : 1. Holotype NMD XXIX. 3 from ‘Carboniferous Slate’, Killybrone, Killala, Eire: probably Upper Tournaisian or Lower Visean. 2. Homeotype SM E. 5231 from ‘Carboniferous Limestone’, Kildare, Eire: probably Visean. 3. Homeotype SM E. 12990 from ‘Carboniferous Limestone’, Dairy, Scotland: probably Visean. 4. Homeotype SM E. 17840 from ‘Carboniferous Limestone’, Dairy, Scotland: probably Visean. 5. Homeotype NMD XXVIll. 11 from ‘Upper Limestone’, Black Lion, Enniskillen, Northern Ireland: labelled Fenestella ejimcida: probably Visean. Micrometric formulae : Holotype ...... 17-20 8-10 17-20 ? Homeotypes ...... 15-18 8-10 17-20 10-20 F. aff. plebeia M‘Coy; Oakley 1948 . | 18 i 8-9 1 18-20 1 7 F. aff. plebeja b/c] M‘Coy; Prantl 1934 . [ 16 1 9-10 1 9 Description. So far as can be made out from fragments, the largest of which measures 50x60 mm., the zoarium is a slightly flexuous fan-shaped, conical or cup-shaped ex- panded mesh, of subparallel branches joined by short transverse dissepiments. Branches rather slender to moderately robust (ratio of branch-width to fenestrule-width varies from about 1 : 1 to 1 : 2). Branch-width in stabilized part of zoarium 0-12-0-24 mm. (average 0-18 mm.). Obverse smooth, with distinct, rounded, nodiferous carina. Carinal nodes rounded, with slightly elliptical bases, regularly disposed. Reverse rounded, finely striated, with a row of small granules along the axis. Expansion of the zoarium occurs by irregu- larly spaced symmetrical bifurcation of the branches, more frequent proximally, where it occurs at intervals of about 10 mm. along the branches. The branches are thickwalled tubes longitudinally divided by a regularly zigzag septum set normal to the general plane of the zoarial expansion. The two secondary tubes thus formed are in turn regularly sub- divided by transverse walls into rows of box- or coffin-shaped zooecial cells or chambers, the cells of the row on one side of the median septum alternating with those of the row on the other side. In sections in the plane of the zoarial expansion the form of the zo- oecial chambers (the ‘zooecial bases’) is subpentagonal or ‘hemi-hexagonaT (text-fig. 2). In transverse sections, in which the median septum is seen dividing the branches intern- T. G. MILLER; TYPE SPECIMENS OE THE GENUS FENESTELLA 111 ally, the inner wall of the zooecial chambers is seen to be ribbed externally, so that the ribs appear as sharp projections of the main skeletal material into the sclerenchymal envelope. The dissepiments are subcylindrical or flat rod-shaped, rather narrow compared with the branches, of which they are usually little more than half the width, i.e. OTO mm. for a branch-width of 0T8 mm. The sclerenchymal outer tissue of the dissepiments is striated parallel to the main axis of the dissepiment. Where the dissepiments join the branches they widen, and the branches also show a slight corresponding bulge. Because of the difference in thickness (or width) the dissepiments are slightly depressed below the general branch-surface level on both sides of the zoarium. The fenestrules are regularly quadrate, coffin-shaped, or subelliptical, depending on their position in the zoarium and relation to points of branch-bifurcation . The numerical density of fenestrules along and across the zoarium corresponds to that of the dissepiments and branches. The zooecial chambers are arranged regularly in two alternating rows in the branches, the rows separated internally by the median septum and externally by the carina. Each chamber is itself partially subdivided by hemisepta, and is provided with a circular aperture on the upper, slightly inclined surface of the branch alongside the carina. In un- weathered specimens the zooecial apertures have a thickened margin or peristome. The disposition of the zooecial apertures along the branch is regular, unaffected by the joining-points of the dissepiments, with four or five apertures lying along the side of a fenestrule. When the peristomes are preserved they protrude slightly into the fenestrule, producing a ‘beaded’ effect. Discussion. M‘Coy’s specimen is unsatisfactory for detailed study. It is a badly preserved impression of the reverse of a zoarial fragment in which only at the extreme proximal end are a few relics of the internal structure preserved. The holotype of M‘Coy’s F. ejuncida, here considered conspecific with F. plebeia, is a comparatively well-preserved fragment, but also shows only the reverse. The type-locality for F. plebeia is a roadside exposure one mile north-west of Killala, almost exactly 300 yards east-north-east of triangulation-mark 163, which is figured above the ‘a’ in Mullaghorn on one-inch map sheet 53. It is almost completely overgrown, and I found there only a few badly preserved fragments, none of them suitable for description as topotype material. Nevertheless, it has been possible to determine M‘Coy’s intentions in his description and from the holo- type, and enough other material is available to reinforce this evidence and so to arrive at a reasonably clear diagnosis. Occurrence. F. plebeia seems to be among the most common fenestellid species in the British Lower Carboniferous (Dinantian series). The dimensions of the mesh and the shape and density of the zooecial chambers remain remarkably constant from the earliest Tournaisian to the latest Visean examples, but there appears to be a progressive change TEXT-FIG. 2. The ‘hemi-hexagonal’ shape of zooecial bases in Fene- stella plebeia M‘Coy and other fenestellid meshes. 228 PALAEONTOLOGY, VOLUME 4 in the number of carinal nodes, from about 8 in 5 mm. at low Tournaisian horizons, to 1 8 or 20 towards the top of the Visean. Further work is needed to establish this develop- ' ment : in any case, since the function (if any) of the carinal nodes and their relation both ' to the zooecia and the zoarium is unknown, and since the main mesh-dimensions seem to remain constant, it is not reasonable to attempt any subdivision of the species at this ] time. Many attributions to F. plebeia must be regarded as doubtful until the material j has been compared with types described here. Conversely, it is likely that examples of F. plebeia will be found included under other names. The important North American ' Mississippian species-group of which F. rudis Ulrich is typical (Elias 1937) may well be referable in part to F. plebeia. Elias (1943) has recorded F. plebeia from Mississippian formations, and F. Kaisin junior (1942, p. 104, pi. vi, fig. 1 ; not pi. v, as quoted in the text) ascribes to F. aff. rudis Ulrich specimens from the Belgian Tournaisian having micrometric formulae (16-18 | 9-11 || 20-21 | 14—16) within the limits appropriate to i F. plebeia. Until corrected identifications have been made in the light of the present redescription it is not possible to draw rehable conclusions as to the stratigraphic range . or geographic distribution of F. plebeia. The type species of Fenestella Lonsdale. The question arises whether Fenestella plebeia M‘Coy 1844 should be put forward as the type species of Fenestella Lonsdale. Confusion in this matter stems from three causes. First, the type species of Fenestella Lonsdale 1839 should be Gorgonia antiqua Goldfuss 1829 {"Gorgonia flabellata, ramis tetragonis, ramulis teretibus reticulatum coniunctis, cortice tenui, oscidis lateralibus uniserialibus remotiusculis') as selected by King in 1850, but the holotype of this species is lost (Toots, 1951) and unrecognizable from the published description and figures (Goldfuss 1826- 44, p. 99, pi. xxxvi, fig. 3). Secondly, Fenestella Lonsdale for a bryozoan is a junior homonym of Fenestella Bolten 1798 for a molluscan. It should be noted, as Spjeldnaes (1957) does, that both these names were changed, possibly by misprinting, to Fenestrella (Bolten’s by Gray in 1848, and Lonsdale’s by d’Orbigny in 1850). Thirdly, a practice has arisen, apparently started by Ulrich in 1890, of taking, without formality, Fenestella plebeia M‘Coy 1844 as the ‘accepted type’ of the genus, de mieux, the holotype of the real type species being lost. In recent decades several authors, aware of the unsatisfactory situation, have used the name Fenestrellina for fenestellids formerly included in Fenestella, but, as Elias (1956) points out, Fenestrellina d’Orbigny 1849 has irregularly spaced dissepiments. Further- more, Bassler (1953) now regards both Fenestella and Fenestrellina as morphologically distinct and valid genera. The situation has been still further complicated by the re- , description by Elias (1956) of Fenestella subantiqua (d’Orbigny), and the designation of this species as the ‘genotype’, despite Toots’s (1951) demonstration of the technical im- propriety of this action. In any case, as Spjeldnaes indicates, Fenestella patida M‘Coy ! 1850, regarded by Elias as conspecific with F. subantiqua (d’Orbigny), should take pre- cedence, and would then become the new type species of Fenestella. It may be useful, in the meantime, to place on record the reasons why F. plebeia can- not, without a special decision of the International Commission, be taken as the valid type species: 1. Because it was not an ‘included species’, and is therefore not eligible for selection as the type species. (Even Gorgonia antiqua Goldfuss, which was referred to F. T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 229 plebeia by Shrubsole (1880), was only doubtfully referred to Fenestella by Lonsdale, and is also therefore not directly eligible for selection.) 2. Because Fenestella antiqua Lonsdale was validly selected as type species of Fenes- tella Lonsdale by King (1849). Fenestella hemispheriea M‘Coy 1844 Plate 24, fig. 4 Fenestella hemispheriea M‘Coy 1844, p. 202. McCoy's description. ‘Hemispherical, cup-shaped; interstices and dissepiments exceedingly minute; interstices thin, sharply carinated, reverse longitudinally striated; dissepiments one-fourth the thickness of the interstices; fenestrules rectangular, wider than the interstices, and somewhat longer than wide; pores small, twice their diameter apart, with raised margins which do not indent the edge; about three pores to the length of a fenestrule; . . . about seven interstices in one line.’ Material : 1. Holotype NMD XXIX. 4 from ‘Carboniferous Lower Limestone’, Little Island, Cork, Eire: probably Tournaisian-Visean boundary. 2. Homeotype SM E. 17841 from ‘Carboniferous Limestone’ Easky, Sligo, Eire: probably low Visean. Micrometric formulae : 1. Holotype 2U-27 (av. 22i) 12-15 20 12 2. Homeotype 20-24 13-15 20-21 10-12 Description. The holotype of F. hemispheriea is the only specimen in M‘Coy’s material that shows the form of the zoarium, but, unfortunately, extensive recrystallization of both calcareous skeletal material and matrix has almost completely obscured the fine structural details, particularly the zooecial apertures and carinal nodes. Zoarium cup-shaped, poriferous face external, zoarial expansion with only minor flexure. Branches straight, relatively thick (OT 6-0-27 mm.), sides on obverse rising rather steeply to a prominent narrow carina with large nodes; nodes with elongate-oval bases. Dissephnents short, straight, about half (0-10 mm.) the thickness of the branches, set well below the general surface of the zoarium. Fenestrules rectangular, a little narrower than the branches, with rounded corners. Zooecial apertures circular, about their own diameter apart, with low, narrow peristomes, not indenting the sides of the fenestrules, 3h-4 to a fenestrule. Zooecial bases subpentagonal (hemi-hexagonal) to subrectangular. Discussion. The mesh-dimensions of F. hemispheriea are close to those of several other species, namely F. stocktonensis Condra and Elias 1944, F. cavifera Shulga-Nesterenko 1941, F. retiformis Schlotheim in Shulga-Nesterenko (1941), and F. modest a Ulrich 1890. Of these, the first three differ in having more carinal nodes (about 15 in 5 mm.) than F. hemispheriea. F. modest a Ulrich has a less dense branch packing (17-20, as against 21-27), low, rounded carina with small nodes, and zooecial apertures ‘almost twice their diameter apart’. Fenestella oculata M‘Coy 1844 Plate 26, fig. 1 Fenestella oculata M‘Coy 1844, p. 203. B 9425 Q 230 PALAEONTOLOGY, VOLUME 4 M‘ Coy 's description. ‘ Interstices very broad, flattened, rarely branched, obscurely keeled ; dissepiments less than one-fourth the thickness of the interstices, regularly placed; fenestrules half the width of the interstices, rectangular, three times as long as wide; pores placed close to the margin, very large, with a thickened margin, which deeply indents the sides of the fenestrule, three between each dissepiment ; reverse smooth.’ Material : 1. Holotype NMD XXVIII. 15. i, from ‘Carboniferous Slate’, Ballynacourty, Dungarvan, Water- ford, Eire: probably Tournaisian. 2. Paratype NMD XXVIII. 15. ii, ditto. Micrometric formulae : 1. Holotype 16-18 9-10 15-17 18-19 2. Paratype 12-14 8-13 15-17 20-24 Description. The matrix of M‘Coy’s specimen is a dark-grey irregularly laminated shaly mudstone. There are two fenestellid fragments, both showing the obverse surface; one, 15x15 mm., is heavily recrystallized, obscure, and somewhat compressed; the other, 10x4 mm., is slightly bent, but shows a fairly clear surface. No positive conclusion can be reached as to the form of the zoarium. The larger of the two fragments is slightly flexed, and there is nothing to suggest any departure from the ‘normal’ form of fenestel- lid fronds, namely a fan-shaped, cup-shaped, or conical expansion. Branches thick (0-35-0-50 mm.) and straight, except near points of bifurcation, with steep sides, and a distinct, slightly sinuous, noded carina. Dissepiments short, relatively slender (about 0-20-0-24 mm.). On both specimens some of the dissepiments are set slightly oblique to the meshwork symmetry axes, and are thus ahgned across the zoarium so as to give a slanting appearance to the cross-members of the mesh ; this is taken to be a secondary distortional effect, and to be without morphological or taxonomic signifi- cance. Fenestrules quadrate, rather angular, narrow, the length (0-60-0-75 mm.) usually approximating to or slightly exceeding twice the width (0-27-0-36 mm.). Zooecial apertures large, with prominent peristomes indenting the fenestrule sides, about their own diameter apart (internal diameter 0-07-0-08 mm. ; external diameter 0- 1 6-0- 1 9 mm.). Usually two apertures ‘ occupy ’ a fenestrule side, with one opposite the insertion-point of the corresponding dissepiment, there being thus three apertures to a fenestrule. Zooecial bases subpentagonal or hemi-hexagonal. Discussion. It is clear that M‘Coy’s diagnosis was based on the larger and less well pre- served of the two fragments. In this, recrystallization and compression have caused thickening of the branches, which are also pressed together, so that the dissepiments are bent downwards into the matrix. This compression is the cause of the discrepancy be- tween the two branch-density counts, 16-18 for the holotype, 12-14 for the paratype. The smaller fragment, which is almost certainly structurally continuous with the larger one within the matrix, gives a clearer and undistorted view of the mesh, but even here the EXPLANATION OF PLATE 24 Figs. 1-3. Fenestella plebeia M‘Coy. 1, Proximal part of holotype NMD XXIX. 3, showing internal structure of branches, X 30. 2, SM E. 5231, moderately weathered part of obverse showing mature mesh, X 30. 3, SM E. 5231, heavily weathered part of obverse, showing arrangement of zooecial chambers above their bases, x 25. Fig. 4. Fenestella hemispherica M‘Coy. SM E. 17841, showing mature mesh, X 25. Palaeontology, Vol. 4. PLATE 24 MILLER, Carboniferous Fenestella ■ii .'W t f* ) <■ T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 231 sclerenchymal tissue has recrystallized too much for the external ornamentation to be determined. The species is superficially close to F. plebeia, but differs in the distribution of zooecial apertures and carinal nodes. The mesh elements of F. oculata are, in general, stouter than those of F. plebeia. Nikiforova {\92>2>b) lists the species from the Upper Carboni- ferous of Samarskaia Luka in the Urals. Fenestello quadradecimalis M‘Coy 1844 Plate 26, fig. 2 Fenestella quadradecimalis M‘Coy 1844, p. 204 McCoy's description. ‘Interstices slightly flexuous, thin, irregularly branching; dissepiments thin, dis- tant ; fenestrules very large, irregular in shape, pores very numerous, prominent, about fourteen to the length of a fenestrule; reverse finely striated longitudinally.’ Material : 1. Holotype NMD XXVIII. 13, from ‘Carboniferous Upper Limestone’, Black Lion, Enniskillen, Northern Ireland: probably Visean. Micrometric formula : 1. Holotype . . | 9-13 | 2U3 || 21-22-|- | 3 Description. M‘Coy’s specimen is roughly triangular, measuring 40x40 mm. It is a proximal fragment of a zoarium but does not include the point of origin or ‘root’. At this stage of development of the colony the rate of branch-bifurcation is greater than in the mature or ‘stabilized’ part, and the mesh is, in consequence, less regular. Zoarium probably a fan-shaped expansion, rendered rather flexible by the markedly sinuous, widely separated branches, and the short, sometimes slightly obliquely set, dissepiments. Branches relatively slender for the general scale of the mesh (but, compared with other species of Fenestella, still moderately thick) 0-27-0-36 mm. Obverse not visible in the unprepared holotype, but in thin-section appears rounded, with a carina carrying small, widely separated nodes. Reverse rounded, with fine longitudinal ribs or striae, five to a branch. Dissepiments short, slender (OT 4-0-20 mm.), about half the thickness of the branches or often less. Occasionally, as in the proximal part of the zoarium, slightly oblique. Smooth, without ribs or striations. Fenestrules variable in shape proximally, but generally long and narrow, commonly with one end, at the bifur- cation of a branch, pointed, but tending distally towards a long rectangular or roughly coffin-shape (0-50-T0 mm. wide, 3-0-3-5 mm. long). Zooecial apertures (not seen on the natural surface of the holotype, but revealed locally by abrasion and polishing), small, circular, about their own diameter apart, eleven to fourteen to a fenestrule. Discussion. M‘Coy’s figure gives a fair impression of the species, except that the slender- ness of the dissepiments is exaggerated. The thick, protruding peristomes figured by M‘Coy are not directly visible in the holotype, but have been confirmed by preparation. Comparable species are F. regal is Ulrich 1890, F. undecimal is Shulga-Nesterenko 1941, and F. longa Nekhoroshev 1932, but none of these has the remarkably close zooecial packing of F. quadradecimalis (Z/5 22; cf. F. regalis 14, F. undecimalis 15, F. longa 17-20). 232 PALAEONTOLOGY, VOLUME 4 Fenestella frutex M‘Coy 1844 Plate 25, figs. 1-4 Fenestella frutex M‘Coy 1844, p. 201. Fenestella lyelli Dawson 1878, p. 288. Fenestella limbata Foerste 1887, p. 83. Fenestella limbata Foerste; Nikiforova 1926, p. 175. Fenestella lyelli ‘mut.’ Dawson; Bell 1929, p. 101. Fenestella aff. limbata Foerste; Likharev 1934, p. 155. Fenestrellina limbata Foerste; Elias 1937, p. 318. McCoy's description. ‘Flabelliform; rising from a distinct root or trunk, and suddenly expanding to a nearly circular network; fenestrules broad, usually quadrangular, but rather irregular in size and shape; interstices thick, frequently branching, slightly flexuous, irregular; dissepiments thin, at regular distances ; pores very prominent, their own diameter apart, placed much on the sides, so as to indent the margins of the fenestrules deeply; they are placed alternately, usually two to each fenestrule and one at the origin of each dissepiment; about five interstices in the space of one line; reverse with coarse, waving striae. ’ Material : 1. Holotype NMD XXVIII. 10, from ‘Carboniferous Upper Limestone’, Killymeal, Dungannon: probably Upper Visean. 2. Syntype NMD XXVIII. 9. ii, ditto. 3. Homeotype SM E. 12985, from ‘Carboniferous Lower Limestone Series’, Auchenmade Quarry, Dairy, Ayrshire, Scotland. 4. Homeotype SM E. 5275, from ‘Carboniferous Lower Limestone’, Hook Head, Wexford, Eire. Micrometric formulae: 1. Holotype and syntype 2. Homeotype SM E. 12985 3. Homeotype SM E. 5275. i 22-26 27-31 23-29 21-26 20-23 18-20 24 26-27 25-26 20- 24 23 21- 23 cf. F. limbata Foerste . 20-26 19-26 26 15-25 F. limbata Nikiforova 20-24 22-24 20-24 16-24 F. limbata Nikiforova 24-26 20-21 24-26 24-26 F. lyelli BeW . 22-26 19 21-26 20 Description. The holotype, a fragment about 10 mm. square, is the reverse of the extreme proximal part of a colony, and has three abnormally thick primary branches growing from an even thicker root-like process. The disposition of the branches in this immature condition is irregular. Moreover, the branches and dissepiments appear to be slightly distorted by the compaction-compression into one plane of a structure originally slightly curved. The syntype is a fragment 9x5 mm. of the distal mature part of a zoarium and shows the obverse face. Zoarium probably a fan-shaped expansion. Branches straight, or very gently curved, moderately thick (OT 4-0-20 mm.), steep-sided above, with a prominent narrow carina EXPLANATION OF PLATE 25 Figs. 1^. Fenestella frutex M‘Coy. 1, Holotype NMD XXVIll. 10, showing proximal part of zoarium, with ‘root’, X 15. 2, SM E. 12985, mesh dissected to show internal structure, X 20. 3, SM E. 12985, mature mesh, obverse, X 20. 4, SM E. 5275, mature mesh, obverse, showing carinal nodes pro- truding through matrix, X 25. Palaeontology, Vol. 4. PLATE 25 MILLER, Carboniferous Fenestella T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 233 bearing closely set nodes; reverse rounded, with fine longitudinal ribs or striae, 4-6 to a branch. Dissepiments short, narrow (0-04-0-06 mm.), slightly below the general surface- level of the zoarium, often sharply expanded where the region of insertion coincides with a zooecial aperture. Fenestrules quadrate-oval, only slightly wider (0-22-0-30 mm.) than the branches, and 0-33-0-39 mm. long. Zooecial apertures large, circular, set close together on the branches, with thick, prominent, collar-like peristomes, which indent the fenestrule borders. Usually 3 or ‘3 | ’ apertures along a fenestrule, and almost always one of the apertures is set opposite a dissepiment, so that it appears more prominent than the others. Zooecial bases subpentagonal or hemi-hexagonal, with strongly developed hemisepta set obliquely within the zooecial chambers so as to produce in certain states of weathering an apparently trapezoidal or triangular zooecial base-shape. Discussion. F. frutex is one of the easiest of M‘Coy’s species to recognize, mainly on account of the regularity and symmetry of the mesh, and the prominence of the zooecial apertures that lie opposite the ends of dissepiments. Elias and Condra (1957) place F. liinbata Foerste, now referred to F. frutex M‘Coy, in a group with F. tenax Ulrich, which is referred to F. bicelhdata R. Etheridge jun. : ‘ [This] large polyphyletic group includes two conservative long-range species, F. tenax and F. liinbata, and several species and varieties of the comparatively rapidly evolving lineage of F. miniiea, type-species of the group. . . . The two more conservative stocks of the group, F. liinbata and F. tenax, range from Lower Des Moines [Upper Namurian] to Big Blue [Sakmarian] . . . and from Warsaw [Lower Visean] to Lower Leonard [Lower Artinskian] respectively, surviving to Permian time without appreciable change.’ It is significant that these two very characteristic species should occur in European as well as North American Carboniferous sections. Records of F. liinbata Foerste, now referred to F. frutex M‘Coy, are fairly common in studies of Lower Carboniferous rocks, of Europe, Turkestan, and North America. In Britain the species occurs in the Visean Bryozoan Band of Westmorland (Garwood 1912) in a fenestellid faunule of markedly North American aspect, with Fenestella rectangularis Condra and Elias as the com- monest species, closely followed by Hemitrypa hibernica M‘Coy. Fenestella polyporata (Phillips) 1836 Plate 26, figs. Z-A Retepora polyporata Phillips 1836, pp. 199, 245. Fenestella polyporata (Phillips); Portlock 1843, p. 323. Fenestella multiporata M‘Coy; M‘Coy 1844, p. 203. Fenestella polyporata (Phillips); Shrubsole 1879, p. 280. Fenestella polyporata (Phillips); Shrubsole 1881, p. 185. Fenestella polyporata (Phillips); Nikiforova 1926, p. 179. Fenestella aff. polyporata (Phillips); Nikiforova 1927, p. 251. Fenestella polyporata (Phillips); Nikiforova 1933a, p. 23. Fenestella ex. gr. polyporata (Phillips); Nekhoroshev 1935, p. 69. Fenestella ci. polyporata {Phillips)', Oakley 1948, p. 88. Phillips's description. ‘Interstices thick; fenestrules large, irregular; pores numerous, small, round. This somewhat resembles retepora cyathiformis [s'ic] Goldfuss ix. 11.’ M‘Coy’s description of Fenestella polyporata (Phillips): ‘Interstices thick, rounded (not carinated?), irregularly branched; dissepiments short, thin, placed at irregular distances, fenestrules large, very irregular in size and shape; pores very small, impressed, from five to seven in the length of a fenestrule.’ 234 PALAEONTOLOGY, VOLUME 4 M‘Coy’s description of Fenestella multiporata M‘Coy : ‘Foliaceous; interstices thin; sharply keeled, irregularly branched; dissepiments thin, distant, fenestrules large, very elongate, irregular; pores very numerous, small, margins tumid, seven or eight to the length of a fenestrule; reverse regularly striated.’ Material. I believe Phillips’s specimen is lost. Fenestella multiporata M‘Coy is now referred to Fenestella polyporata (Phillips), and the holotype of M’Coy’s species is here designated as neotype of F. poly- porata (Phillips). 1. Neotype NMD XXVIII. 9 from ‘Carboniferous Upper Limestone’, Killymeal, Dungannon, Tyrone, Northern Ireland: probably Upper Visean. 2. Homeotype SM E. 5244 from ‘Carboniferous Limestone’, Settle, Yorkshire: Visean. Micrometric formulae : 1. Neotype 2. Homeotype . 12-15 9-10 4 3-5 16-18 15 ? ? F. polyporata Phillips, Niki- forova 1933a 9-12 4|-6 16 7 F. ex gr. polyporata (Phillips) : Nekhoroshev 1935 11-12 4| 13^-14 7 F. cf. polyporata (Phillips): Oakley 1948 14 6 18-20 7 Description. Zoarium probably a limp flexuous expansion. Branches relatively thin (0-22-0-33 mm.), bifurcations frequent (at intervals of about 3 mm.), producing an effect of irregularity ; obverse of branches smooth, rounded, with a narrow, indistinct, slightly sinuous carina carrying small, indistinct nodes; reverse finely ribbed or longi- tudinally striated, eight to twelve ribs on each branch. Dissepiments short, relatively thin (0-1 1-0-16 mm.), finely ribbed on both sides, the ribs conforming to the long- axis shape of the dissepiment. Fenestrules long, narrow, rectangular, with rounded corners, 2-05-2-25 mm. long, 0-45-0-60 mm. wide. Zooecial apertures large, circular, diameter 0-13 mm., rather less than their own diameter apart, usually 8 or 9 to a fenes- trule. Peristomes distinct, narrow, entire. Zooecial bases subpentagonal or compressed hemi-hexagonal. Hemisepta strongly developed and very oblique, giving to the branches in certain states of weathering the appearance of a branch of Polypora. Discussion. There can be little doubt as to the identity of Phillips’s and M‘Coy’s species. The large number of zooecial apertures to a fenestrule is shown clearly in the published figures of both authors (Phillips pi. i, figs. 19, 20; M‘Coy pi. xxviii, fig. 9), although the general appearance of the zoarium is equally distorted in the two cases, Phillips exag- gerating the irregularity, and M‘Coy the regularity, of the branch disposition. Phillips’s figure does not show the characteristic thread-like carina. I I EXPLANATION OF PLATE 26 Fig. 1. Fenestella oculata M‘Coy. Paratype NMD XXVIII. 15. ii, part of obverse, X 20. Fig. 2. Fenestella quadradecimalis M‘Coy. Flolotype NMD XXVIII. 13. partly ground and polished to show features of obverse, X 20. Figs. 3-4. Fenestella polyporata (Phillips). 3, Neotype NMD XXVIII. 9, part of weathered obverse showing gross characters of mesh, X 3. 4, Neotype NMD XXVIII. 9, showing Polypora-Wkt appear- ance when hemisepta are exposed by weathering, x 15. Palaeontology, Vol. 4. PLATE 26 MIL LE R, Carboniferous Fenestella T. G. MILLER; TYPE SPECIMENS OF THE GENUS FENESTELLA 235 Fenestella longa Nekhoroshev 1932 has a micrometric formula close to that of F. poly- porata : F. polyporata (Phillips) 9-15 3-5 15-18 9 F. longa Nekhoroshev 13-15 4-5 17-20 9 It is possible that on re-examination these two may be found conspecific. F. pseudovirgosa Nikiforova 1938 also has a similar micrometric formula, but its mesh is much stouter, and its zooecial bases are triangular. The type-material is Visean. Nikiforova lists F. polyporata from the Visean of the Donetz basin and the Urals, and from the Tournaisian of Turkestan; and a variety — var. orlovskensis — from the Middle Carboniferous of the Donetz basin. Fenestella biceJMata R. Etheridge jun. 1873 Plate 27, fig. I Fenestella bicellulata R. Etheridge jun. 1873, p. 101. Fenestella tenax Ulrich 1888, p. 71. Fenestella tenax Ulrich; Ulrich 1890, p. 546. Fenestella cf. tenax Ulrich; Nikiforova 1933n, p. 15. Fenestella aff. tenax Ulrich; Prantl 1934, p. 231. Fenestella tenax Ulrich; Condra and Elias 1944, p. 99. Fenestella cf. tenax Ulrich; Oakley 1948, p. 88. Fenestella submicroporata Shulga-Nesterenko 1952, p. 35. Fenestella tenax Ulrich; Elias and Condra 1957, p. 106. Etheridge's description. ‘Polyzoarium, probably flattened, expanding. Interstices straight, carinated, occasionally bifurcating, the whole of the carina is occupied by large prominent pores, the openings of which are visible with a strong lens; one pore is placed at the end of each dissepiment, and one between. Dissepiments thin, sub-opposite, and a little arched, not expanding at their junction with the interstices. Eenestrules nearly square, with the margins slightly indented by the cells. Cells, in alternating rows on the margins of the fenestrules, one placed in each angle formed by the junction of the interstices and the dissepiments; a larger cell is placed at each angle of bifurcation of the interstices; all the cells have prominent margins. Non-poriferous face, not known. When highly magnified the foramina are dis- tinctly visible. The characteristic points in this species are the very few cell apertures in a fenestrule, and the regularity with which the interstices are pored. ’ Etheridge did not publish a figure of his new species, and his specimen is now presumed lost. Material: 1. Neotype GSE. 1994, from shale between First and Second Calderwood Limestone, ‘Lower Carboniferous Limestone Group’, Boghead, East Kilbride, Scotland. Micrometric formulae : Neotype . . . . | 24-27 | 27-28 | 27-29 [ 29-31 | F. tenax Ulrich 1890 . 