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III LlJ XCSTlr77>v tu o z o z o Z _J z VIITHSONIAN INSTITUTION NOlifUliSNI NVINOSHXmS SBiavaail LIBRARIES SMITHSONIAN l^ z z_!z — I :: / ^ /JT/I > .•?/ Zl m pc^ ^ X^oiSgV' rn xoms^x m ^ m to _ to^. _ to — to viNOSHiiy^s S3 1 a va an libraries smithsonian institution NoiiniiisNi nvinoshiiins s W z .... to z .V,. ^ ^ ^ ^ ^ v^vt E E .-2 i5x - g F - ■— — - S? 8 '^£m S > 2 '* > XOjIX'igX 2 ” — -, Z to »Z <0 *^ 2 tO ^ VIITHSONIAN INSTITUTION NOlifUliSNI NVINOSHilWS S3iavaail LIBRARIES SMITHSONIAN _ H to — to — to 2 aviTv^TX ^ tu fn tiJ ^ CO O pc>^ _ X^ociisgx o '' — O O VIN0SHiHNS^S3 I ava9ll**'LIBRARI ES^SMITHSONIAN~’lNSTiTUTION^NOIiniliSNI NVINOSHillNS S \, Z r- Z I” Z [I ^ f*i r\ ~ >v \v t_> n 3>- to — to MITHSONIAN INSTITUTION NOIiOiliSNI NVINOSHilWS S3iavaail LI B RAR I ES SMITHSONIAN If Z - to Z CO Z > 5 S -. ^ v% . =5 /4kwi^ 0 ^ \v to , . 0/ nZ ^ 1 | /^ g ' i I to • .*^' CO Z! to ^ to viNOSHiiiNS S3 1 a va an libraries smithsonian institution NoiiniiiSNi_NvmosHims s to — to = to _ fo IMITHSONIAN INSTITUTION NOlifliliSNI NVlNOSHillMS S3IHVaan LIBRARIES SMITHSONIAN I m ^ m to m ^ to to _ \ ^ to — to iviNOSHiiws S3 lava an libraries smithsonian institution NOiiniiiSNi NviNOSHims s Vi'Nv’i I i W THE PALAEONTOLOGICAL ASSOCIATION The Association publishes Palaeontology and Special Papers in Palaeontology. Details of member- ship and subscription rates may be found inside the back cover. PALAEONTOLOGY The journal Palaeontology is devoted to the publication of papers on all aspects of palaeontology. Review articles are particularly welcome, and short papers can often be published rapidly. A high standard of illustration is a feature of the journal. Four parts are published each year and are sent free to all members of the Association. SPECIAL PAPERS IN PALAEONTOLOGY This is a series of substantial separate works. Members may subscribe to the Series; alternatively. Ordinary and Student members only may obtain individual copies at reduced rates. The following Special Papers are available : 1. (for 1967): Miospores in the Coal Seams of the Carboniferous of Great Britain, by a. h. v. smith and M. A. BUTTERWORTH. 324 pp., 72 te.xt-figs., 27 plates. Price £8 (U.S. $22.00), post free. 2. (for 1968): Evolution of the Shell Structure of Articulate Brachiopods. by a. williams. 55 pp., 27 text- figs., 24 plates. Price £5 (U.S. $13.00). 3. (for 1968): lipper Maestrichtian Radiolaria of California, hv HELEN P. foreman. 82 pp., 8 plates. Price £3 (U.S. $8.00). 4. (for 1969): Lower Turonian Ammonites from Israel, by R. freund and M. raab. 83 pp., 15 text-figs., 10 plates. Price £3 (U.S. $8.00). 5. (for 1969): Chitinozoa from the Ordovician Viola and Fernvale Limestones of the Arbuckle Moun- tains, Oklahoma, by w. a. m. jenkins. 44 pp., 10 text-figs., 9 plates. Price £2 (U.S. $5.00). 6. (for 1969): Ammonoidea from the Mata Series (Santonian-Maastrichtian) of New Zealand, by R. A. HENDERSON. 82 pp., 13 text-figs., 15 plates. Price £3 (U.S. $8.00). 7. (for 1970): Shell Structure of the Craniacea and other Calcareous Inarticulate Brachiopoda, by A. WILLIAMS and A. D. WRIGHT. 51 pp., 17 text-figs., 15 plates. Price £1-50 (U.S. $4.00). 8. (for 1970): Cenomanian Ammonites from Southern England, by w. j. Kennedy. 272 pp., 5 tables, 64 plates. Price £8 (U.S. $22.00). 9. (for 1971): Fish from the Freshwater Lower Cretaceous of Victoria, Australia, with Comments on the Palaeo-environment, by m. waldman. 130 pp., 37 text-figs., 18 plates. Price £5 (U.S. $13.00). 10. (for 1971 ) : Upper Cretaceous Ostracoda from the Carnarvon Basin, Western Australia, by r. h. bate. 148 pp., 43 text-figs., 27 plates. Price £5 (U.S. $13.00). 11. (for 1972): Stromatolites and the Biostratigraphy of the Australian Precambrian and Cambrian, by M. R. WALTER. 268 pp., 55 text-figs., 34 plates. Price £10 (U.S. $26.00). 12. (for 1973): Organisms and Continents through Time. A Symposium Volume of 23 papers edited by N. F. HUGHES. 340 pp., 132 text-figs. Price £10 (U.S. $26.00) (published with the Systematics Asso- ciation). 13. (for 1974): Graptolite studies in honour of O. M. B. Bulman. Edited by R. b. rickards, d. e. jackson, and c. p. HUGHES. 261 pp., 26 plates. Price £10 (U.S. $26.00). 14. (for 1974): Palaeogene foraminiferida and palaeoecology, Hampshire and Paris Basins and the English Channel, bv J. w. Murray and c. a. wright. 171 pp., 45 text-figs., 20 plates. Price £8 (U.S. $22.00). 15. (for 1975): Lower and Middle Devonian Conodonts from the Broken River Embayment, North Queensland, Australia, by p. g. telford. 100 pp., 9 text-figs., 16 plates. Price £5-50 (U.S. $15.00). 16. (for 1975): The Ostracod Fauna from the Santonian Chalk (Upper Cretaceous) of Gingin, Western Australia, by J. w. neale. 131 pp., 40 text-figs. Price £6-50 (U.S. $17.00). SUBMISSION OF PAPERS Typescripts on all aspects of palaeontology and stratigrapliical palaeontology are invited. They should conform in style to those already published in this journal, and should be sent to The Secretary, P.A. Publications Committee, Department of Geology, Sedgwick Museum, Downing Street, Cambridge, CB2 3EQ, England, who will supply detailed instructions for authors on request (these are published in Palaeontology, 15, pp. 676-681). Q) The Palaeontological Association, 1975 Cover: Marrolitlnis favus (Salter). Reconstruction of Ordovician trinucicid trilobitc, prepared by Dr. J. K. Ingham as the symbol for the Symposium on the Ordovician System, Birmingham, lt)74. Based on silicified material collected by Dr. R. Addison from limestones of Upper Llandcilo age from Wales. PALAEOECOLOGY OF A BITUMINOUS SHALE- THE LOWER OXFORD CLAY OF CENTRAL ENGLAND by K. L. DUFF Abstract. Quantitative palaeoecological studies, using triangular plots, rarefaction curves, trophic nuclei, trophic group composition, and Diversity Index, have allowed the definition of ten different biofacies within the Lower Oxford Clay (Upper Jurassic, Middle Callovian) of central England. Analysis of the distribution of these biofacies and seven lithofacies groups, has led to the recognition of the Lower Oxford Clay as a deepening-water sequence, in which two distinct environmental cycles are present. By comparison with other Mesozoic shale facies, the Lower Oxford Clay appears different in having its fauna dominated by infaunal deposit-feeders and by high-level (‘pendent’) epifaunal suspension-feeders; only the Upper Lias is comparable. Evolutionary changes are considered between Palaeozoic and Mesozoic deposit-feeder dominated assemblages, with siphonate bivalves occupying most of the niches previously held by articulate brachiopods. Palaeoecological studies on clay sequences are of great importance in building up an understanding of Mesozoic environmental conditions. Most thick clay sequences seem homogeneous, but close inspection reveals many lithological and faunal varia- tions capable of analysis. This is especially true of bituminous shale sequences, which until the work of Hallam (1960, p. 10), were usually thought of as homogeneous. Hallam showed that in the Blue Lias several lithologies, each with a characteristic fauna, could be recognized; only some lacked benthonic fossils, which had previously been considered a typical feature of bituminous shales. Since then other studies have been made on similar rock sequences, and it is the purpose of this paper to show the high variability, both in lithology and fauna, that exists within the Lower Oxford Clay. STRATIGRAPHY The Callovian deposits of England represent a transgressive marine phase after the lagoonal and estuarine conditions of the Bathonian, the base of the transgression being marked by the Upper Cornbrash, which passes upwards into the Kellaways Clay and Kellaways Rock. After the deposition of the Kellaways Rock, conditions appear to have stabilized, with deposition of a thick argillaceous sequence of bitu- minous shales, shaly clays, and more calcareous clays. The Yorkshire succession (text-fig. 1) differs in that it is developed in a more marginal facies, and has been well described by Wright (1968, p. 367): in this paper only the clay facies will be con- sidered in detail. The Lower Oxford Clay has been defined by Callomon (1968, p. 265), and occupies the whole of the Middle Callovian together with the top subzone of the Lower Callovian and the lower part of the Upper Callovian (text-fig. 2). It eonsists of about 16-25 m of grey bituminous shaly clays with other minor lithologies developed within them (text-fig. 3). The biostratigraphy is further described else- where (Duff, unpublished Ph.D. thesis, Leicester University, 1974). The Lower Oxford Clay is of great importance for brickmaking, and is extensively quarried [Palaeontology, Vol. 18, Part 3, 1975, pp. 443-482.] 444 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 1 . Comparison of the lower part of the Upper Jurassic of Yorkshire and southern England, showing the development of a marginal facies in Yorkshire during Callovian times. After Wright (1968). All zones drawn to equal thickness, therefore the lithological sections are not to scale. between Peterborough and Aylesbury. Higher parts of the Oxford Clay are more plastic, less bituminous, and not so easily used for brickmaking; consequently exposures are rarer. The zonal divisions (text-fig. 2) have been considered by Callomon (1955, p. 254, 1964, 1968, p. 265), and are now widely accepted. Previous workers on the Oxford Clay have dealt mainly with the general stratigraphy of the formation, and paid scant attention to the Lower Oxford Clay itself (Woodward 1 895, p. 5 ; Morley Davies 1916; Neaverson 1925; Arkell 1933, p. 341), although Brinkmann (1929, p. 28) and Callomon (1955, 1968) have dealt with that part of the formation in considerable detail. The only palaeoecological studies have been by Rutten (1956) and Hudson and Palframan (1969). DUFF: OXFORD CLAY PALAEOECOLOG Y 445 STAGES ZONES SUBZONE DIVISION C. cordatum z < Cardioceras cordatum C. costicardia UPPER o QC CC tu C. bukowskii OXFORD O u. O u Quenstedtoceras C. praecordatum CLAY X o mariae C. scarburgense oc Quenstedtoceras lamberti MIDDLE Q. a D Peitoceras athleta Upper Middle OXFORD CLAY Lower K. (Zugokosmoceras) Erymnoceras grossouvrei coronatum K. (Zugokosmoceras) LOWER LU obductum z O o K. (Gulielmites) OXFORD < s Kosmoceras jason > jason K. (Gulielmites) CLAY o _I medea S. (Catasigaloceras) o enodatum GC Sigaloceras calloviense Sigaloceras calloviense KELLAWAYS LU $ Proplanulites ROCK o koenigi Macrocephalites M. (Kamptokephalites) kamptus KELLAWAYS CLAY macrocephalus M. (Macrocephalites) UPPER macrocephalus CORNBRASH TEXT-FIG. 2. The zonal sequence of the Callovian and Lower Oxfordian stages of NW. Europe. After Callomon (1968). NATURE OE THE FAUNA The composition of the Lower Oxford Clay fauna has been considered elsewhere (Callomon 1968, p. 269); molluscs are very dominant, mostly cephalopods and bivalves. Other common macrofauna include gastropods, scaphopods, brachiopods, Crustacea, annelids, and occasional echinoderms ; a diverse and well-preserved verte- brate fauna has been described by several authors (Arkell 1933, p. 357). A faunal list of the macro-invertebrates is as follows: POLYCHAETA CEPHALOPODA Genicularia vertebralis (J. de C. Sowerby) "Binatisphinctes' comptoni (Pratt) Serpula sp. 