28-30 28-30 27-29 26 F. tenax Ulrich: Nekhoroshev 1926 28-30 22-25 24-26 ? F. tenax Ulrich: Condra and Elias 1944 24-35 25-30 25-31 25-30 Description. Zoarial form unknown. Branches relatively thick (0T0-0T25 mm.), straight, steep-sided above, with a wide, well-defined earina carrying numerous large, high, eonical nodes, their bases nearly as large as the zooecial apertures ; reverse smooth, rounded, with a distinet zigzag. Dissepiments short, straight, thin (0-05 mm.), faintly ridged on the obverse, smooth and rounded on the reverse. Fenestrules rectangular. 236 PALAEONTOLOGY, VOLUME 4 appearing almost square in some cases, often with irregular sides due to the protrusion of the zooecial apertures ; on the reverse almost circular due to accretion of sclerenchymal tissue and zigzag shape of the branches. Zooecial apertures circular, with narrow peri- ^ stomes, two to three to a fenestrule, so that rather often one aperture lies at the end of a ' dissepiment and one in the middle of a fenestrule-side. Zooecial bases obliquely elon- gate pentagonal. Discussion. F. bicelluJata is an extremely distinctive species, easily recognized by its relatively fine, symmetrical mesh, and large, closely packed carinal nodes. There is little doubt of its conspecificity with F. tena.x Ulrich, a well-known and widely distributed species in North America and elsewhere. ! The neotype is from the Visean of Scotland. F. tenax Ulrich occurs in the Mississip- pian Warsaw group (Lower Visean) and the Chester group (Upper Visean-Lower Namurian), in association with F. rectangularis Condra and Elias, F. serratida Ulrich, F. matheri Condra and Elias, F. cumingsi Condra and Elias, F. multispinosa Ulrich, and Archimedes spp. Almost exactly the same faunule, with the notable exception of Archimedes (whose nearest occurrence is in Spitzbergen (Forbes, Harland, and Hughes 1958), occurs in the Visean Bryozoan Band of north-western England (Garwood 1912, i and my unpublished determinations). ' Fenestella tuberculo-carinata R. Etheridge jun. 1873 I Plate 27, fig. 2 Fenestella tuberculo-carinata R. Etheridge jun. 1873, p. 101. Fenestella tuberculo-carinata R. Etheridge jun.; Young 1882, p. 182. Etheridge's description. ‘A large number of fragments of a species of Fenestella allied to F. formosa M‘Coy were obtained from shale in connexion with the Elosie Limestone, yet differing sufficiently to be worth recording. The interstices are carinate and occasionally bifurcate, with a large cell-aperture in each angle of bifurcation, as in M'Coy’s species. The dissepiments are short and alternate one with ' the other, but, unlike F. formosa, without any trace of cell openings on them. The fenestrules are quadrangular, having a bulging appearance caused by slight undulation of the interstices. The cells, which are very large, with prominent margins, are arranged in alternating series on each side the inter- stices, three to each side the fenestrule, with very small interspaces between each aperture. Along the i keel of the interstices are ranged numerous small, blunt, tubercle-like pores, one at the end of each dissepiment, and three between — that is, one between each pair of obliquely-opposite cell-apertures. On the non-celluliferous aspect, the fenestrules appear quite oval, and the whole aspect smooth and plain, /i Although somewhat resembling F. formosa, this form differs in not having the dissepiments celluli- || ferous, by a less number of cell-apertures to each fenestrule, by a larger number of pores on the keel, « and by the nature of the reverse aspect. If better specimens should prove this to be a new species, a 1 good name for it would be that of Fenestella tuberculo-carinata. ’ Etheridge did not publish a figure of his new species, and his specimen is now presumed lost. | Material. Slide-mount in H.M. Geological Survey collection, number GS 89041, containing nine frag- EXPLANATION OF PLATE 27 Fig. 1. Fenestella bicellulata R. Etheridge jun. Neotype GSE. 1944, obverse, X30. Fig. 2. Fenestella tuberculo-carinata R. Etheridge jun. Neotype GS. 89041. 03, obverse, x30. Figs. 3-4. Parafenestella formosa (M‘Coy). 3, Holotype NMD XXIX. 2, obverse, X 20 (the dark band along Carina and dissepiments is a weathering effect). 4, Holotype NMD XXIX. 2, oblique view of a dissepiment, showing the dissepimental node (casting its shadow to the ‘south-east’), x70. Palaeontology, Vol. 4. PLATE 27 MILLER, Carboniferous Fenestella T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 237 ments of zoaria, from shale below Hosie Limestone, ‘Lower Carboniferous Limestone group’, at the head of Mouse Water, Wilsontown, Scotland. The fragments are each about 2-3 mm. square; four show the obverse and five the reverse face of the mesh. These fragments are probably topotypes (Dr. F. W. Anderson, in litt.) They have been labelled for precise identification, according to the face show- ing, in the top row from left to right, Rl, R2, Ol, 02, R3; and in the bottom row, also from left to right, 03, R4, 04, R5. Of these specimens, 03 is selected as neotype, 04 is rejected, and the rest are homeotypes. Horizon : topmost Visean. Micrometric formulae : 1. Neotype GS. 89041. 03 . 18-19 13-14 21-22 29-30 2. Homeotype GS. 89041. Ol 20 12-14 21 26-28 3. Homeotype GS. 89041. 02 18-19 12-13 20-22 7 Description. Zoarial form unknown. Branches regular, tending towards a slight zigzag, rather thick (0-25 mm.), moderately steep-sided, with a narrow, feebly-defined carina carrying numerous small, rounded nodes; reverse smooth, rounded. Dissepiments short, thick (OT 0-0-20 mm.), ridged. Fenes- trules quadrate-oval, with wavy margins where deeply indented by the zooecial apertures, reverse almost circular, with accretion of sclerenchymal tissue in fine concentric ridges. Zooecial apertures round, diameter 010 mm., rather less than their own diameter apart, three to a fenestrule, with narrow, prominent peristomes projecting well into the fenestrules. Zooecial bases pentagonal or hemi-hexa- gonal, with convex outer walls. Discussion. F. tuberculo-carinata differs from all other described British species of Fenestella in the large number of carinal nodes in unit length of branch. Comparable examples of this character are F. parvipora Condra 1902 18-20 15 25 25-33 F. densinodosa Kaisin 1 942 25-28 16-18 22-23 25-30 Of these F. densinodosa has a much finer mesh than F. tuberculo-carinata, while F. parvipora, although fairly close in its micrometric formula, has much thicker dissepiments (0-30 mm.) 'Fenestella carinata M‘Coy 1844 Fenestella carinata M‘Coy 1844, p. 200. Fenestella earinata M‘Coy; Eichwald 1860. Fenestella cf. carinata M‘Coy; Waters 1878, p. 461. {non Fenestella carinata Fenton and Fenton 1924, p. 78.) Discussion. The specimen from M‘Coy’s collection (now numbered NMD XXVIII. 12) labelled Fenestella carinata, from the ‘Carboniferous Shale’ of Enagh, Tyrone, Northern Ireland, is a piece of massive pale grey-buff crystalline fragmental limestone containing several fenestellid frond-fragments. The upper of M‘Coy’s two drawings (pi. xxviii, fig. 12) clearly corresponds to a small (10x7 mm.) fragment showing the reverse side of a fenestellid zoarium, although in drawing and printing its position has been reversed relative to a large crinoid ossicle. A few centimetres away lies the obverse face of another fragment, partly covered by matrix; it is from this fragment that the second and larger of M‘Coy’s two drawings must have been made. This second drawing shows the relative position and size of the various obverse elements of a fenestellid mesh. It is probable that the use of these two specimens lying side by side on the same piece of rock accounts for contradictions in M‘Coy’s description. For example, he refers to the fenestrules as both circular and elongate oval. In fact, the fenestrules on the smaller, reverse-face specimen are almost circular, while on the other specimen they are elongate- oval. Suspicion as to the nature of the species was aroused on observing the abnormally strongly developed and prominent carinal nodes of the larger specimen, and a minute 238 PALAEONTOLOGY, VOLUME 4 examination led to the discovery at one point on the zoarial surface of a remnant of a hexagonal superstructure corresponding in orientation to the underlying fenestellid mesh, and exactly similar to the superstructure of Hemitrypa Phillips 1841. The micrometric formula of the mesh of "Fenestelld’ carinata M‘Coy is I 18-22 I 13^-17 II 22-23 | 10-13 | The micrometric formula of the main mesh of Hemitrypa hibernica M‘Coy, measured from the holotype, is i jg_22 i n 21-23 | 14 | ] j Specimens of Hemitrypa hibernica from the Visean Bryozoa Band of Ash Fell Edge, Westmorland, have the micrometric formula I 19-24 I 14-17 II 20-24 | 11-15 | There seems little doubt that these are identical with M‘Coy’s ‘F.’ Carinata. From the same bryozoan locality I have collected pieces of 'FenesteUa' which are, in fact, pieces of Hemitrypa from which the superstructure has broken away. 'Fenestella' carinata M‘Coy must therefore be referred to Hemitrypa hibernica M‘Coy. ' Fenestella'’ varicosa M‘Coy 1844 Discussion. The holotype of F. varicosa has branches of two kinds supporting a typical fenestellid mesh. One set of branches is thick, the other thin, the thin branches arising regularly from the thick ones. The species is therefore referred to Ptiloporella Hall 1885 as Ptiloporella varicosa M‘Coy. "Fenestella' crassa M‘Coy 1844 Discussion. The holotype of F. crassa was figured by M‘Coy as having branches with a prominent carina carrying, apparently, apertures rather than nodes (on one branch; but with a suggestion of nodes on the other: cf. Bassler (1953, p. 122) who gives a re- drawn and reversed version of M‘Coy’s figure) in a zoarium with ‘ fenestrules large, very elongate, irregular’, F. crassa was taken by d’Orbigny (1849) as the type of his new genus Fenestrellina, and this attribution has been maintained by Bassler (1935, p. Ill and 1953, p. 122). M‘Coy’s specimen does show a zoarium with a large and rather irregular mesh, but the branches are not carinate and there are no carinal pores, but instead, a straightforward arrangement of three or four rows of zooecial chambers. ' Fenestella’ crassa M‘Coy is therefore referred to Polypora M‘Coy 1844 as Polypora crassa (M‘Coy), as already suggested by Shrubsole (1881); and Fenestrellina d’Orbigny 1849 is thus made a junior homonym of Polypora M‘Coy 1844. ' Fenestella" morrisii M‘Coy 1844 Discussion. The specimen in M‘Coy’s collection is a small cup-shaped example of the proximal part of a fenestellid zoarium in such a bad state of preservation that nothing of its structure can be determined. " Fenestella’’ morrisii is therefore declared nomen dubium. Genus parafenestella gen. nov. Type species. Parafenestella formosa (M‘Coy); M‘Coy 1844, p. 201. Diagnosis: Like Fenestella, but the dissepiments carry a node or tubercle approximating in external shape and size to the carinal nodes of the zoarial branches. T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 239 ParafenesteUa fonnosa (M‘Coy) 1844 Plate 27, figs. 3-4; text-fig. 3 Fenestella formosa M‘Coy 1844, p. 201. M' Coy's description. ‘Flat, leaf-like; interstices thin, irregularly branching; fenestrules large, irregular in size and shape; dissepiments very thin; pores of the sides of the interstices large, numerous, their thickened edges indenting the margin, four or five to the length of a fenestrule ; at each bifurcation, and at each setting off of a dissepiment, is one pore, nearly twice the size of the others ; in the middle of each dissepiment is placed one oval pore, and on the strong keel of the interstices is a very regular row of small pores, all having raised margins.’ Material : 1. Holotype NMD XXIX. 2 from ‘Carboniferous Upper Limestone’, Killymeal, Dungannon, Eire; Upper Visean. Micrometric formula : 1. Holotype. | 16-21 (av. 20) [ 9-10 |1 19-21 | 22-241 Description. The holotype is a fragment (of which part remains as reverse impression only) 18x14 mm., showing in excellent pre- servation the obverse of the proximal end of a frond and its ‘root’. Zoarium probably a gently flexed, fan- shaped, possibly cup-shaped or conical expansion. Branches straight, rather thick (0-27-0-33 mm.), bifurcating about every 3 or 4 mm. in the proximal part (i.e. about 15 mm. from the ‘root’), steep-sided, rising to a narrow, flat-topped carina with circular- based nodes. Reverse rounded, with fine ribs or striae. The points of bifurcation of the branches are in a region of characteristic and unusual arrangement of carina, carinal nodes, and zooecial apertures; an ‘addi- tional’ zooecial aperture is placed imme- diately above (i.e. proximal to) the point of branch division, and is surrounded sym- metrically by carinal nodes and a cross- carina, arranged in a triangle (text-fig. 3). Dissepiments short, straight, fairly thick (OT 1-0-22 mm.), and bear on the obverse a small node or tubercle, subcircular to ellip- tical in base-plan, the long axis of the ellipse lying along the main axis of the dissepiment. Fenestrules rectangular, with rounded corners, T0-M5 mm. long, 0-20-0-25 mm. wide, the sides indented by the zooecial apertures. Zooecial apertures round, four or five to a fenestrule, diameter 0-07-0-09 mm., slightly more than their diameter apart, equal, with a narrow collar-like peristome TEXT-FIG. 3. Semi-diagrammatic representation of ParafenesteUa formosa (M‘Coy) mesh, showing dissepimental nodes and triangular carinal pattern above a branch bifurcation. Drawn from a photo- graph: X 60 (approx.). 240 PALAEONTOLOGY, VOLUME 4 projecting into the fenestrules. The peristomes are higher and more prominent on the fenestrule side of the aperture than on the carinal side. Zooecial bases almost rectangular. Discussion. The presence of dissepimental nodes distinguishes Parafenestella from Fenestella just as the presence of a double row of carinal nodes distinguishes Minilya Crockford. The possibility that these structures may at least in part be homologous with the acanthopores of the Trepostomata is a sufficient reason for placing species with dissepimental nodes in a new genus. I have not found any other example of the genus or species in British fenestellid assemblages or collections nor do I know of any published descriptions that might suggest the presence of Parafenestella. Nikiforova (19336) lists Fenestella fonnosa from the Visean of the Moscow basin, but it is not clear whether the species is in fact a Parafenestella as here understood, or whether it is a true Fenestella of similar micrometric formula. Acknowledgements. The work was suggested by Dr. K. P. Oakley, and I am grateful to him for much valuable advice and help, and for the gift of several Russian publications otherwise difficult to acquire. The cost of punched-card equipment was met by a grant-in-aid administered by the Royal Society, and for this I return thanks to the Council of the Royal Society, and in particular to Professor W. B. R. King, F.R.S., and Professor O. M. B. Bulman, F.R.S. Various museums kindly allowed the borrowing and examination of material, and I am grateful to their Directors or Curators — to the Director of H.M. Geological Survey and Dr. F. W. Anderson, to Mr. A. G. Brighton (Sedgwick Museum), to Mr. J. M. Edmonds (Oxford University Museum), to Professor W. F. Whittard (Bristol University Museum) ; and to the Keeper, Natural History Division, National Museum of Ireland. I also thank Mr. W. G. C. Austin, Demonstrator in Geology at University College, Keele, and Mr. Albert Barlow and Mr. Arthur Foulger, of the Sedgwick Museum, for their help in the preparation of photographs and thin sections. Mr. J. Selwyn Turner, Dr. D. W. Bishopp, and Dr. Alan Lees kindly provided use- ful information on localities and stratigraphic horizons in Ireland, and to them I accordingly return thanks. I am indebted to the Librarian of the Geological Society of London, Miss A. Barber, and her staff, for unlimited patience in tracing many obscure publications. I am most grateful for a grant from the publications fund. University College of North Staffordshire, towards the cost of plates. REFERENCES BASSLER, R. s. 1935. In Fossilium Catalogus I: Animalia, pars 67: Bryozoa, pp. 229. ’s-Gravenhage: W. Junk. 1953. In Treatise on Invertebrate Palaeontology (Moore, R. C., editor), part G: Bryozoa, pp. xiiiH-253. Geological Society of America and University of Kansas Press. BELL, w. A. 1929. Horton-Windsor District, Nova Scotia. Mem. Geol. Surv. Canada, 155. CONDRA, G. E. 1902. Coal Measure Bryozoa of Nebraska. Amer. Geol. 30, 6. and ELIAS, M. K. 1941u. The generic names Fenestella and Fenestrellina. Nature, 148, 339. 19416. Fenestella Lonsdale and Fenestrellina d’Orbigny. J. Palaeont. 15, 565. 1944. Study and Revision of Archimedes Hall. Geol. Soc. Amer. spec, paper, 53, pp. viii+ 243. CROCKFORD, i. M. 1944. Bryozoa from the Wandagee and Nooncabah Series (Permian) of Western Australia, Part I. J. Roy. Soc. W. Australia, 28 (for 1941-2), 165. COMINGS, E. R. 1905. Development of Fenestella. Amer. Jour. Sci. (4th ser.), 20 (117), 169. DAWSON, J. w. 1878. Acadian Geology (3rd edition). London: Macmillan, pp. xxviii+694+suppl. pp. 103. EiCHWALD, E. 1860. Letliaea Rossica: Paleontologie de la Russe: Ancienne Periode: Bryozoa. ELIAS, M. K. 1937. Stratigraphic significance of late Palaeozoic fenestrate Bryozoa. J. Palaeont. 11, 306. • 1943. On Palaeocoryne (abstract only). Bull. Geol. Amer. 54, 1830. T. G. MILLER: TYPE SPECIMENS OF THE GENUS FENESTELLA 241 ELIAS, M. K., 1956. A revision of Fenestella antiquaand related Silurian Fenestellids. J. Palaeont. 30, 314. and CONDRA, g. e. 1957. Fenestella from the Permian of W. Texas. Geol. Soc. Amer. Mem. 70, pp. ix+ 158. ETHERIDGE, R. jun. 1873. In Explanation of Sheet 23, Lanarkshire, Central Districts, Appendix III. Mem. Geol. Surv. Scotland. FENTON, c. L. and FENTON, M. A. 1924. Stratigraphy and Fauna of the Hackberry Stage of the Upper Devonian. Contr. Mus. Geol. Univ. Michigan, 1. FOERSTE, A. F. 1887. Flint Ridge Bryozoa. Bull. Sci. Lab. Denison Univ., 2 (1), 77. FORBES, c. L., HARLAND, w. B., and HUGHES, N. F. 1958. Palaeontological evidence for the age of the Carboniferous and Permian rocks of Central Vestspitsbergen. Geol. Mag. 95, 465. GARWOOD, E. j. 1912. Lower Carboniferous Succession in North-west England. Quart. J. Geol. Soc. 88, 449. GOLDFUSS, A. 1826-44. Petrefacta Musei Universitatis Regiae Borussicae Rlienanae Bonnensis, 1. Diisseldorf: Arnz and Co. pp. 252. KAisiN, F. jun. 1942. Les Bryozoaires Fenestrellinides et Acanthocladiides du Tournaisien de la Belgique. Mem. Inst. Geol. Univ. Louvain, 13 (3), 93. KING, w. 1850. English Permian Fossils. A/cw. Pa/. 5oc., pp. xxxvii + 258. DE KONiNCK, L. G. 1876. Recherches sur les fossiles paleozoiques de la Nouvelle-Galles du Sud (Australie). Mem. Soc. Roy. Sci. Liege, ser. 2, 6, 171. LIKHAREV, B. 1934. Upper Carboniferous of Ferghana. Bull. Geol. Soc. China, 13 (2), 155. LONSDALE, w. 1839. Coials. In Murchison, R. I., Silurian System, 2, 675. iM‘coY, F. 1 844. Synopsis of the Characters of the Carboniferous Limestone Fossils of Ireland. Dublin : pp. viii-h207. MCNAIR, A. H. 1942. Upper Devonian Bryozoa. J. Palaeont., 16, 343. MEEK, F. B. 1872. Palaeontological Report. In F. V. Hayden’s Final Report on the Geology of Nebraska. NEKHOROSHEV, v. N. 1926a. Lower Carboniferous Bryozoa from the Kuznetsk Basin. Bull. Com. geol. Leningrad, 43, 1237. 1926h. On the affinities of some European and North American species of Carboniferous Fene- stellidae. Ann. Soc. Pal. Russia, 5 (2), 105. 1929. Resultats de I’etude des collections des bryozoaires paleozoiques dans quelques musees de I’Europe occidentale. Bull. Com. geol. Leningrad, 48, 105. 1930. On certain Palaeozoie Bryozoa in the British Museum (Nat. Hist.). Geol. Mag. 67, 178. 1932a. Die Bryozoen des deutschen Unterkarbons. Abh. preuss. geol. Landesanst. (n.s.), 141, 1. 1932A. Microscopical method of exploration of Palaeozoic Bryozoa of the family Fenestellidae. Bull. Unit. Geol. Prosp. Serv. USSR, 17. 1935. Upper Palaeozoic Bryozoa of the Kolyma region. Akad. Nauk. SSSR : Report of Kolyma Geological Expedition, 1 (3), 65. NiCKLES, J. M. and bassler, r. s. 1900. A synopsis of American fossil Bryozoa. U.S. Geol. Surv. Bull. 173, 37. NIKIFOROVA, A. 1926. Lower Carboniferous Bryozoa of Turkestan. Bull. Com. geol. Leningrad, 45 (3), 175. 1927. Lower Carboniferous Bryozoa of the Donetz Basin. Ibid., 46 (3), 245. 1933a. Contribution to the Knowledge of the Lower Carboniferous Bryozoa of the Turkestan. Trans. Unit Geol. Prosp. Serv. USSR. 207, 1. 1933/). Stratigraphic Range of the Carboniferous Bryozoa of the USSR. Trans. Unit. Geol. Prosp. Serv. USSR. 268, 1 . 1938. Types of Carboniferous Bryozoa of the European part of the USSR. Pal. of USSR. 4 (5), 1. OAKLEY, K. p. 1948. In Muir-Wood, H. M. Malayan Lower Carboniferous Fossils. Publ. Brit. Mus. (Nat. Hist.) d’orbigny, a. 1849. Description de quelques genres nouveaux de mollusques bryozoaires. Rev. et Mag. de Zool. 1, 501. 1850. Prodrome de Paleontologie. Paris: Masson, pp. lx+394 (vol. i), 427 (vol. ii), 196 (vol. iii), 189 (table). PHILLIPS, J. 1836. Illustrations of the Geology of Yorkshire, 2. London: John Murray, pp. xx+254. PORTLOCK, J. E. 1843. Report on the Geology of Londonderry &c., Dublin: H.M.S.O., pp. 784. 242 PALAEONTOLOGY, VOLUME 4 PRANTL, F. M. 1934. Carboniferous Bryozoa from Dobsina (Slovakia). Bull. Internat. Acad. Sci. Prague, 35, 225. SHRUBSOLE, G. w. 1879. A Rcvicw of the British Carboniferous Fenestellidae. Quart. J. Geol. Soc. 35, 275. 1881. Further Notes on the Carboniferous Fenestellidae. Ibid., 37, 178. SHULGA-NESTERENKO, M. I. 1941. Lower Permian Bryozoa of the Urals. Akad. Nauk SSSR. Tr. Pal. Inst.: Pal. USSR, 5 (5), 1. 1949o. Study of the phylogenetic groups of Lower Carboniferous-Lower Permian bryozoa of the family Fenestellidae. Ibid. 20, 293. 19496. On the microstructure of bryozoa. Ibid., 23, 1. 1952. New Lower Permian Bryozoa from the Ural region. Ibid., 37, 35. SPJELDNAES, N. 1957. The genus Fenestella. J. Palaeont., 31, 675. STUCKENBERG, A. 1888. Anthozoen und Bryozoen des oberen mittelrussischen Kohlenkalkes. Mem. Com. geol. St. Petersburg, 5 (4), 1. 1895. Korallen und Bryozoen der Steinkohleablagerungen des Urals usw. Ibid., 10 (3), 138. TOOTS, H. 1951. liber einige cryptostome Bryozoen aus dem Mitteldevon des Rheinischen Schiefer- gebirges. Neu. Jahrb. Geol. Paldont. Abh. 93 (2), 233. ULRICH, E. o. 1888. Bryozoa of the Waverley group in Ohio. Bull. Sci. Lab. Denison Univ. 4, 62. 1890. Palaeozoic Bryozoa. Geol. Surv. Illinois, 8 (2), 205. WATERS, A. w. 1878. Remarks on some Fenestellidae. Trans. Manchester Geol. Soc. 14. YOUNG, J. 1882. Remarks on some of the external characters which distinguish Fenestella plebeia M‘Coy from those of Fenestella tuberculo-carinata Etheridge jun. Trans. Geol. Soc. Glasgow, 7, 182. T. G. MILLER Department of Geology, University College, Keele. Manuscript received 18 July 1960 DENTITION AND RELATIONSHIPS OF THE ECHINOID GENUS PYGASTER J. L. R. AGASSIZ, 1836 by R. V, MELVILLE Abstract. Fragments of the lantern in a specimen of Pygaster fn'geri Cotteau, from the Bathonian of France, show that previous hypotheses of the relationships of Pygaster need to be reconsidered. The action of Durham and Melville (1957) in establishing a separate order for the Pygasteridae is held to be justified. The echinoid genus Pygaster J. L. R. Agassiz, 1836, was regarded until recently as a member of the order Holectypoida, and the implication of direct relationship with Holectypus Desor, 1842, was expressly accepted by, among others, Lambert (1900, p. 46 and folding tables), Lambert and Thiery (1914, p. 277), and Hawkins (1920, p. 453, text-fig. 2; 1943, p. Ixix). In 1948 Mortensen (pp. 14-15) thought that the two genera (and the families based on them) were of different origins, although he still retained both in the Holectypoida. Finally, in 1 957, Durham and Melville (p. 246) accepted Mortensen’s view and its implications and (p. 251) established a distinct order Pygasteroida for the single family Pygasteridae. This action rested partly on the assumption that Pygaster must have had grooved (aulodont) teeth, whereas those of Holectypus are known to be keeled (stirodont). In studying the echinoids in the Cotteau Collection at the Ecole nationale superieure des Mines de Paris in April 1956, 1 noticed a specimen of Pygaster trigeri Cotteau, from the Bathonian of Villey-St. Etienne (Meurthe et Moselle), France, bearing a number of adherent radioles and with parts of the jaw-apparatus within the peristome. By kind per- mission of the authorities of the Ecole des Mines I was allowed to borrow this specimen for study, and I am glad to acknowledge their generosity. I am also grateful to Dr. Porter M. Kier (U.S. National Museum, Washington) and to Dr. W. H. C. Rams- bottom for taking the photographs that illustrate this paper, and to Dr. R. Casey for the drawings reproduced as PI. 29, figs. 4 and 5. The expenses of the work were met by an allocation from the Government grant in aid of Scientific Investigations administered by the Royal Society, and thanks are expressed for this help. This paper is published with the permission of the Director, Geological Survey and Museum. LANTERN FRAGMENTS The specimen referred to is preserved in a buff marly limestone packed with rounded and ovoid ooliths and pellets. The marly parts of the matrix are soft and easily removed, but there are patches of denser material and of crystalline calcite which are harder than the fossil. When first studied, the peristome contained two rotulae and parts of three pyramids, two of which proved to contain teeth. The rotulae show no remarkable features and are not further considered. Two general views and an enlarged adoral view [Palaeontology, Vol. 4, Part 2, 1961, pp. 243-6, pis. 28-29.] 244 PALAEONTOLOGY, VOLUME 4 (PL 28, figs. 1, 2, 4) show the appearance of the specimen and the disposition of the lantern fragments in the peristome before preparation. Two of the pyramids were dissected out of the matrix and further cleaning of each was attempted. Owing to their fragility and small size, both were somewhat damaged in this process; moreover, the fragment that contained part of a tooth was embedded in crystalline calcite, so that the structure of the tooth could not be satisfactorily displayed. The third pyramid was left in place, but its tooth could only be exposed by working jl from above, and the specimen was sawn into two pieces for this purpose. The pyramids are not remarkable in structure (PI. 28, figs. 5, 6). The depth of the foramen magnum is not clearly shown, but it seems to have extended for about half the height of the pyramid i and to have been fairly wide. Viewed from the oesophageal side (PI. 29, fig. 1), the pyra- mid tapers rapidly adorally to a point about midway along its length and has a slightly expanded, spatulate termination (PI. 29, fig. 3). The top surface (PI. 29, fig. 2) appears to i be smooth. The interpyramidal muscle-scars are regular, strongly marked and gently | sinuate; there are between twenty-five and thirty grooves on the interpyramidal face i: (PI. 28, fig. 6). The peripheral side of each demipyramid (PI. 28, fig. 5) bears a strong ’ sulcus, deepening and narrowing adorally, on the interpyramidal side. This sulcus defines ' a rounded keel on the side towards the suture joining the demipyramids of a pair. The greatest interest of the specimen lies in the structure of the teeth (PI. 29, figs. 3, 4, 5). Each tooth is a stout, nearly straight beam of calcite, triangular in cross-section. Although no internal boundaries exist between the parts of the tooth, its form can be simply explained in terms of a nearly flat back, or base, upon which rests a pair of stout longitudinal buttresses, separated by deeply impressed longitudinal grooves from the i base beneath and from the rounded crest of the tooth above. The adoral end of the tooth , is not known, but was presumably of the bluntly pointed, triangular shape with chisel- edged sides generally seen in regular echinoids. This structure is unlike any described I previously in echinoids. As is well known, echinoid teeth are of two types. The aulodont type, regarded as the more primitive, has a grooved or trough-like blade, and the stirodont type consists of a base supporting a longitudinal keel. In both types the back ( of the tooth is gently rounded transversely to the length, with a weak median ridge, and j the sides project laterally a little beyond the edges of a broad longitudinal strap, which | has the appearance of reinforcing the tooth. Furthermore, in both types the cutting part EXPLANATION OF PLATE 28 Figs. 1-7. Pygaster trigeri Cotteau, Bathonian, Villey-St. Etienne (Meurthe et Moselle), France. 1, Adapical view, X 1. 2, Adoral view, x 1. 3, Part of adapical view enlarged x 14 showing radioles. 4, Part of adoral view enlarged x 1 4 showing two demipyramids and part of a rotula. 5, The | same, external view of a demipyramid ,x 10. 6, The same, interpyramidal view of same demipyra- ' mid, X 10. 7, The same, rotula, x 10. EXPLANATION OF PLATE 29 ' Figs. 1-6. Pygaster trigeri Cotteau, same specimen as in Plate 28. 1, Broken demipyramid with part of tooth in oesophageal view, X 10. 2, The same, adapical view of same demipyramid, X 10. 3, The same, oblique view of tooth lying slightly askew in its demipyramid; note also part of perignathic girdle, X 10. 4, The same, drawing of structures seen in fig. 3, approx. X 12; a, b, auricles of peri- gnathic girdle; c, spatulate end of demipyramid; d, crest of tooth. 5, The same, drawing of cross- section of tooth seen in fig. 3, X 45. 6, Enlarged view of part of Plate 28, fig. 3, to show radioles, X 7. Palaeontology , Vol. 4. PLATE 28 M ELVI LLE, Pygaster Palaeontology, Vol. 4. PLATE 29 MELVILLE, Pygaster R. V. MELVILLE: ECHINOID GENUS PYGASTER J. L. R. AGASSIZ 245 of the tooth is a bluntly pointed triangle, the sides of which cut by shearing against the corresponding edges of adjacent teeth, and the keel of the stirodont type stops short of this part of the tooth. That is, the keel has nothing to do with the cutting function. The whole structure is light, yet strong, very different from the massive construction seen in Pygaster. RADIOLES Although no complete radiole is known, it appears (PI. 28, fig. 3) that they were com- paratively short, not more than one-quarter to one-third of the diameter of the test. The smooth base flares gently out to the collar and the stem is strongly striated. The axis is solid. These radioles are of the same sort as those occasionally found adhering to tests of Plesiechinus oniatus (J. Buckman) from the Inferior Oolite (Pea Grit) of the Cotswolds, which also have a solid axis. The late Dr. Mortensen, when he was shown such speci- mens, was reluctant to accept the radioles as certainly of Plesiechinus, since none was in its original relationship to a tubercle, and many other species of echinoids occur in the Pea Grit. The abundance of these radioles on the present specimen of Pygaster trigeri, however, and the fact that no other kind of radiole has been observed in either genus, shows that there is no reason to doubt their genuineness. The radioles of Holectypus (Mortensen 1948, text-fig. 10, p. 24) have a hollow axis, as do those of certain early Pseudodiadematidae which it is hoped to describe elsewhere. RELATIONSHIPS 0¥ PYGASTER As mentioned in the Introduction, earlier theories of the direct relationship between Pygaster and Holectypus were discarded by Mortensen (loc. cit.). For him, the main distinguishing feature lay in the tubercles, which are smooth in Pygaster and crenulate in Holectypus, and he therefore derived the first from a Pedinid and the second from a Diadematid source. Durham and Melville ( 1957, p. 246) assumed that the teeth Pygaster were grooved, on account of the hypothetical Pedinid origin of Pygaster. I think it unsound, and hope soon to explain my reasons elsewhere, to refer any genus older than the Upper Cretaceous Palaeopedina Pomel, 1887, to the Diadematidae, and consider that the origin of Holectypus is to be sought among the early Pseudodiadematidae. With regard to the Pedinidae, however, there is no doubt that in every feature except the periproct and the teeth, Diademopsis and "Palaeopedina" show the closest possible re- semblance to Pygasteridae. The differences in the periproct are well known. The differ- ences in the teeth, now made known for the first time, are striking; for while Diademopsis has typically aulodont grooved teeth, like those of all other Pedinidae whose teeth are known, those of Pygaster are not merely keeled, but seem to have gone a stage farther in developing the massive longitudinal buttresses described above. It thus appears desirable to postulate some unknown form, intermediate between Pedinidae and Pygasteridae, in which the teeth were of normal stirodont type. Such an echinoid, if it were endocyclic, would ordinarily be referred either to the Phymosomatidae or to the Stompneustidae, but neither of these families at present includes any genus that is both morpho- logically and stratigraphically suitable as a possible ancestor for Pygaster. If, on the other hand, the periproct in such a form were not enclosed within the apical system, then it would be a Plesiechinus. Thus the assumed progression from a Pedinid ancestor B 0425 R 246 PALAEONTOLOGY, VOLUME 4 to Pygaster would have involved evolutionary changes not only in the position of the periproct, but also in the structure of the teeth — in the latter case to a stage beyond any hitherto known. This suggestion does no violence to the assumption (Durham and Melville 1957, p. 247) that all the irregular echinoids except the Pygasteridae descended from stirodont regular ancestors, for there is no a priori reason why the teeth in an irregular echinoid with fully functional jaws in the adult should have remained always in the condition obtaining in the regular ancestor, nor why they should not themselves evolve along lines either parallel to or divergent from those followed by regular forms. In particular, the evidence of the teeth emphasizes the distinctness of Pygaster from the true Holectypoids, and justifies the establishment of the order Pygasteroida Durham and Melville, 1957. The Pygasteridae may, perhaps, be regarded as an abortive attempt by one stock of regular echinoids to evolve into the Holectypoid condition. REFERENCES DURHAM, J. w. and melville, r. V. 1957. A classification of Echinoids. J. Paleoiit. 31, 242-72. HAWKINS, H. L. 1920. The morphology and evolution of the ambulacrum in the Echinoidea Holecty- poida. Phi!. Trans. Roy. Soc. London, B, 209, 377-480. 1943. Evolution and habit among the Echinoidea: some facts and theories. Quart. J. Geol. Soc. London, 99, lii-lxxv. LAMBERT, J. 1900. Etude SUE quelques Echinides de ITnfra-Lias et du Lias. Bull. Soc. Sci. Hist. Nat. Yonne, Ann. 1899, 53 (2), 1-57, pi. 1. and THiERY, p. 1914. Essai de nomenclature raisonnee des Echinides, fasc. 4, 241-320, Auxerre. MORTENSEN, T. 1948. A Monograph of the Echinoidea, 4 (1), Copenhagen. R. V. MELVILLE Geological Survey and Museum, Manuscript received 26 October 1960 London, S.W. 7. 5 NAMURIAN PLANT SPORES FROM THE SOUTHERN PENNINES, ENGLAND by R. NEVES Abstract. Selected fossil spores from coals and carbonaceous shales of Namurian age from the Southern Pennines area of England are described, and their stratigraphic ranges given with reference to the standard sequence of goniatite stages. The types of sediment in which the spores are found are recorded, and the apparent association of certain spore types with particular sediments is discussed. Two new series of fossil spores are proposed — Pseudocingulati and Membranati ; two new genera — Secarisporites and Hymenospora — and twenty- seven new species are described and illustrated. Disaccate pollen grains of the Pityosporites-Vesicaspora type are recorded for the first time from strata of Namurian age. The value of fossil plant spores for purposes of coal-seam correlation has been adequately demonstrated by Kosanke (1950), Balme and Butterworth (1952), and Butter- worth and Millott (1954 and 1955). These authors were concerned with typical coal- measures sequences in which the coal seams form a prominent lithological constituent. In other sedimentary successions, however, coal seams are often absent or, if present, are of spasmodic occurrence and limited areal extent. Such is the case in the Namurian suc- cession of the Southern Pennines area of England, where carbonaceous shales provide the most readily available source of fossil spores. The spore assemblages obtained from the thin coals are used to supplement the data obtained from studies of the shales. Hoffmeister, Staplin, and Malloy (1955) and Neves (1958) have already indicated that the types of spores present and their relative abundance differ considerably in coal seams and closely allied carbonaceous shales. Such an occurrence is to be expected, in that the spores obtained from coal will mainly represent a parent vegetation which, although rich in constituent members, is of a somewhat restricted and specialized nature; the vegetation consisting of plants which are adapted to the swamp environment. It is probable, therefore, that certain spore types produced by a vegetation which existed outside the coal swamps will not be represented in the coal-seam assemblages. However, should some of these spores have been carried into the swamp region by wind or water agencies, their presence will be masked to the observer, by the profusion of spore types dispersed more or less in situ from the local swamp vegetation. The allochthonous nature of the shales, on the other hand, implies that the contained fossil spores will be derived from a variety of parent plant assoeiations occupying various ecological stations. The assemblages preserved in shales will be representative of the vegetation which was grow- ing in and around the basin of sedimentation. Consequently the complete microflora and the absolute time ranges of the component forms can only be obtained by an examina- tion of all those sedimentary types which make up the geological succession of the region. In this way the succession of coal swamp vegetations, as represented by the coal seams, will be determined and the characteristics of other contemporaneous vegetation estab- lished. The sum total of this combined evidenee enables a closer appreciation of the flora to be achieved, and this appears to be an essential criterion in the utilization of microfloral evidence to the problems of stratal subdivision. [Palaeontology, Vol. 4, Part 2 1961, pp. 247-79, pis. 30-34.] 248 PALAEONTOLOGY, VOLUME 4 In the present paper, certain new spores are described from coals and shales of Namurian age from the Southern Pennines area of England. The stratigraphical occurrences of these spores in this region, together with several already described species, have been recorded and are shown in Table 1. These spores have been selected on account of their value as stratigraphic indicators and represent a small part of the TEXT-FIG. 1. Index map of localities and outcrop distribution in the Southern Pennines Basin. total Namurian microflora. The sequence of goniatite stages, which is used as the basis for Table 1, is that proposed by Bisat (1928, p. 117) and subsequently redefined by Hudson and Cotton (1943, p. 152). The majority of the samples used during the investigation were collected by the author from outcrop and mine exposures which are described in literature and are listed below. Other samples were kindly provided by Dr. R. M. C. Eagar from the Wigan district in the west of the region. A sketch map of the region (text-fig. 1) indicates sample localities and the outcrop of the Namurian measures. Stratigraphy and palaeogeography. The Southern Pennines area of the Central Province of England, comprising parts of Yorkshire, Lancashire, Derbyshire, Cheshire, and Staffordshire, was a region of general subsidence throughout Upper Carboniferous R. NEVES: NAMURIAN PLANT SPORES 249 times. The basin of sedimentation was bounded to the south by the land mass of St. George’s Land and to the north by the Lake Distriet and Southern Uplands massifs. Within the basin, the areas of maximum subsidence and sedimentation were not con- stant so that locally non-sequences and even unconformities are present at the base of the Namurian successions. The stratigraphical succession of the region, based mainly on the goniatite faunas contained in the marine shales, has been thoroughly established through the work of Bisat (1928), Bisat and Hudson (1943), Hudson and Cotton (1943, 1945), Jackson (1927), Hester (1932), Cope (1945), and Trotter (1951). In general, the lower stages of the Namurian, when present, consist of marine, argillaceous deposits interleaved with thin, sandy horizons or crowstones. The younger Namurian measures are characterized by an increased arenaceous component which takes the form of thick, lenticular beds of sand- stone and gritstone, such as the Kinderscout Grit series. Observations on current bedding carried out by Gilligan ( 1920) in the northern areas and the author in the southern parts of the basin indicate that the arenaceous material was derived both from the north and south respectively. Sometimes associated with the sandy horizons are thin coals and bluish grey, non-marine shales, which give rise to a primitive form of rhythmic sedimenta- tion of the coal-measure type in the higher Namurian stages. List of sample localities and horizons examined. The locality numbers correspond to those used in text- fig. 1 and also occurring in the section dealing with the Systematic Palaeontology. 1. Exposure in lane leading to Limekiln Farm, near Congleton, Staffordshire (G.R. SJ. 861591). Astbury Coal, Pendleian stage. 2. Exposure near Moor Hall Farm, Bagnall, Staffordshire (G.R. SJ. 945509). Horizon: marine shale with Enmorphoceras bisidcatnm Girty. 3. Stream exposure, Hollywood Dingle, near Endon, Staffordshire (G.R. SJ. 928554). Horizon: marine shale with Anthracoceras paucilobum. 4. Ganister Quarry, Congleton Edge, Staffordshire (G.R. SJ. 869591). Horizons: Marine shale with Hudsonoceras proteum. Grey Non-marine shales. Thin Coal Seam. 5. Tip from old workings of the Congleton Edge Coal, near Biddulph, Staffordshire (G.R. SJ. 870590). Horizon: coal seam above Congleton Edge Grit, Marsdenian stage. 6. Stream exposure south of Rushton Hall, north Staffordshire (G.R. SJ. 928614). Horizon: Marine shale with Reticidoceras inconstans s.l. 7. Exposure in Marsh Brook, Ashover, Derbyshire (G.R. SK. 344634). Horizon: marine shale with Reticidoceras inconstans s.l. 8. Stream exposure in Lindup Wood, near Rowsley, Derbyshire (G.R. SK. 255675). Horizon: marine shales with Reticidoceras bilingiie. 9. Sandstone quarry. Stone Edge, Derbyshire (G.R. SK. 344674). Horizon: Baslow Coal, Marsdenian stage. 10. Stream exposure, Crowborough Wood, near Biddulph, Staffordshire (G.R. SJ. 902556). Horizon: marine shales with Gastrioceras cancellatiim. 1 1. Smeekley Bore Hole, Cordwell Valley, Derbyshire (G.R. SK. 296767). Horizons: Marine shale with Gastrioceras listeri. Marine shale with Gastrioceras siibcrenatum. Non-marine shale with Carbonicola exporrecta. Marine shale with Gastrioceras cancellatiim. 12. Exposures in stream banks, Hipper Sick, Derbyshire (G.R. SK. 312683). Horizons: Marine shale with Gastrioceras siibcrenatum. Non-marine shale with Carbonicola exporrecta. 250 PALAEONTOLOGY, VOLUME 4 Marine shale with Gastrioceras cumbriense. Marine shale with Gastrioceras caiicellatian. 13. Canister Drift Mine, Holymoorside, Derbyshire (G.R. SK. 327680). Horizons : Marine shale with Gastrioceras subcrenatum. Pot Clay Coal and non-marine roof shales. 14. Stream exposure, near The Wash, Quarnford, Staffordshire (G.R. SJ. 014662). Horizons: as locality 13. 15. Stream exposure, near Consall village, Staffordshire. (G.R. SJ. 975483). Horizon: Six Inch Mine Coal. Yeadonian stage. 16. Exposure in the bank of the Little Don river, near Langsett, Yorkshire (G.R. SE. 222005). Hori- zons: as localities 13 and 14. 17. Canister Quarry, Wessington, Derbyshire (G.R. SK. 349566). Horizons: marine shale with Gastrioceras listeri, and Alton Coal. 18. Canister Drift Mine, Neepsend, Sheffield, Yorkshire. Horizons: as locality 17. Previous palynological literature. Literature dealing with Namurian plant spores is available from several continents. Luber and Waltz (1938) described Lower Carboni- ferous assemblages from the Moscow and Karaganda Basins of the U.S.S.R.; Ischenko (1952, 1956, and 1958) published his work on the fossil plant spores from coals of the Donetz and Dneiper Basins; Horst (1955) dealt with the Namurian spores of Upper Silesia and in 1957 Dybova and Jachowicz gave a further account of Upper Carboni- ferous spores from this region; Artuz (1957, 1959) described the spore assemblages of three coal seams of Namurian and Lower Westphalian A age, from the Zonguldak Coalfield of Turkey. Hoffmeister, Staplin, and Malloy (1955) gave the results of an investigation into the plant spore assemblages contained in coals and shales of Upper Mississippian age from Illinois and Kentucky, U.S.A. In Britain, Millott (1939) con- sidered briefly the fossil spores found in certain coal seams of Namurian age from north Staffordshire; Knox (1942) and Butterworth and Williams (1958) investigated the small spore content of coal seams of Namurian A age in the Limestone Coal Group and the Upper Limestone Group of Scotland. The present author (Neves, 1958) gave a pre- liminary account of an investigation into the plant spore content of coals and associated carbonaceous shales from the Central Province of England. Most authors, however, have been concerned with the small spore assemblages present in coal seams, with little attention having been directed to the spore content of shales. Furthermore, the strati- graphical occurrences of the various spore types are rarely referred directly to the established sequence of goniatite zones. Maceration techniques. The various methods which have been employed for the isolation of organic remains from coals and shales have been fully described elsewhere by several authors. The technique used throughout the present work relies on Schulze solution to oxidize the humic matter which is in close association with the plant tissues. The oxidized products were then removed in a dilute solution of potassium hydroxide. The mineral matter of the shales is eliminated by digestion in hot hydrofluoric acid following an initial treatment with bromine to break the shale down. The details of the technique are more fully described in Neves (1958). SYSTEMATIC PALAEONTOLOGY The system proposed by Potonie and Kremp (1954) for the description and classification of the fossil dispersed spores is used in this account. Slight modifications are introduced R. NEVES: NAMURIAN PLANT SPORES 251 where it is considered to be of practical advantage in light of additional information. Two new Series, Pseudocingulati and Membranati, are erected to accommodate newly described spore types. Two new genera, Secarisporites and Hymenospora, are described and illustrated together with new species of the following genera; Leiothletes, Pimcta- tisporites, Acanthotriletes, Ibrahimispores, Neoraistrickia, Mooreisporites, Caniptotriletes, Dictyotriletes, Convolutispora, Secarisporites, Ahrensisporites, Triquitrites, Densosporites, Knoxisporiles, Stenozonotriletes, Cirratriradites, Proprisporites, and Tholisporites. As a result of observations made during the course of the present investigation, the genus Knoxisporites Potonie and Kremp 1954 is here transferred to the Series Cingulati Details of occurrence are given in Table 1 or in the text. All slides referred to in the text are lodged in the Micropalaeontology Laboratory, Department of Geology, University of Sheffield. Division sporites H. Potonie 1893 Group triletes Reinsch 1881 Subgroup AZONOTRiLETES Luber 1935 Series laevigati (Bennie and Kidston) Potonie 1956 Genus leiotriletes (Naumova) Potonie and Kremp 1954 Type species. L. sphaerotriangidus (Loose) Potonie and Kremp 1954 Leiotriletes densus sp. nov. Plate 30, figs. 1, 2 Holotype. Plate 30, fig. 1 . Type locality. Non-marine roof shales of the Pot Clay Coal, Langsett, Yorkshire (Loc. 16). Yeadonian stage. Diagnosis. Size range 85-110 ft (fifteen specimens measured), holotype 96 ft; equatorial outline triangular; trileterays three-quarters radius of the spore; exine dense and thick. Description. Colour dark brown. Equatorial outline triangular, sides straight to slightly convex, apices broadly rounded. Trilete rays prominent, lips thin, sutures usually closed. Exine thick, laevigate to faintly infrapunctate. Comparison. The compact triangular shape, longer trilete rays, and the absence of a darkened contact region distinguish these spores from those of the species L. grandis (Kosanke) Bhardwaj 1957. Occurrence. Upper Namurian C and Lower Westphalian A, rare. Genus punctatisporites (Ibrahim) Potonie and Kremp 1954 Type species. P. pimctatiis Ibrahim 1933 Punctatisporites pseudopunctatus sp. nov. Plate 30, fig. 3 Holotype. Plate 30, fig. 3. Type locality. Non-marine shale with Carbonicola exporrecta, Hipper Sick, Derbyshire (Loc. 11). Yeadonian stage. 252 PALAEONTOLOGY, VOLUME 4 Diagfwsis. Size range 90-120 [x (nineteen specimens measured), holotype 116 yu.; equa- torial outline subcircular; trilete rays short, approximately half spore radius; exine ! strongly and densely infrapunctate. Description. Colour light brown to yellow. Tecta of the tetrad mark tapering, lips often associated with small folds. At the margin of the compressed spores a narrow ‘rim’, 2-3 p wide, is present. The inner line of the ‘rim’, corresponding to the intexine mem- brane, clearly shows the infra-punctate nature of the exine. Outline smooth. Small secondary folds of the exine occur infrequently. Comparison. The spores of this species are slightly larger than those of P. aerariiis Butterworth and Williams 1958, and the structure of the exine is much stronger. P. grandis and P. psendoelevatiis Hoffmeister, Staplin, and Malloy 1955 differ in possessing a positive surface ornamentation. Occurrence. Namurian A and C ; sometimes common, particularly in marine shales. Punctatisporites giganteus sp. nov. Plate 30, fig. 4 Holotype. Plate 30, fig. 4. Type locality. Marine shale with Eumorphoceras bisulcatiim Girty, Bagnall, Staffordshire (Loc. 2). Arnsbergian stage. Diagnosis. Size range 150-170 p (ten specimens measured), holotype 15S p; equatorial outline subcircular to sub triangular; trilete rays two-thirds to three-quarters radius of the spore; exine laevigate to strongly infrapunctate. Description. Colour yellow-brown; exine 2-3 p thick, margin smooth, occasional secondary folds. Trilete rays distinct; lips thin, subparallel to tapering. Comparison. P. obesus (Loose) Potonie and Kremp is smaller. Occurrence. Namurian A, rare. Punctatisporites {Sinuspores) sinuatus (Artuz) comb. nov. 1958 Punctatisporites densoarcuatus Neves; p. 6, pi. ii, fig. 7. 1958 Punctatisporites coronatus Butterworth and Williams; p. 360, pi. i, fig. 12. Remarks. Sinuspores sinuatus was described by Artuz (1957, p. 254) as possessing a variably thickened exine and a ‘Gurtelzone’. Neves (1958, p. 6) and Butterworth and Williams (1958, p. 360) described this structure as simple exinous folding. The material examined by the current author clearly shows all stages in the development of the pro- nounced curving fold as seen in the holotype (Artuz 1957, pi. 7, fig. 48), from simple. EXPLANATION OF PLATE 30 All magnifications X 500. Figs. 1-2. Leiotriletes densus sp. nov. Slide ref. s.Z. 1, holotype, 96 p. 2, 96 p. Fig. 3. Punctatisporites pseudopunctatus sp. nov., holotype, 116 p. Slide ref. s.H. Fig. 4. Punctatisporites giganteus sp. nov., holotype, 158 p. Slide ref. s.B. Fig. 5. Acanthotriletes slendidus sp. nov., holotype, distal surface, 105 p. Slide ref. 5.261818. Figs. 6-7. Acanthotriletes ? piliis sp. nov. 6, holotype, 69 p. 7, 84 p. Slide ref. s.E. Palaeontology, Vol. 4 PLATE 30 NEVES, Namurian microspores R. NEVES: NAMURIAN PLANT SPORES 253 small amplitude folds of the exine. Since these structures are clearly secondary effects it is proposed to transfer the species S. sinuatus Artuz to the genus Piinctatisporites. Occurrence. Artuz (1957) — Westphalian A. Butterworth and Williams (1958) — Namurian A of Scotland. Series apiculati (Bennie and Kidston) Potonie 1956 Genus apiculatisporis Potonie and Kremp 1956 Type species. A. aciileatus (Ibrahim) Potonie and Kremp 1954 Apiculatisporis macuJosus (Knox) Potonie and Kremp 1955 Occurrence. Lower Namurian A, rare. Butterworth and Williams (1958) recorded this species from the Namurian A measures of Scotland. Genus acanthotriletes (Naumova) Potonie and Kremp 1954 Type species. A. ciliatus (Knox) Potonie and Kremp 1954 Acanthotriletes splendidus sp. nov. Plate 30, fig. 5 Holotype. Plate 30, fig. 5. Type locality. Marine shale with Anthracoceras paucilobum, Hollywood Dingle, Staffordshire (Loc. 3). Arnsbergian stage. Diagnosis. Size range 90-110 g (ten specimens measured), holotype 105 p; equatorial outline triangular; trilete rays two-thirds spore radius; exine ornamented with slender, broad-based spines; thirty to fifty spines overtop the equatorial margin. Description. Colour light brown. Equatorial outline triangular, sides concave, apices rounded. Trilete rays with narrow lips, sutures sometimes open. The spines which orna- ment the exine are 2-10 p high, and 2-4 p wide at the base. The spines are not densely spaced and there is room between them for elements of equal size. Exine between spines laevigate. Comparison. These spores are characterized by their large size and the ornament of slender spines. Acanthotriletes horridus Hacquebard 1957 is larger and possesses stronger more densely spaced spines. Occurrence. Namurian A, rare. Acanthotriletes^ pihis sp. nov. Plate 30, figs. 6, 7 Holotype. Plate 30, fig. 7. Type locality. Marine shale with Gastrioceras caacellatum, Hipper Sick, Derbyshire (Loc. 1 2). Yeadonian stage. Diagnosis. Size range 50-90 p (twenty specimens measured), holotype 84 p; equatorial outline rounded triangular; trilete rays two-thirds to three-quarters radius of the spore; exine densely covered by short, slender, ‘mushroom ’-topped pila. 254 PALAEONTOLOGY, VOLUME 4 Description. Colour light brown to yellow. Original shape ± globular, and the spores are often compressed obliquely with no preferred orientation. Trilete rays straight, tecta slightly tapering, lips thin. Exine 2 p thick, decorated by closely spaced, discrete pila the tips of which are expanded to a mushroom form; height 2-3 p, width at base 0-5-1 p. Comparison. Acanthotriletes {Azonotriletes) midlisetosus (Luber and Waltz) Potonie and Kremp 1955 is superficially similar to ^4? pilus. However, the spores of the former species are rounded to oval in outline and the ornament consists of essentially parallel- sided spines. Occurrence. Namurian C; this species has been recorded only from the type horizon. Acanthotriletes baculatus sp. nov. Plate 31, fig. 1 Holotype. Plate 3 1 , fig. 1 . Type locality. Marine shale with Hiidsonoceras pwteum, Congleton Edge ganister quarry, Staffordshire (Loc. 4). Sabdenian stage. Diagnosis. Size range 34-45 p (fifteen specimens measured), holotype 34 p; equatorial outline triangular; trilete rays two-thirds radius of the spores; exine beset with upstand- ing blunted spines; fifteen to twenty elements occur at the equatorial margin. Description. Colour pale yellowish-brown. Equatorial outline triangular, sides concave, apices rounded. Rays of the trilete mark simple, often obscured by the ornamentation elements which consist of relatively long, in part parallel sided, and terminally truncate spines; height 4-10 p, width 1-2-5 p. The spines are not densely set and between them the exine is laevigate. Comparison. Acanthotriletes falcatus has stouter, cone-like spines which are closely spaced; in A. castanea the spines are uniformly tapering and more densely set. Occurrence. Namurian A, infrequent. Genus ibrahimispores Artuz 1957 Type species. I. microhorridus Artuz 1957 Ibrahimispores brevispinosus sp. nov. Plate 31, fig. 2 Holotype. Plate 31, fig. 2. EXPLANATION OF PLATE 31 All magnifications X 500. Fig. 1. Acanthotriletes baculatus sp. nov., holotype, 34 p, distal view. Slide ref. 1.302744. Fig. 2. Ibrahimispores brevispinosus sp. nov., holotype, 80 p, distal view. Slide ref. s.Y. Fig. 3. Ibrahimispores magnificus sp. nov., holotype, 81 p, distal view. Slide ref. s.Ao. Fig. 4. Neoraistrickia inconstans sp. nov., holotype, 71 p, distal view. Slide ref. 1.285759. Fig. 5. Mooreisporites trigallerus sp. nov., holotype, 77 p, distal view. Slide ref. s.T. Fig. 6. Mooreisporites fastis Neves, distal view, 75 p. Fig. 7. Mooreisporites bellus sp. nov., holotype, 105 p, distal view. Slide ref. s.E. Fig. 8. Camptotriletes superbus sp. nov., holotype, l\9 p, proximo-lateral view focus low on ornament. Slide ref. 3.240769. Palaeontology, Vol 4. PLATE 31 NEVES, Namurian microspores R. NEVES: NAMURIAN PLANT SPORES 255 Type locality. Non-marine shales with Carbonicola exporrecta, Hipper Sick, Derbyshire (Loc. 11). Yeadonian stage. Diagnosis. Size range 70-100 p. (fifteen specimens measured), holotype 80 p.; equatorial outline rounded-triangular; exine ornamented with stout, hollow pointed spines which are thickened at the tips. Description. Colour yellow-brown to brown. Equatorial outline rounded-triangular to subcircular. The rays of the trilete mark are usually associated with dark, flexuous folds of the exine; approximately three-quarters radius of the spores. The ornamentation elements are short, hollow spines, uniformly tapering to the sharply pointed, solid tip. Spines 6-10 p high, 3-5 p wide at the base and are densely spaced; forty to fifty elements occur at the equatorial outline. Comparison. I. microhorridus Artuz is more circular in outline and the spines appear to be solid and without thickened tips. Ibrabiniispores niagnificiis sp. nov. Plate 31, fig. 3 Holotype. Plate 31, fig. 3. Type locality. Non-marine shale with Carbonicola exporrecta, Hipper Sick, Derbyshire (Loc. 11). Yeadonian stage. Diagnosis. Size range 75-90 p (ten specimens measured), holotype 81 p; equatorial outline rounded-triangular, sides convex, apices broadly rounded; trilete mark often obscured by dark flexuous folds of the exine. Exine beset with long, hollow pointed spines; fifteen to twenty elements occur at the equatorial margin. Description. Colour light brown. The large spines which decorate the exine are not densely set and elements of equal size could be placed between them. Spines 15-20 p high, 3-8 p wide at the base. The tips of the spines are solid and appear as darker, conical terminations; bifurcation of the spines is infrequently seen. Exine infra-punctate between the spines. Comparison. I. magnificus is probably closely related to I. brevispinosus. However, on account of the recognizable difference in size and disposition of the ornamentation ele- ments, it proposed as a new species. Occurrence. Namurian