'B.' fluctuosus (Pratt) 446 PALAEONTOLOGY, VOLUME 18 CEPHALOPODA {COnt.) ‘fi.’ spp. Chojfatia spp. Erymnoceras spp. Hecticoceras spp. Kosmoceras (Gulielmiceras) gulielmi (J. Sowerby) K. (Kosmoceras) baylei Tintant K. (K.) grossouvrei Douville K. (K.) nodosum Callomon K. (Spinikosmoceras) aculeatum (Eichwald) K. (Sp.) acutistriatum Buckman K. (Sp.) castor (Reinecke) K. (Sp.) pollux (Reinecke) K. (Zugokosmoceras) enodatum (Nikitin) K. (Z.) Jason (Reinecke) K. (Z.) medea Callomon K. (Z.) obductum (Buckman) K. (Z.) zugium (Buckman) Pseudocadoceras spp. Reineckeia spp. Sigaloceras calloviense (J. Sowerby) Belemnopsis sulcata (Miller) Belemnoteuthis antiquus Pearce Cylindroteuthis puzosianus (d’Orbigny) BIVALVIA Anisocardia (Anisocardia) tenera (J. de C. Sowerby) Bositra buchii (Roemer) "Entolium' sp. nov. Camptonectes (Camptonectes) auritus (Schlotheim) Chlamys (Cblamys) sp. nov. C. (Radulopecten) fibrosa (J. Sowerby) C. (R.) scarburgensis (Young and Bird) Corbulomima macneillii (Morris) Discomiltha lirata (Phillips) Entolium (Entolium) corneolum (Young and Bird) Grammatodon (Grammatodon) clathrata (Leckenby) G. (G.) concinna (Phillips) G. (G.) minima (Leckenby) G. (G.) montaneyensis (de Loriol) Gryphaea (Bilobissa) sp. nov. Isocyprina (Isocyprina) roederi Arkell MeleagrineUa braamburiensis (Phillips) Mesosaccella morrisi (Desha yes) Modiolus (Modiolus) bipartitus J. Sowerby Myophorella (Myophorella) irregularis (Seebach) Nanogyra nana (J. Sowerby) Neocrassina (Neocrassina) sp. nov. N. (N.) ungulata (Lycett) Nuculoma sp. nov. N. pollux (Raspail ex d’Orbigny) Oxytoma (Oxytoma) inequivalvis (J. Sowerby) Palaeonucula cottaldi (de Loriol) Palaeonucula sp. nov. Parainoceramus subtilis (Lahusen) Pinna (Pinna) mitis Phillips Plicatula (Plicatula) cf. fistulosa Morris and Lycett Pleuromya alduini (Brongniart) P. uniformis (J. Sowerby) Protocardia (Protocardia) striatulum (J. de C. Sowerby) Protocardia sp. Pteroperna? pygmaea (Dunker) Rollierella minima (J. Sowerby) Solemya woodwardiana Leckenby Thracia (Thracia) depressa (J. de C. Sowerby) Trautscholdia phillis (d’Orbigny) GASTROPODA Dicroloma bispinosa (Phillips) D. trifida (Phillips) Pleurotomaria reticulata (J. Sowerby) ' Procerithium' damonis (Lycett) Spinigera spinosa d’Orbigny SCAPHOPODA Prodentalium calvertensis Palmer BRACHIOPODA Lingula craneae Davidson 'Orbiculoidea' sp. ' Rhynchonella' sp. CRUSTACEA Mecocheirus pearcei M’Coy ECHINODERMATA Unidentified ophiuroids The microfauna is more restricted than that of the Middle and Upper Oxford Clays, the foraminifera having been studied by Cordey (1962, 1963) and Barnard (1952, 1953), the ostracodes by Whatley (1970), and the coccoliths by Rood, Hay and Barnard (1971) and Rood and Barnard (1972). Apparently, the darker, more organic rich shaly clays of the Middle Callovian were less conducive to the development of a diverse benthonic microfauna than were the more calcareous clays of the Upper Callovian-Lower Oxfordian. This paper is based on detailed studies made on the Lower Oxford Clay in 1970- DUFF: OXFORD CLAY PALAEOECOLOG Y 447 1971 at four brickpits in central England (text-fig. 4), collections coming from beds of Calloviense-Coronatum Zone age. The beds are well exposed in continuously accessible profiles, and are clearly marked off at the base by the sandy Kellaways Rock, and at the top by a concretionary limestone bed, the Acutistriatum Band (text- fig. 3); this marker horizon was shown by Callomon (1968, p. 272) to be the basal bed of the Athleta Zone. The palaeoautecology of the bivalves is summarized in Table 1. TABLE 1. Life habits of the bivalve genera recognized in the Lower Oxford Clay of southern England. Epifaunal Infaunal Genera and feeding Taxonomic groups *u CL) ■c •D X _ o o Vi c c (J Maximum s length (mm Swimming Free-living > cemented Vi Vi CQ ‘Pendent’ o -c: .9r '55 C O Z o O s: c/5 o .9" C o h-J -D 2 CO 72 U s Vi Vi ffl Mobile Deposit-feeders Superfamily Palaeonucula 18-4 X NUCULACEA Mesosaccella 17-6 X NUCULANACEA Suspension-feeders Solemya 380 X SOLEMYACEA Grammatodon 28-0 X X ARCACEA Modiolus 700 X MYTILACEA Pinna 82-4 X PINNACEA Pteroperna 15-3 X PTERIACEA Parainoceramus 72-5 X PTERIACEA Bositra 15-0 X PECTINACEA Oxytoma 39-8 X PECTINACEA Meleagrinella 33'7 X PECTINACEA Entolium 310 X PECTINACEA 'Entolium' gen. nov. 12-3 X PECTINACEA Camptonectes 580 X PECTINACEA Chlamvs 9-7 X PECTINACEA Radulopecten 760 X PECTINACEA Plicatula 26-8 X PECTINACEA Gryphaea 800 X OSTREACEA Nanogyra 11-2 X OSTREACEA Myophorella 880 X X TRIGONACEA Discomiltha 47-0 X X LUCINACEA Neocrassina 21-2 X X ASTARTACEA Trautscholdia 12-5 X X ASTARTACEA Protocardia 30-3 X X CARDIACEA Anisocardia 25-0 X X ARCTICACEA Isocyprina 20-0 X X ARCTICACEA Rollierella 24-0 X X ARCTICACEA Corbulomima 6-8 X X MYACEA Pleuromya 71-0 X PHOLADOMYACEA Thracia 650 X X PANDORACEA 448 PALAEONTOLOGY, VOLUME 18 •3 I/I (T LiJ > Z 8S to CD ^ 3 O to cc o tri to o O N to CD < Z| Q IS] I Ltl ffl , 2 3I (/) I TEXT-FIG. 3. Lithological sections measured at the four quarries examined in central England. DUFF: OXFORD CLAY PALAEOECOLOG Y 449 The life habits of the benthonic invertebrates other than bivalves which occur in the Lower Oxford Clay are as follows : Suspension-feeders : Genicularia vertehralis (epifaunal), Serpula sp. (epifaunal), "Orbiculoidea sp. (epifaunal), 'Rhynchonella sp. (epifaunal), Lingula craneae (infaunal). Deposit-feeders: Procerithium damonis (epifaunal), Dicroloma bispinosa (infaunal), Dicroloma trifida (infaunal), Spinigera spinosa (infaunal), Prodentalium calvertensis (infaunal). Scavengers: Mecocheirus pearcei, ophiuroids. Browsing herbivores: Pleurotomaria reticulata. The methods of analysis used here are a combination of those introduced by both zoologists and palaeontologists, and have not previously been applied to Mesozoic clay deposits. Thus there is a lack of comparative data, and the Lower Oxford Clay has been compared only qualitatively with other Mesozoic sediments, especially clays. TEXT-FIG. 4. The outcrop of the Oxford Clay in Britain, showing the location of the major sections examined. Preservation. The Lower Oxford Clay is notable for the preservation of original shell aragonite in the shales, especially in the bituminous shales; a feature caused by the impervious nature of the sediment (Hudson and Palframan 1969, p. 398). However, most of the material is crushed. 450 PALAEONTOLOGY, VOLUME 18 In some of the more porous lithologies, notably the shell beds, there has been replacement of the original aragonite by secondary calcite, precipitated from cal- careous fluids moving through the rock, or by recrystallization of shell material in situ. A more notable post-depositional preservational change has been the growth of pyrite in many of the shell beds, and in local pockets within the shales. It appears that the porous shell beds have acted as ‘aquifers’ along which sulphide-rich fluids moved, and that when the pyrite was precipitated it became concentrated in the central parts of the shell beds. This is particularly noticeable in many of the Nuculacean shell beds, where the central part of the shell bed is strongly pyritized, with pyritiza- tion decreasing towards the margins. Many pyritized shells have had the shell material replaced by pyrite, rather than having had pyrite grow outward from the shell surface. Within the bituminous shales, many shells have developed pyrite overgrowths. The pyrite is usually rather patchily developed and often seems to be concentrated on aragonitic shells such as Thracia, Pinna, and Palaeonucula where it occurs as small patches on the shell surfaces. Hudson and Palframan (1969, p. 404) describe a com- parable situation in the Middle and Upper Oxford Clay of Woodham, Bucks., where pyrite is patchily developed on the surfaces of bivalves preserved as clay moulds. They attribute the pyrite formation to local sulphate reduction by bacteria acting on the organic matrix of the dissolving shell. It is possible that the patchy pyrite developed on aragonitic shells in the Lower Oxford Clay formed in a similar manner, although the aragonite has not totally disappeared. Another characteristic feature of the Lower Oxford Clay is the presence of con- cretionary limestones at certain levels (text-fig. 3). Dr. J. D. Hudson informs me of the existence of two phases of concretion development, one pre-compaction and the other post-compaction, each with distinctive carbon and oxygen isotopic com- positions. The early pre-compaction concretions are septarian, and are found within the various Lower Oxford Clay bituminous shales and shell beds (text-fig. 3); they contain uncrushed fossils preserved in partially dissolved aragonite or secondary calcite. The later, post-compaction concretions occur as lenticular limestones within the Acutistriatum Band (text-fig. 3), and contain crushed fossils, usually preserved in secondary calcite. Both limestones are of diagenetic origin, and contain the same fauna as the enveloping shales. Methods of analysis. At the four pits studied (text-fig. 4), the Lower Oxford Clay is up to 18 m thick, and worked in large open-cast pits by means of draglines, giving sloping faces for collections on which a continuous profile may also be measured. As the sections were measured, detailed counts were made of all the fossils found in each bed, collections being made over a horizontal distance of up to 2 m, and con- tinuing until no new species appeared in the sample. In practice, collection ceased after about 2000 specimens had been counted, and when all the dominant species had appeared. In the case of beds over 50 cm thick, each 50 cm was then considered as a separate sample; this gave a method for evaluating the faunal similarity of dif- ferent parts of the thicker units. In addition to these field counts (usually conducted on up to 2000 specimens), blocks from each sampled bed were taken back to the laboratory and broken up under more controlled conditions to check the accuracy of the field counts. While this sometimes revealed the presence of one or two DUFF: OXFORD CLAY PALAEOECOLOGY 451 TEXT-FIG. 5. Distribution of the ten biofacies at each of the four Midlands quarries. 452 PALAEONTOLOGY, VOLUME 18 additional species (in small quantities), in most cases it merely confirmed the field counts, and so the analysis presented here is based on the field data only. Analyses of the organic carbon and insoluble residue percentages of the samples are shown in Tables 2 and 3. The organic carbon content was determined volumetric- ally, the clay samples being treated with a solution of potassium chromate in phos- phoric acid, and gives a measure of the amount of detrital organic matter available TABLE 2. Organic carbon contents measured in the various Lower Oxford Clay biofacies. Biofacies N Max Min Mean Silts and silty clays 1 10 10 10 Deposit-feeder bituminous shales 10 3-5 2-1 2-9 Gramniatodon-rich bituminous shales 2 61 3-4 4-8 Foram-rich bituminous shales 3 4-9 3-5 41 Nuculacean shell beds 1 1-8 1-8 1-8 Gryphaea shell beds 1 L7 1-7 L7 Meleagrinella shell beds 4 3-8 2-3 2-9 Calcareous clays 1 M 11 11 N = number of samples; Max = maximum observed value; Min = minimum observed value, for collection by feeding organisms. The insoluble residue determinations give a measure of the amount of lime present in the sediment, either as cement or as original particles of shell or other carbonate. Organic carbon contents of over 3% in Recent mud deposits have been shown by Bader (1954, p. 40) to cause a diminution in bivalve diversity, with infaunal deposit-feeding protobranchs becoming dominant. The organic carbon contents of many of the Lower Oxford Clay samples (Table 2) show that they belong to this type of lithology, with an impoverished benthonic fauna. The degree of correlation between the organic carbon contents of Recent muds and fossil shales is uncertain, and it is not possible to tell whether or not the values obtained from compacted rocks are true reflections of the primary organic carbon content. Comparison of Bader’s values with those from the Lower Oxford Clay suggests that in some cases, they are. Most of the analysis was carried out on the benthonic fauna only, with the nektonic elements (such as the cephalopods) removed from consideration. However, before the nektonic elements were deducted, the relative percentages of nektonic predators and scavengers were calculated; in the bituminous shales they constitute 10-15% of the fauna. Having removed the nektonic elements, the data for the remaining benthos were recalculated to give percentages of epifaunal suspension, infaunal suspension, and deposit-feeders only. The reasons for using feeding groups were discussed by Rhoads ct a/. ( 1 972, p. 1 1 00), who suggested that it is sedimentary and hydrographical conditions which most closely control the distribution of bivalves, with sediment grain-size and texture, bottom turbidity, and food availability all being of importance in determining the spatial distribution of suspension and deposit-feeding bivalves. The status and mode of life of bivalve feeding groups in general have been studied by Stanley (1970). The ecological positions of the various bivalve genera are shown in Table 1. The data for the bivalves was then further subdivided, because of the high pro- portion of epifaunal suspension-feeders such as Bositra, Oxytoma, Meleagrinello, Parainoceranms, and Pteroperna in some beds. It seems very likely that these genera DUFF: OXFORD CLAY PALAEOECOLOG Y 453 were not strictly benthonic, but lived byssally attached to organic matter at some distance above the sea floor, as there appears to be a lack of suitable benthonic attach- ment areas, and the genera show a tendency to occur in clusters. It is suggested that they were attached to algal fronds, probably not cemented to the sea floor, and which could be moved by currents; attachment to floating driftwood is also likely, as this material is characteristic of the bituminous shales, and is often associated with clusters of Parainoceramus and Meleagrinella. There is also the possibility that Bositra was pseudo-planktonic (Jefiferies and Minton 1965). This group of genera is grouped together as ‘pendent’ epifaunal suspension-feeders, and as they tend to be rather abundant in the bituminous shales, thereby obscuring the relative importance of the more strictly benthonic elements, the bivalve percentages were recalculated to omit them. Consideration of the whole bivalve assemblage then shows the over-all faunal composition of a bed, the relative abundance of the strictly benthonic species being seen after the removal of the pendent species. The abundance of driftwood, frequently in large pieces, suggests that the bituminous shales were probably laid down fairly near shore, in a quiet-water environment, and where a large amount of suspended organic particles provided a rich food source for high-level suspension- feeders. BIOFACIES ANALYSIS Ten biofacies have been recognized within the Lower Oxford Clay of the Midlands, the major lithofacies groupings being subdivided by faunal content; the data are summarized in Table 3, while text-fig. 5 shows the distribution of each of these facies at the major pits. The data were then analysed in five ways to give a synthesis of the palaeoecology, the plots used being (a) triangular plots, (h) rarefaction curves, (c) trophic nuclei, (d) trophic group composition, (e) Diversity Index. The triangular diagrams are based on bivalve feeding groups, the corners of the triangles representing 100% epifaunal suspension-feeders (ES), 100% infaunal suspension-feeders (IS), and 100% infaunal deposit-feeders (ID). Each sample has both the total bivalve fauna and the over-all benthonic fauna (excluding pendent genera) divided into these three groups, and may then be represented on the diagram by a single point. It can be seen from text-figs. 6 and 7 that each biofacies yields a group of points, all falling within a certain field of the triangle, with varying degrees of overlap. The rarefaction curve method was conceived by Sanders (1968) as a means of comparing the diversities of different samples of benthonic organisms. He showed that most diversity measurements were affected by sample size, as individuals are added to a population at an arithmetic rate, while species are added at a decreasing logarithmic rate. The rarefaction method depends on the shape of the species abundance curve rather than the absolute number of specimens in a sample, and has the advantage that each sample generates a curve. The method of calculating and plotting rarefaction curves is described by Sanders (1968, p. 245). Each aquatic environment was shown by Sanders to have its own characteristic rate of species increment, with its rarefaction curves lying in a particular field. The curves generated by the various Lower Oxford Clay biofacies (text-fig. 8) agree closely with those 454 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 6. Triangular plots of bivalve feeding groups (ID, infaunal deposit; ES, epifaunal sus- pension; IS, infaunal suspension) for three of the biofacies, a, silts and silty clays, all bivalves; b, silts and silty clays, pendent bivalves removed ; c, deposit- feeder bituminous shales, all bivalves; d, deposit- feeder bituminous shales, pendent bivalves removed ; e, Grammatodon-nch bituminous shales, all bivalves ; /, Grammatodon-r'ich bituminous shales, pendent bivalves removed. TEXT-FIG. 7. Triangular plots of bivalve feeding groups for the remaining biofacies, a, foraminifera- rich bituminous shales, all bivalves; /), Meleagrinella shell beds, all bivalves (a); blocky claystone, all bivalves (b); c, shell beds (apart from Meleagrinella shell bed), all bivalves; Gryphaea shell beds (a), Nuculacean shell beds (b), Grammatodon-nch. shell beds (c); d, shell beds (apart from Meleagrinella bed), pendent bivalves removed; Gryphaea shell beds (a), Nuculacean shell beds (b), Grammatodon shell beds (c); e, calcareous clays, all bivalves; /, calcareous clays, pendent bivalves removed. generated by Recent Boreal shallow-water samples, and Hallam (1969, p. 1 1) placed England in his Boreal Province during Callovian times. However, the Boreal Province of the Jurassic is not necessarily equivalent to the Recent Boreal area. The trophic nucleus of an assemblage or community is defined as the numerically dominant species which make up 80% of the fauna (Neyman 1967, p. 151). Analysis of the trophic nucleus helps clarify the relationships between the various members of the assemblage, notably in the relative abundance of the species, and the importance of deposit-feeders. The trophic nucleus of most communities consists of up to five species, although in some tropical marine environments high specific diversity DUFF: OXFORD CLAY PAL AEOECOLOGY 455 TABLE 3. A summary of the main faunal and lithological characteristics of the ten Lower Oxford Clay biofacies. Biofacies Lithology Dominant faunal elements Organic Insoluble carbon 7o residue % Silts and silty clays Silts and silty clays Cephalopods, Pinna, Protocardia, Trautscholdia, Corbulomima, Meleagrinella 10 93 Deposit-feeder bituminous shales Dark olive-green shaly clays Pendent epifaunal suspension- feeders (Bositra, Meleagrinella, and Oxytoma), together with Palaeonucula and Mesosaccella 2-9 90 Grammatodon-rkh bituminous shales Dark olive-green shaly clays Bositra, Oxytoma, Meleagrinella, Palaeonucula, Mesosaccella, together with infaunal suspension-feeders such as Grammatodon, Thracia, and Isocyprina 4-8 90 Foram-rich bituminous shales Light green, rather fissile, shaly clays Bositra, Parainoceramus, Mesosaccella, Corbulomima, Prodentalium, foraminifers (Brotzenia) 41 87 Nuculacean shell beds Shell concentrate Palaeonucula, Mesosaccella 1-8 79 Grammatodon-rkh shell beds Shell concentrate in clay matrix Grammatodon, Isocyprina, oysters, Oxytoma, Discomiltha, Protocardia, Trautscholdia, Neocrassina, Myophorella 80 Gryphaea shell beds Shell concentrate Gryphaeate oysters, bone fragments, cephalopods 1-7 82 Meleagrinella shell beds Shell concentrate Meleagrinella 2-9 69 Blocky claystone Light grey plastic clay with dark streaks Bositra, Meleagrinella, Palaeonucula, Mesosaccella, Procerithium, Lingula, Solemya 96 Calcareous clays Light grey or grey- green, rather plastic, clay Palaeonucula, Mesosaccella, Discomiltha, Isocyprina, Myophorella, ^ Entolium' , Genicularia, oysters 11 74 greatly increases its size. Table 4 shows the over-all trophic nucleus of the whole benthonic fauna, whilst Table 5 shows the trophic nucleus discounting the pendent bivalves. Columns 7-9 of each table show the percentage of the various kinds of deposit-feeders within each biofacies. As well as determining the size of the trophic nucleus, it is useful to examine the trophic group composition of each biofacies, a technique introduced, and later refined, by Turpaeva (1948). This method of determining the trophic relationships of all the benthonic invertebrates in an assemblage was shown by Walker (1972, p. 83) to be a useful method of ecological analysis. Turpaeva’s work on the Recent faunas of the Barents Sea revealed several generalizations which apply to most Recent communities; Walker also showed that they could be applied to many Lower Palaeozoic communities, and the evidence from the Lower Oxford Clay suggests that they are also applicable to Mesozoic assemblages. Turpaeva chiefly showed that (a) each community is dominated by a single trophic group, (b) each of the dominant species in the trophic nucleus belongs to a different trophic group, (c) one species 456 PALAEONTOLOGY, VOLUME 18 'O a a c .5 E ^ o S 'TD -T3 aj E I ' aj (u n c *-H ^ QJ J- C/5 X) o- 3 c O ^ § E U Z .£ c ^ ^r. o c a, q> (D > T3 Crt 0> c/> W) C cd o O a o ^ o> T3 -a c •TD 3 . • S o (U c/3 Q, O 5o •5 c ^ bN i c/:) C cS o O ^ -G >^lj Cd 3 ^ S T3 ■ = u -C 0 a ';< 2 1 - n ^ ►3 •" (U ,«« j: o O c/3 cd • — O t-i .- “L) "u TD 3 C bO-ti C3 c/3 S -o "O s I- }J IX o '-£ c X r-- O ro CO ro fO (N s: 3 ■2 ■€ "§ g .3 ■§ Grammai minima 6-9 ' 2 S S 3 minima 8-1 cu Grammai concinna 3-2 1 Bositra 3 Co a S S 3 •1 1 2 3 so 3 R .3 Palaeot 80 jo U Bositra 9-9 Cj i 3 O 2 ^ c-» Cj «3 S 9 r'- I- 2^ ~S; (N ^fN 05 bo Q CN -2 ^ rn a o u H cE o S '5b Q i tu cn -D O, :3 C O ^ X) cd H -o - c . Cu (U • CUj.ti c3 c/i C 2 S Cl, (X O ci^ o a^ g.s ^ => o « O O £■ ,c3 c^3 § - '5. u ^ W T3 £ a o, E o ;b^ ,nS U T3 u cS X o Sw 60 __i r 50 mm 25 mm L 0 TEXT-FIG. 14. Trophic group composition of the Nuculacean shell bed biofacies. All benthos included. triangular plots (text-fig. 7c, d) show the relationship between this and the preceding biofacies, indicating that there is some overlap. However, the two biofacies are easily distinguished by their faunal content and the surrounding lithology. This biofacies is also likely to be caused by slower sedimentation, and slight increase in current activity. Gryphaea shell beds, like the two preceding types, are restricted to a particular lithology, the transition beds between the Kellaways Rock and the Oxford Clay. They, too, have a low dominance diversity, with Gryphaea 62-2% of the fauna (text- fig. 16), the remaining 37-8% being fairly evenly distributed between twelve species of suspension-feeder (28-7%) and three species of deposit-feeder (8-5%). Amongst the dominant species, there is evidence of niche separation, although in general the biofacies is characterized by suspension-feeders. The high oyster content places the field of this biofacies close to the epifaunal suspension-feeder corner of the triangle (text-fig. Id, e). Again, the fauna is similar to that of the beds in which the shell beds occur, and the sediment seems to be another shell concentrate formed more or less in situ. There is, however, evidence to suggest that the fossils found in this biofacies may have been transported, as bivalves occur as disarticulated shells rather than articulated shells, many of the valves are fragmented, and there are disproportionate amounts of left and right valves. In addition, broken cephalopod fragments, reptile bones, and fish teeth are fairly common, and it seems likely that the Gryphaea shell beds represent a transported fossil assemblage. Facies associations (their occurrence in the silts and silty clays), and consideration of the mode of life of the various faunal DUFF: OXFORD CLAY PALAEOECOLOGY 469 Percent 0 10 20 30 40 1 I I I i_ 50 60 -I 1 Mesosaccella morrisi Palaeonucula sp nov 3 a Procerithium damonis Bositra buchii Grammatodon minima Meleagrinella braamburiensis Corbulomima macneillii Flat oyster Trautscholdia phillis □ LF Entolium corneolum r 50 mm - 25 mm •- 0 Thracia TEXT-FIG. 15. Trophic group composition of the Grammatodon shell bed biofacies. All benthos included. elements, particularly the oysters, suggest that these were deposited in shallower water than the bulk of the Lower Oxford Clay, subject to wave-scouring at times. Meleagrinella shell beds are largely confined to the upper part of the Grossouvrei Subzone, where they are interbedded with calcareous clays, and consist over- whelmingly of a concentration of broken and unbroken specimens of Meleagrinella braamburiensis. Accurate counts are difficult, and consequently the data in text- fig. 17 is less accurate than that of other biofacies. Over 70% of the fauna is Melea- grinella, the remainder consists of well niche-partitioned species occupying several habitats. Most of the shell beds are bounded above or below by burrowed surfaces, where fragments of the overlying bed are piped down into the bed beneath. Burrowed horizons are very rare elsewhere in the Lower Oxford Clay (except in the silts), and these may represent phases of slow or nil-deposition, with increased current activity. 