C, rare. Genus neoraistrickia Potonie 1956 Type species. N. truncatus (Cookson) Potonie Neoraistriekia ineonstans sp. nov. Plate 31, fig. 4 Holotype. Plate 31, fig. 4. Type locality. Marine shale with Hudsonoceras proteian, Congleton Edge ganister quarry, Staffordshire (Loc. 4). Sabdenian stage. Diagnosis. Size range 55-75 p (twenty specimens measured), holotype 71 p; equatorial 256 PALAEONTOLOGY, VOLUME 4 outline triangular, sides concave to straight, apices rounded. Trilete rays two-thirds spore radius. Distal surface and proximal surface decorated with short baculae. Description. Colour light brown. Trilete rays distinct, tecta straight, lips thin. Exine laevigate between ornamentation elements. The baculae which are present on the distal surface of the spores are 3-8 p. high, 2-4 p wide, parallel-sided elements; interspersed between these are small, blunt conical projections. The ornamentation encroaches on to the proximal surface of the spores, particularly in the region of the spore body apices. Whilst the latter radial regions may be densely ornamented, the inter-radial margin is often devoid of projections. Comparison. The triangular equatorial outline and the baculose ornamentation are typical of the genus Neoraistrickia. Occurrence. Namurian A, fairly common at specific horizons. Genus mooreisporites Neves 1958 Type species. M. fastis Neves 1958 Mooreisporites trigaUenis sp. nov. Plate 31, fig. 5 Holotype. Plate 31, fig. 5. Type locality. Marine shale with Hudsotioceras proteam, Congleton Edge ganister quarry, StaflFordshire (Loc. 4). Sabdenian stage. Diagnosis. Size range 55-80 p (thirty specimens measured), holotype 77 p; equatorial outline triangular; trilete rays short, half radius of the spore; apices of spore body ornamented with short, fused baculae. Description. Colour light brown, apical ornament darker. Equatorial outline triangular, sides straight, apices expanded due to the projecting baculae. Trilete rays short, lips thin, suture narrow. Exine ornamented overall with small, scattered coni. At the apices of the spore body short baculae are developed, size 8-10 p high; these elements are often fused laterally in the lower part. Comparison. Triquitrites tricuspis is similar but possesses a narrow equatorial cingulum (Horst 1955, p. 175); Tripartites hicidus Artuz 1957 is slightly larger and the rays of the trilete mark reach the margin of the spore body. Mooreisporites fastis is characterized by heavy branching baculae both in the apical regions and also on the distal surface of the spores. Remarks. Mooreisporites trigallerus sp. nov. should not be placed in the genus Tri- partites (Schemel) Potonie and Kremp 1954 since none of the specimens observed possesses the inter-radial, equatorial flange which is present in Tripartites vetustus, the type species of the genus. Occurrence. Namurian A, common at certain horizons. Mooreisporites fastis Neves 1958 Plate 31, fig. 6 Occurrence. Spores of this species first appear in the Upper Namurian A assemblages and are to be found in both shale and coal preparations. R. NEVES; NAMURIAN PLANT SPORES 257 Mooreisporites bellus sp. nov. Plate 31, fig. 7 Holotype. Plate 31, fig. 7. Type locality. Baslow Coal, Stone Edge Quarry, Derbyshire (Loc. 9). Marsdenian stage. Diagnosis. Size range 95-115 /x (fifteen specimens measured), holotype 105 p; exine decorated with small scattered coni; apical regions with large, irregular patches of thickening and terminal baculae. Description. Colour light brown, apical thickening dark brown. Trilete rays half radius of the spore body, suture and lips narrow. The large, bifurcating baculae, which project beyond the apical margins of the spores, arise from extensive, irregular patches of distal thickening. The latter often extend polewards on the distal surface. The baculae are 4-8 /u. wide, of variable height and with partate terminations. Comparison. M. bellus is characterized by spores of large size, possessing in the radial positions irregular patches of exinous thickening from which arise the squat baculae seen at the spore margin. Genus verrucosisporites (Ibrahim) Potonie and Kremp Type species. V. verrucosus Vovahim 1933 Remarks. The spores of this genus are very rare in the Namurian assemblages of the Central Province of England. Verrucosisporites morulatus Knox 1950 Remarks. For description see Knox (1950) and Butterworth and Williams (1958 p. 62). Occurrence. Lower Namurian A, rare. Butterworth and Williams (1958) found this species was confined to the Limestone Coal Group of Scotland. Series murornati Potonie and Kremp 1954 Genus camptotriletes (Naumova) Potonie and Kremp 1954 Type species. C. corrugatus (Ibrahim) Potonie and Kremp 1954 Camptotriletes superbus sp. nov. Plate 31, fig. 8 Holotype. Plate 31, fig. 8. Type locality. Pot Clay Coal, Holymoorside, Derbyshire (Loc. 13). Yeadonian stage. Diagnosis. Size 75-125 p (thirty specimens measured), holotype 119 p; equatorial out- line subcircular; trilete rays long, three-quarters radius of the spore, tecta sharp and tapering. Exine ornamented with irregular, disjointed, subconical ridges. Description. Colour golden to reddish-brown. Spore margin overtopped by twenty to twenty-five rounded, conical processes. The discontinuous ridges which ornament the surface of the spores are 3-5 p high and up to 25 p long; and appear as a verrucose to 258 PALAEONTOLOGY, VOLUME 4 | conate ornament in which the elements are connected laterally by irregular ridges. The , ridges are separated by irregular regions of thinner, laevigate exine. Comparison. The spores of this species are characterized by their large size and the variable nature of the rudimentary cristae. , Occurrence. Upper Namurian B-Westphalian A, common in certain coal-seam assem- f blages. j Camptotriletes verrucosus Butterworth and Williams 1958 Occurrence. Lower Namurian A, rare. The species was originally described from the Limestone Coal Group of Scotland. : Genus dictyotriletes (Naumova) Potonie and Kremp 1954 Type species. D. bireticulatiis (Ibrahim) Potonie and Kremp 1954 Dictyotriletes tuberosus sp. nov. jj Plate 32, fig, 1 III Holotype. Plate 32 fig. 1 . !' Type locality. Marine shale with Hiidsoiioceras proteian, Congleton Edge ganister quarry, Staffordshire (Loc. 4). Sabdenian stage. Diagnosis. Size range 90-120 p. (ten specimens measured), holotype 120 p, equatorial I outline subcircular to oval; exine decorated with very strong muri which appear as ;i: rounded elevations at the spore margin ; the muri enclose seven to twelve large lacunae. Description. Colour light brown, muri dark brown. Trilete rays three-quarters spore radius, lips often slightly thickened. The muri of the reticulum are heavy, solid walls, 5-10 /X wide at the base, 5-7 p high, and rounded conical in profile. The lacunae enclosed by the muri are large and of variable shape. Comparison. Dictyotriletes (Azonotriletes) subalveolaris (Luber) Potonie and Kremp 1955 resembles D. tuberosus in the nature of the muri, however in the former species, there are many more lacunae present in the reticulum. The muri in D. tuberosus show no tendency for the membranous zone at the spore outline, a feature which characterizes the genus Reticulatisporites. EXPLANATION OF PLATE 32 All magnifications x 500. Fig. 1. Dictyotriletes tuberosus sp. nov., holotype, 120 p, distal surface, focus low. Slide ref. s.A, Fig. 2. Convolutispora sp. A., distal view, 122 p. Fig. 3. Convolutispora obliqiia sp. nov., holotype, 122 p, focus low on ornament. Slide ref. 1.295827. Figs. 4-5. Convolutispora laminosa sp. nov. 4, Holotype, 72 p, distal view. Slide ref. 7.221665. 5, Proximo-lateral view, 69 p. Figs. 6-7. Secarisporites lobatus sp. nov. 6, Holotype, 81 p, proximal view and low focus. Slide ref. 4. 175850. 7, Distal view, 80 p. Figs. 8-9. S. remotus sp. nov. 8, Distal view, 48 p. 9, Holotype, proximal view, 46 p. Slide ref. 8.343708. Fig. 10. Ahrensisporites beeleyensis sp. nov., holotype, 56 p, distal view, low focus. Slide ref. s.Z. Fig. 11. Ahrensisporites guerickei var. ornatus var. nov., holotype, 66 p, distal surface. Slide ref. 4.296768. Fig. 12. Triquitrites nodosus sp. nov., holotype, 88 p. Slide ref. s.Av. PLATE 32 Palaeontology , Vol 4. NEVES, Namurian microspores R. NEVES: NAMURIAN PLANT SPORES 259 Dictyotriletes varioreticulatus Neves 1958 Occurrence. Upper Namurian B-Westphalian A, common in some coals. Genus convolutispora Hoffmeister, Staplin and Malloy 1955 Type species. C.florida Hoffmeister, Staplin and Malloy 1955 Convolutispora sp. A Plate 32, fig. 2 Deseription. One specimen only, size 122 p. Equatorial outline it circular, margin sinuous to smoothly indented. Trilete rays three-quarters spore radius, sutures thin. Exine with broad anastomosing ridges, 6-10 p wide, and which form an irregular reticulum when seen in high focus. Comparison. The organization of the ridges is somewhat similar to that present in C. mellita Hoffmeister, Staplin, and Malloy. Occurrenee. Marine shale with Gastrioceras canceUatum, Hipper Sick, Derbyshire (Loc. 12). Yeadonian stage. Convolutispora obliqua sp. nov. Plate 32, fig. 3 Holotype. Plate 32, fig. 3. Type locality. Marine shale with Eumoiphoceras bisulcatum, Bagnall, Staffordshire (Loc. 2). Arns- bergian stage. Diagnosis. Size range 100-130 p (twenty specimens measured), holotype 122 p; equatorial outline subcircular, spores usually compressed obliquely; exine with an ornament of long, anastomosing ridges, 2-5 p high, 1-6 p wide, and up to 25 p long. Description. Colour brown. Trilete rays two-thirds to three-quarters radius of the spores, slightly flexuous due to the ornament, suture and lips narrow. The sinuous, anastomosing ridges appear at the spore margin as subcortical processes with rounded or flattened crests. Between the ridges there appear narrow channels of thinner exine. Secondary folds of the exine are infrequently present. Comparison. C. mellita and C. tessellata are smaller, and the ridges in these species are shorter with less tendency for the linear disposition present in C. obliqua. C.flexuosa has flatter, more widely spaced ridges. Convolutispora laminosa sp. nov. Plate 32, figs. 4, 5 Holotype. PI. 32, fig. 4. Type locality. Marine shale with Gastrioceras canceUatum, Hipper Sick, Derbyshire (Loc. 12). Yea- donian stage. Diagnosis. Size range 50-80 p (twenty specimens measured), holotype 72 p\ equatorial outline subcircular; exine characterized by broad regions of thickening which are sinuous in outline. 260 PALAEONTOLOGY, VOLUME 4 Description. Colour brown. Trilete rays hair-like, two-thirds to three-quarters radius of the spores. The exine of these spores bears extensive regions of thickening, between which narrow channels of thin exine are to be found. Locally the patches of thickening break up into broad, flat, ± linear ridges. Thickenings 5-20 p wide, length variable. Comparison. In all other described species of Convolutispora the linear, sinuous orna- mentation ridges predominate. Occurrence. Namurian B-C, restricted to marine shale assemblages where the species is sometimes fairly common. Genus microreticulatisporites (Knox) Potonie and Kremp 1954 Type species. M. lacunosiis (Ibrahim) Knox 1950 Microreticulatisporites concavus Butterworth and Williams 1958 Occurrence. Namurian A, rare and restricted to marine shale assemblages. Series pseudocingulati ser. nov. This Series is proposed for those miospores in which the ornamentation of the exo- exine, large warts and lobate outgrowths, extends beyond the line of the spore body membrane (int-exine) in the equatorial region. The compressed spores are consequently characterized by a marked outer marginal rim which is deeply dissected and often dis- continuous. Comparison. Spores of the Series Membranati ser. nov. differ in that the exo-exine is membranous and encloses the spore body partially or completely, in the manner of a mantle. Remarks. The outer zone of these spores is not a true cingulum in the sense of a con- tinuous equatorial structure of the type present in Densosporites, Lycospora, &c. The peripheral zone in the Pseudocingulati arises as a result of the compression of upstand- ing ornamentation elements which overlap laterally at the spore margin. Genus secarisporites gen. nov. Text-fig. 2 Type species. S. lobatus sp. nov. Diagnosis. Trilete, iso- or microspores, equatorial outline subcircular, ovate to sub- triangular. The exo-exine is expanded into a series of lobate outgrowths which are of such dimensions as to give rise to an outer zone or pseudo-flange in the compressed spores. The outer zone is not continuous and deep indentations frequently occur between the bulbous lobes. The distal polar region of the spores is covered by an ornament of loosely spaced ridges and warts. Remarks. The distal ornamentation found in some of these spores closely resembles that seen in spores of the genus Convolutispora Hofffneister, Staplin, and Malloy 1955. However, the lateral overlap and fusion of the ornamentation elements in the region of R. NEVES: NAMURIAN PLANT SPORES 261 the equator give rise to the discontinuous peripheral rim which characterizes the spores of this genus. With careful focusing, the spore body outline can be distinguished as a sharp line of regular form, lying concentric with the spore outline (PI. 32, figs. 6 and 9). Hacquebard and Barss (1957, pi. vi, figs. 11, 12) illustrate Spore Type A, which TEXT-FIG. 2. Secarisporiles gen. nov. Diagrammatic reconstruction; distal surface. closely resembles in structural oganization spores which are here attributed to the genus Secarisporites. Secarisporiles lobatus sp. nov. Plate 32, figs. 6, 7 Hohtype. Plate 32, fig. 6. Type locality. Marine shales with Gastrioceras cancellatian, Hipper Sick, Derbyshire (Loc. 12). Yea- donian stage. Diagnosis. Size range 55-85 p. (twenty specimens measured) holotype 81 /x; equatorial outline subcircular, margin lobate and deeply incised ; trilete rays thin, reaching to the inner limit of the peripheral zone. Description. Colour medium to dark brown. Equatorial outline of the spore body rounded triangular to subcircular, outer margin of the enclosing rim is ± conformable. The ‘pseudoflange’ is composed of lobate outgrowths of the exine, which extend 10-18 p beyond the spore body wall. Between the rounded, in part overlapping, lobes the rim is deeply incised. The distal polar region is decorated with rounded thickenings and irregular, linear ridges. Comparison. The spores of this species are characterized by the wide, dissected marginal B 9425 S 262 PALAEONTOLOGY, VOLUME 4 rim. In Secarisporites remotus the rim consists of more widely spaced elements, and the spores are smaller. Secarisporites remotus sp. nov. Plate 32, figs. 8, 9 Holotype. Plate 32, fig. 9. Type locality. Non-marine roof shales of the Pot Clay Coal, Holymoorside, Derbyshire (Loc. 13). Yeadonian stage. Diagnosis. Size range 35-50 /r (fifteen specimens measured), holotype 46 /j.; equatorial outline triangular, subcircular to ovate; exine ornamented with narrow ridges and small warts; outline of spore with rounded lobes of variable size. Description. Colour brown. Trilete rays thin, reaching to the line of the spore body wall, often obscured by the ornamentation elements. The spore outline is strongly lobate with elements of variable size and lateral continuity, height 2-8 fj- and up to 12 ^ wide. Over the distal surface of the spores the ornamentation consists of narrow ridges and discrete wart-like thickenings. Comparison. These spores are characterized by their small size, the variable size and often isolated nature of the peripheral lobes. Occurrence. Upper Namurian B-Namurian C, rare. Division zonales (Bennie and Kidston) Potonie 1956 Group AURiTOTRiLETES Potonie and Kremp 1954 Series auriculati (Schopf) Potonie and Kremp 1954 Genus ahrensisporites Potonie and Kremp 1954 Type species. A. guerickei (Horst) Potonie and Kremp 1954. Remarks. Potonie (1956, p. 16) transferred the genus Ahrensisporites to the Series i Laevigati, Subdivision Azonotriletes. Based on observations made during the present ij study, the current author retains the genus in the original supra-generic position sug- | gested by Potonie and Kremp (1954, p. 155). !' Ahrensisporites beeleyensis sp. nov. Plate 32, fig. 10 Holotype. Plate 32, fig. 10. ij Type locality. Non-marine shales with Carbonicola e.xporrecta, Hipper Sick, Derbyshire (Loc. 12). ; Yeadonian stage. i' Diagnosis. Size range 45-60 p. (twenty specimens measured), holotype 56 p; equatorial outline triangular, sides straight to slightly concave, apices rounded; kyrtome built up ; from a series of small, bluntly conical elements, which also occur scattered in the inter- radial regions. Description. Colour golden-brown to brown. Exine laevigate between the ornamentation elements. Trilete mark simple, rays straight, three-quarters radius of the spores. Small blunted cones are serially arranged on the distal surface of the spores, giving rise to the , characteristically dentate kyrtome. The elements are closely spaced and the bases are , fused in part. Scattered cones are found also in the inter-radial regions. | R. NEVES: NAMURIAN PLANT SPORES 263 Comparison. The presence of a composite kyrtome, constructed from discrete, regularly arranged, small blunted cones, distinguishes the spores of this species. Little morpho- logical variation has been observed in this species group. Occurrence. Upper Namurian B-Namurian C appears to be more characteristic of non- marine shale assemblages. Ahrensisporites guerickei Horst 1955 Occurrence. Upper Namurian B-Westphalian A, common in certain assemblages. Ahrensisporites guerickei var. ornatus var. nov. Plate 32, fig. 1 1 Holotype. Plate 32, fig. 1 1 . Type locality. Marine shales with Eumorphoceras bisukatum, Bagnall, Staffordshire (Loc. 2). Arns- bergian stage. Diagnosis. Size range 65-80 p (twenty specimens measured), holotype 77 p; equatorial outline triangular, sides straight or slightly convex, apices somewhat truncate; kyrtome arise from strong folds of the exine of the distal surface; spore body decorated with irregularly, rounded thickenings. Description. Colour yellow-brown, kyrtome and exinous thickenings darker. Trilete rays simple, straight, three-quarters spore radius. The exine of the distal surface is ornamented with irregular thickenings of a wart-like nature. The kyrtome is a more or less continuous, heavy wall which, when compressed beyond the outline of the spores, appears to be 7-10 p high. Remarks. A clearly defined group of spores, closely comparable to the holotype of Ahrensisporites gueriekei figured by Horst (1955, pi. 7, fig. 58), appears in the upper part of the Marsdenian stage (Namurian B) and persists into the Westphalian measures of the English Central province. In addition, a variety of A. guerickei (designated above) pos- sessing an ornamentation of irregular exinous thickenings similar to the forms figured by Horst (1955, pi. 7, fig. 61) and Butterworth and Williams (1958, pi. iii, fig. 18) has been found during the current study to persist throughout the Namurian succession from the Arnsbergian stage to the Lower Westphalian horizons. Genus triquitrites (Wilson and Coe) Potonie and Kremp 1954 Type species. T. arculatiis Wilson and Coe 1940 Triquitrites nodosus sp. nov. Plate 32, fig. 12 and Plate 33, fig. 1 Holotype. Plate 32, fig. 12. Type locality. Non-marine shale with Carbonicola e.xporrecta, Hipper Sick, Derbyshire (Loc. 12). Yeadonian stage. Diagnosis. Size range 80-95 p (fifteen specimens measured), holotype 88 p; equatorial outline triangular, sides straight to slightly convex, apices broadly rounded; valvae broad, protruding slightly at the equatorial margin; distal surface of the spores is orna- mented by conical to wart-like elements. 264 PALAEONTOLOGY, VOLUME 4 Description. Colour light brown, valvae darker. Trilete rays two-thirds to three-quarters radius of the spores. The valvae are centrifugal thickenings of the exine in the radial positions, projecting 3-5 p beyond the general equatorial outline. The margins of the valvae are somewhat angular and resemble the upper part of a partially opened fan, arising from the distal surface of the apices. Blunted cones and warts are dispersed randomly over the distal surface of the spores. Comparison. The spores of this species are distinguished by their large size, the arcuate form of the valvae, and the nature of the distal ornamentation. Triqiiitrites verrucosus Alpern 1958 is smaller and is recorded from much higher horizons. Group ZONOTRILETES Waltz 1935 Series cingulati Potonie and Klaus 1954 Genus densosporites (Berry) Potonie and Kremp 1954 Type species. D. covensis Berry 1 937 Densosporites spinosus Dybova and Jachowicz 1957 Occurrence. Namurian A-B, common in some marine shale and coal seam assemblages. Densosporites vulgaris sp. nov. Plate 33, fig. 2; text-fig. 3 Ho to type. Plate 33, fig. 2. Type locality. Pot Clay Coal, Holymoorside, Derbyshire (Loc. 13). Yeadonian stage. Diagnosis. Size range 50-65 p (twenty-five specimens measured), holotype 59 p; equa- torial outline rounded triangular; trilete rays thin, reaching almost to the spore body wall; contact region thickened; cingulum smooth with slight equatorial taper. Description. Colour light brown to yellowish. Equatorial margin generally smooth, occasionally a few scattered coni may be present. The cingulum has a faint radial, fibrous structure, an ill-defined inner thickened zone and a gradual equatorial taper. Inner thickened zone one-quarter to one-third width of the cingulum and overlapping the spore body margin 2-3 p, proximally. The proximal polar region bears a thickened contact area, the outer margin of which is concentric with the spore body outline and lies 4-7 p nearer the proximal pole. The exine of the spore body is laevigate to faintly infra-punctate. Remarks. The spores of this species are characterized by the thickened proximal polar region. Genus knoxisporites Potonie and Kremp 1954 emend. Type species. K. hageui Potonie and Kremp 1955. Emended diagnosis. Trilete iso- or microspores with an equatorial cingulum which is of more or less uniform thickness throughout its width, possibly tapering slightly in the immediate vicinity of the equator. The distal hemisphere of the spores is characterized by a variable pattern of radial and/or concentric bands of thickening. The equatorial outline of the cingulum is more or less conformable to that of the spore body, only R. NEVES: NAMURIAN PLANT SPORES 265 departing from it locally where the fusion of radial elements and the equatorial girdle produces a swollen node of thickening. Small thickened lobes may project from the cingulum on to the proximal surface of the spore body. Remarks. From a critical study of author’s photographs and descriptions, it becomes TEXT-FIG. 3. Deusosporites vulgaris sp. nov. Diagrammatic reconstruction; a, polar section; b, proximal polar view. apparent that the majority of spores allocated to the genus Knoxisporites Potonie and Kremp 1954 possess an equatorial extension of the exo-exine in the form of a cingulum. In the diagnosis of the type species, K. hageni Potonie and Kremp (1955, p. 1 16), the authors repeatedly refer to the presence of a cingulum. At the same time, the figure of the holotype (pi. 16, fig. 316) clearly shows the presence of a continuous equatorial girdle or cingulum. Similarly, Hoffmeister, Staplin, and Malloy (1955, p. 391), in considering K. triradiatus, discuss the structure in terms of ‘ a central body ’ and an ‘ equa- torial girdle’. Furthermore, whilst the disposition of the distal thickenings varies con- siderably in the species groups, the equatorial girdle remains a constant feature. It is not 266 PALAEONTOLOGY, VOLUME 4 a question of muri lying parallel with equator, as in Reticulatisporites, but of a definite equatorial structure, as was indeed suggested by Potonie and Kremp (1955) for the type species. Since the presence of a cingulum has been used by Potonie and Kremp (1954) as the major criterion in the definition of the Series Cingulati, the genus Knoxisporites is here transferred to this Series. Comparison. Simozonotriletes is characterized by a triangular equatorial outline. Stenozonotriletes (Naumova) Hacquebard 1957 has no thickened bars on the distal surface. Cincturasporites Hacquebard and Barss 1957 possesses a thickened equatorial girdle which partly overlaps the spore body polewards. Knoxisporites dissidius sp. nov. Plate 33, figs. 4, 6; text-fig. 4 Holotype. Plate 33, fig. 4. Type locality. Non-marine roof shales of the Pot Clay Coal, Holymoorside, Derbyshire (Loc. 13). Yeadonian stage. Diagnosis. Size range 50-80 /x (twenty-five specimens measured), holotype 70 p; equa- torial outline somewhat hexagonal, margin slightly irregular; outline of the spore body rounded triangular; distal surface of the spores with a Y-shaped thickening, distal polar region unthickened. Description. Colour yellow to brown. The hexagonal tendency of the equatorial outline is due to the prolongation of the radial bars of thickening on to the cingulum. Outline of the spore body clearly defined, rounded triangular. Trilete rays three-quarters radius of the spore body, lips thin. Cingulum fleshy, tapering only slightly towards the equatorial margin. The distal surface of the spores bears three radial bars of thickening which are rotated 60° relative to the rays of the trilete mark. The thickened bars unite over the distal surface of the spore body to enclose a circular to triangular region of unthickened exine at the distal pole. Subsidiary bars of thickening often appear proximally in the cingulum, opposite the ends of the trilete rays. Exine laevigate to infra-punctate. Remarks. The spores of K. dissidius are distinguished by the rounded triangular spore body, the slightly discordant fleshy cingulum, and the pattern of distal thickenings. Occurrence. Namurian A-Westphalian A, rare. EXPLANATION OF PLATE 33 All magnifications X 500. Fig. 1. Triqiiitrites itodosits sp. nov., 87 p. Fig. 2. Densosporites vulgaris sp. nov., holotype, 59 p, proximal view. Slide ref. 9.177820. Fig. 3. Cirratriradites oruatus sp. nov., holotype, 92 p, distal view, low focus. Slide ref. s.Al. Figs. 4, 6. Knoxisporites dissidius sp. nov. 4, Holotype, 70 p, distal view, low focus. Slide ref. 4.307719. 6, Distal view, 56 p. Fig. 5. K. seniradiatus sp. nov., holotype, 88 p, proximal view, low focus. Slide ref. s.Bf. ■ Figs. 7-8. Stenozonotriletes triangulus sp. nov. 7, Holotype. 77 p, proximal view. Slide ref. 1.361656. 8, Proximal view, 65 p. Figs. 9-10. Proprisporites laevigatus sp. nov. 9, Holotype, 77 p, distal view, low focus. Slide ref. 5. ' 304770. 10, Proximal view, low focus, 101 p. Figs. 11-12. Hynienospora palliolata sp. nov. 11, Holotype, 87 p, distal view. Slide ref. 8.319715. 1 12, 74/x. ! Palaeontology, Vol. 4 PLATE 33 NEVES, Namurian microspores R. NEVES; NAMURIAN PLANT SPORES 267 TEXT-FIG. 4. Knoxisporites dissidius sp. nov. Diagrammatic reconstruction; a, elevation; b, distal polar view. Knoxisporites seniradiatus sp. nov. Plate 33, fig. 5 Holotype. Plate 33, fig. 5. Type locality. Non-marine shales with Carbonicola exporrecta, Hipper Sick, Derbyshire (Loc. 12). Yeadonian stage. 268 PALAEONTOLOGY, VOLUME 4 Diagnosis. Size range 60-105 (twenty specimens measured), holotype 88 p,; equatorial outline of the spore body subcircular; distal surface with tri-radial bars of thickening, rotated 60° relative to the trilete rays of the proximal surface ; rays of the trilete mark with prominently thickened lips. Description. Colour light brown. Outline of the spore body sharp ; equatorial girdle is of uniform width. Trilete rays three-quarters radius of the spore body, tecta sharp and straight ; lips associated with prominent bands of thickening, 5-7 p wide, margin away from the suture often slightly undulating. Cingulum 6-14 p wide. The Y-shaped bars of distal thickening, 6-10 p wide, often persist into the cingulum. Exine faintly infra- punctate. Comparison. Knoxisporites triradiatus is very similar, but the spores of that species lack the prominent thickenings which in K. seniradialus are associated with the trilete rays. Occurrence. Namurian B-C, rare. Genus stenozonotriletes (Naumova) Hacquebard 1957 Type species. S. conformis Naumova 1953 Stenozonotriletes triangulus sp. nov. Plate 33, figs. 7, 8 Holotype. Plate 33, fig. 7. Type locality. Marine shales with Gastrioceras cancellatum, Hipper Sick, Derbyshire (Loc. 12). Yea- donian stage. Diagnosis. Size range 60-80 p (twenty-five specimens measured), holotype 77 p; equa- torial outline triangular, sides straight to slightly convex, apices rounded; equatorial girdle narrow, 4-8 p wide, and smooth. Description. Colour yellowish-brown. Trilete rays three-quarters radius of the spore body, lips often associated with small folds of the exine which taper towards the proximal pole; a darker contact region is often present. The equatorial girdle is of uniform width and possesses little or no equatorial taper. Exine laevigate to slightly infra-punctate. Comparison. Stenozonotriletes conspersus Naumova 1953 is of similar shape but is smaller. Genus crassispora Bhardwaj 1957 Type species. C. ovalis Bhardwaj 1957 Crassispora kosankei (Potonie and Kremp) Bhardwaj 1957 Occurrence. Namurian B-Westphalian A, occasionally common in certain coal-seam and non-marine shale assemblages. The first appearance of this species can be correlated accurately with measures of Namurian B age. Series zonati Potonie and Kremp 1954 Genus cirratriradites Wilson and Coe 1940 Type species. C. saturni (Ibrahim) Schopf, Wilson and Bentall 1944 R. NEVES: NAMURIAN PLANT SPORES 269 Cirratriradites oniatus sp. nov. Plate 33, fig. 3 Holotype. Plate 33, fig. 3. Type locality. Non-marine shale with Carbonicola exporrecta, Hipper Sick, Derbyshire (Loc. 12). Yeadonian stage. Diagnosis. Size range 80-110 p (fifteen specimens measured), holotype 92 p; equatorial outline rounded triangular; trilete rays are associated with long folds which extend on to the thin, fibrous zona; the whole of the distal surface of the spores is beset with dis- persed coni. Description. Colour light brown, zona pale yellow-brown. Exine of the spore body punctate; decorated on the distal surface with delicate cones and small spines. The zona has a radial fibrous appearance, width 14-20 p. Where the zona passes over the spore body margin, a darker band, 7-10 p wide, is present. No foveae are present. Remarks. C. ornatus is distinguished by its large size, the ornamentation of the distal surface, and the lack of foveae. Occurrence. Namurian C, present in non-marine shales only, rare. Series membranati ser. nov. This series is proposed for those trilete iso- or miospores in which the outer membrane of the exine, the exo-exine, has partially separated from the inner membrane or int- exine, and projects at the spore margin as a clear, thin membrane. The two membranes may be attached to one another only in the region of the trilete mark, or the exo-exine can be arranged as a series of folds which run over the surface of the spore body mem- brane. Remarks. The infra-reticulate structure which characterizes the cavity between the spore body wall and the saccus membrane, in many forms attributed to the Division Sacciti, is never present in the Series Membranati. Genus proprisporites Neves 1958 Type species. P. rugosus Neves 1958 Proprisporites laevigatas sp. nov. Plate 33, figs. 9, 10 Holotype. Plate 33, fig. 9. Type locality. Marine shales with Hudsonoceras proteum, Congleton Edge ganister quarry, Stafford- shire (Loc. 4). Sabdenian stage. Diagnosis. Size range 70-115 p (fifteen specimens measured), holotype 77 p; equatorial outline of the spore body rounded triangular; trilete rays three-quarters radius of the spore body; exo-exine translucent, laevigate and strongly folded over the laevigate spore body. Description. Colour light brown; exine laevigate. Spore body compact, outline smooth and regular. The outer spore membrane is plicated into a series of sinuous folds which 270 PALAEONTOLOGY, VOLUME 4 run over the surface of the spore body. The folds in places lie parallel to the compressed spore margin, where they appear as membranous projections ; they may also appear as subconical projections at the spore outline when the fold axis lies at an angle to the outline. Comparison. The only other described species of this genus, F. rugosiis, is distinguished by the strong punctation of the spore body membrane. Occurrence. Namurian A-B, more typical of the marine shale assemblages. Genus hymenospora gen. nov. Text-fig. 5 Type species. H. palliolata sp. nov. Diagnosis. Trilete iso- or microspores; equatorial outline circular to subcircular. The exo-exine is attached to the int-exine in the region of the trilete mark. In addition the TEXT-FIG. 5. Hymenospora gen. nov. Diagrammatic reconstruction; distal surface. exo-exine is deeply furrowed, and along the troughs of the furrows the two membranes are still in contact. In the compressed spores the exo-exine projects beyond the body margin as a laevigate, membranous zone. Remarks. The zonate aspect of these spores is due entirely to the marginal projection of the exo-exine, and the outer zone is not necessarily in the equatorial position relative to the trilete mark, an essential character of the Series Cingulati and Zonati. The outer membrane, although detached for the greater part from the int-exine, is fairly rigid due to the subsidiary lines of adhesion along the furrows in the exo-exine. R. NEVES: NAMURIAN PLANT SPORES 271 Hymenospora palliolata sp. nov. Plate 33, figs. 11,12 Holotype. Plate 33, fig. 11. Type locality. Marine shales with Gastrioceras cancellatum, Crowborough Wood, Stalfordshire (Loc. 10). Yeadonian stage. Diagnosis. Size range 70-105 p (twenty specimens measured), holotype 87 p; equatorial outline subcircular; trilete rays sharp, three-quarters radius of the spore body; exo- exine laevigate and crenulate. Description. Colour of spore body light brown, outer membrane pale yellow; exine laevigate. Trilete rays three-quarters spore body radius, tecta tapering, lips thin. The mantle-like outer membrane is wrinkled into a series of narrow linear furrows, along which lines it is attached to the inner membrane. The two membranes are also in contact in the region of the trilete mark. In the compressed spores the exo-exine projects beyond the margin of the spore body as a more or less uniform rim with an outer crenulate border. An original globular form of these spores is indicated by the frequent oblique compression. Comparison. Knox (1947, pi. 6, fig. 54) illustrates Spore Type 46K from the Limestone Coal Group of Scotland (Namurian A); this form closely resembles Hymenospora palliolata. Occurrence. Namurian A and Namurian C, marine-shale assemblages only, rare. Series patinati Butterworth and Williams 1958 Genus Tholisporites Butterworth and Williams 1958 Type species. T. scoticiis Butterworth and Williams 1958 Tholisporitesl bianulatus sp. nov. Plate 34, fig. 2; text-fig. 6 Holotype. Plate 34, fig. 2. Type locality. Marine shales with Eiimorphoceras bisulcatiim Girty, Bagnall, Staffordshire (Loc. 2). Arnsbergian stage. Diagnosis. Size range 55-90 p (twenty specimens measured), holotype 80 p; equatorial outline circular, spores commonly preserved in the lateral position; two raised bands of thickening encircle the spores subequatorially; a large circular patch of thickening is centred on the distal pole. Description. Colour: thickenings dark brown; remainder of the exine pale brown. Exine laevigate to faintly infra-punctate. The spores are usually compressed in the plane of the polar axis, indicating an original spherical to subspherical form. Trilete rays two-thirds radius of the spores. The exine bears two thickened bands, 7-20 p wide, which lie adjacent to the equator, displaced slightly on to the proximal and distal hemi- spheres. These annular bands are separated by a channel of thinner exine, which appears as a rounded depression at the spore margin. The distal polar region is contained within a broad, circular patch of thickening, up to 45 p in diameter, and which is separated from 272 PALAEONTOLOGY, VOLUME 4 the distal annular band by a narrow channel of thinner exine. The margins of all the thickenings are slightly wavy and thickened lenses may be present in the separating channels. Remarks. These spores are tentatively referred to the genus Tholisporites since the thickening of the distal hemisphere is not complete. TEXT-FIG. 6. Tholisporites? bianulatus sp. nov. Diagrammatic lateral view. Division pollenites R. Potonie 1931 Group SACCiTES Erdtman 1947 Subgroup MONOSACCiTES (Chitaley) Potonie and Kremp 1954 Series extrornati Butterworth and Williams 1958 Genus remysporites Butterworth and Williams 1958 Type species. R. maguificus (Horst) Butterworth and Williams 1958 Remysporites magnificus Plate 34, fig. 1 Occurrence. These distinctive spores are relatively rare in the Namurian measures of Central England, and appear to be restricted to assemblages of Namurian A age. Butterworth and Williams (1958) described this species from the Namurian A of Scot- land. Horst (1955) first recorded spores of this type from the Namurian A of Upper Silesia and the Moravian Ostrau. EXPLANATION OF PLATE 34 All magnifications X 500. Fig. 1. Remysporites magnificus (Horst) Butterworth and Williams 1958, 159 p. Fig. 2. Tholisporites ? bianulatus sp. nov., holotype, 80 p. Slide ref. 18.263816. Lateral view, common habit. Fig. 3. Cf. Pityosporites sp., distal view, 105 p. Fig. 4. Schopfipollenites ellipsoides (Ibrahim) Potonie and Kremp 1955, 188 p. Fig. 5. Schopfipollenites ellipsoides var. corporeus var. nov., holotype, 168 p. Slide ref. 4.236800. Palaeontology, Vol. 4 PLATE 34 NEVES, Namurian microspores R. NEVES: NAMURIAN PLANT SPORES 273 Genus grandispora Hoffmeister, Staplin, and Malloy 1955 Type species. G. spinosa Hoffmeister, Staplin, and Malloy 1955 Grandispora spinosa Hoffmeister, Staplin, and Malloy 1955 Occurrence. Pendleian stage, Namurian A, rare. Hoffmeister, Staplin, and Malloy recorded this species from the Hardinsburg Formation of Illinois and Kentucky, U.S.A. Series aletesacciti Leschik Genus Florinites Schopf, Wilson, and Bentall 1944 Type species. F. antiquus Schopf, in Schopf, Wilson, and Bentall 1944 Remarks. The presence of large numbers of spores of the genus Florinites, particularly the species, F. elegans, F. similis, F. visendus, and F. pumicosus, has been found to characterize marine shale assemblages of miospores from the Central Province of England. The presence of these spores in assemblages of Namurian A age represents the earliest known occurrence of these monosaccate grains. Subgroup DiSACCiTES Cookson 1947 Genus Pityosporites (Seward) Potonie and Klaus 1954 Type species. P. ontarcticus Seward Cf. Pityosporites spp. Plate 34, fig. 3 Horizon. Marine shales with Gastrioceras canceltatiim, Hipper Sick, Derbyshire (Loc. 12). Yeadonian stage, Namurian C. Occurrence. Disaccate grains of the Pityosporites-Vesicaspora type are present as a minor constituent in shale assemblages at several horizons in the Yeadonian stage. This record represents the lowest horizon from which pollen grains of this type have been recorded. Remarks. The absence of these grains in the coal-seam separations would seem to sug- gest that the parent plants, presumably Coniferalean type, existed outside the coal swamp regions. They were possibly associated with a marginal area of high land, as was suggested for the South Wales occurrence by Williams (1955, p. 471). Group PRAECOLPATES Potonie and Kremp 1954 Genus schopfipollenites Potonie and Kremp 1954 Type species. S. ellipsokles (Ibrahim) Potonie and Kremp 1955 Schopfipollenites ellipsoides sensu stricto Plate 34, fig. 4 Occurrenee. Plant spores of this species occur in measures of Pendleian age and range spasmodically throughout the Namurian sequence examined, and into the Westphalian. 274 PALAEONTOLOGY, VOLUME 4 SchopfipoUenites eUipsoides var. corporeus var. nov. Plate 34, fig. 5 Holotype. Plate 34, fig. 5. Type locality. Pot Clay Coal, Consall, north Staffordshire (Loc. 15). Yeadonian stage. Diagnosis. Size range 145-210 p (twenty-five specimens measured), holotype \6S p; equatorial outline oval; proximal surface with a narrow suture, characteristically bent about its middle point; distal surface bears two major longitudinal folds of the exo- exine; the inner spore membrane is preserved as a circular to ovate ‘spore body’. Description. Colour reddish-brown. Equatorial outline of the spore oval, that of the body is usually more circular. Exo-exine laevigate to faintly infra-punctate; spore body laevigate and strongly folded; the folds are arranged approximately transversely and longitudinally tending to form a more or less regular pattern. For the remainder these spores are comparable with SchopfipoUenites eUipsoides Potonie and Kremp (1955, p. 184). Remarks. Schopf, Wilson, and Bentall (1944, p. 38), in a discussion of the genus Mono- letes, refer to the ‘endosporal membrane’, which in certain specimens appeared as a ‘crumpled, translucent sack’. Although the authors gave no illustration, the structure described by them closely resembles that present in S. eUipsoides var. corporeus. Occurrence. Namurian C ; the spores of this variety are not restricted in occurrence to the same assemblages as S. eUipsoides. DISTRIBUTION OF THE FOSSIL SPORES IN THE SEDIMENTS Before it is possible to assess the stratigraphical value of the various spore types, it is necessary to consider the distribution of the spores in the different sedimentary types. Several authors (Hoflfmeister, Staplin, and Malloy 1955; Neves 1958; Staplin 1960) have already drawn attention to the quantitative and qualitative variations in the fossil spore content within a short sequence of sediments. During the current investigation, similar observations have been made and the association of certain fossil spore species with particular sediments can be readily appre- ciated from Table 1 . Many species have been recorded only from shale preparations and the majority of the newly described species fall into this latter category. For example, spores of the genera Ibrahimispores, Proprisporites, and Hymenospora are restricted en- tirely to these allochthonous deposits. Furthermore, the species Acanthotriletes bacidatus, A . splendidus, A . ? pilus, Hymenospor apalUolata, and Proprisporites rugosus are confined to the marine-shale assemblages. In contrast, other species transgress the ‘ facies boundaries ’ and are present in coal, non-marine shale, and marine-shale assemblages. Such species as Punctatisporites sinuatus, Camptotriletes superbus, Mooreisporites fustis, Seea- risporites lobatus, Ahrensisporites guerickei var. ornatus, Crassispora kosankei, and Remysporites ntagnificus could thus prove to be of value for wider correlation. The coal- seam assemblages are generally dominated by spores of the genera Lycospora and TABLE 1. Chart showing observed stratigraphical ranges of selected spore species in the Namurian of the Southern Pennines Basin. TABLE. I 60NIM ST/VQ > O c «/> A,> £&. a VI V) “S fi. E o <_> l/> 3 ja a o *£ o ' C o > j_2* o o o > ■f o v> D 3 ’w v> i2! ’ u o a- ' iz i5 U c a CL > o c xL V) v> ' v> c >> J0» ' c o* t_ -jr § c xL V) a V) o 'T3 O C o2f 5^ > o c a. V) CM o _sr a o o E £: o a. (/I *1 *_n a -Q »-— • tf> c e c “o a. o u in O 'C a (T» v> ’ C o n. a ' 5i c «» < c ? -o o o- ”oi ,Q« ■ c "o a. o _c to >: o c xL in iP ,a a c o v> -5 o o u L-> £ xL m 3 tn e (U -0 ,a» Of O Of 1 a tn o <7» a o fi. rt ” u au £ D. u A £ MA.Rn X X X X X X X X X NON- X X X X X X X X X X X COAL X X X X X 2 t i U) < w X ^ 0. GASTRl 1 r 1 1 1 Z 4 3 4 2 O U GASTR.S (V 1 1 1 1 — I — 1 1 T 1 1 CD U RETICU (ma 1 1 1 1 i 1 1 L< RETICU (WNDE 4 MOM (sab U EUMORI (arm L( EUN10RP (pen TULE- !■ R. NEVES: NAMURIAN PLANT SPORES 275 Densosporites which are found in association with Calamospora, Apiculatisporis, Cyclo- granisporites, Ahrensisporites, and Schulzospora. The marine-shale assemblages from thirty horizons examined have been found to be dominated by saccate spores, principally of the genus Florinites; the remainder of these assemblages is variable in the relative proportions of the various spore types present, although the genera Pimctatisporites, Lophotriletes, Raistrickia, Comolutispora, and Auroraspora usually figure prominently. It would appear probable that the spore assemblages of the coal seams and the marine shales are representative of two completely distinct plant associations. The autochtho- nous peat deposits, as represented by the coal seams, contain for the greater part the spores of lycopods, calamites and pteridosperms, &c., which constituted the swamp vegetation. The widespread nature of the marine-shale deposits would necessitate the temporary withdrawal of the latter vegetation and the elimination of extensive coal swamps. Consequently, any vegetation existing on the land areas adjacent to the marine basin would automatically provide the majority of the dispersed spores entombed in the marine muds. An upland flora of the type suggested by Chaloner (1958, p. 261), clothing the St. George’s Land mass to the south, forms an attractive hypothesis. The evidence for at least moderate relief in this massif can be seen in the coarse and often pebbly nature of the deltaic deposits which were swept northwards. These deposits now con- stitute prominent gritstone horizons such as the Ashover and Belper grits in Derbyshire, and from which abundant current-direction data are available to indicate their southerly origin. The intermixing of the two principal spore associations is to be found in the non- marine shales, which often occupy an intermediate stratigraphic position between the coal seam below and the marine shale above. The non-marine shales represent the initial aqueous inundation of the coal swamps and the establishment of mud flats and isolated lagoons within the sedimentary basin. In this way, any masking effect by the products of the swamp vegetation will be reduced, so permitting the spores of a marginal vegetation to play an increasing role in the assemblages. This is substantiated to some extent by the diversity of the spore content of the three sedimentary rock types. The calculated average numbers of genera and species recorded in the various assemblages during the present investigation are as follows: Assemblage Genera Species Marine shale . . 20 32 Non-marine shale . . 25 45 Coal . 18 29 The wider diversity of morphological types present in the non-marine shale, together with the fact that these assemblages frequently contain many spore species in common with closely associated coals and marine sediments, is considered to indicate the inter- mixing of the two principal microfloras. Those spores which appear to be confined to the non-marine shale assemblages could be produced by plants capable of colonizing a wet, possibly brackish water environment. In conclusion, it would appear to be essential to consider the microfloral remains from all sedimentary rock types available in order to achieve a more complete under- standing of their distribution and also that of the parent plants. These studies will assist the observer to determine those spores which are sensitive to facies changes and are consequently of restricted value for the purpose of stratal subdivision. 276 PALAEONTOLOGY, VOLUME 4 STRATIGRAPHICAL APPLICATIONS A general scheme for the stratigraphic subdivision of the Upper Carboniferous of the Midlands Coalfields proposed by Butterworth and Millott (1954) was based on the spore content of the coal seams. A sequence of microspore assemblages, SO to S4 and transi- tion zones, were defined by the occurrence of certain fossil spores with restricted stratigraphic ranges. The Namurian spore assemblages of the Central Province fall entirely within the SO assemblage of Butterworth and Millott. However, since the latter authors were dealing only with coal seams, it could be expected that an investigation of the carbonaceous shales would permit a finer accuracy in stratal subdivision. For the purpose of the present account certain useful spores, with restricted or characteristic ranges and those which are of interest on account of their geographical occurrence, have been extracted from the complete assemblages and are listed in Table 1. Pendleian assemblages. These assemblages are characterized by little diversity in the spore types present, although some spores appear to be restricted to strata of this age in the southern part of the Central Province basin. Such spores are Apiculatisporis maeu- losus, Verrucosisporites morulatus, Camptotriletes verrucosus, and Grandispora spinosa. In addition Ahrensisporites guerickei var. ornatus, Reticulatisporites karadanizensis, Scludzospora occellata, Auroraspora solisortus, Microsporites radiatus, &c., are present in these Lower Namurian assemblages. The presence of Florinites elegans, F. similis, and F. viseudus at these horizons represents the first record of these monosaccate grains in Namurian A assemblages. Unfortunately, due to the lack of information concerning the spore content of Lower Carboniferous sediments in this region, it is impossible at the present time to assess any change in the microflora at the base of the Namurian. Arnsbergian assemblages. A wide range of spore types has been obtained from samples of Arnsbergian age, and many of the spores appear for the first time in this region. Whilst satisfactory preparations have not been forthcoming from the northern parts, those in the south and west have proved to be closely comparable in content. Con- volutispora is a common constituent, as are Florinites spp., Scludzospora, Auroraspora, Callisporites, Cyclogranisporites, &c. Acanthotriletes splendidus, Proprisporites laevigatas, Hymenospora palliolata, Remysporites magnificus, and Tholisporitesl bianulatus occur together in an association which seems to be diagnostic of this stage. Discernisporites and Mooreisporites are present in relatively small numbers at these horizons, whilst Alatisporites nudus appears for the first time, although infrequently. Sabdenian assemblages. In many respects these assemblages are comparable with those of the Arnsbergian stage. Many species persist into the Sabdenian; for example Ac- anthotriletes baculatus, Simozonotriletes trilinearus Artuz, Ibrahimispores microhorridus Artuz, and Proprisporites laevigatas are usually to be found in these upper Namurian A separations. Neoraistrickia inconstans appears to be confined to these two stages, and in certain Sabdenian assemblages exhibits a wide diversity of form. At the same time several new spore types appear, including Secarisporites lobatus, Knoxisporites dissidius, Reinschospora speciosa, and an undescribed species of Grandispora. Tholisporites? bianulatus has not been recorded in these assemblages. Kinderscoutian assemblages. These assemblages have been found to be relatively im- R. NEVES: NAMURIAN PLANT SPORES 277 poverished in the constituent spore types present, a feature which may be related to the widespread arenaceous facies which occurs throughout the region during this stage. In the lower horizons, the assemblages are closely comparable with those of the Sabdenian. Densosporites spinosiis is often quite common in these separations and forms approaching Cristatisporites indignabimdus represent a similar form in which the ornamentation of the flange (laterally fused spines) becomes more strongly developed. A few spore types appear for the first time and the two species Crassispora kosankei and Knoxisporites seniradiatiis are quite distinctive. Marsdenian assemblages. Many spores make an initial appearance in the Marsdenian and persist through into the Westphalian assemblages. The former assemblages are easily distinguished, therefore, from those of the Namurian A and lower Namurian B. Apicidatisporis is present and is characterized by a considerable variety of morpho- logical types, of which A. selidosus and A. laiigranifer are quite distinctive and become fairly common in the overlying Yeadonian stage. Mooreisporites bellus, Camptotriletes superbus, and Ahreusisporites beeleyensis are completely new types and become established forms in the Yeadonian assemblages. The genera Armatisporites Dybova and Jachowicz and Mooreisporites occur commonly in the coal-seam assemblages of this stage. Yeadonian assemblages. The Westphalian aspect of the spore assemblages, initiated in the Marsdenian stage, is developed further in the spore florules above the Gastrioceras cancellatum marine band. The latter horizon has been found to contain a rich and varied association of spore types in the several localities from which the shales have been examined. The related occurrence of Acantliotriletes? pilus, Ibrahimispores magnificus, I. brevispinosus, Knoxisporites dissidius, and K. seniradiatiis in an assemblage dominated by Florinites appears to be typical of this horizon throughout the basin. In contrast, the overlying marine shales containing Gastrioceras cumbriense have yielded very poor spore assemblages from the four localities at which they were sampled. The succeeding sequence of sandstones, shales, and coals is characterized by a wide variety of spore types and the succession is distinguished by a specific morphological variation pattern shown by spores of the genus Ahreusisporites. The non-marine shales with Carbonicola exporrecta contain a diverse assemblage of fossil spores in the extreme east of the region and extending to the extreme west, in the Wigan district. The occurrence of the alga, Botryoeoecus braunii, is a persistent feature of these shales. The coal-seam and associated non-marine roof shales, found immediately below the Gastrioceras subcrenatum marine band, marks the first occasion on which the entire basin was colonized by a swamp vegetation. Based on the study of the fossil spore content of the coal seam it would appear that the vegetation was relatively uniform over the whole region. The assemblage is usually dominated by spores of the genus Lycospora, although locally the general Calamospora and Densosporites assume the dominant role. The Yeadonian assemblages as a whole are characterized by the following species in particular, Camptotriletes superbus, Dictyotriletes varioreticulatus, Ahreusisporites guerickei sensu stricto, Densosporites vulgaris, Cirratriradites ornatus, Proprisporites rugosus, Schopfipollenites ellipsoides var. corporeus. Crassispora kosankei is sometimes a common constituent of both non-marine shale and coal-seam assemblages, whilst the presence of disaccate pollen grains in the shales is of particular interest on account of their possible Coniferalean affinity. B 9425 T 278 PALAEONTOLOGY, VOLUME 4 Lower Westphalian A assemblages. Lying between the marine horizons of Gastrioceras I subcrenatiim and G. Jisteri is a variable series of coal seams, sandstones, and shales which contain a microflora closely comparable in broad aspect to that of the Yeadonian stage of the Namurian. Immediately below the higher marine horizon, the Alton or Crabtree coal seam is persistent across the basin. Samples from this seam are characterized by an abundance of the species Anulatisporites amilatus and Densosporites spp. In addition, i) typical spores of the genus Triquitrites appear strongly for the first time in the succession. Conclusions. The observed stratigraphic ranges of the fossil spores shown on Table 1 implies a characteristic ‘drift’ in the content of the spore assemblages from older to younger horizons. On account of this distribution pattern, spore assemblages from ran- dom samples of coal or shale from the Namurian succession of the Central Province Basin can be dated in relation to the sequence of goniatite stages. Furthermore, when the ranges of these spores are considered in conjunction with more complete assemblage data, the recognition of specific horizons is possible, as for example in the Yeadonian stage. Further investigation into the distribution of fossil spores in this type of succession could lead to an independent system of stratal subdivision, providing sufficient attention is paid to the facies characteristics of the various spore types. Acknowledgements. The author wishes to thank Professor L. R. Moore whose initial suggestion and subsequent guidance through the work have made this publication possible. To Dr. H. J. Sullivan, for helpful discussion, and to Messrs. G. S. Bryant and F. Neves, for technical assistance, the author would like to extend his gratitude. The work was carried out in the Department of Geology, Sheffield Uni- versity, whilst the author was in receipt of a Robert Styring Research Scholarship. REFERENCES ALPERN, B. 1958. Description de quelques microspores du Permo-Carbonifere frangais. Rev. Micro- paleont. 1, 2, 75-86, pi. 1-2. ARTUZ, s. 1957. Die Sporae dispersae der Turkischen Steinkohle von Zonguldak Gebiet. Rev. de la Facidte des Sciences de VUniversite d' Istanbul, Ser. B, 22, 240-63, pi. 1-7. 1959. Zonguldak bolgesindeki Alimolla, Sulu ve Biiyiik Komiir Damarlarinin Sporolojik Etiidu. Fen Fakidtesi Monographileri, Sayi 15, 1-73. BisAT, w. s. 1928. The Carboniferous goniatite zones of England and their continental equivalents. Congr. Carb. Strat., Heerlen, p. 117. BUTTER WORTH, M. A., and WILLIAMS, R. w. 1958. The small spore floras of coals in the Limestone Coal Group and the Upper Limestone Group of the Lower Carboniferous of Scotland. Trans. Roy. Soc. Edin. 63, 2, 353-92. — — and Millot, j. o’n. 1954. Microspore distribution in the seams of North Staffordshire. Trans. Inst. Min. Engrs. 114, 501-20. CHALONER, w. G. 1958. The Carboniferous Upland Flora. Geol. Mag. 95, 261. DYBOVA, s., and jachowicz, a. 1957. Microspory. Instytut Geologiczny, Prace. 23, 1-328, pi. 1-16. HOFFMEiSTER, w. s., STAPLiN, F. L., and MALLOY, R. E. 1955. Mississippian Plant spores from the Hardins- burg Formation of Illinois and Kentucky. J. Palaeont. 29, 372-99. HORST, u. 1955. Die Sporae dispersae des Namurs von Westoberschlesien und Mahrisch-Ostrau. Palaeontographica, B 98, 137-236. HUDSON, R. G. s. 1945. Thc Goniatite Zones of the Namurian. Geol. Mag. 82, 1-9. HUDSON, R. G. s., and COTTON, G. 1943. The Namurian of Alport Dale, Derbyshire. Proc. Yorks. Geol. Soc. 25, 142-73. R. NEVES: NAMURIAN PLANT SPORES 279 iscHENKO, A. M. 1958. Spores and pollen of the Dneiper-Donetz Basin. Izd. Zkad. Naiik Ukraine, U.R.S.S., Kiev, 150 pp., 13 pis. MiLLOTT, J. o’n. 1939. Microspores in the coal seams of North Staffordshire. Part 1 — The Millstone Grit — Ten Foot Coals. Trans. Inst. Min. Engrs. 96, 317-53. MULLER, J. 1959. Palynology of Recent Orinoco delta and shelf sediments. Micropalaeontology, 5, 1, 1-32. NEVES, R. 1958. Upper Carboniferous plant spore assemblages from the Gastrioceras subcrenatian horizon. North Staffordshire. Geol. Mag. 95, 1-19. POTONiE, R., and kremp, g. 1954. Die Gattungen der palaozoischen Sporae dispersae und ihre Strati- graphie. Geol. Jb. 69, 111-94. 