470 PALAEONTOLOGY, VOLUME 18 Percent 0 10 20 30 40 50 60 1 1 1 I I I I LF Meleagrinella braamburiensis HF Procerithium damonis Corbulomima macneillii © EZD LF Grammatodon concinna Palaeonucula sp nov Discomiltha 1 1 rata r 50 mm - 25 mm L 0 Anomalodesmatan LF sp. A TEXT-FIG. 16. Trophic group composition of the Gryphaea shell bed biofacies. All benthos included. Others The overwhelming abundance of Meleagrinella is probably original, as the shells are too fragile to have withstood much post-mortem transport, and if the shell bed were current-concentrated, there would be more larger, heavier shells. To explain the numerous Meleagrinella, bearing in mind the inferred pendent mode of life of the genus, it is probable that there was a large amount of floating organic matter to which Meleagrinella may have been attached; the resulting environmental reconstruction may be comparable with the Recent S'^rga^^wm-dominated environments. However, this comparison is tentative, as most of the epifauna of Sargassum is soft bodied (Friedrich 1965, p. 198), and would leave no traces, and there is no direct evidence for large amounts of floating organic material in the Lower Oxford Clay, and its existence is deduced from the abundant thin-shelled byssally attached Pteriacea and Pectinacea in sediments such as bituminous shales, where the substrate would have been too soft to allow such animals to live on the sea floor. DUFF: OXFORD CLAY PALAEOECOLOGY 471 Percent 0 10 20 30 40 50 60 70 ■ ■ ■ I I 1 I 1 Others [ 1 TEXT-FIG. 17. Trophic group composition of the Me/eagr/«e//a LJ shell bed biofacies. All benthos included. Blocky clay stone. This lithology is known only from the Jason Subzone (Bed 3B) of Calvert. As with the deposit-feeder bituminous shales (within which it occurs), the first two dominance positions are occupied by pendent bivalves (58-4%), whilst the remainder of the fauna is dominated by an alternation of infaunal deposit and suspension-feeders, Lingula and Solemya being the characteristic members of the latter group (text-fig. 18). The total number of species found is small (only eleven), but there is a relatively high dominance diversity, with only two species less than 1% of the fauna. The lithology is a distinctive light grey, rather plastic, non-fissile clay, with many black organic fragments spread throughout it. Many of the Lingula are preserved upright in life position, unknown elsewhere in the Oxford Clay, which suggests that there was no deep scouring of the sea floor. The over-all trophic nucleus (Table 4) is similar to the normal bituminous shales, due mainly to the large content of pendent species, and it is not until these are removed (Table 5) that the unusual nature of the fauna becomes apparent. Calcareous clays. This facies is restricted to the upper Grossouvrei Subzone, where it forms a regular alternation with the Meleagrinella shell beds with the junctions between the two always burrowed. The main characteristic of the calcareous clays is their high dominance diversity, with five species each more than 10% of the fauna (text-fig. 19), and a relatively large trophic nucleus (Table 4). The most abundant species is an infaunal deposit-feeder (Mesosaccella), the next two species being pendent bivalves {'Entoliuni and Meleagrinella), which together make up 60-8% of the fauna. 'Entolium' (a new genus to be described elsewhere) is the most charac- teristic faunal element, known only rarely from other facies; the polychaet worm Genicular ia is also typical. Further analysis reveals that there is an approximately equal distribution of deposit and suspension-feeders (Table 4), with most of the suspension-feeders being pendent; infaunal suspension-feeders are not abundant (text-fig. 19), and the degree of aeration within the sediment was probably not great, in the same way as in the more calcareous Middle and Upper Oxford Clays. The low content of infaunal suspension-feeders is also apparent from the triangular plots 472 Meleagrinella braamburiensis Bositra buchii Palaeonucula sp nov Lingula craneae Mesosaccella morrisi Solemya woodwardiana Dicroloma trifida Oxytoma inequivalvis Procerithium damonis PALAEONTOLOGY, VOLUME 18 Percent 0 10 20 30 1 I I I 40 50 I 60 HF Others - 50 mm - 25 mm - 0 TEXT-FIG. 18. Trophic group composition of the blocky claystone biofacies. All benthos included. (text-fig. le-f). The calcareous clays are rather rich in carbonate, and consequently have a low insoluble residue content (74%), together with a low organic carbon content (M%). Relations between the hiofaeies. The over-all succession in the Lower Oxford Clay at the major pits examined in the Midlands (text-fig. 5) is generally similar, although there are local variations, especially at Stewartby and Calvert. Superimposed on these local variations in the details of the succession is a marked southward increase in thickness, the Enodatum-Grossouvrei Subzone succession being 12 m thick at Peterborough, and gradually increasing through 14 m at Stewartby, 17 m at Bletchley, to 18 m at Calvert. These thickness changes probably indicate greater distance from the shoreline or a submarine swell, with consequent decrease in the number and thick- ness of shell beds. This is particularly noticeable in the case of the shell bed which occurs at or just above the base of the Obductum Subzone at Peterborough and Stewartby; the shell bed is missing from the Bletchley section. Most of the thickness variation occurs within the Jason and Calloviense Zones (text-fig. 6), which thicken from 0-5 m at Peterborough to over 3 0 m at Calvert, suggesting that during the deposition of the initial subzones of the Oxford Clay, conditions were more variable, and controlled by local configurations of the sea floor. By the time of the Coronatum DUFF: OXFORD CLAY PALAEOECOLOGY 473 Percent 10 I 20 I 30 —I 40 _l_ 50 1 60 _j Mesosaccella mornsi 5w Entolium sp.nov Meleagrinella braambunensis Procerithium damonis 1 HP HP . Co. Bositra buchii Palaeonucula sp nov. ]hf iiiliiiii Sw. Corbulomima macneillii Genicularia vertebralis © CZI LP ■ 50 mm - 25 mm TEXT-FIG. 19. Trophic group composition of the calcareous clay biofacies. All benthos included. Zone, conditions appear to have stabilized over the whole of the Midland area, giving a much more uniform thickness of Lower Oxford Clay. The transition beds between the Kellaways Rock and the Oxford Clay are best developed at Peterborough and Bletchley, where they consist of an alternation of silts and silty clays, Gryphaea shell beds, and deposit-feeder bituminous shales. At Peterborough the transition beds occupy the whole of the Enodatum and Medea Subzones (0-5 m), but at Bletchley are restricted to the Medea Subzone (2 0 m), Kellaways Rock deposition having continued until the top of the Enodatum Subzone. At Stewartby the transition beds appear to be absent, a bipartite shell bed, the upper part a Grammatodon shell bed and the lower part a Gryphaea shell bed, rests directly on the silts of the Kellaways Rock, which are dated as Enodatum Subzone; deposit- feeder bituminous shales of the Medea Subzone follow these shell beds directly. Thus Kellaways Rock deposition ended earlier in the northern parts of the Midlands, and Oxford Clay did not reach the south Midlands until the end of Enodatum Sub- zone times; this suggests that the shoreline lay to the south during this time. There then appears to have been rather variable current activity, phases of shallowing and increased current activity giving Gryphaea shell beds, whilst in the intermittent quiet phases silts or bituminous shales were laid down. The bituminous shales indicate that 474 PALAEONTOLOGY, VOLUME 18 the influence of the olfshore clay facies was greater at that time, and that distance from shore, and probably water depth, was gradually increasing. The transition beds are not exposed at Calvert, the pit ending in the Jason Subzone, although Callomon (1968, p. 287) records 10 ft of combined Medea and Enodatum Subzones in a bore- hole there. Gradual recession of the shoreline during deposition of the transition beds eventu- ally allowed the establishment of quiet water conditions in which bituminous shales were laid down. At Peterborough, Bletchley, and Calvert, this phase seems to have begun more or less at the start of Jason Subzone times, while at Stewartby similar conditions became established slightly earlier. At all the pits the lowermost few centimetres of the shales are markedly fossiliferous and contain the same species as the underlying shell beds, indicating the gradual dying out of the fauna of the pre- ceding bed. There then followed thick dominantly deposit-feeder bituminous shales, which occupy the whole of Jason and Obductum Subzone time at Peterborough, Bletchley, and Calvert, with the exception of the 1-m band of blocky claystone near the base at Calvert. During this time bottom conditions were quiet, and water circulation probably poor, producing an impoverished benthonic fauna dominated by deposit-feeding bivalves and gastropods, with rare benthonic suspension-feeders. Living above the bottom and attached to postulated organic material were large numbers of pendent epifaunal suspension-feeding bivalves, chiefly Bositra, Melea- grinella, and Oxytoma. The suspension-feeder dominated fauna is unusual, and was probably caused by a superabundance of the suspended food source, as discussed above. The general sequence seen in the Lower Oxford Clay of the Midlands, Kellaways Rock through transition beds to bituminous shales and then to more fossiliferous shales, adds substance to the suggestion of Hallam (1967a, p. 489) that bituminous shales are often laid down in relatively shallow water. Hallam suggested that near the base of transgressive sequences widespread bituminous shale deposition was charac- teristic, and that it was followed by more fossiliferous, deeper-water clays and shales, laid down as water circulation improved, and sediment oxygenation increased. The Kellaways Beds-Upper Oxford Clay sequence agrees with this model, the bulk of the Lower Oxford Clay representing the bituminous shale part of the cycle. The presence of the 1-m band of blocky claystone near the base of the Jason Sub- zone at Calvert indicates that conditions were slightly different there during much of the Jason Subzone times, as the Lingula-hc\\ blocky claystone fauna continues for most of the subzone. Both Lingula and Solemya have been considered by previous authors to be genera tolerant of poorly aerated water, and this, together with the low organic carbon content, the increased thickness, and reduced benthonic fauna, suggests that in the south Midlands area this part of the sequence was laid down more rapidly than the deposit-feeder bituminous shales and possibly in slightly deeper water. At Stewartby the Obductum Subzone sequence is different to that seen at the other pits, a thin development of deposit-feeder bituminous shale, containing two very well-developed Nuculacean shell beds, being followed by a very thick Meleagrinella shell bed, and a development of foraminifera-rich bituminous shale. The combina- tion of the two Nuculacean shell beds, being followed by a very thick Meleagrinella DUFF: OXFORD CLAY PALAEOECOLOGY 475 shell bed, suggests that local current activity must have been increased at this time, probably on a local swell. The foraminifera-rich bituminous shale above the Melea- grinella shell bed shows a return to quieter and deeper water, with well-developed niche partitioning within the benthonic fauna. Throughout the Midlands the end of the Obductum Subzone coincides with a wide- spread phase of slow deposition, marked by Nuculacean or Grammatodon shell beds. Brinkmann (1929, p. 81) showed that at Peterborough the shell bed at the top of the Obductum Subzone represents a significant pause in sedimentation, and it seems likely that a similar situation prevailed over much of the Midlands. This phase of condensed deposition is followed at all the pits by a similar succession in the Grossouvrei Subzone. The well-aerated conditions of the Nuculacean and Gram- matodon shell beds persisted into the next phase of bituminous-shale deposition, giving a sequence of Grammatodon-nch bituminous shales, rich in infaunal suspension- feeders such as Grammatodon, Isocyprina, and Thracia. The start of the Grossouvrei Subzone sees the first appearance in the Oxford Clay of Grammatodon minima, and also marks the arrival of abundant Isocyprina. This event can be recognized at the same level in Dorset, and is useful for defining the base of the Grossouvrei Subzone. Phases of increased current activity during this time are marked by Grammatodon shell beds. As subsidence continued, and oxygenation of the water gradually decreased, the Grammatodon-rich bituminous shales were replaced by foraminifera-rich bituminous shales in which deposit-feeders became more abundant and infaunal suspension-feeders fewer, although the conditions which resulted in the deposit- feeder bituminous shales never became re-established. Later, in Grossouvrei Subzone times, there was a renewed phase of shallowing, producing the characteristic alternation of calcareous clays and Meleagrinella shell beds, bringing the Middle Callovian to a close in southern England. As suggested above, this sequence must have been characterized by periodic explosions in coloniza- tion by organic matter, allowing dense Meleagrinella shell beds to accumulate, and producing many small non-sequences. Aeration in the calcareous clays must have been relatively good as they supported a diverse fauna of suspension-feeders, and there is a sudden increase in the abundance of tube-building annelid worms. Grossouvrei Subzone deposition was concluded over the whole area by a thick Nuculacean shell bed— the Comptoni Bed— which again represents a phase of increased current activity, and a pause in sedimentation. This part of the sequence is usually capped by a eoncretionary diagenetic limestone, the Acutistriatum Band, which is developed within a band of very bituminous foraminifera-rich shaly clay, and which represents the basal bed of the Athleta Zone. Thus within a relatively thin sequence of Lower Oxford Clay (12-18 m), occupying just over two ammonite zones, there are two cycles of environmental conditions. Firstly, there is the deepening sequence from the Kellaways Rock through the transi- tion beds into the deposit-feeder bituminous shales of the Jason-Obductum Subzones, with indications of shallowing towards the top, and secondly, the more balanced cycle of the Grossouvrei Subzone, which shows distinct deepening and shallowing phases, ending with a pronounced non-sequence. c 476 PALAEONTOLOGY, VOLUME 18 COMPARISONS WITH OTHER FACIES In view of the lack of comparable quantitative data from similar environments, comparisons must be limited to more qualitative observations, largely gleaned from the literature. In particular, the work of Melville (1956), Hallam (1960, 1967), Palmer (1966, 1966fl, 1973), and Sellwood (1972) on the Lias, Hudson and Palframan (1969) on the Middle and Upper Oxford Clay, Price (1879) on the Gault, and Scott (1970) on the Lower Cretaceous of the United States, has been used for comparison of clay faunas, and shows the Lower Oxford Clay to be unusual because of its very high content of pendent epifaunal suspension-feeders and infaunal deposit-feeders. With the exception of Scott, no quantitative data was given, fossils merely being recorded, or being said to be rare, common, or occur, and thus direct comparison is difficult. There is also the assessment of the relative importance of evolutionary and environ- mental changes when the palaeoecology of different ages is being compared. However, in this consideration all the rocks are of Jurassic or Lower Cretaceous age, and the importance of evolutionary changes appears minor; there is little change in the over- all faunal composition, although there is much variation in the relative importance of species within it. Protobranch bivalves are known to be a slowly evolving group, so evolutionary effects in this protobranch-dominated assemblage are likely to have been small. In general terms it appears to be environmental conditions which have exercised the greater control over benthonic assemblages during Jurassic and Lower Cretaceous times. The shales of the Oxford Clay have frequently been compared with the Lias, but this study shows many differences between the two deposits. Hallam (1960, p. 12) described the bituminous shales of the Blue Lias of Dorset and Glamorgan, and showed them to have a very high organic carbon content (3-9-8-0%), and a fauna consisting almost entirely of ammonites, fish scales, and bivalve spat, indicating that bottom conditions must have been anaerobic. Most of the fossils are preserved in the marls and limestone bands, which Hallam showed to be essentially of primary origin, although he later (1964) amended his views, but similarities with the Lower Oxford Clay are negligible, as in the Lias limestones there is a rich and varied fauna of normal infaunal and epifaunal suspension-feeders, while deposit-feeders and pendent bivalves are rare. It thus seems very likely that the limestone part of the Blue Lias rhythm was much better aerated than the Lower Oxford Clay, as it contains a much more varied fauna, including gastropods, brachiopods, and echinoderms. Sellwood (1972) gives similar results on the Sinemurian-Pliensbachian Lias to those of Hallam (1960, p. 10), in so far as the fauna is dominated by infaunal and epifaunal suspension-feeders, with few deposit-feeders. Rocks of this age over most of Britain are clearly less bituminous and more well aerated than the bituminous shales of the Blue Lias, and contain many genera which are also characteristic of the Lower Oxford Clay, but again there is a lack of abundant pendent bivalves and deposit-feeders. The same is true of the Middle and Lower Lias described by Melville (1956, p. 74) from the Stowell Park borehole in Gloucestershire, pendent bivalves and deposit-feeders again not being abundant, the fauna being dominated by infaunal and epifaunal suspension-feeders. Palmer’s (1973, p. 252) work on the upper parts of the Lower Lias in Gloucestershire shows a faunal list rather similar to that of the DUFF: OXFORD CLAY PALAEOECOLOGY 477 Lower Oxford Clay, but again pendent bivalves and deposit-feeders are neither abundant nor widespread. The Middle Lias (Palmer 1966, 1966a; Hallam 1967) shows similar conditions to have prevailed during deposition of the more sandy shales. The Upper Lias (Melville 1956; Hallam 1967) of Britain is probably the most similar deposit to the Lower Oxford Clay, consisting of dark shales and shaly clays with a sparse benthonic bivalve fauna, dominated by deposit-feeding Nuculaceans such as Nuculana and 'Nucula\ often with a pendent bivalve fauna of Bositra radiata and Inoceramus dubius. These shales, which are also rich in cephalopods and Pro- cerithium, often contain local concentrations of comminuted fish debris, insect remains, and Crustacea, emphasizing the similarity with the bituminous shales of the Lower Oxford Clay. Quantitative work on the fauna of the Upper Lias shales would be of interest for detailed comparisons with the Oxford Clay. Hudson and Palframan (1969) have described the palaeoecology of part of the Middle-Upper Oxford Clay of the Midlands, and shown that there are clear dif- ferences between the fauna of this part of the Oxford Clay and the Lower Oxford Clay. The dark grey, well-laminated bituminous shales have been replaced by light grey, rather calcareous clays, often rich in fossils preserved as pyritic internal moulds, with no preserved aragonite. The Spinosum Clays (Athleta-Lamberti Zones) have a sparse benthonic fauna, dominated by shallow infaunal species (mostly deposit- feeders), with the epifauna characteristically rich in Chlamys and Gryphaea; other Pectinacea are locally common. Near the top, Gryphaea beds appear, alternating with the normal clay facies, and having, as well as common Gryphaea lituola, suspension- feeders dominating over deposit-feeders. However, these Gryphaea beds are not equivalent to those of the Lower Oxford Clay; they merely consist of a concentration of oysters (estimated at four per square foot) in slightly harder and more calcareous clay, and do not represent phases of non-deposition, although there must have been some slowing of sedimentation. The rest of the Spinosum Clays make up a sequence of quiet water muds similar to, but not equivalent to, the bituminous shales of the Lower Oxford Clay. The faunal density is also less than that of the Lower Oxford Clay, and there are none of the abundant Bositra, Meleagrinella, or Oxytoma so typical of the Middle Callovian. The abundance of Astarte s.l. in the Spinosum Clays suggests that the bottom sediments must have been fairly well aerated. The Mariae Clays (Mariae Zone) are darker and more organic-rich than the Spinosum Clays, and have a different faunal composition. The benthonic fauna is reduced in variety, and is mostly infaunal, with Dicroloma, Procerithium, and Nuculacea abundant, and Pinna the only common suspension-feeder. This part of the Upper Oxford Clay is much more similar to the Lower Oxford Clay in faunal content, although the presence of pyritic ammonites is a notable difference and the shales are not well laminated. It seems likely, however, that during at least part of the Mariae Zone conditions were somewhat similar to those of the Lower Oxford Clay. The fauna of the Gault Clay (Cretaceous, Albian) has been summarized by Casey (1966, p. 102), but a more comprehensive faunal list was given by Price (1879, p. 60), who charted the distribution of the bivalve fauna. Price recognized eighty-six bivalve species in the English Gault, fourteen of which are deposit-feeders, almost all species of "Nucula\ In spite of this apparently high diversity of deposit-feeding protobranchs. 478 PALAEONTOLOGY, VOLUME 18 they are not as abundant as they are in the Lower Oxford Clay, nor are there so many siphonate forms. There are, however, large swarms of Inoceramus through- out the Gault, and so in this respect there are close similarities with the Lower Oxford Clay. The main difference is in the greater diversity of infaunal and epifaunal suspension-feeders, especially deep burrowers. The Gault has long been divided into two lithological parts, the Upper Gault, consisting of light-coloured rather calcareous clay, while the Lower Gault is much darker, less calcareous, and is generally more similar to the Lower Oxford Clay, although it is not bituminous. Casey (1966, p. 105) records Inoceramus and Nuculacea (Nucula spp., Acila, and Mesosaccella) as the most abundant bivalves of the Lower Gault, with infaunal suspension-feeders becoming more abundant in the Upper Gault. Most of the molluscs preserved in the Lower Gault retain the original unaltered shell aragonite, although the cephalopods in particular, as well as some of the bivalves and gastropods, are usually pyritized. As in the Lower Oxford Clay, preservation of aragonite is related to the very impervious nature of the sediment. Scott (1970) has described the palaeontology and palaeoecology of the Kiowa Formation (Lower Cretaceous, Aptian-Cenomanian) of Kansas, and recognized six lithofacies groupings, of which one, the dark-grey shale lithofacies, is comparable with the Lower Oxford Clay. It is a dark grey, fissile, well-laminated shale, with a general lack of small-scale sedimentary structures, and Scott believes the fossil assemblages to represent ‘disturbed neighbourhood’ and mixed-fossil assemblages. This lithofacies is characterized by the Nuciilana association, dominated by Nuculana, Yoldia, Nucula (nuculaceans), Breviarca (Arcacea), Pholadomya, Turritella, Drepano- cheilus, and Lingula, which constitute 18-84% of the fauna; most of the remainder of the fauna is composed of a corbulid. The other comparable lithofacies recognized by Scott is his shell conglomerate facies, which corresponds closely to the Gryphaea shell beds of the Lower Oxford Clay. Similarities include the high content of Gryphaea (51-100%), the common occurrence of calcitic shells, and the laterally discontinuous nature of the shell beds. There are, however, some sedimentary structures which suggest that the Kiowa shell conglomerates were deposited in very shallow water, possibly by storm-generated currents, and there is no direct evidence that this is the case for the Lower Oxford Clay Gryphaea shell beds. Evolutionary changes — comparison with Palaeozoic and Recent assemblages. Deposit- feeder dominated assemblages occur in many argillaceous deposits, from the Ordovician to the present. In general trophic composition the assemblages are similar, but marked evolutionary changes have altered the structure of the younger ones, showing the importance of evolutionary changes over a long period. The main changes are in the composition of the suspension-feeding part of the fauna since the Lower Palaeozoic; bivalves having taken the place of the articulate brachiopods, as a result of the development of siphon formation (Stanley 1 968, p. 224). The suspension- feeder groups present in the Lower Palaeozoic have also been replaced by more highly evolved superfamilies, leaving only the slowly evolving deposit-feeding Nuculoida as a conservative stock. The most similar assemblages to those of the Lower Oxford Clay are the various DUFF: OXFORD CLAY PAL AEOECOLOG Y 479 Lingula ‘communities’ described from the British and American Palaeozoic (Bretsky 1970, p. 61 ; Ziegler et al. 1968, p. 5; Craig 1955, p. 114). The data for these com- munities have been replotted by Walker (1972, pp. 87, 88, 90) to show the trophic structure of the assemblages, and it is clearly apparent that both the Ordovician and the Lower Carboniferous Lingula assemblages (described by Bretsky and Craig respectively), are dominated by deposit-feeders, and show well-developed niche partitioning. As in parts of the deposit-feeder bituminous shale biofacies, Lingula is an important constituent of the fauna, and occupies second place in the assemblage ; the dominant species in both these Lower Palaeozoic assemblages is an infaunal nuculoid. In the Ordovician Lingula community described by Bretsky, third and fifth places are occupied by archaeogastropods, which functioned as epifaunal browsing herbivores. These elements are absent from the equivalent Mesozoic assemblages. Ziegler et