1955. Die Sporae dispersae des Ruhrkarbons, ihre Morphographie und Stratigraphie mit Ausblicken auf Arten anderer Gebiete und Zeitabschnitte. Falaeontographica, B 98, 1-136. POTONIE, R. 1956. Synopsis der Gattungen der Sporae dispersae. Teil I. Geol. Jb. 69, 111-94. STAPLiN, F. L. 1960. Upper Mississippian Plant Spores from the Golata Formation, Alberta, Canada. Falaeontographica, B 107, 1^0. WILLIAMS, R. w. 1955. Fityosporites westphalensis, sp. nov., an abietinous type pollen grain from the Coal Measure of Britain. Ann. Mag. Nat. Hist. 8, 90, 465-73. R. NEVES Department of Geology, University of Sheffield. Manuscript received 23 September 1960 SLIMONIPHYLLUM, A NEW GENUS OF LOWER CARBONIFEROUS CORAL FROM BRITAIN by M. KATO and M. MITCHELL Abstract. The genus Slimoniphylluni is erected with Rodophyllum slimonianwn Thomson as type species. A new description of the type species is largely based on a series of specimens in the Garwood Collection. The onto- geny, variations, affinities, and distribution of Slimoniphyllwn slimomamim are discussed. The species Rodophyllum slimonianum was first described by Thomson (1874, p. 558, pi. 20, fig. 2) from a fragmentary corallite collected by R. Slimon from the lower beds of the Carboniferous Limestone of Scotland (Lower Limestone Group) at Brockley, near Lesmahagow. The species was again figured by Thomson and Nicholson (1876, pi. 1, fig. 1) and redescribed by Thomson (1883, p. 482), but little was added to the original description. Thomson noted the presence of ‘ more or less clavate and cellular septa, numerous angular dissepiments’, and a weak axial structure. Garwood and Goodyear (1924, p. 261) erected the species Dibimophyllum rhodo- phylloides and Rhodophylliim distans, the main distinction between the two being that D. rhodophylloides has a weak medial plate. Both species have thickened, vesicular septa, shortened cardinal and counter septa marking prominent fossulae, a weak axial structure, and dissepiments varying from angular and irregular to concentric. Hill (1939, p. Ill) redescribed R. slimonianum using Thomson’s material, and selected a lectotype for the species. She doubtfully referred the species to the genus Caninia but suggested affinities with the Chsiophyllids. In the same monograph (1938-9, pp. 78-79) D. rhodophylloides is listed as a synonym of D. biportitum konincki (Edwards and Haime) and R. distans as a synonym of D. bipartitum craigianum (Thomson). A re-examination of Thomson’s material and the study of specimens in the Geological Survey Museum, London, suggests that the species slimonianum belongs to a new genus, and that D. rhodophylloides and R. distans are synonymous with slimonianum. A new genus Slimoniphylluni is proposed to include this group of corals, with R. slimonianum as the type species. The possession of an axial structure, often weakly developed, dilated and vesicular septa, and a counter fossula as well as a cardinal fossula, distinguishes Slimoniphylluni from Caninia Michelin, Dibimophyllum Thomson (= Rodophyllum Thomson), and Auloclisia Lewis. Auloclisia is the closest related form and Slimoniphylluni is believed to have evolved from it. The Thomson Collection is housed in the Glasgow Museums and Art Galleries, Kelvingrove, Glas- gow, and specimens from this collection have the prefix ‘KM.T’. All specimens in the Geological Survey Museum, including the Garwood Collection, have the prefix ‘GSM’, while ‘BM.R’ refers to specimens in the British Museum (Natural History). The authors acknowledge the encouragement and assistance of Dr. H. Dighton Thomas of the British Museum (Natural History), and of Dr. F. W. Anderson and the other officers of the Palaeonto- logical Department of the Geological Survey during the preparation of this paper. Mr. Kato has had [Palaeontology, Vol. 4, Part 2, 1961, pp. 280-91, pis. 35-36] KATO AND MITCHELL: SLIMONIPHYLLUM, A NEW GENUS 281 the constant encouragement of Prof. M. Minato of the Hokkaido University, and acknowledges a British Council Scholarship during the tenure of which this work was carried out. Mr. M. Mitchell publishes with the permission of the Director of the Geological Survey and Museum. Our thanks are given to Mr. C. E. Palmar of the Glasgow Museums and Art Galleries, for the loan of the lectotype, and Dr. C. L. Forbes of the Sedgwick Museum, Cambridge, for the loan of a celluloid peel taken from the lectotype. The photographs are the work of Mr. J. M. Pulsford and Miss H. Seymer of the Geo- logical Survey. SYSTEMATIC DESCRIPTION Class ANTHOZOA Ehrenbcrg 1834 Order rugosa Milne Edwards and Hainie 1850 Family aulophyllidae Dybowski 1873 Subfamily aulophyllinae Dybowski 1873 Genus slimoniphyllum nov. Type species. Rodophyllimi slimonianum Thomson 1874 Diagnosis. Simple, ceratoid to trochoid rugose coral, with a weak axial structure in which the medial plate tends to degenerate, and the thin septal lamellae tend to become twisted. The septa are dilated in the tabularium and are commonly vesicular (with spaces to one side of the medial line). The cardinal fossula is marked by the shortening of the cardinal septum, is open and parallel sided, and is situated on the convex side of the corallite. A counter fossula is also present, indicated by the shortening of the counter septum, but is less conspicuous than the cardinal fossula. The dissepiments vary from concentric to angular and irregular. The tabulae are flat and complete in the young stages, but later become incomplete and inclined upwards towards the loose axial structure. Distribution. The genus is at present only known from the Midland Valley of Scotland, the north of England and Derbyshire, where it occurs in beds of high Visean age (includ- ing the Da Subzone, Pa, and Coral Zone 3). Slimoniphyllum slimonianum (Thomson) Plates 35 and 36 1874 Rodophyltum Slimonianum Thomson, p. 558, pi. 20, fig. 2. 1876 Rhodophyllum Slimonianum Thomson; Thomson and Nicholson, pi. 1, fig. 1. 1883 Rhodophyllum Slimoni (Thomson); Thomson, p. 482. 71913 Dibunophyllum muirheadi Nicholson and Thomson; Garwood, p. 540 (in list only). 1924 Dibuuophyllum aff. mallockense Sibly; Garwood and Goodyear, p. 201 (in list only). 1924 Dibunophyllum rhodophylloides Garwood and Goodyear, p. 261, pi. 17, figs. 2a, 2b. 1924 Rhodophyllum distans Garwood and Goodyear, p. 261, pi. 17, figs. 4n, 46, pi. 18, fig. 3. 1938 Dibunophyllum bipartitum konincki (Edwards and Haime) pars'. Hill, p. 78. 1939 Dibunophyllum bipartitum craigianum (Thomson) pars'. Hill, p. 79. 1939 Caninia? slimonianum (Thomson); Hill, p. Ill; 1940, pi. 6, figs. 3, 4. Lectotype (selected by Hill 1939, p. Ill) KM.T 1021 a, b, from the Lower Limestone Group of the Carboniferous Limestone of Scotland (Coral Zone 3 of Hill), at Brockley, Lesmahagow. Diagnosis. As for genus. Description. External characters. The corallite is simple, large, and varies in shape from ceratoid to trochoid. The lectotype is a fragment of a large corallite with a diameter 282 PALAEONTOLOGY, VOLUME 4 greater than any other individual seen, i.e. 5-6 cm. The longest corallite measures more than 10 cm. along its convex side, excluding the tip which is not preserved. The surface is ornamented with fine transverse striae and weak septal grooves ; interseptal ridges are present in some corallites. No root-like projections are visible. The cahce is deep, its walls are moderately steep and a calicular boss is formed at the centre, except when the Caninioid stage is developed. The cardinal fossula is situated on the convex side of the corallite. Rejuvenescence occurs in some specimens. Internal characters, (a) in transverse section: the corallite is smooth in outline and the wall thin. Both major and minor septa are straight except occasionally in the late stages when they are crenulate in the dissepimentarium; they consist of fibres diverging from EXPLANATION OF PLATE 35 Figs. 1-17. Sliinoniphylluin slinioniamim (Thomson). Natural size. 1-7, GSM 65275, coral bed in Lower Lonsdaleia Subzone (Da), beck above Hunt Pot, 1 1 miles north-east of Horton. 1 , 2, Sections A and B, of early neanic stage; 3, 4, sections C and D, of late neanic stage, with dissepiments beginning to develop; 5, section E, L.S. with irregular tabellae and weak axis; 6, 7, sections F and H, major septa are not strongly dilated in the late stages of this specimen and the dissepimental zone is narrow. 8-12, GSM 65277, same locality. 8, 9, Sections A and B, of early neanic stage; 10, section C, L.S. showing irregular tabellae and downward sloping widely spaced tabulae; 11, section D, with weak axis, and thickened major septa (note: dissepiments are late-forming in this specimen); 12, section F, calicular section with thin septa, crenulate in the dissepimentarium. 13, 14, GSM 65288, same local- ity. 13, Section C, L.S. showing conical tabellae forming axial structures poorly differentiated from tabularium; 14, section A, showing weak axis, short minor septa and wide dissepimentarium. 15-17, GSM 6461 1, Lonsdaleia Subzone (Dj), railway cutting, at Humphrey Head, Grange. 15, Section A, with weak axial column and tapering vesicular septa; 16, 17, calicular and lateral views, showing ornament and external form. Figs. 1-15 are of celluloid peels. For position of sections see text-figs. 1-8. EXPLANATION OF PLATE 36 Figs. 1-14. Slimoniphyllnm sUmonianum (Thomson). 1-6, GSM 101891, X 1, high Da of Shining Cliff, 800 yards south-south-west of Mattock Station, showing development of advanced form with weak axial column. 1, Section A, early neanic stage; 2, section B, L.S. with incomplete tabulae raised in the centre to form a weak axial column; 3, section C, late neanic stage; 4, section D, with tapering septa running into axis; 5, section F, with wide, loosely constructed axial column, vesicular septa both bluntly terminate and slightly tapering and wide dissepimentarium with lonsdaleoid dissepi- ments; 6, section G, L.S. showing caninomorphic features with complete flat tabulae and no axial column in the final stages, and steeply inclined dissepiments. 7-11, GSM 64675, X 1, Cyathaxonia shales, D. muirheadi Subzone (Pj), Great Bundle Beck, near Dufton. This corallite has a strong, well- defined axial column. 7, Section D, early neanic stage; 8, 9, sections E and G, late neanic stages with dissepiments developing; 10, section K, large strongly defined axis, major septa blunt ended or slightly clavate; 11, section J, L.S. showing well-formed axial column with conical tabellae and weak medial plate, and upward sloping tabulae with gutter formed at outer ends. 12, 13, GSM 65287 section A and 65286 section B, X 1 , both from coral bed in Lower Lonsdaleia Subzone (Dj), beck above hunt Pot, If miles north-east of Horton. 12, Shows well-formed axis with short medial plate and straight septal lamellae, vesicular major septa, irregular, angular, crowded inner dissepiments, and con- centric outer dissepiments; 13, L.S. with incomplete tabulae, irregular tabellae forming weakly defined axis and large steeply inclined dissepiments. 14, GSM 65291, X 4, holotype of Dibnnophylliim rhodophylloides Garwood and Goodyear, P. gigantens bed (Dj), stream above Dry Lathe Cave, south of Cave Hill (Old Ing) 3 i miles northof Horton. Part of T.S. (PF991 ), figured by Garwood and Goodyear 1924, pi. 17, fig. 2a. Showing details of vesicular septa, axial column with weak medial plate, and arrangement of dissepiments. Figs. 1-13 are of celluloid peels; fig. 14 is of a section. For position of sections see text-figs. 1-8. Palaeontology, Vol. 4 PLATE 35 KATO and MITCHELL, Slimoniphyllum PLATE 36 Palaeontology, Vol. 4 KATO and MITCHELL, Slimoniphyllum KATO AND MITCHELL; SLIMONIPHYLLUM, A NEW GENUS 283 TEXT-FIGS. 1-8. Shape and size of specimens of SHmoniphyllum slimouianum (Thomson), showing positions from which thin sections and celluloid peels have been taken. Thin sections are referred to as T.S. for transverse and L.S. for longitudinal sections, celluloid peels are referred to by letters. The prefix ‘PF’ indicates slides in the Geological Survey collection. Details of horizon and locality are given in the section on distribution. 1, GSM 64611, Humphrey Head, 1 peel, A = PF 1018; 2, GSM 65288, Hunt Pot, 2 peels, A and C = PF 1014-15; 3, GSM 65287, Hunt Pot, 1 peel, A = PF 1013; 4, GSM 65286, Hunt Pot, 1 peel, B = PF 1012; 5, GSM 65277, Hunt Pot, holotype of /?. distans, 2 T.S. = PF 993^, 2 L.S. = PF 995-6 (PF 993 is figured by Garwood and Goodyear 1924, pi. 17, fig. Aa, and PF 995, pi. 17, fig. 4/5), and 6 peels, A-F = PF 997-1002; 6, GSM 65275, Hunt Pot, 8 peels, A-H = PF 1003-10; 7, GSM 64675, Great Bundle Beck, 1 T.S. = PF 1019 and 12 peels, A-L = PF 1020-31; 8, GSM 101891, Matlock, 8 peels. A, B, B', C-G = PF 1032-39. All figures x |. the central part of the septa (B type of Kato 1959, p. 267). The number of septa is closely related to the diameter of the corallite, and there are forty-four septa of each order at a diameter of 5-6 cm. (see text-fig. 9). The major septa are dilated in the tabularium, but attenuated in dissepimentarium. The axial ends are tapering or bluntly terminated, and occasionally shghtly clavate (PI. 36, fig. 14). Small spaces are often left between the medial line and the dilated part of the septa, giving the septa a vesicular appearance. The cardinal fossula is clearly marked by the short cardinal septum which is about half as long as the other major septa and is situated on the convex side of the corallite. The counter septum is also shortened and is almost two-thirds the length of the others, so 284 PALAEONTOLOGY, VOLUME 4 that the counter fossula is not so prominent as the cardinal fossula. (Note: the counter quadrants of the lectotype are damaged, and the counter fossula is not seen clearly.) The number of septa in the counter quadrants is usually larger than that in the cardinal quadrants, where dilatation of the major septa is sometimes more pronounced. In the younger stages the minor septa are prolonged into the tabularium where they are slightly dilated, but in the mature stage they are usually attenuated and confined to the dissepi- mentarium and are occasionally crenulate. The dissepimentarium is wide in the mature corallite, and can be divided into an inner and an outer zone. The dissepiments of the inner zone are angular, irregular, and of the pseudo-herringbone type (i.e. herringbone pattern between major and minor septa, Minato 1955, p. 63). They are also more closely packed than in the outer zone, and this feature, together with the septal dilatation in the tabularium, clearly marks the position of the inner wall. In the outer zone the dissepiments are less crowded and are more regular and con- centric. Narrow concentric lonsdaleoid dissepiments may develop in the outer zone of some mature coralhtes. The size and shape of the axial structure are very variable. In some coralhtes thin septal lamellae, tabellae, and a thin weak medial plate are present, forming a distinct axial column, usually separated from the axial ends of the septa, but with an occasional septal lamella joined to the septa. In other coralhtes the medial plate is degenerate and the column consists of several weak, thin lamellae together with the axial portions of the incomplete tabulae. This tendency towards degeneration leads in the extreme case to caninomorphs in which no axial structure is present. The axial column in some cases has a distinct border (GSM 64675, PI. 36, figs. 1-11) and is well differentiated from the tabularium. In other cases the axis is not so clearly differentiated and the septal lamellae are joined to the septa (GSM 101891, PI. 36, figs. 1-6). {b) In longitudinal section; when the axial structure is strongly developed, it is clearly marked off from the tabularium. The tabellae are closely packed and steeply inclined against the thin medial plate (GSM 64675j, PI. 36, fig. 11). With degeneration of the medial plate the tabellae become loosely arranged (GSM 65277c, PI. 35, fig. 10). In some cases the axial structure may degenerate until it only consists of the slightly elevated axial parts of the incomplete tabulae, bound together with a few lamellae (GSM 65286b, PI. 36, fig. 13). When the axial structure is absent the tabulae are flat and complete (GSM 101891G, PI. 36, fig. 6). The tabularium is wide and in the young stages the tabulae are flat and complete. In the mature stages they are incomplete, widely spaced, and are inclined upwards against the axis, with a well-formed gutter at the outer end (GSM 64675j, PI. 36, fig. 11). The width of the dissepimentarium varies considerably, and the dissepiments are moderately large and steeply inclined. Ontogeny. Brephic stage: in all the coralhtes examined the tip is missing so that no brephic stage has been seen. Early neanic stage : in the earliest stage seen (GSM 65275a, PL 35, fig. 1) the coral is of simple construction. The counter septum is already shortened and a simple columella is present. There are seventeen major septa at this stage and they are not thickened. The axial end of the septa fall short of the centre, leaving an open space around the columella. Minor septa and dissepiments are not yet developed. KATO AND MITCHELL: SLIMONIPHYLLUM, A NEW GENUS 285 The 3rd and 4th cycle of insertion of major septa marks the next stage when there are eighteen to twenty-two major septa. At this stage minor septa are beginning to be formed, and all the septa are becoming thickened (GSM 65275b, PL 35, fig. 2). Septal lamellae and tabellae are added to the columella and a small simple axial column is developed (GSM 65277c, PI. 35, fig. 10; note the tabulae are here inclined downwards to the axis and are widely spaced). Late neanic stage : dissepiments first develop at about the 4th or 5th septal insertion TEXT-FIG. 9. Diagram showing the relationship oetween the number of major septa and the diameter of the corallite in Slimoniphylliini slimoniaman (Thomson) and two related species. (24-26 major septa), although in one case (GSM 65277) they do not appear until the 7th insertion. At this stage (4th or 5th insertion) both the cardinal and the counter fossulae are distinct. The axial column is differentiated from the tabularium and usually has a medial plate. All the septa are dilated in the tabularium and the minor septa are pro- longed into that area. The stage at which the medial plate is lost differs from specimen to specimen, but the earliest case is when the number of major septa is thirty (GSM 65277). The minor septa tend to shorten with the growth of the corallite, but the stage at which they are confined to the dissepimental zone varies between the stage with thirty-four major septa and that with forty-six. After the 7th septal insertion (about thirty-five major septa) the septa start to become vesicular and small spaces appear between the dilated parts of the major septa and the medial line. This vesicular tendency increases with the growth of the corallite. Adult stage: when the number of major septa is more than thirty-five, all the specific characters are attained and the corallite is considered to be mature. The axial structure 286 PALAEONTOLOGY, VOLUME 4 tends to merge with the tabularium, the differentiation of the axis becomes less distinct, I the medial plate is lost, and the septal lamellae are twisted. The vesicular tendency of j the dilated major septa becomes prominent, and the minor septa are confined to the ;i dissepimental zone which is well developed. The tabulae are incomplete and inclined ! upwards to the axial structure. The dissepiments are concentric during the early stages 1 of development, but with the increase in the width of the corallite they tend to become [ irregular, angular, and of pseudo-herringbone type, especially at the inner margin of the [ dissepimentarium. Lonsdaleoid dissepiments first appear when the number of major i septa is between forty-two and forty-six, with the exception of GSM 101891 in which i they are formed when there are only thirty-three major septa. The most advanced stage is seen when the caninomorphic features are developed. The lectotype (KM.T 1021) approaches this stage. In GSM 101891g the axial structure is entirely degenerate, and the tabulae are complete and flat. The septa remain dilated in the tabularium until the final stages, but in the calice all the septa are thin and of equal ! thickness and may be crenulate in the dissepimentarium (GSM 65277e). ^ The structure of the axial column can be divided for convenience into five stages, j representing both a morphological and an ontogenetic series and is summarized thus : I A. Axial column not yet formed. Simple columella present and free from septa. Like young stage of j Auloclisia and Carcinophylliun. \ B. Medial plate present. Axial structure clearly differentiated from tabularium. Like Cravenia, Auloclisia, and Clisiophyllum. C. Axial column composed of loose axial tabellae, several septal lamellae and occasionally a short medial plate. Column weakly differentiated from tabularium. Like Auloclisia. Example GSM 65287. D. Tabulae incomplete, gently arched at centre of corallite where they make a weak axial structure together with several twisted lamellae. Like Rodophyllum. Example GSM 65275. E. Tabulae complete and flat. Axial structure lost. Eike Caninia. Example GSM 101891. Variation. The general shape of the corallite may be trochoid or ceratoid. The trochoid form is represented by GSM 101891 and probably includes KM.T 1021 which is too incomplete to be definite. GSM 65277 is an example of the ceratoid form, to which most specimens belong. The convexity of the latter group is variable, with GSM 64611 less convex, and GSM 64675 much more convex than, normal. The trochoid forms appear to have the strongest development of lonsdaleoid dissepiments and of the caninioid tendency, whereas the ceratoid types have more strongly developed axial structures. The greatest variation among the internal characters is in the shape and size of the axial structure. Each individual passes through several stages during development, but the diameter at which a certain stage is reached varies greatly with the individual. The pattern in the mature corallite varies from type C to type E, A and B types only being present in immature sections. The different types, however, are developed earlier in some specimens than in others. In GSM 101891 the column already shows D type features when there are only thirty-seven major septa, whereas in GSM 64675 at this stage a B-C type column is developed. The adult axial types are listed in the following table. Etype GSM 101891. D type KM.T 1021. GSM 64611, 65275, 65276, 65286, 101892. BM.R 17321, 17322. C type GSM 65277, 65287, 65288, 65290, 65291. B-C type GSM 64675. KATO AND MITCHELL: SLIMONIPHYLLUM, A NEW GENUS 287 The vesicular tendency of the major septa develops when about thirty-five major septa are present, but although it starts at about the same time in most corallites, the degree of development is variable. In one specimen (GSM 65275) it occurs earher than is normal, the vesicular tendency being weakly developed when the septal dilatation starts. But the spaces soon disappear and the tendency develops again at the normal stage. The vesicular tendency is most strongly developed in G.S.M. 101891 and KM.T 1021, both stratigraphically higher specimens. Axially the major septa usually end bluntly, and are occasionally slightly clavate. But when the axial column becomes poorly differentiated, the axial portions of the septa taper and are joined to the septal lamellae (GSM 65287, 64611, 101891, and KM.T 1021). Remarks and comparisons. In Slimoniphyllwn the cardinal fossula is situated on the con- vex side of thecorallite, the normal arrangement in most rugose corals. The position of the cardinal fossula is usually a stable character, but in Dibiinophyllnm and ClisiophyUum, which also have the cardinal fossula on the convex side, the reversed arrangement occurs in a few specimens. This suggests that the position of the cardinal fossula is not neces- sarily a genetic character, but may be an adaptation. Both the cardinal septum and the counter septum are shortened in SUmoniphyllum. In AuJoclisia Lewis, ClisiophyUum Dana, Dibiinophyllnm Nicholson and Thomson, Koninckophyllwn Thomson and Nicholson, and Caninia Michelin, however, only the cardinal septum is shortened, and the counter septum is the same length as, or even longer than, the other major septa. The shortening of the counter septum is not unique to SUmoniphyllum, also being a characteristic feature of Cryptophyllum Carruthers and Rhopalolasma Hudson. But it is rare among corals with a dissepimental zone, and only three examples have been noted in British Carboniferous corals. Very slight shortening of the counter septum is seen in one calicular section of ClisiophyUum ingletonense Vaughan (GSM 65070), and in the mature sections of Auloclisia mutatum Lewis (1927, pi. 2, fig. 1). In Caninia buxtonensis Lewis, a species based on a single specimen, the counter fossula is prominent (Lewis 1924, pi. 30, fig. 3d). A. mutatum is closest to S. sUmonianum and the very slight shortening of the counter septum in mature sections of Auloclisia is here considered to be a transitional feature linking Auloclisia, which is con- fined to Di, and SUmoniphyllum, which occurs in D2. The typical axial structure of S. sUmonianum is of the Rodophyllum type, in which the cobweb-like axial column has lost its medial plate and the septal lamellae are twisted. This type is known in several Carboniferous corals, and possibly represents a trend. Rodophyllum (= Dibunophyllum of the bipartitum craigianum subspecies group) and Auloclisia are both distinguished by this type of axis, and the trend is also recorded in Cravcnia lamcllata Howell. In many of these forms the column retains its general outline after the degeneration of the medial plate, but in SUmoniphyllum, degeneration continues until the column is completely lost. Similar cases of the degeneration of the axial column have been described by Vojnovsky-Krieger (1956) with a gradual change from a Cyathoclisia-Wkc form, through a Koninckophylloid form to a Caninioid form: and Hudson and Anderson (1928) also recorded a Caninioid stage in the late ontogenetic stage of Hettonia fallax. The vesicular type of septal development of S. sUmonianum has also been observed in 288 PALAEONTOLOGY, VOLUME 4 Clisiophyllum keyserUngi M‘Coy (Hill 1938, pi. 1, fig. 6), A. mutatum Lewis (1927, pi. 2, fig. 2a), Koninckophyllwn scarlettense Lewis (1930, pi. 22, fig. 2a, BM.R 27914), and Caninia hettonensis Wilmore (1910, pi. 39, fig. 6, BM.R 34898). The degree of vesiculation is very small in these forms, and in some specimens may only be represented by an iso- lated case. This vesicular tendency in the septa clearly indicates that there is a time gap between the original formation of the septum and the next addition of fibres to it. The thickening, however, must take place before the covering of the septa by tabulae, but as Wang (1950) points out, secondary thickening is not a satisfactory description of this dilatation of the septa. The development of lonsdaleoid dissepiments is another common trend in rugose corals. When present, they usually appear in the late stages of development, but are sometimes connected with rejuvenation. Both Palaeosmilia murchisoni Edwards and Haime and P. regia (Phillips) show this feature, most commonly in the stratigraphically higher forms. Lonsdaleoid dissepiments are also present in Caninia buxtonensis. Affinities. S. slinionianwn was originally assigned by Thomson (1874, p. 558) to the genus Rodophyllum. Hill (1938, p. 66) considered Dibunophyllum (1876) to be a junior synonym of Rodophyllum (1874), but proposed the retention of the former name for the genus on the grounds that it is a well-known and widely used name, although Rodophyllum has priority under the rules of nomenclature. This case has yet to be put to the International Commission on Zoological Nomenclature for a decision, but meanwhile Dibunophyllum continues to be used for this important group of corals. Hill grouped seven generic and seventy-one of the specific names proposed by Thomson into three subspecies of Dibunophyllum bipariitum (M‘Coy) and R. craigianum Thomson 1874, the type species of Rodophyllum, is also the type species of the third of these subspecies, D. bipartitum craigianum. S. slimonianum differs from this subspecific group in that it has a shorter counter septum, thickened vesicular septa, long minor septa, and an axial column which degenerates beyond the stage usually reached in D. bipartitum craigianum. Hill (1938, p. Ill) doubtfully referred S. slimonianum to the genus Caninia but drew attention to its Clisiophyllid affinities. Caninia is undoubtedly a polyphyletic genus, and even taking it in its broadest sense, the present species differs from Caninia by the de- velopment of an axial structure and also a counter fossula. The ontogeny of the present form is very similar to that of Auloclisia. Slimoniphyllum differs from Auloclisia, however, in the following features. The axial column degenerates and is ultimately lost, the counter septum is weak and shortened, the vesiculation of the septa is more strongly developed, and lonsdaleoid dissepiments are more common. The compact, well-defined axial column of Aulophyllum with its closely packed lamellae immediately distinguishes this genus from Slimoniphyllum. By the character of its wide dissepimentarium, axial column, and by the microscopic structure of the septa, Slimoniphyllum is seen to belong to the family Aulophyllidae. The closest related species is A. mutatum, and it is suggested that S. slimonianum de- veloped from this species by progressive degeneration of the axial column and counter septum. Distribution. S. slimonianum has so far only been recorded from the Midland Valley of Scotland, the north of England, and Derbyshire, where it occurs in the Upper Dibuno- phyllum Zone (Da) and Hill’s coral Zone 3. KATO AND MITCHELL: SLIMONIPHYLLUM, A NEW GENUS 289 (a) Midland Valley of Scotland. Thomson’s original specimen, KM.T 1021, ‘was found at Brockley, Lesmahagow in the lower beds of the Carboniferous Limestone’ (1874, p. 558). Hill revised Thomson’s material and recorded the species (1938, p. 21) from bed (d)-‘shale interstratified with thin beds of limestone near the base-’ of the Brockley section. The beds present in this section, the Main to the MacDonald Lime- stone, belong to the Lower Limestone Group, and form the upper part of Hill’s Coral Zone 3 (= Cockleshell to Great Limestone of the north of England). {b) North of England. The north of England specimens occur in four areas. In three of these, the Pennine Region near Appleby, Humphrey Head near Grange, and the Grassington area, only single specimens have been recorded. The bulk of the material comes from the fourth region, centred on Horton in Ribblesdale. The fossil numbered GSM 64675, identihed in the Geological Survey Register as RhodophyJlum distaiis, comes from the Dibimophylhim muirheadi Subzone, Cyathaxonia shales, of Great Rundle Beck, near Dufton, Appleby. This specimen was probably that listed by Garwood (1913, p. 540) as D. muirheadi Nicholson and Thomson, from the ‘shales overlying the Scar Limestone in Great Rundle Beck’. The Scar Limestone is of Pa age and the association with Cyathaxonia cornu Michelin gives a link with the Cyathaxonia Beds of Derbyshire, which are also of Pg age. The specimen from the Grange area, GSM 64611, is from the railway cutting at Humphrey Head, in beds doubtfully referred to the Lonsdaleia floriforniis Subzone (Da). It was originally named Caninia? by Garwood, and later re-identified by S. Smith as ' Dibunophyllum of the Rhodophyllwn type’. Most of the Ribblesdale specimens are from Hunt Pot, Penyghent, 1 1 miles north-east of Horton, and are numbered GSM 65275-7 and 65286-8. They were collected from a coral bed in the Lower Lonsdaleia Subzone (Da), which outcrops in the beck immediately north of the wall above Hunt Pot (Garwood and Goodyear 1924, pp. 201-2). With the exception of GSM 65288, which was listed as DibunophyUum aff. matlockense Sibly, all the specimens were identified as Rhodophyllum distans, GSM 65277 being the holotype (1924, p. 261, pi. 17, figs. 4a, 46), and GSM 65275 was also figured (1924, pi. 18, fig. 3). The same coral band crops out in the beck above Hull Pot, about 500 yards north of Hunt Pot, and GSM 65290 from here (1924, pp. 201-2) is recorded as D. rhodophylloides. This horizon is noted for the size and abundance of specimens of Productus (Giganto- productus) giganteus J. Sowerby, and is sometimes referred to as the P. giganteus bed. The same bed is also found in the stream above Dry Lathe Cave, south of Cave Hill, 32 miles north of Horton (1924, p. 202), and from this locality, sometimes called Old Ing, GSM 65291, the holotype of D. rhodophylloides (1924, p. 261, pi. 17, figs. 2a, lb) was collected. Old Ing, Penyghent, is one of the localities listed by Garwood and Goodyear (1924, p. 262), for R. distans, but no specimens of this species from this locaUty are preserved in the Garwood collection. All the specimens of S. slimonianum from the Horton area, therefore, come from a coral bed (= P. giganteus Bed) in the Lower Lonsdaleia Beds which are of low Dg age. The single specimen of S. slimonianum, GSM 101892, from 22 miles north of Gras- sington, was collected by Dr. C. J. Stubblefield at 1,150 feet O.D., 2,100 yards east- north-east of St. Mary’s Church, Conistone, and 1,500 yards north-north-west of Bare House. The beds here are just above the Girvanella Band, therefore of basal D-2 age. 290 PALAEONTOLOGY, VOLUME 4 j The specimen was originally identified by S. Smith as Auloclisia mutatum variant, with , the comment that ‘the form differs from the typical A. mutatum in the large size, more weakly developed minor septa, and more pronounced lonsdaleoid dissepiments’. The counter septum is also shortened and the specimen undoubtedly belongs to the present species. (c) Derbyshire. Only three other examples of the species have so far been traced. One | of these, GSM 101891 , was recently collected by Geological Survey officers from Shining | Cliff, 800 yards south-south-west of Matlock Station. The horizon is 1 foot above the j massive limestone near the base of the ‘reefy’ limestone which is exposed in the upper j part of the cliff. The horizon of these beds is high in Da. ' The remaining two specimens, BM.R 17321-2, were collected by Mr. A. Hammond | from ‘near Wirksworth, north of Derby’, and presented to the British Museum (Natural j History) in 1892. BM. R 17322 is an almost complete specimen, of the ceratoid form i with the calice weathered out, and an axial column of the D type. In the absence of an | exact locality in this case, it is only possible to say that the pale-buff colour of the sped- ■ mens suggests that they may have come from the D^ limestones, which are typically pale coloured in this area (Shirley 1959). ; REFERENCES GARWOOD, E. J. 1913. The Lower Carboniferous succession in the North-West of England. Quart. J. Geol. Sac. Loud. 68 (for 1912), 449-586, pi. 44-56. and GOODYEAR, E. 1924. The Lower Carboniferous succession in the Settle district and along the line of the Craven faults. Ibid. 80, 184-273, pi. 10-21. HILL, D. 1938-41. A monograph on the Carboniferous rugose corals of Scotland. Palaeoutogr. Soc. HUDSON, R. G. s. and ANDERSON, E. w. 1928. On the Lower Carboniferous corals: Hettonia falla.x, gen. et sp. n. Proc. Leeds Phil. Soc. (Sci. Sect.), 1, 335—40, pi. 1-2. KATO, M. 1959. Some Carboniferous rugose corals from the Ichinotani formation, Japan. J. Fac. Sci. Hokkaido Univ. (4), 10, no. 2, 263-87, pi. 1-3. LANG, w. D., SMITH, s., and THOMAS, H. D. 1940. Index of Palaeozoic coral genera. Brit. Mas. {Nat. Hist.). London. LEWIS, H. p. 1924. Upper Visean corals of the genus Cauinia. Quart. J. Geol. Soc. Loud. 80, 389-407, pi. 27-30. 1927. On Auloclisia, a new coral genus from the Carboniferous Limestone. Proc. Yorks. Geol. Soc. (N.s.) 21, 29-46, pi. 1-2. 1930. The Avonian succession in the South of the Isle of Man. Quart. J. Geol. Soc. Loud., 86, 234-90, pi. 20-25. MiNATO, M. 1955. Japanese Carboniferous and Permian corals. J. Fac. Sci. Hokkaido Uuiv. (4), 9, no. 2, 1-202, pi. 1^3. RYDER, T. A. 1930. Notcs On " Carciuophyllum' Nich. & Thom., with descriptions of two new species, Auu. Mag. Nat. Hist. (10), 5, 337-51. SHIRLEY, J. 1959. The Carboniferous Limestone of the Monyash-Wirksworth area, Derbyshire. Quart. J. Geol. Soc. Loud. 114, 411-29, pi. 20. THOMSON, J. 1874. Descriptions of new corals from the Carboniferous Limestone of Scotland. Geol. Mag. 11, 556-9, pi. 20. ■ 1883. On the development and generic relation of the corals of the Carboniferous Limestone of Scotland. Proc. Phil. Soc. Glasg. 14, 296-520, pi. 1-14. THOMSON, J. and nicholson, h. a. 1876. Contributions to the study of the chief generic types of the Palaeozoic corals. Auu. Mag. Nat. Hist. (4), 18, 68-73, pi. 1-3. VOJNOVSKY-KRIEGER, K. G. 1956. [On the development of Caninioid structure in the ontogeny of the coral Cyathoclisia coniseptum (Keys.).] Ann. Soc. paleont. russe, 15, 69-75, pi. 1-3 [in Russian]. KATO AND MITCHELL: SLIMONIPHYLLUM, A NEW GENUS 291 WANG, H. c. 1950. A revision of the Zoantharia Rugosa in the light of their minute skeletal structures. Phil. Trans. Roy. Soc. LoncL 234b, 175-246, pi. 4-9. wiLMORE, A. 1910. On the Carboniferous Limestone south of the Craven fault (Grassington-Hellifield district). Quart. J. Geol. Soc. Loud. 61, 539-85, pi. 38-41. M. KATO Dept, of Geology and Mineralogy, Hokkaido University, Japan. Manuscript received 9 November 1960 M. MITCHELL Geological Survey and Museum, London S.W. 7. FURTHER INTERPRETATION OF EUCOMMIIDITES ERDTMAN 1948 by N. F. HUGHES Abstract. A new interpretation is given of the genus Eucommiidites and further illustration of the type species E. troedssonii. E. delcoiirtii sp. nov. is erected for pollen observed in the micropyle and pollen chamber of a new Lower Cretaceous seed Spennatites pettensis sp. nov., which is also described. This new evidence is all believed to support the gymnospermous origin of Eucommiidites. The finding of pollen of the Eucommiidites type in the mieropyle and pollen chamber of a dispersed Lower Cretaceous seed has led to a reassessment of the nature and distribu- tion of this unusual type of pollen grain. The importance of the Jurassic pollen grain species Eucommiidites troedssonii Erdtman has been widely discussed, e.g. Scott et al. (1960), Harris (1960h), Hughes (1961), because it was originally described by Erdtman (1948) as tricolpate. The pressure to find Jurassic angiosperms has been such that in spite of various attributions of this species to a gymnospermous origin, the suspicion remains that Erdtman may have been right. Some further interpretation is attempted here and a restated diagnosis is given in neutral terms which are better used at least until the grain has been seen in its tetrad. The specimens discussed below were collected by the author and are deposited in the Sedgwick Museum, Cambridge, numbers K2277-84. SYSTEMATIC DESCRIPTION AND DISCUSSION Anteturma pollenites R. Potonie 1931 Turma plicates (Naumova) Potonie 1960 Subturma praecolpates Potonie and Kremp 1954 Genus eucommiidites Erdtman emend. 1948 Erdtman G., Geol. Foren. Fork., 70, 267. 1958 Couper R. A., Palaeoiitographica, 103B, 160. Restated diagnosis. Pollen grains with oval equatorial outline in usual viewing position. On one face, which is flat, is a long furrow with rounded ends, parallel with the long axis ; in the unexpanded condition, the margins of this furrow may close over it in the middle. The opposite face, which is more convex, bears a ring-furrow near the margin, separating the larger part of the face (zonisulcate condition of Erdtman 1952). Ring- furrow exine thin; ring may be incomplete at the ends in the long axis. Pollen wall with thin inner layer and thicker less refractive outer layer. Generic name. Rouse (1959) preferred TrifossapoUenites Rouse 1957 on grounds of priority over Couper’s final removal of Trieolpites from the name in 1958. Rouse’s view is not accepted because although Erdtman (1948) used the name Eucommiidites only as ‘nomen typicum concretum’ rather than as a genus, his meaning was perfectly clear in Palaeontology, Vol. 4, Part 2, 1961, pp. 292-9, pis. 37-38.] N. F. HUGHES: EU CO M M 1 1 D ITES ERDTMAN 1948 293 using Tricolpites as a ‘nomen typicum abstractum’, which could be taken as a higher grouping; the information given by Erdtman was also adequate in other respects. T. (Eiicommiidites) had appeared several times in European literature before 1957. It is only fair to point out that Rouse (1959) did not actually make the change which he advocated. Finally, if Rouse’s name is reconsidered, it will also be necessary to assess the validity of Protoquercus agdjakeudensis of Bolkhovitina (1953) which may well represent the same pollen. The classification of this genus adopted by Potonie (1960, p. 88) is considered to be flexible and appropriate. Type species. E. troedssonii EvAtman 1948. Eucommiidites troedssonii Erdtman Plate 37, figs. 1-16; text-figs. 1a-f Material. Preparation C104 from Sample B13, Parrot Shale at base of Brora Coal, Brora Mine, Sutherland. Middle Jurassic. Description. The facts given by Erdtman (1948) and Couper (1958) form a good descrip- tion except that the two minor ‘colpi’ with slightly jagged edges and non-overlapping margins are now interpreted as a ring-furrow which may be complete, or broken for a short distance opposite one or both of the ends of the grain as in the figure of Castalia pollen by Wodehouse (1935, p. 344). Consequently the back face of the grain with this ring-furrow is now interpreted as zonisulcate. Reference to ‘colpi’ and to decisions on orientation (mention of poles) should be omitted until evidence is conclusive ; the legend of fig. 1/in Hughes and Couper (1958) is in error in this respect. Discussion. The probable orientation of these pollen grains is uncertain because if they are compared with Classopollis Pflug which has these structures (description of Couper 1958, p. 157), the ring-furrow must be distal. Their time range is similar to that of Classopollis and they sometimes occur in the same samples. On the other hand, the main long furrow is very similar to the single furrow of cycad pollen, which is interpreted in recent material also as distal, i.e. anatreme (Erdtman 1960); cycad pollen is frequently found in the same samples as Eucommiidites. As indicated in PI. 37, figs. 7-14, in which the grain lies obliquely, the ring-furrow is believed to have been complete. In the more usual view, PI. 37, figs. 1-5, the minor furrows curve inwards of course but are not seen to join; this may be because the ring is frequently incomplete, or because it passes from view behind the widened and folded end of the long furrow. The holotype (Erdtman 1948, fig. 15) subsequently designated by Nilsson (1958) presents this view. The end views (PI. 37, figs. 15-16), which are in all cases rare (Couper 1958), give a little cause for disquiet over my interpretation as it is not easy to separate the two distinct kinds of furrow in this view ; in fig. 1 5 the main long furrow is on the right side and in fig. 16 it is upper right. It would seem that this difficulty is increased by the fact that these two grains were inflated before compression in the sedi- ment (nearly circular in optical section), which reduces the contrast normally seen be- tween the furrows. Possibly only inflated grains had any real chance of being preserved in this orientation. It is clear that the remarks of both Simpson (1937) and Pflug (1953) lend some support to my interpretation. Simpson (as mentioned in Hughes and Couper 1958) B 9425 U 294 PALAEONTOLOGY, VOLUME 4 A B C E F TEXT-FIG. I . Diagrammatic views of the pollen grain Eucommiidites troedssonii Erdtman. A, Front view showing main furrow and ring-furrow (broken line — behind). B, Back view showing complete ring- furrow. C, Back view showing ring-furrow incomplete at the ends. D, Lateral view showing ring- furrow, difference in convexity of faces and position of main furrows, E, End view (theoretical) with ring-furrow, possibly incomplete, and main furrow unexpanded. F, Grain in end view position but with main furrow (right) expanded, consequently circular in optical section, and ring-furrow. This grain is slightly inclined (top to left) to show ring-furrow more clearly and to compare with Plate 37, fig. 15. EXPLANATION OF PLATE 37 Magnification of all figures X 1,000. Figs. 1-16, Eucommiidites troedssonii Erdtman; sample B13, Brora Coal, Middle Jurassic. 1, Back view; prep. C104/1, 46.0 1 17.2 OR. 2, Back view; prep. C104/3, 44.2 118.2 OR. 3, Front view; prep. C104/1, 39.3 120.7 OR. Figs. 4-5, Front view; prep. C104/3, 50.1 126.6 OR. 4, High focus. 5, Lower focus. 6, Front view, specimen obliquely compressed; prep. C104/3, 43.0 1 14.9 OR. 7, Oblique back view, high focus, showing ring-furrow partly open; prep. C104/1, 36.9 108.2 OR. 8, Slightly oblique front view, showing ring-furrow passing round end of main furrow; prep. C104/1, 35.2 126.2 OR. Figs. 9-10, Slightly oblique back view, showing ring-furrow complete at one end. 9, Prep. Cl 04/1, 53.1 108.2 OR. 10, prep. C104/3, 38.7 127.3 OR. Figs. 1 1-14, Oblique views showing nature of ring- furrow. 11, Prep. C104/1, 37.8 108.9 OR. 12, Prep. C104/3, 43.2 123.7 OR. 13, Prep. C 104/3, 50.7 120.9 OR. 14, Prep. C104/3, 47.8 109.9 OR. Figs. 15-16, End views; prep. C104/1. 15, Inflated specimen, main furrow right, cf. text-fig. 1/; 37.8 108.9 OR. 16, Partly inflated specimen, main furrow — upper right; 51.8 124.1 OR. Figs. 17-18, Eucommiidites minor Groot and Penny. 17, Front view, Hauterivian specimen, sample WM 1618/6; prep. M834/1, 49 122 OR. 18, Front view, Barremian specimen, sample WM 1333/10; prep. BP569/3, 48.1 127.8 OR. Palaeontology, Vol. 4 PLATE 37 HUGHES, Jurassic and Cretaceous pollen N. F. HUGHES: EUCO MMIIDITES ERDTMAN 1948 295 obviously saw Eucommiidites in the Bora Coal and this led him to discuss and figure pollen of recent Nympheaceae which has an ‘opercular’ structure, and even to stress the bilateral symmetry in recent Nelumbium; unfortunately the fossils he actually figured were of an entirely different type (Hughes and Couper 1958). Without agreeing with Pflug’s diagnosis (1953, p. 91) of ClassopoUis, it is worth noting that he regarded Eucom- miidites as similar to it. Comparison. Erdtman’s original comparison (1948) with pollen of Eucommia ulmoides Oliv. has been restudied on material from a tree in the Botanic Garden, Cambridge. As noted by Couper (1958 p. 164), the Eucommia pollen (see also Erdtman 1952) has slight pores (tricolporate) and the iregularities of the colpi do not include development of a single cycad-like furrow. Cercidiphyllum pollen, which also has colpi of irregular length, has true angiosperm colpate symmetry and is even less like Eucommiidites. Pollen of the Nympheaceae, although similar in gross morphology, differs markedly in exine stratifica- tion. Such comparison with recent pollen certainly assists in morphologic interpretation, but does not seem likely to result in determination of affinities. Among fossils the specimens of Delcourt and Sprumont (1956) differ from the holotype and are discussed separately below. The figured specimens of Pons (1956), Delcourt and Sprumont (1957), Oszast (1957), and Nilsson (1958) belong to E. troeds~ son a and also some of those figured by Thiergart (1949), Reissinger (1950), and Kuyl et al. (1955); in these latter cases, however, it appears that another undescribed type may be represented by some of the figures. TrifossapoUenites ellipticus Rouse 1957, of Senonian age, may well prove to be a distinct species, similar to some of the figures of Kuyl et al. (1955, pi. 6, figs. 1-6). T. rugosa {sic) Rouse 1959 is not at all clearly dis- tinguished by its author from T. ellipticus. The figures of Oszast show well the ring- furrow interpretation difficulty, which has been discussed above. Attribution. Kuyl et al. (1955) suggest the Chlamydospermales, and Pons (1956) does so quite separately, without quoting any earlier references or opinions on this fossil. Palynological evidence of the widespread existence of plants similar to the Chlamydo- spermales in Mesozoic times is accumulating; no progress has yet been made, however, with macrofossil identification of the group. In this connexion I regret the placing of fossil pollen species in extant genera such as Ephedra (Scott 1960), which is likely to be a hindrance to understanding, if not actually contrary to the Rules of Nomenclature (Potonie 1960, p. 21). If there was a Mesozoic group at all, it is unlikely that its members will prove to be close in affinity to the three surviving relict genera; as has been shown many times with other groups, the evidence of a single organ is quite insufficient. I see no hope of clear understanding of Mesozoic and earlier plant evolution, while such practices are aimed at focusing attention on so-called long-ranging minor taxa; a com- plete change of attitude is necessary. Eucommiidites delcourtii sp. nov. Plate 38, figs. 3, 4, and 7 Diagnosis. Small species of Eucommiidites Erdtman emend. Exine of back face with small shallow pits of two sizes, both less than 1 ic in diameter ; remainder of exine laevigate, thickness 1-1^ /j.. B 9425 u2 296 PALAEONTOLOGY, VOLUME 4 Dimensions. Length 16-23 fi (mean 19 jx); breadth 12-20 ix (mean 15 [x); twenty-five specimens. Holotype. Preparation 357A, 42.8 111.8 OR (specimen at outer end of micropyle). One other specimen adjacent to the holotype and six others clearly visible in the pollen chamber are necessary as paratypes. Locus typiciis. Loc. H48B, Ashdown Sands, Lower Cretaceous; Cliff End, Hastings. Description. Holotype, 21 X 17 jx, is seen in opercular view; the seven paratypes supple- ment this. These specimens have only been subjected to a short dispersal treatment (to free the seeds from matrix) in boiling water with sodium carbonate; their size is less likely, therefore, to have been increased by swelling, as may well be the case in all men- * tioned (dispersed) specimens of E. troedssonii and E. minor. Comparison. E. delcourtii differs from the other two species in size and/or sculpture; it I has been observed in the micropyles and pollen chambers of four seeds from the same locality. Eucommiidites minor Groot and Penny 1960 Plate 37, figs. 17-18 Description. Small species of Eucommiidites Erdtman emend, which is nearly circular in equatorial outline and was perhaps nearly spherical. Psilate exine, 1^-2 [x thick. As noted by Delcourt and Sprumont (1956, p. 378) the shape causes oblique and ‘end’ views to be more frequent than in E. troedssonii. Occurrence. Dispersed pollen in Wealden facies in England from Hauterivian to prob- ably Aptian. Dimensions. Diameter 18-25 p. Discussion. While I may be held partly responsible for the naming of this species, of which I have good material, Groot and Penny (1960) are entirely responsible for the holotype. E. troedssonii var. baldurnensis of Delcourt and Sprumont (1956) is very likely to be the same as the English material, but I do not elevate or advocate elevating the varietal name because although the drawings are most informative, the photographs could not serve for holotype illustrations. Although the Groot and Penny diagnosis is very tentative and their photograph none too clear, there seems to be no useful purpose in erecting another species for the English material at present. The size range given for E. troedssonii from Eeron-Glageon by Delcourt and Sprumont (1959) suggests the presence of E. minor. Benettiteae-poUenites lucifer Thiergart 1949 included some small grains originally, and Delcourt and Sprumont (1956) use the name (with drawings only) for some very small grains (\3 p) from Baudour. Thiergart (1949) gave eight separate figures (Trias to EXPLANATION OF PLATE 38 Figs. 1-7, Spennatites petteusis sp. nov., Eucommiidites delcourtii sp. nov. Figs. 1-2, S. pettensis, Holotype. 1, Apical part, X 190. 2, whole ovule, X45. Figs. 3-4, E. delcourtii, enlarged from fig. 1. 3, Holotype (above) and paratype, attached to tip of micropyle, X 1,200. 4, Paratypes in pollen chamber, X 1200. 5, S. pettensis, pollen chamber; prep. 357B, 37.8 114.6 OR, X 500. Figs. 6-7, S. pettensis; prep. 357, 43.3 119.6 OR. 6, base of micropyle X 500. 7, E. delcourtii pollen in micropyle, X 1200. Photographs by Miss M. E. Dettman. Palaeontology, Vol. 4 PLATE 38 HUGHES, Cretaceous seeds and pollen N. F. HUGHES: EUCOMMIIDITES ERDTMAN 1948 297 Cretaceous) but six are not usable, and it seems likely that the others refer to larger material perhaps conspecific (if identifiable) with E. troedssonii. There seems to be no reason to use this name for the small grains. DISPERSED ‘seeds’, INCERTAE SEDIS Form-genus spermatites Miner Discussion. Miner did not designate a type-species and the taxon is best treated as a form-genus with no such designation (cf. Andrews 1955, p. 7). This generic attribution is preferred for the present material as it refers to seeds (or parts of seeds) as seen after maceration, in transmitted light. There is undoubtedly overlap with the earlier form- genus Carpolithes Schlotheim, which, however, is better retained for unmacerated compressions. The species discussed here will clearly be reallocated when it is better understood. Spermatites pettensis sp. nov. Plate 38, figs. 1, 2, 5, and 6 Diagnosis. Compressed ovule of generally oval shape with thick nucellar cuticle, which is lightly punctate (punctae < 1 /x). Pollen chamber well developed. Inner integument cuticle thin with longitudinal cellular markings, continued into a protruding micropylar tube of about one-quarter the length of the nucellar cuticle. Pollen of Eucommiidites pettensis in micropyle and pollen chamber. Dimensions. Length of nucellar cuticle 750 p (six specimens), maximum width 540 p; length of micropyle observed to 240 p. Holotype. Preparation 357A, 43.3 112.3 OR (PI. 38, figs. 1, 2). Locus typicus. Sample H48B, Ashdown Sands, Lower Cretaceous; Cliff End, Hastings. Description. Holotype 860 px560 p; 200 p length of micropyle seen. Nucellar cuticle observed to be punctate at base, thickness 1^ or more; large pollen chamber 70 p high by 100 ^ long at apex. Dark rough area of cuticle on one face, 70-100 p in diameter, about one-third of the length above the base. Upper half or more of nucellar cuticle covered by thin (| p) inner cuticle of the integument with elongated cell pattern arranged longitudinally; micropyle with slight irregular folding of cuticle, 30 p wide increasing to pollen chamber at base. Seven grains of E. delcourtii in the pollen chamber, seven more lightly compressed in the upper part of the micropyle and two (one the holotype of E. delcourtii) entangled in the slightly torn open end of the micropyle. Five other specimens, 357/1, 357/2, 357B/1, 357B/2, and 326, show different grades of preservation. Three show pollen in the micropyle and/or the pollen chamber. Two specimens 357B2 and 326 show a dark patch on one face above the base as does the holotype. In these and in 357/1 there is evidence of compression of an original asym- metrical body and the dark patch is probably in the chalazal area although there is no opening. In 357/1 the main cuticle apparently bears isodiametric cell markings overall, but this is a corrosion effect from natural maceration. With such a small number of specimens the state of both development and preservation is bound to differ; further investigation is in hand. 298 PALAEONTOLOGY, VOLUME 4 Comparison. These specimens fit the diagnosis of Spermatites Miner sufficiently well to be included, but they differ from all of the seven species described by Miner (1935) and the three unnamed species of Schemel (1950) in the presence of the micropylar tube. Pant and Nautiyal (1960) describe three new genera of similar type with pollen chamber and long micropyle (one is short) but disaccate pollen is included in the diagnosis, the sizes are much greater, a chalazal hole is described in each case and they are probably of Permian ( Lower Gondwana) age. Thomas and Harris (1960) describe some cycadean seeds and associated pollen from the Y orkshire Middle J urassic but the present material is clearly distinct. There is no close resemblance to the Caytonia seed or pollen of Harris (1960u). Attribution. Speculation on the origin of these gymnospermous ovules is perhaps not yet profitable. The pollen can only be said to resemble that of Cycadophytes, Ginkgoales, and perhaps Chlamydospermales. The probable lack of chalazal opening seems to eliminate Cycadophytes and to suggest Coniferales which, however, do not fit on pollen and other details such as the pollen chamber. There does not appear to be any typical ‘megaspore cuticle’ (Harris 1954, 1960o) and hence Cycads, Ginkgoales, and Conifers are unlikely. The seeds differ in many respects from those of the Caytoniales (Harris 1960a) and therefore the Chlamydospermales become the most likely group; they at least have a conspicuous pollen chamber formed just prior to pollenation and a single true integument greatly elongated as a micropylar tube {Ephedra). The pollen of the three living genera does not closely resemble Eiicommiidites, but if several recent in- dications (Scott 1960) are correct there may have been in the Mesozoic a fairly large Chlamydosperm-like group of which the living genera are mere chance survivors. Some angiosperm seeds possess some of the cuticle characters mentioned but no cases are sufficiently similar to cite. GENERAL CONCLUSION In caution, mention should be made of the description by Sahni (1915) of some Recent Ginkgo ovules with three types of foreign pollen within the micropyle and pollen cham- ber; some of the grains had even germinated. In the present case the pollen (more than twenty-five grains) was all of the same species {E. deJcourtii). Assuming it to belong to the same unknown plant as the ‘seed’, the evidence presented clearly indicates a gymnospermous origin for Eucommiidites Erdtman, thus strengthening the case presented (Hughes 1961) for angiosperm history beginning in mid-lower Cretaceous time. REFERENCES ANDREWS, H. N. 1955. Index of generic names of fossil plates 1820-1950. Bull. Geol. Surv. Amer. 1013, 1-262. BOLKHOViTiNA, N. A. 1953. Caracteristique sporo-pollenique du Cretace de la partie centrale de rU.R.S.S. Trudy Inst. geol. Nauk SSSR, 145, Geol. ser. 61. COOPER, R. A. 1956. Evidence of a possible gymnospermous origin for Tricolpites troedssonii Erdtman. New Pliytol, 55, 280-4. ■ 1958. British Mesozoic microspores and pollen grains. Palaeontographica, B103, 75-179. DELCOURT, A. F., and SPRUMONT, G. 1956. Presence Eucommiidites dans une coupe du Wealdien de Baudour. Bull. Soc. beige Geol. 65, 377-80. N. F. HUGHES: EUCO MMIIDITES ERDTMAN 1948 299 DELCOURT, A. F., and SPRUMONT, G. 1957. Quelques microfossiles du Wealdien de Feron-Glageon. Ibid. 66, 57-76. 1959. Spores, grains de pollen, Hystrichospheres et Peridiniens dans le Wealdien de Feron-Glageon. Ann. Soc. Geol. Nord. 79, 29-64. ERDTMAN, G. 1948. Did dictoyledonous plants exist in Jurassic time? Geol. Foren. Fork., Stockholm, 70, 265-71. 1952. Pollen morphology and plant taxonomy — Angiosperms. Stockholm. 1960. Pollen walls and Angiosperm phylogeny. Bot. Not. Lund, 113, 41-48. GROOT, J. J., and penny, j. s. I960. Plant microfossils and age of non-marine Cretaceous sediments of Maryland and Delaware. Micropalaeontology, 6, 2, 225-36. HARRIS, T. M. 1954. Mesozoic seed cuticles. Svensk. Bot. Tidsk. 48, 281-91. 1960fl. The seed of Caytonia. Palaeobotanist, 7, 2, 93-106. 19606. The origin of Angiosperms. Adv. Sci. 17, 207-13. HUGHES, N. F. 1961. Fossil evidence and angiosperm ancestry. Sci. Progr. 48, 84-102. and couPER, r. a. 1958. Palynology of the Brora Coal of the Scottish Middle Jurassic. Nature, 181, 1482-3. KUYL, o. s., MULLER, J., and WATERBOLK, H. T. 1955. The application of palynology to oil geology with special reference to western Venezuela. Geol. en Mijnb., N.s. 17, 49-76. MINER, A. L. 1935. Palaeobotanical examination of Cretaceous and Tertiary Coals. Amer. Midi. Nat. 16, 4, 585-626. _ NILSSON, T. 1958. tiber das Vorkommen eines mesozoischen Sapropelgesteins in Schonen. Lunds. Univ. Arsskr. N.s. 54, 1-111. OSZAST, J. 1957. Tricolpites (Eucommiidites) troedssonii Erdtman in refractory Jurassic clays from Grojec near Cracow. Bull. Acad. Pol. Sci., Biol. serv. 5, 3, 103-5. PANT, D. D., and NAUTiYAL, D. D. 1960. Some seeds and sporangia of the Glossopteris flora from the Raniganj coalfield, India. Palaeontographica, B107, 41-64. PEARSON, H. H. w. 1929. Gnetales. Cambridge. PFLUG, H. D. 1953. Zur Entstehung und Entwicklung des angiospermiden Pollens in der Erdgeschichte. Palaeontographica, B95, 60-171. PONS, A. 1956. Sur un pollen du Lias inferieur. C.R. Acad. Sci., Paris, 243, 1547-9. POTONiE, R. 1960. Synopsis der Gattungen der Sporae dispersae. Beih. Geol. Jb., 39, 1-189. REissiNGER, A. 1950. Die ‘Pollenanalyze’ ausgedehnt auf alle Sedimentgesteine der geologischen Ver- gangenheit. Teil II. Palaeontographica, B90, 90-1 26. ROUSE, G. 1957. The application of a new nomenclatural approach to Upper Cretaceous plant micro- fossils from Western Canada. Can. J. Bot. 35, 349-75. 