al. (1968) have described several ‘communities’ from the Silurian of the Welsh borderlands, the Lingula community being particularly relevant here. The commonest species is an epifaunal suspension-feeding brachiopod (Camarotoeclua), with Lingula and Palaeoneilo (a nuculanid) oceupying the next two positions; the epifaunal pterioid Pteronitella is also characteristic. This assemblage has a low diversity (Diversity Index 6-2), but shows a wide range of feeding types, although it differs from the other Palaeozoic Lingula associations in having a high content of filter-feeders; Walker (1972, p. 91) has suggested that perhaps this is not a true example of the Lingula assemblage. This Lingula community is usually developed in a more marginal facies, consisting mainly of sandstones, and so epifaunal suspension- feeders, such as Camarotoechia, are most abundant. Thus Lingula communities in general may be of varying type, and developed in several lithologies; only shale occurrences are of relevance here. The Diversity Index value for Ziegler’s Lingula community (6-2) agrees well with the values from the Lower Oxford Clay (5-9- 6-7 in the bituminous shales), in contrast to the other brachiopod-dominated Silurian communities, which have much higher diversities (D.I. 7-8-1 1-8) due to their low dominance diversity. In general terms, there are close similarities between Palaeozoic and Mesozoic deposit-feeder dominated assemblages, notably in the abundance of infaunal deposit- feeding bivalves and infaunal suspension-feeding Lingula. In the Mesozoic, many of the niches originally occupied by brachiopods have been taken over by bivalves, many of the new superfamilies still being extant. One of the major differences between the Lower Oxford Clay and the Palaeozoic assemblages, is the lack of a rich fauna of pendent epifaunal suspension-feeding bivalves in the Palaeozoic, although they oecur sporadically in some of the later assemblages (i.e. the Posidonia Band of Craig 1955, p. 112). Recent offshore soft-mud eommunities have been described by many authors, and are broadly comparable with the Lower Oxford Clay assemblages, although there are differences. The silt-clay facies occupying the central axis of Buzzards Bay, Massa- ehusetts (Sanders 1960; Rhoads and Young 1970; and Rhoads 1973) is dominated by deposit-feeders, both infaunal and epifaunal. Sanders identified the fauna as belonging to the Nucula proxirna-Nephthys incisa community, with these two species (the latter a polychaet) making up 76% by number of the specimens collected. The 480 PALAEONTOLOGY, VOLUME 18 trophic nucleus consists of three deposit-feeders, Nucula proxima being the most abundant, and suspension-feeders are of minor importance; no pendent epifaunal suspension-feeding bivalves are known. The same is true of other offshore mud com- munities (Jones 1950, p. 308) which are usually dominated by deposit-feeding proto- branchs and polychaets, usually with a conspicuous associated fauna of infaunal suspension-feeding bivalves. In this respect, the similarities with the various Lower Oxford Clay biofacies are many when the strictly benthonic fauna alone is considered, but, again, there is a noticeable lack of pendent suspension-feeders. The only known Recent assemblage with a high content of pendent epifaunal species is that found on Sargassum weed (Friedrich 1965, p. 198), but molluscs are not of great importance, only five species having been described from this habitat. Stanley (1972, p. 189) has recorded that many Recent species of Pteria attach preferentially to alcyonarian sea- whips, a method of obtaining stable fixation in an agitated environment. Recent parallels for the mode of life postulated for the Oxford Clay pendent bivalves are not known, and this may be accounted for by evolutionary effects. Alcyonarians did not appear until the Jurassic, and gorgonaceans until the Cretaceous (Stanley 1972, p. 190), so it is possible that the lack of abundant rooted organic material during the Jurassic led to the colonization of floating or rooted organic material (including algae) by species that needed to live above, rather than on, a soft-mud substrate. Thus the Lower Oxford Clay bituminous shale assemblages were both of different structure and occupied slightly different environments to Palaeozoic and Recent offshore mud assemblages, a consequence of evolutionary, rather than environmental changes^ CONCLUSIONS Hallam ( 1967a, p. 489) suggested that bituminous shales were relatively shallow- water deposits laid down in quiet, but not invariably stagnant water below wave base, in contrast to the deep-water ‘barred basin’ model postulated by earlier authors. The evidence deduced from the Oxford Clay appears to support this hypothesis, as there is a deepening sequence from the sands and silts of the Kellaways Rock, through the laminated bituminous shales of the Lower Oxford Clay, into the more massive calcareous clays of the Middle-Upper Oxford Clay. The many small-scale alterna- tions of lithology within the Lower Oxford Clay indicate relatively shallow-water deposition, where a slight change in water depth could have a marked effect on hydro- graphic conditions. Faunally, bituminous-shale sequences show variability through time, with Palaeozoic black shales either lacking benthonic elements (the graptolitic shales), or with a benthonic fauna dominated by deposit-feeding nuculoids and suspension- feeding linguloids. At various times pendent or benthonic byssally attached bivalves were fairly common, but were never as important as in the Mesozoic. In the European Jurassic, bituminous shales are particularly important in the Lower Hettangian, Lower Toarcian, and the Middle Callovian, and all tend to show a fauna consisting mainly of nuculoids and pendent bivalves. Recent organic-rich mud communities have rather more infaunal suspension-feeders and no pendent bivalves, but, again, nuculoids are numerically dominant. The role of the infaunal deposit-feeding proto- branchs seems to have persisted more or less unchanged since the Lower Palaeozoic, DUFF. OXFORD CLAY PALAEOECOLOG Y 481 their mode of life (inhabiting quiet water muds in areas of environmental stability) needing little adaptive change. The replacement of brachiopods by bivalves as the dominant members of the epifauna after the Palaeozoic followed siphon formation in the Bivalvia, and marks the main change in the composition of the faunas of organic-rich shales since the Palaeozoic. Acknowledgements. I would like to thank Dr. J. D. Hudson for help and advice given during the period of this research, and Mrs. A. M. Bowden, also of Leicester University, who carried out the organic carbon determinations. The work was largely financed by an N.E.R.C. research studentship. REFERENCES ARKELL, w. J. 1933. The Jurassic System in Great Britain. Clarendon Press, Oxford. BADER, R. G. 1954. The role of organic matter in determining the distribution of pelecypods in marine sediments. J. mar. Res. 13, 32-47. BARNARD, T. 1952. Foraminifcra from the Upper Oxford Clay of Warboys. Proc. Geol. Ass. 63, 336-350. 1953. Foraminifcra from the Upper Oxford Clay (Jurassic) of Redcliff Point, near Weymouth, England. Ibid. 64, 183-197. BRETSKY, p. w. 1970. Upper Ordovician ecology of the central Appalachians. Bull. Peabody Mus. nat. Hist. 34, 150 pp., 44 pis. BRiNKMANN, R. 1929. Statistisch-Biostratigraphische Untersuchungen an Mitteljurassischen Ammoniten fiber Artbegriff und Stammesentwicklung. Abh. Akad. IViss. Gottingen Math. Phvs. Kl. n.f. 13 (3), 1-249, pis. 1-5. 1929a. Monographic der Gattung Kosmoceras. Ibid. 13 (4), 1-124, pi. 1. CALLOMON, J. H. 1 955. The ammonite succession in the Lower Oxford Clay and Kellaways Beds at Kidlington, Oxfordshire, and the zones of the Callovian stage. Phil. Trans. R. Soc. B. 239, 215-264, pis. 2, 3. 1964. Notes on the Callovian and Oxfordian stages. C.r. Mem. Coll. Jurassique, Luxembourg, 1962, 269-291. 1968. The Kellaways Beds and the Oxford Clay. In sylvester-bradley, p. c. and ford, t. d. (eds.). The Geology of the East Midlands. Leicester, 264-290. CASEY, R. 1966. Palaeontology of the Gault. In smart, j. g. o., bisson, g. and worssam, b. c. Geology of the country around Canterbury and Folkestone. Mem. geol. Surv. G.B. 102-113. CORDEY, w. G. 1962. Foraminifcra from the Oxford Clay at Loch Staffin, Isle of Skye, Scotland. Senckenberg. leth. 43, 375-409, pis. 46-48. 1963. The genera Brotzenia and Voortlmysenia (Foraminifcra) and Hofkers classification of the Epistomariidae. Palaeontology, 6, 653-657, pi. 93. CRAIG, G. Y. 1955. The palaeoecology of the Top Hosie shale (Lower Carboniferous) at a locality near Kilsyth. Q. Jl geol. Soc. Lond. 110, 103-119. DAVIES, A. M. 1916. The zones of the Oxford and Ampthill Clays in Buckinghamshire and Bedfordshire. Geol. Mag. 53, 395-400. DiNAMANi, p. 1964. Feeding in Dentalium conspicuum. Proc. malac. Soc. Lond. 36, 1-5. FARROW, G. 1966. Bathymetric zonation of Jurassic trace fossils from the coast of Yorkshire. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2, 103-151. FRIEDRICH, H. 1965. Marine Biology. Sidgwick & Jackson, London. HALLAM, A. 1960. A Sedimentary and faunal study of the Blue Lias of Dorset and Glamorgan. Phil. Trans. R. Soc. B. 243, 1-44, pis. 1, 2. 1964. Origin of the limestone-shale rhythms in the Blue Lias of England : a composite theory. J. Geol. 72, 157-169. 1967. An environmental study of the Upper Domerian and Lower Toarcian in Great Britain. Phil. Trans. R. Soc. B. 252, 393-445, pi. 20. 1967a. The depth significance of shales with bituminous laminae. Mar. geol. 5, 481-493. 1969. Faunal realms and facies in the Jurassic. Palaeontology, 12, 1-18. HUDSON, J. D. and palframan, d. f. b. 1969. The ecology and preservation of the Oxford Clay fauna at Woodham, Buckinghamshire. Q. Jl geol. Soc. Lond. 124, 387-418, pis. 19, 20. 482 PALAEONTOLOGY, VOLUME 18 JEFFERIES, R. p. s. and MINTON, p. 1965. The mode of life of two Jurassic species of ' Posidonia'. Palaeontology. 8, 156-185, pi. 19. JOHNSON, R. G. 1964. The community approach to palaeoecology. In imbrie, j. and Newell, n. d. (eds.). Approaches to Paleoecology, Wiley, New York, 107-134. JONES, N. s. 1950. Marine bottom communities. Biol. Rev. 25, 283-313. MELVILLE, R. V. 1956. The stratigraphical palaeontology, ammonites excluded, of the Stowell Park borehole. Bull. geol. Surv. G.B. 11, 67-139, pis. 2-8. NEAVERSON, E. 1925. The zones of the Oxford Clay near Peterborough. Proc. Geol. Ass. 36, 27-37. NEYMAN, A. A. 1967. Limits to the application of the trophic group concept in benthic studies. Oceanology, Acad. Sci. USSR, 7, 149-155. PALMER, c. p. 1966. Note on the fauna of the Margaritatus Clay (Blue Band) in the Domerian of the Dorset coast. Proc. Dorset nat. Hist, archaeol. Soc. 87, 67-68. 1966a. The fauna of Day’s shell bed in the Middle Lias of the Dorset coast. Ibid. 69-80, pis. 1-3. 1971. The stratigraphy of the Stonehouse and Tuffley clay pits in Gloucestershire. Proc. Bristol Nat. Soc. 32, 58-68. 1973. The palaeontology of the Liassic (Lower Jurassic) clay pits at Stonehouse and Tuffley in Gloucestershire. Geol. Mag. 110, 249-263, pi. 1. PRICE, F. G. H. 1879. The Gault. Taylor & Francis, London. RHOADS, D. c. 1973. The influence of bottom-feeding benthos on water turbidity and nutrient recycling. Am. J. Sci. 273, 1-22, pis. 1, 2. SPEDEN, I. 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Hist. Geol. 19, 297-358, pis. 1-15. WOODWARD, H. B. 1895. The Jurassic rocks of Britain. V. The Middle and Upper Oolitic rocks of England. Mem. geol. Surv. G.B. WRIGHT, J. K. 1968. The stratigraphy of the Callovian rocks between Newtondale and the Scarborough coast, Yorkshire. Proc. geol. Ass. 79, 363-399, pis. 10, 11. ZIEGLER, A. M., COCKS, L. R. M. and BAMBACH, R. K. 1968. The composition and structure of Lower Silurian marine communities. Lethaia, 1, 1-27. K. L. DUFF The Nature Conservancy Council Foxhold House, Thornford Road Crookham Common Newbury, Berkshire, RG15 8EL Original typescript submitted 1 October 1974 Revised typescript submitted 4 December 1974 MEGASPORES AND MASSULAE OF AZOLLA PRISCA FROM THE OLIGOCENE OF THE ISLE OF WIGHT by K. FOWLER Abstract. Scanning and transmission electron microscopy, ultra-thin sectioning and light microscopy are employed in this investigation of Azolla prisca, which is placed in Section Trisepta sect. nov. of the genus. The columella and structural modifications of the proximal megaspore wall of A. prisca are compared with other species, both fossil and modern, and the phylogenetic interrelationship of these structures are discussed. The complex megaspore wall reveals an exine and two-layered perine, the outer perine layer being further subdivided into four zones. The inner perine layer thickens to form the proximal wall and associated labra. The wall structure of most Azolla species appears to be of this same basic pattern. Massulae, found dispersed and attached to megaspore apparatuses, reveal funnel- shaped cavities connecting the microspores to the exterior. Although previously unrecorded in Azolla such structure is present in both fossil and modern species, and is thought to form an escape mechanism for spermatozoids. A list of the better-known pre-Miocene Azolla species is presented, which includes stratigraphic range, and characteristics expressed as a formula. The evolutionary trends in Azolla are briefly reviewed. The genus Azolla belongs to the Salviniaceae, a family of heterosporous ferns. Plants are free-floating, occurring in freshwater habitats mainly in warm temperate to tropical zones. Some forty-eight species are recorded, six of which are extant. The fossil record of Azolla, dating back to the late Cretaceous of North America (Hall \969b), is based mainly on its highly distinctive reproductive structures, the mega- spore apparatus, and massula. In modern species, sporocarps are borne in pairs which arise from the ventral lobe of the first leaf of a branch. These paired sporocarps may be male and female, termed microsporocarp and megasporocarp respectively, or they may be of the same sex. The microsporocarp contains microsporangia hold- ing a number of massulae; the megasporocarp contains a megasporangium within which is a single megaspore apparatus. The latter consists of a megaspore with an elaborate wall, and a unique complex swimming apparatus. The term ‘Schwimmaparrat’, first applied by Strasburger (1873), is a misnomer in that the structure does not endow buoyancy, mature megaspores sinking following liberation (Sculthorpe 1967). The massula is a frothy pseudocellular structure in which micro- spores are embedded. The six modern species, together with their present geo- graphical distribution are as follows (data from Mahabale 1963; Sculthorpe 1967; and Svenson 1944); A. filiculoides Lam. From Alaska to Guatamala in North America, and in Andean and southern South America. Introduced into eastern U.S.A., Hawaii, and Europe. A. filiculoides var. ruhra(K. Br.) Strasburger, originally described from Australia, has since been found scattered throughout America. A. caroliniana Willd. Essentially warm temperate. In eastern U.S.A. from Massachusetts to Florida, extending to the West Indies and Brazil. Introduced in western, central, and southern Europe. A. pinnata R. Br. Australasia, Indomalaya, and Africa, including Madagascar. Introduced into southern Europe (Sculthorpe 1967). A. microphylla Kaulfuss. Mainly South America, especially lowlands of Brazil and British Guiana. [Palaeontology, Vol. 18, Part 3, 1975, pp. 483-507, pis. 59-61.] 484 PALAEONTOLOGY, VOLUME 18 Scattered distribution in western South America and northward to central America, extending into California and the West Indies. A. mexicana Presl. Mainly Mexico, with scattered occurrences northward through the Pacific States to British Columbia, and eastward to Lake Michigan. Extending southward in lowlands to French Guiana and Bolivia. A. nilotica Dene. African species with a less extensive latitudinal span than A. pinnata, occurring from Senegal and Ethiopia south to northern Transvaal. As early as 1847 Mettenius reported seven species of Azolla, together with an already confused synonymy, and interpretation of the development of reproductive structures had commenced (Meyen 1836; Griffith 1844). The most significant work on morphology and development of reproductive structures in Azolla concentrates on A. filiculoides (Strasburger 1873, 1889; Campbell 1893; Hannig 1911; Duncan 1940; and Bonnet 1957). A. caroliniana was studied by Berggren (1880) and Pfeiffer (1907), A. pinnata by Rao (1935), and A. nilotica by Demalsy (1954). Initial develop- mental stages of megasporangium and microsporangium are identical, until the production of thirty-two spores embedded in a multinucleate mass derived from a periplasmodial tapetum. Subsequent megasporangial development involves abor- tion of all but a single spore, the degenerating nuclei becoming aggregated into three large vacuoles which later form floats of the swimming apparatus above the develop- ing megaspore. Thickening of the megaspore wall occurs with deposition of an elaborate perine derived from surrounding cytoplasm. The hairs which then develop on the perine surface are considered homologous with glochidia which form on the massula. Glochidia serve as a means of attaching the massula to the megaspore apparatus. During microsporangial development, sixty-four spores are produced, eight to twelve of which become distributed toward the periphery of each of five to eight vacuoles. Each vacuole develops into the pseudocellular massula which bears glochidia at the surface. A float is regarded as the homologue of a massula. Although the fundamental development and organization of reproductive strue- tures in Azolla have been understood since 1889, little detailed comparative work of taxonomic importance has been attempted on modern species. This seems especially surprising in that probably no other group of embryophyte plants possess such complex spores. The genus ranges from the late Cretaceous to the present. Taxonomic diversity within the genus, eoupled with short stratigraphic ranges of individual species, renders Azolla a potentially valuable stratigraphic indicator. The stratigraphic ranges and characteristic features of the more important, and best-known, Azolla species from the late Cretaceous and Palaeogene are presented in Table 1. This list excludes certain species considered synonymous with others, and those established on such limited information as (i) only vegetative remains recorded, (ii) only massulae known, and (hi) megaspore apparatus inadequately described. Certain species established mainly on the basis of megaspore wall structure are included, but should be regarded as temporary, awaiting further information. Taxonomically, Azolla species are placed in six sections of the genus, based on features of the megaspore apparatus and massulae. The essential characteristics of each section are given below, together with a list of suggested members which includes extant species, and those from the late Cretaceous and Palaeogene. TABLE 1. Stratigraphic range and characteristic features of the reproductive structures of late Cretaceous and Palaeogene species of Azolla. Important literature related to each species is listed in the second column. Characteristics are expressed as a formula in the third column. The formula is in three sections, referring to swimming apparatus, proximal pole of megaspore, and massula. Swimming apparatus: prefixed by C for columella, considered the basic component. Followed by columellar type (d dome— or cone-shaped; t triseptate), nature of floats (F = smooth, pseudovacuolate ; f ^ hairy, or poorly known float-like structures), float number (N = numerous) and number of float tiers (in brackets). Proximal pole: prefixed by P; c = collar; 1 labra, or similar structures. Massula: prefixed by M ( + M = massulae found attached to megaspores). In brackets, g = glochidia recorded; -g = eglochidiate; a =- anchor-shaped glochidia; d = anchor-shaped with distal dilation ; s = simple hair-like or coiled glochidia. In some instances the presence of certain features is indicated only as a possibility. CRETACEOUS PALAEOCENE EOCENE OLIGOCENE MIOCENE A. simplex Hall (1969b) Cd I/P / M (gad) A. barbata Snead (1969) Cd FN(2)/P / +M (gs) Hall & Bergad (1971) A. extinota Jain (1971) Cd fN /P (?!)/ +M (-g) A. geneseana Hills & Weiner (1965) Cdl /P / M (ga) A. lauta Snead (1969) Cd fN /P / M A. distincta Snead (1969) Cd FN(3)/ P(?l)/ +M (ga) Hall & Bergad (1971) A. sahapfi Dijkstra (1961) Cd fl8(3)/P (1)/ M (ga) Snead (1969) A, montana Hall k Swanson (196R) Cd f 15-20/P (1)/ +M (ga) Jain & Hall (1969) A. bulbosa Snead (1969) Cd fl8(3)/P / M A. fragilis Jain & Hall (1969) Cd FN/P (1) +M A. Stanley i Jain & Hall (1969) Cd FI5+/P /+M (ga) A . ve lus Jain & Hall (1969) Cd FN/P (1) / +M (ga) A. tesohiana Florschutz (1945) Cd F24(3)/P / +M (ga) Dijkstra (1961) A. intertrappea Sahni & Rao (1943) C? F3/P(c + 1)/ +M (gad) Hall (1969a) Trivedi & Verma (1971) A. indica Trivedi & Verma (1971) C? F3/P(c + 1)/ M (gad) A. primoBVa Arnold (1955a) Cd FI/P /M (gad) Hills & Weiner (1965) Hills S Gopal (1967) Hall (1969a) A. antiqua Dorofeev (1959) Ct F6-9(2)/P (c+1)/ M A. prisoa Reid & Chandler (1926) Ct F9 (2)/P (c+1)/ +M (gad) ■ A. nana Dorofeev (1959) Ct F9 (2)/P (c+1)/ M (-g) A. turgaioa Dorofeev (1959) Ct F9 (2)/P (c+1)/ M (-g) A. sibirioa Dorofeev (1959) Ct F9 (2)/P (c+1)/ M A. ventrioosa Nikitin (1955) Ct F9 (21/P (c+1)/ M f-a) Dorofeev (1959) A, YiiM.'itvYi'i'i Dorofeev (1955) Ct F9 (2)/P (c+1) / M A. aspera Dorofeev (1963) Ct F9 (2)/P (c+1) / M • 486 PALAEONTOLOGY, VOLUME 18 Section simplicispora Hall, 1970. Float-like columella or single float; anchor-shaped glochidia. Fossil species A. geneseana, A. primaeva, A. simplex. Section kremastospora Jain and Hall, 1969. Megaspore apparatus with more than nine floats; anchor- shaped glochidia. Fossil species A. distincia, A. montana, A. schopfi, A. stanleyi, A. tescliiana, A. velus. Section filifera Hall, 1 968. Megaspore apparatus with more than nine floats ; hair-like or coiled glochidia. Fossil species A. harbata. Section antiqua Dorofeev, 1959. Megaspore apparatus with six to nine floats in two tiers; massulae undescribed. Fossil species A. antiqua, A. aspera, A. nikitinii, A. sibirica. Section rhizosperma Meyen, 1836. Megaspore apparatus with nine floats in two tiers; glochidia absent, or simple, straight or branched structures. Fossil species A. nana, A. turgaica, A. ventricosa. Modern species A. nilotica, A. pinnata. Section azolla Meyen, 1836. Megaspore apparatus with three large floats; glochidia simple, hooked or anchor-shaped. Fossil species A. indica, A. intertrappea. Modern species A. caroliniana, A. filiculoides, A. mexicana, A. microphylla. Important contributions to our knowledge of the morphology of the megaspore apparatus and massula of fossil species of Azolla and their phylogenetic significance, have been made by Hills and Gopal (1967), Hall and Swanson (1968), Jain and Hall (1969), and Jain (1971). In some instances lack of suitable material has caused mis- interpretation of structure. This has resulted in some terminological confusion, especially with regard to the application of the term columella. Apart from variation in form of the glochidia, little has been written concerning the structure of the massula. It now seems clear that the multifloated swimming apparatus is more primitive than both the nine-floated and three-floated type. Massulae with anchor-shaped glochidia appear to be more primitive than those with hair-like glochidia, or those in which the glochidia are absent. Although the megaspore wall structure of several fossil species has now been examined, comparatively few have received detailed attention. The most important of such contributions is that of Kempf (1969a and h) who examined, by means of light and transmission electron microscopy, the megaspore wall of A. tescliiana, A. nana, A. cf. aspera, A. tomentosa, and A. tegeliensis. Structural details of the megaspore wall of modern species of Azolla are equally lacking, with the exception of A. filiculoides (Bonnet 1957), A. nilotica (Demalsy 1954), and A. pinnata (Kao 1935 ; Sweet and Hills 1971), and surprisingly little progress has been made in tracing the developmental history of the wall layers. Some confusion has resulted from the number of different terms which have been applied to these wall layers in both fossil and modern species. Structural variation of the megaspore wall between fossil Azolla species has been demonstrated, and attention drawn to this potentially useful method of identifying wall fragments (Kempf 1969a; Snead 1969, 1970; Hall and Bergad 1971). A. prisca has the distinction of being the earliest fossil species of Azolla in which both vegetative and fertile remains were described (Reid and Chandler 1926). The only record prior to this was that of Azollophyllum prirnaeviim Penhallow based on vegetative material (Dawson 1890), later to be known as Azolla primaeva. Increasing interest shown by many workers in Upper Cretaceous and Palaeogene species of Azolla stimulated this reappraisal of A. prisca, using ultra-thin sectioning, and both scanning and transmission electron microscopy. A. prisca is consistently described in the literature as an enigmatic species which cannot be placed in any existing FOWLER: OLIGOCENE AZOLLA 487 section of the genus due to the presence of anchor-shaped glochidia (Arnold 1955; Hills and Gopal 1967; Trivedi and Verma 1971). In this present work, the establish- ment of a new section to accommodate this species is considered both desirable and necessary. Azolla species with nine floats in the swimming apparatus are particularly characteristic of the Oligocene (see Table 1), a number of species having been recorded from Britain and the U.S.S.R. (Reid and Chandler 1926; Dorofeev 1959). Its occur- rence in the lowest Oligocene makes A. prisca one of the oldest nine-floated species to be recorded, this type of swimming apparatus being rare in pre-Oligocene rocks. This species affords the opportunity of investigating what may possibly be an important evolutionary link between the Eocene and Oligocene representatives. Critical study, coupled with adequate description and illustration, has never previously been attempted for any Oligocene species of Azolla. LOCALITY AND STRATIGRAPHY A. prisca was described from the Insect Limestone of the Isle of Wight as part of the rich Bembridge flora (Reid and Chandler 1926). The Insect Limestone is a fine- grained blue-grey argillaceous limestone, varying in thickness up to 0-3 m and located just above the base of the Bembridge Marls which reaches a maximum thick- ness of some 33 m. The Bembridge Marls rest on the freshwater Bembridge Lime- stone. Much of the Insect Limestone is barren and, according to Reid and Chandler (1926), the plant collection was made from small pockets over a twenty-five year period. Numerous insect remains are reported from this horizon (Woodward 1879). The Insect Limestone is seen in the cliff-section of Gurnard Bay (SZ 467 943), but to the west in Thorness Bay it reaches shore level. During the Palaeogene, Hampshire occupied a marginal position between sea to the east and land to the west. The Bembridge Marls accumulated during a regressive phase when non-marine conditions were re-established after an initial transgressive phase of short duration. According to Daley (1973), the depositional environment of the Insect Limestone is not well understood. Most workers consider the Bembridge Marls to be of Oligocene age, though an Upper Eocene age has been suggested (Blondeau, Cavelier, Leugueur and Pomerol, 1965). Machin (1971), using palynological evidence, placed the Eocene-Oligocene boundary at the base of the Lower Hamstead Beds, at the same time suggesting that the base of the Bembridge Marls, lower in the succession, might be considered a possible alternative. Preliminary palynological investigation of the Insect Lime- stone by the author suggests that a lowermost Oligocene age might be appropriate for the base of the Bembridge Marls. Rock specimens used in this investigation had well-preserved massulae and mega- spore apparatuses scattered over the surface (Specimens V. 17729 and counterpart, British Museum (Natural History)). This material was originally collected by J. E. E. A’Court Smith during the latter half of the nineteenth century. Repeated attempts by the author to find suitable material of A. prisca from the type locality were unsuccessful. 488 PALAEONTOLOGY, VOLUME 18 METHODS Megaspore apparatuses and massulae were excavated from the rock surface by means of fine needles, cleaned of adhering particles of matrix in 40% hydrofluoric acid, then washed thoroughly in distilled water. Megaspore apparatuses were examined and photographed, in dry condition and in water, using a Wild-Heerbrugg M7 Stereomicroscope and Photoautomat camera. Massulae were examined and photo- graphed by means of a Wild-Heerbrugg M20 light microscope with Photoautomat. Air-dried specimens for scanning electron microscopy, using a Cambridge Instru- ments Company Stereoscan, were attached to double-sided sellotape on stubs, and coated with gold using a Polaron E5000 Spatter Coater. Ultra-thin sections of the megaspore apparatus were cut with a LKB Ultratome and glass-knife, after embedding in Taab resin. Sections of thickness 1-5 /xm stained with basic fuchsin and methylene blue were used for light microscopical examination, and of thickness 600 A stained with uranyl acetate and lead citrate for examination with the transmission electron microscope (Philips EM 300). SYSTEMATIC DESCRIPTION Order salviniales Family salviniaceae Genus azolla Lamarck, 1783 Section trisepta sect. nov. Azolla prisca Reid and Chandler, 1926 The new section Trisepta is erected to include species of Azolla with the following characteristics: megaspore apparatus clearly differentiated into megaspore and swimming apparatus; swimming apparatus consisting of a hairy peltate columella forming three compartments, each separated by a septum of columellar material; attached to the columella are nine floats arranged in two tiers, three triangular floats above and six oval floats beneath ; each compartment of the columella accommodates one triangular and two oval floats; the massula bears non-septate anchor-shaped glochidia each with a distal dilation immediately beneath the anchor-shaped tip. The name Trisepta refers to the three septa of the columella which divide the swimming apparatus into compartments housing the floats. Details of vegetative features, structure of the sporocarp and sporangial wall of A. prisca, are not included in this investigation which is concerned solely with the dispersed megaspore apparatus and massula. According to Reid and Chandler (1926) the megasporocarps and microsporocarps occur together in pairs with at least twelve massulae in the microsporangium. TEXT-FIG. 1. Azolla prisca Reid and Chandler, a and b, swimming apparatus, x 160. a, intact, b, floats removed showing columella and labra on proximal surface of megaspore, c and d, section of megaspore wall, c, with tubercle, and showing stratification, x 1750. d, at proximal pole, showing structural modifica- tion and labra, x700. b base of striated layer; c columellate zone; ca ^ tomentose cap; co -= collar; d dense zone; E = exine of megaspore proper; G granular layer, much thickened at proximal pole; h hairy zone; H homogeneous layer; 1 labrum;o oval float; p = proximal surface of megaspore; p perine;s tomentose septum; sp = spongy zone; S = striated layer; t ~ triangular float; tr position of triradiate suture in exine. FOWLER: OLIGOCENE AZOLLA 489 D P I ^ ''"^1 > t3::i5Mji:ra E P 490 PALAEONTOLOGY, VOLUME 18 DESCRIPTION OF MEGASPORE APPARATUS The megaspore is rounded, thick-walled, and bears several large rounded to vermi- culate tubercles toward the distal surface. Above the proximal surface of the mega- spore lies the swimming apparatus, the basic component of which, the columella, is composed of long, unbranched and intertwined hair-like filaments. This columella is peltate, with a small dome-shaped cap at the apex, and a hollow central strand with wing-like longitudinal extensions dividing the swimming apparatus into three com- partments. Attached to the columella are nine floats, an upper tier of three triangular floats and a lower tier of six smaller, oval floats (text-fig. 1a, b; PI. 59, figs. 1, 2). Most of the hairs forming the columella originate from a thickened area of mega- spore wall which forms a prominent collar around the megaspore delimiting the periphery of the proximal face. The columellar structure of A. prisca may best be understood if it is regarded as resulting from the invagination of a dome-shaped tomentose columella to form three compartments, each compartment being lined by hairs. As a result, adjoining compartments are separated by a thick double-layer of tomentose material which forms the septum. The thinner tomentose layer covering the base of each compartment is supplemented by hairs from the proximal surface of the megaspore. Each compartment accommodates a single upper triangular float and two oval floats beneath. Hair-like filaments of the columella are continuous with similar structures on the megaspore wall which, though scattered over the surface, are particularly abundant near tubercles. The cap covering the uppermost area of the triangular floats (PI. 59, figs. 1-3) has an inner layer of closely interwoven hairs, continuous with the columella, and an outer darkly pigmented membraneous layer. Length of megaspore apparatus 446 ixm to 475 ixm, average 455 /um; width of mega- spore apparatus 237 ju,m to 270 ^um, average 255 |um (twelve specimens measured). The floats are vacuolate pseudocellular masses, loosely attached to the columella by relatively few hairs limited to the inner faces of the float (PI. 60, fig. 1). The central region of the float is occupied by pseudocellular cavities approaching 25 |U,m in diameter, whilst a well-delimited narrow zone of smaller cavities, average diameter 2-5 ju.m, occurs at the surface (PI. 60, fig. 3). Hairs on the floats are tubular extensions of the peripheral cells (PI. 60, fig. 2) with a uniform diameter of approximately 2 jum, often exceeding 75 |um in length and with blunt ends. A few closely spaced septa may occasionally be found toward the hair base. The knot-like structure described by various authors (Strasburger 1873; Campbell 1893; Hannig 1911; Kempf 1969^) can often be seen within the float occupying a more or less central position (PI. 61, fig. 1). EXPLANATION OF PLATE 59 Figs. 1 -5. Scanning electron micrographs of Azolla prisca Reid and Chandler from the Insect Limestone (Bembridge Marls, Oligocene), Gurnard Bay, Isle of Wight. 1-2, intact megaspore apparatuses in dif- ferent view. 1, swimming apparatus showing triangular float and two oval floats above hairy collar, and apical cap. Distal surface of megaspore shows tubercles, x 175. 2, tomentose septum between two smooth oval floats, x 175. 3, megaspore apparatus dissected revealing megaspore exine within perine. Vacuolate floats and apical cap clearly seen, x 170. 4-5, perine surface. 4, tubercles formed of anastomos- ing cylindrical elements. The spherical bodies are fungal spore contaminants, x 750. 5, surface regulate verrucate, with foveae in which hair bases lie, X 1900. PLATE 59 FOWLER, Azolla prisca 492 PALAEONTOLOGY, VOLUME 18 The substance forming this structure is regarded as rudimentary exine by Hannig (1911) and Kempf (19696). Removal of the columella shows a triradiate wall which attains a height of some 75 (um at the centre of the proximal surface of the megaspore, decreasing in height toward the periphery (text-fig. 1b). In median longitudinal section the triradiate wall is seen to be formed by the close association of two vertically orientated labra bordering a suture (text-fig. Id; PI. 61, fig. 1). Pronounced sculptural and struc- tural differences occur between the wall of the proximal face and that of the rest of the megaspore. This was initially indicated by the darker coloration of the latter, later to be confirmed by examination of the wall in thin section. The three compart- ments of the columella lie directly above the inter-labral areas, the septa thus coinciding with the labra. The megaspore wall is composed of two principal parts, the exine of the megaspore proper to the inside, and perine to the outside. The perine surface is rugulate-verrucate, with foveae to a depth of some 2 ^um. Hairs scattered over the surface are 0-5-1 i^Lin in diameter, their bases appearing to originate in the depressions of the foveae (PI. 59, figs. 4, 5). Dissection of the megaspore apparatus, via the proximal surface, reveals the detached exine of the megaspore proper with the trilete mark uppermost (PI. 59, fig. 3). This simply bordered trilete mark is small, with laesurae extending little more than a third of the way to the equator; its position is coincident with the trilete suture on the proximal face of the megaspore. The diameter of the megaspore proper is approximately 190 |U.m; the surface is finely pitted to reticulate (PI. 60, figs. 4-7). The megaspore wall is composed of three main layers, an exine and two-layered perine, structural details of which can be seen in text-fig. Ic and Plate 61, figs. 3, 4. In optical and thin section the exine is seen to have a thin basal zone above which it is striated, the total thickness approaching 3 (PI. 60, fig. 5; PI. 61, fig. 3). As seen with the transmission electron microscope, the exine has an essentially granular structure, with the basal zone formed by fusion of elements (PI. 61, fig. 4). Above the basement zone the elements, though fused to form a spongy network, are orientated in such a way as to provide numerous narrow, radially arranged sinuous cavities of varying length. Lateral fusion of these radially arranged elements in the uppermost part of this layer provides a relatively smooth exinous surface. Numerous