1959. Plant microfossils from Kootenay coal-measures strata of British Columbia. Micropalae- ontology, 5, 3, 303-24. SAHNi, B. 1915. Foreign pollen in the ovules of Ginkgo and of fossil plants. New Phytol. 14, 149-51. SCHEMEL, M. p. 1950. Cretaceous plant microfossils from Iowa. Amer. J. Bot. 2>1, 750-4. SCHNARF, K. 1937. Anatomic der Gymnospermen-Samen. Handb. der Pflanzen-Anatornie II, 10, 1. SCOTT, R. A. 1960. Pollen of Ephedra from the Chinle formation (Upper Triassic), etc. Micropalaeonto- logy, 6, 3, 271-6. ■ BARGHORN, E. s., and LEOPOLD, E. B. 1960. How old are the Angiosperms? Amer. J. Sci. 258A, 284-99. SIMPSON, J. B. 1937. Fossil pollen in Scottish Jurassic coal. Nature, 139, 673. THiERGART, F. 1949. Der stratigraphische Wert mesozoischer Pollen und Sporen. Palaeontographica, B89, 1-33. THOMAS, H.H., and HARRIS, T. M. 1960. Cycadean cones of the Yorkshire Jurassic. Senck. leth. 41, 139-61. THOMSON, p. 1953. Zur Entstehung und Ausbreitung der Angiospermen im Mesophyticum. Paldont. Z. 27, 47-51. WODEHOUSE, R. p. 1935. Pollen grains. New York. N. F. HUGHES Department of Geology, Sedgwick Museum, Manuscript received 14 September 1960 Cambridge. SMALL NAIADITES OBESUS FROM THE CALCIFEROUS SANDSTONE SERIES (LOWER CARBONIFEROUS) OF FIFE by G. M. BENNISON Abstract. Small specimens of Naiadites occur at two horizons in the Calciferous Sandstone Series of Eastern Fife. At one horizon the small shells constitute an indigenous ‘life-assemblage’ (now a fossil community), and are described as dwarfed, whereas at the other the shells are exotic, comprising a fossil assemblage that should be termed a ‘pebble necrocoenosis’. Variation is illustrated, and the affinities of these small Naiadites are re- examined. All are referred to the species N. obesus sd. Leitch (1942, p. 219) makes reference to collections of ‘dwarfed’ Naiadites from a shaly mudstone above the No. 9 Limestone, Randerstone (Kirkby 1901), and from the shore near the Rock and Spindle, St. Andrews. The latter collection was made by Mr. W. Manson of the Geological Survey. Although Kirkby (1901) measured the entire shore section at Randerstone, and Kirk (1925) mapped the Rock and Spindle shore in very great detail, the relative positions of these two AnzW/to-bearing beds cannot be determined, and the faunal relationships examined by the writer suggest that their tentative correlation by Leitch cannot be sustained. 1. Fauna above the No. 9 Limestone, Randerstone. In a shell bed above the No. 9 Limestone, Randerstone, the disposition of the small Naiadites, mean L = 12-6 mm. (figured by Leitch 1942, pi. iii and fig. 9) relative to a large Naiadites obesus fauna is remarkable (text-fig. 1). The small Naiadites make their appearance 3 feet higher than the large forms which are immediately above the limestone. There is no abrupt replace- ment of one by the other : from 3 feet to 3 feet 6 inches above the limestone the two occur in close proximity. In the highest 6 inches of the shell bed only the small form is found. Histograms showing the distribution of length of shell from three samples and from the samples combined (text-fig. 2) clearly confirm the presence of two forms, the latter being bimodal. The small shells, sample 3, have a very small range of length (an in- dication of sorting by waves or currents), and therefore do not comprise a ‘fife assem- blage’ or fossil community. Shells of N. obesus from the lowest 3 feet of the bed (sample 1) have, on the other hand, a wide range of length, both juvenile and gerontic specimens being present, and represent a fossil community (see Craig 1953, p. 547). The large and small forms differ in the nature of their preservation. The ‘dwarfed’ form usually comprising both valves, which are tumid and little affected by crushing (‘solids’). The ‘normal’ Naiadites obesus, on the contrary, is ffattened, often comprising single valves only (as far as one can tell), in a beautiful state of preservation despite the deUcate and fragile postero-dorsal area. The ‘dwarfed’ form, however, is frequently incomplete; in no case could the postero-dorsal region be found adhering to the adjacent shale. The normal N. obesus cannot have been far removed from its ecological station and the shells appear to constitute a life assemblage ; but the associated ‘ dwarfed ’ [Palaeontology, Vol. 4, Part 2, 1961, pp. 300-11.] G. M. BENNISON: SMALL NAIADITES OBESUS 301 TEXT-FIG. 1. Detailed succession above Nos. 9 and 10 Text-fig. 2. Histograms showing distribution of the length of shells Limestones, Randerstone. from three collections of N. obesus s.l. 302 PALAEONTOLOGY, VOLUME 4 form may have drifted into the bed. These ecologically foreign shells, which may be termed exotic, present a problem, for they have remained articulated. The infilling of ironstone protected the shells from the effects of compaction of the sediment. Some specimens retained their shape despite the removal by erosion of the shell material. The TEXT-FIG. 3. Graphs to show the ratio of length (L) to height (H) in collections of Naiadites from a bed above the No. 9 Limestone, Randerstone. continuance of N. obesus through a further 6 inches of strata after the appearance of the ‘dwarfed’ form suggests that the incoming of the latter is not indicative of a change in the biotype. Since the distinction between ‘ dwarfed ’ or small Naiadites and normal N. obesus, as used above, is largely dependent on visual recognition of the two forms, and hence is subjective, frequency polygons have been drawn on the basis of stratigraphical samples (text-figs. 3 and 4). Only those for H/L and y (see Trueman and Weir 1955, p. 212) are G. M. BENNISON: SMALL NAIADITES OBESUS 303 here reproduced. The difficulties of making comparison between crushed and uncrushed Naiadites have been explored (Bennison 1959, pp. 48-59), and crushing shown to result in a generally lower value for H/L and y (the coefficient of correlation between them is high, c. 0-5). The observed differences, both of mode and range of variation of H/L, TEXT-FIG. 4. Graphs to show the variation in the value of the angle y in collections of Naiadites from a bed above the No. 9 Limestone, Randerstone. cannot therefore be ascribed to the effects of crushing of the normal N. obesus, for this would tend to produce a difference contrary to that observed. The difference of values of H/L might be a function of growth, since the direction of maximum marginal incre- ment changes during ontogeny, as shown by the tilted growth lines. That this may reflect a change in the attitude of the shell to the byssus is discussed in a later section: the immediate consideration is whether the difference in values of H/L in the two forms 304 PALAEONTOLOGY, VOLUME 4 indicates a diagnostic criterion of specific or varietal stature; but the observed differences in H/L cannot reliably be attributed to either growth changes or crushing, since the reductions in H/L tend to ‘cancel out’. 2. Dwarfed Naiadites from a bed near die Rock and Spindle. Small shells (mean L = c. 13 mm.), referable to Naiadites, are common in a bed of hard grey shaly mudstone exposed in a low cliff, 35 yards to the south of the Rock and Spindle vent. The bed is at least 3 feet thick ; its stratigraphical position is uncertain, although this shore section is assigned by Kirk (1925) to a high position in the Calciferous Sandstone Series, by virtue of the correlation of his ‘Marine Fossil Bed III’ with the ‘Encrinite Bed’ of Kirkby’s main Pittenweem-Anstruther section (Kirkby, in Geikie, 1902, p. 87). The bed now in question outcrops between Kirk’s Marine Fossil Beds III and IV and, unless the faults bounding it are of very considerable magnitude, it must be much higher in the succes- sion than the bed above the No. 9 Limestone, Randerstone. With Kirk (op cit., p. 369), the writer rejects Kirkby’s suggestion (1880, p. 136) that Kirk’s Marine Fossil Bed III (the Myalina Limestone of the Geological Survey) is equivalent to Kirkby’s No. 3 Limestone of the Randerstone shore section. The mode of occurrence of the shells in this bed near the Rock and Spindle is distinc- tive, in that a large number comprise both valves, agape but not disarticulated. Detailed work has shown that there is a reduction in size of shell (mean length) at the top of the shell bed before the final disappearance of Naiadites. Frequency polygons for H/L, DM/L, A/L, the angle y and the angle ^ show modal values closely comparable with those of collections of N. obesus. The modal value of H/L is low (c. 60 per cent.), and the anterior end is relatively long, as would be expected in a collection of small shells. Further, regression of the angle y on H/L, as well as the regression of the angle ^ on DM/L, show no appreciable difference from the corresponding regression in collections of N. obesus of normal size. It is concluded that this is an assemblage of N. obesus s.l. which is exceptional only in size; in the high percentage of articulated shells; and in the wide range of variation in shape of shell. Broadhurst (1959, p. 532) considers that in any assemblage the presence of a high percentage of shells which have not become disarticulated may be taken as evidence of freedom from turbulence and sorting, unless the ratio of articulated /disarticulated shells is due to a variation in the resistance of the hinge mechanism. Boucot (1953, p. 32) suggests that a single assemblage with a large percentage of articulated specimens, of a species with easily disarticulated shells, may represent a ‘life assemblage’. Histograms showing the distribution of length of shell in samples from the main part of the shell bed and the top inch, and their summation (text-fig. 5) provide evidence of the probability of a life assemblage. The histogram for the main sample has the character- istic right skew, indicative of a fife assemblage, but the sample from the top inch of the bed shows an irregular distribution of length of shell. Summing the two samples gives the typical ‘bell-shaped’ distribution curve, which is found in so many samples of fossil ‘populations’, which are aggregations or assemblages (see Craig loc. cit.). 3. A small form o/N. obesus from a bed above the No. 10 Limestone, Randerstone. Small N. obesus (mean L = 1 5 mm.) occurs in a 2-foot bed of dark shaly mudstone immediately above the No. 10 Limestone, Randerstone (text-fig. 1). N. obesus here chiefly comprises disarticulated flattened valves, intermediate in size between the smaller shells, discussed G. M. BENNISON: SMALL NAIADITES OBESUS 305 above, and the larger N. obesus, which commonly occurs in the Calciferous Sandstone Series of this area. In this bed, a decrease in size of the shells found near the top is associated with a decrease in numbers accompanied by a lithological change. Maximum observed size is, by itself, no criterion of dwarfing, and in a bed of shale TEXT-FIG. 5. Histograms showing distribution of the length of shells in two samples of N. obesus from a bed near the Rock and Spindle, Kinkell shore, St. Andrews, compared with a sample from a bed above the No. 9 Limestone, Randerstone. succeeding the No. 3 Limestone, Randerstone N. obesus attains its greatest size — the shells are somewhat larger than the topotype material from the Water of Leith (True- man and Weir 1956, p. 262); in other occurrences it shows some reduction in size. The term dwarfing, used conservatively — following Tasch (1953), who restricts it to forms in which there is evidence of failure to attain the normal size of adult shells, as a result of stunting due to adverse ecological conditions — can seldom be applied. Certainly, in the case of the small shells described in section 1, there is no evidence of such stunting. 306 PALAEONTOLOGY, VOLUME 4 The Other instances of small Naiadites, described in sections 2 and 3, are examples of either the failure of individuals to attain full size, although adult, or failure to reach the adult stage. If the former, we have true examples of dwarfing. The rather low values for H/L are inconclusive, but the distribution of length of shell points to an example of dwarfing in the bed near the Rock and Spindle. 4. The specific identity of the small Naiadites. Many of the small shells are similar TEXT-FIG. 6. Pictograph showing variation in the shape of shells of N. obesus s.l. from shaly mudstone above the No. 9 Limestone, Randerstone. (i) Excluding ‘dwarfed’ shells. to typical Naiadites obesus, although smaller, but Leitch (1942, p. 219) has raised the problem of their generic identity — as well as their specific identity — because of the presence of Anthraconaia-like variants. Leitch, for purposes of description, divides the dwarfed shells into two groups, while agreeing that simulants of Anthraconaia ‘ . . . can be intergraded to other members of the community which are more naiaditiform and can in turn be intergraded with Naiadites obesus’. Frequency polygons drawn for the ratios H/L, DM/L, and A/L, as well as for the angles y and /S, are all unimodal, establish- ing that variation is continuous from one extreme to the other. Having shown that separation of the small and the normal Naiadites is not arbitrary, it is now necessary to show that both are referable to the species N. obesus s.l. The re- gression of y on H/L, as well as the correlation between y and H/L, is similar in both cases, also pictographs (text-figs. 6 and 7) supplement the evidence of the graphs. In both G. M. BENNISON; SMALL NAIADITES OBESUS 307 cases, the figured intergrades are arranged into the series used by Leitch (op. cit., p. 212) so that close comparison can be made between the two collections, and the conclusion drawn that the small shells may also be referred to N. obesus s.l. Variation in N. obesiis from the bed above the No. 9 Limestone is illustrated by means of figured intergrades (text-fig. 6) and comparison with Leitch’s fig. 5 shows that variants representing most of his series of intergrades can be found. Similarly, variation in the small Naiadites from SERIES 5 SERIES 1 TEXT-FIG. 7. Pictograph showing variation in the shape of shells of N. obesus S.L from shaly mudstone above the No. 9 Limestone, Randerstone. (ii) ‘Dwarfed’ shells only. the same bed is illustrated by selected intergrades (text-fig. 7) arranged into identically defined series. The figured intergrades of text-figs. 6 and 7 are not identical, but are closely similar: the purpose of the pictographs is not to show that the collections of shells are indistinguishable, but to establish that the range of variation in shape of shell is closely comparable. Newell (1940, pp. 291, 294) has shown anterior musculature to be of some importance in the identification of genera of the Mytilacea. The writer has seen little evidence of the musculature of the small Naiadites, but Weir (1945, p. 319) describes the relatively large anterior adductor muscle observed in one specimen. Moulds do not commonly show muscle scars and it is probable that the muscles may not have been deeply inserted. The large size of the anterior adductor described by Weir, and the absence of a deep anterior muscle pit, are not typical of Naiadites, but do not preclude these shells from 308 PALAEONTOLOGY, VOLUME 4 reference to that genus. The position of the umbo is the most important single factor in the determination of genera of MyaUnidae. In Naiadites the sinuous carina (or um- bonal ridge) has a forward twist carrying the umbones towards the anterior end (thus distinguishing these shells from the small Curvirimula [Anthraconauta] which are known from the Calciferous Sandstone Series (see Weir 1945, p. 318; 1960, pp. 301, 314-20)) but the umbones are never terminal, except in a few shells which show clear signs of distortion due to crushing; on the contrary, the small Naiadites possesses an unusually long anterior end (the modal value is c. 16 per cent). In general, the anterior end of Naiadites is short — Trueman and Weir give a figure of 10-12 per cent, of the length; A/L commonly exceeds this figure in the case of N. obesus, as well as in these small specimens, and it seems probable that this early Naiadites may not have been derived from an ancestral form with an amphidetic ligament since, even at this early date (Visean, Stage B, Currie 1954), Myalina and Naiadites were clearly differentiated. Although N. obesus is referable to Naiadites as interpreted by Trueman and Weir, its relationship to later forms is not satisfactorily established. A long period elapsed between the demise of N. obesus and the appearance of Westphalian species, with only N. tumidus, the Namurian form, providing a link in time. It is not suggested that N. obesus provides evidence of the origin of the genus as a whole, and Newell (1942, p. 72) suggests that Westphalian Naiadites may have been derived from a more distinctly amphidetic Devonian form. Weir (1945, pp. 321 and 323) suggests that Naiadites of the obesus-tumidus group is probably not derived from Myalina, and the relatively long anterior end of N. obesus appears to preclude its secondarily redeveloped origin. N. obesus, in the early growth stages, is less asymmetrical than in the adult form : in spat of Naiadites generally, the umbones are almost central. During ontogeny there is a gradual change is the direction of maximum marginal increment, as shown by the tilted growth-lines, and this may reflect a change in the attitude of the shell to the byssus. The angular relationship between the shell axis (Jackson 1890, p. 509, footnote 3) and the presumed byssal axis has been studied in numbers of adult shells from assemblages of small N. obesus and normal N. obesus. An attempt to deduce from growth-lines the change in angular relationship during ontogeny has also been made (text-fig. 8). In assemblages of small N. obesus, where the modal value of H/L is rather low, the angle between the shell axis and the byssal axis ranges from 90° to 110°; Weir (1945, p. 319) deduces the range of variation from a re-examination of Leitch’s material. The study of additional material has not extended the known range of variation, but has confirmed Weir’s figures. In larger N. obesus the angle varies from something less than 100° to 120°, thus certainly overlapping the lower figure for N. tumidus given by Weir (loc. cit.). In young individuals the angle between the shell axis and the byssal axis is a right angle, and the ventral margin is parallel, or very nearly so, to the hinge-line. As growth proceeds, the angle gradually in- creases, but in ‘dwarfed’ shells the process is not continued as far as in large N. obesus. Also, the angle of obliquity in ‘dwarfed’ shells is less than in large N. obesus. The implication of these observations is that ‘dwarfed’ individuals are N. obesus in which development has been terminated prematurely — and so they are not truly dwarfed. The small Naiadites from the bed above the No. 9 Limestone, Randerstone, described in section 1, is referable to the species N. obesus s.I. Anthraeonaia-like variants are pre- sent though not numerous; this is true of all assemblages of N. obesus examined by the G. M. BENNISON: SMALL NAIADITES OBESUS 309 writer. The presence of Curvirimula [Anthraconauta pars.] cannot be confirmed. Only in distorted shells have terminal umbones been found. Evidence that the shells have been sorted and washed into the bed implies that they are not dwarfed, but comprise what Tasch (1953, p. 403) describes as a ‘pebble necrocoenosis’. The small shells, described in section 2 from the bed near the Rock and Spindle, com- prise N. obesus s.l. Here, it is exceptional only in the small size and high percentage of 2003 N. obQsus from bed near Rock and Spindle, Kinkell shore. 2201 N ot>9sus from bed O-3'O' above No. 9 Lst Randerstone 2225 N obesus from bed O - 3'0*’ above No 9 Lst Randerstone 2321 N obesus from bed 3'6"- 4‘0" above No.9 LSt , Randerstone 2003 2201 e:::> 2225 2321 f\ (Ax A /\ A /\ TEXT-FIG. 8. The relationship of byssal axis to shell axis in some specimens of Naiadites obesus s.l. articulated shells. A large number of shells (over ninety) were obtained; the range of variation in shape appears to be unusually great, a circumstance which may be in part attributable to the size of the sample. Variation is illustrated by pictograph (text-fig. 9), but since one of the shortcomings of Leitch’s figure (1942, p. 213, fig. 5) is that it in- cludes completely flattened as well as uncrushed tumid specimens, the series of figured intergrades are here redefined as follows : Series 1 (9 A, B, C) is characterized by shells with a high value for H/L, a low value for ^ and a rounded ventral margin. Series 2 (9 A, D) includes shells with a rather low value for H/L and with ^ a little over 90°. 310 PALAEONTOLOGY, VOLUME 4 Series 3 (9 A, E, F) includes shells with a high value for H/L, in which the anterior-ventral slope becomes nearly parallel to the posterior end. Series 4 (9 A, G) includes forms resembling Anthraconaia. Series 5 (9 A, H, I) includes sub-triangular shells with a low value for H/L. TEXT-FIG. 9. Pictograph showing variation in the shape of shells of N. obesiis s.l. from a bed near the Rock and Spindle, Kinkell shore, St. Andrews. Series 6 (9 A, J, K) includes shells with a high value for the angle /S. Series 7 (9 A, L, M) comprises highly carinate forms showing a tendency for the anterior-ventral slope to become nearly straight. The distribution of the assemblage relative to the figured intergrades is shown in the inset of text-fig. 9. The latter provides the best illustration of shape variation, excluding G. M. BENNISON: SMALL NAIADITES OBESUS 311 the grosser effects due to flattening, not merely in this particular assemblage, but in N. obesus s.l. 5. Lithological observations. A modification of a technique using bakelite cement, de- scribed by Legette (1928, pp. 551-7), was employed in making thin sections. The matrices of the shell beds which include N. obesus appear to contain little quartz, although high magnification reveals many virtually ultramicroscopic grains (less than 10 /x), and its presence in the fine fraction was confirmed by X-ray analysis. The sample from the top inch of the shell bed near the Rock and Spindle proved exceptional, revealing an increase in the coarseness of the silt to 25 /u,. It appears that, in this case, the decrease in size of shell can be related to a change in conditions of sedimentation, that stunting occurred as a result of adverse conditions — since there is no evidence of sorting — and that it is an example of a dwarfed fauna. Acknowledgements. The author is most grateful to Dr. J. Weir, who read the manuscript, for his advice and criticisms. REFERENCES BENNISON, G. M. 1959. Variation in communities of non-marine lamellibranchs from the Calciferous Sandstone Series (Lower Carboniferous) of Eastern Fife. Ph.D. Thesis, University of Aberdeen. 1960. Some Lower Carboniferous non-marine lamellibranchs from East Fife, Scotland. Palaeonto- logy, 3, ii, 137-52, pi. 25. BOUCOT, A. J. 1953. Life and death assemblages among fossils. Anier. Journ. Sci. 251, 25^0. BROADHURST, F. M. 1959. Antliiaconala piilchella sp. nov. and a study of palaeoecology in the Coal Measures of the Oldham area of Lancashire. Quart. Journ. Geol. Soc. 114, 523-45. CRAIG, G. Y. 1953. Discussion. Fossil communities and assemblages. Amer. Journ Sci. 25, 547-8. CURRIE, E. D. 1954. Scottish Carboniferous Goniatites. Trans. Roy. Soc. Eclin. 62. Pt. 2, 527-602. GEiKiE, A. 1902. The Geology of Eastern Fife. Mem. Geol. Surv. Scotland. JACKSON, R. T. 1890. Phylogeny of the Pelecypoda. The Aviculidae and their allies. Mem. Boston Soc. Nat. Hist. 4, 277-400. KIRK, s. R. 1925. The geology of the coast between Kinkell Ness and Kingask, Fifeshire. Trans. Edin. Geol. Soc. 11, 366-82. KiRKBY, J. w. 1880. On the zones of marine fossils in the Calciferous Sandstone Series of Fife. Quart. Journ. Geol. Soc. 36, 559-90. 1901. On Lower Carboniferous strata and fossils at Randerstone. near Crail, Fife. Trans. Edin. Geol. Soc. 8, 61-75. LEGETTE, M. 1928. The preparation of thin sections of friable rock. Journ. Geol. 36, 547-57. LEiTCH, D. 1942. Naiadites from the Lower Carboniferous of Scotland: a variation study. Trans. Geol. Soc. Glasgow, 20, 208-22. NEWELL, N. D. 1940. Palaeozoic Pelecypods: Mvalina and Naiadites. Amer. Journ. Sci. 238, Pt. 3, 286-95. 1942. Late Palaeozoic pelecypods: Mytilacea. State Geol. Surv. Kansas, 10, Pt. 2, 1-115. TASCH, p. 1953. Causes and palaeontological significance of dwarfed fossil marine invertebrates. Journ. Pal. 27, 356-444. TRUEMAN, A. E., and WEIR, J. 1955, 1956. The British Carboniferous non-marine Lamellibranchia. Pu/. Soc., London, Pt. 8, 207-42; Pt. 9, 243-70. Continued by J. Weir (1960), Pt. 10, 273-320. WEIR, J. 1945. A review of recent work on the Permian non-marine lamellibranchs and its bearing on the affinities of certain non-marine genera of the Upper Palaeozoic. Trans. Geol. Soc. Glasgow, 20, 291-340. 1960. See Trueman, A. E. and Weir, J. G. m. bennison Department of Geology, The University, Birmingham, 15. Manuscript received 12 September 1960 NOTE STRATIGRAPHICAL PALAEONTOLOGY OF THE LOWER GREENSAND: NOMENCL ATURAL CORRECTIONS by RAYMOND CASEY Two new names introduced in my recent paper on the stratigraphical palaeontology of the Lower Greensand (Casey 1961) have proved to be invalid and stand in need of replacement. (i) On p. 590 I proposed the patronymic Brightonia for a genus of Cretaceous gastro- pods. Mr. D. G. Stephenson of the Department of Geology, University of Reading, has drawn my attention to the fact that the name Brightonia is preoccupied, having been used by Kier (1957, p. 871) for a genus of echinoids. Brightonella is here proposed as a substitute name for Brightonia Casey 1961 non Kier 1957. (ii) On pp. 557-8 I have referred to a locality ‘Hopton Wood’, situated one-third of a mile south-west of the hamlet of Small Dole and a mile and a half north-east of Upper Beeding, Sussex. Elsewhere (ibid., pp. 557-60, table 1 on p. 497) I have applied the term ‘Hopton Wood Clay’ to an argillaceous development of the Lower Albian encountered in borings in that neighbourhood. It now appears that the word ‘Hopton’ is a mis-spelling of ‘Horton’. The correct name of the locality as given on the current 6-inch Ordnance Survey map (Sussex 52 NW/W) is Horton Wood and the stratum in question should therefore be called the Horton Wood Clay. This revised name removes any risk of confusion with the Hopton Wood Stone of the Carboniferous Limestone Series of Derbyshire. REFERENCES CASEY, R. 1961. The Stratigraphical palaeontology of the Lower Greensand. Palaeontology, 3, 4^1- 621, pi. 77-84. KIER, PORTER M. 1957. Tertiary Echinoidea from British Somaliland. /. /’n/co;;/. 31, 839-902, pi. 103-7. RAYMOND CASEY Geological Survey and Museum, London, S.W. 7. THE PALAEONT JLOGICAL ASSOCIATION COUNCIL 1961 President Professor O. M. B. Bulman, Sedgwick Museum, Cambridge Vice-Presidents Professor T. N. George, The University, Glasgow Professor W. F. Whittard, The University, Bristol Treasurer: Professor P, C. Sylvester-Bradley, Department of Geology, The University, Leicester Assistant Treasurer: Dr. T. D. Ford, Department of Geology, The University, Leicester Secretary: Dr. Gwyn Thomas, Department of Geology, Imperial College of Science, London, S.W. 7 Assistant Secretary: Dr. C. H. Holland, Department of Geology, Bedford College, London, N.W. 1 Editors Dr. W. H. C. Ramsbottom, Geological Survey Office, Ring Road Halton, Leeds, 15 Mr. N. F. Hughes, Sedgwick Museum, Cambridge Dr. W. S. McKerrow, University Museum, Oxford Other members of Council Dr. D. V. Ager, Imperial College of Science, London Dr. F. T. Banner, British Petroleum Company, Sunbury on Thames Dr. A. J. Charig, British Musemn (Natural History), London Dr. L. R. Cox, British Museum (Natural History), London Dr. R. H. Cummings, The University, Glasgow Dr. R. Goldring, The University, Reading Dr. J. C. Harper, The University, Liverpool Professor F. Hodson, The University, Southampton Dr. M. R. House, The University, Durham Dr. R. G. S. Hudson, Trinity College, Dublin Dr. J. W. Neale, The University, Hull Dr. Dorothy H. Rayner, The University, Leeds Mr. J. D. D. Smith, Geological Survey and Museum, London Dr. C. D. Waterston, Royal Scottish Museum, Edinburgh Overseas Representatives Australia: Professor Dorothy Hill, Department of Geology, University of Queensland, Brisbane, Queensland Canada: Dr. D. J. McLaren, Geological Survey of Canada, Department of Mines and Technical Services, Ottawa New Zealand: Dr. C. A. Fleming, New Zealand Geological Survey, P.O. Box 368, Lower Hutt West Indies and Central America : Dr. L. J. Chubb, Geological Survey Department, Kingston, Jamaica Eastern U.S.A.: Professor H. B. WHimNOTON, Museum of Comparative Zoology, Harvard Uni- versity, Cambridge 38, Mass. Western U.S.A.: Dr. J. Wyatt Durham, Department of Paleontology, University of California, Berkeley 4, Calif. PALAEONTOLOGY VOLUME 4 • PART 2 CONTENTS The origin of the loop in articulate brachiopods. By a.williams and a.d.wright 149 Upper Llandeilo brachiopods from the Berwyn Hills, North Wales. By a. r. MACGREGOR 177 Some additions to our knowledge of antiarchs. By d. m. s, watson 210 Type specimens of the genus Fenestella from the Lower Carboniferous of Great Britain. By t. g. miller 221 Dentition and relationships of the echinoid genus Pygaster J. L. R. Agassiz, 1836. By R. V. melville 243 Namurian plant spores from the southern Pennines, England. By r. neves 247 Slimoniphyllum, a new genus of Lower Carboniferous coral from Britain. By m. kato and m. mitchell 280 Further interpretation of Eucommiidites Erdtman 1948. By N. F. hughes 292 Small Naiadites obesus from the Calciferous Sandstone Series (Lower Car- boniferous) of Fife. By g. m. bennison 300 Note. Stratigraphical palaeontology of the Lower Greensand ; nomenclatural corrections. By r. casey 312 PRINTED IN GREAT BRITAIN AT THE UNIVERSITY PRESS, OXFORD BY VIVIAN RIDLER, PRINTER TO THE UNIVERSITY * I k »: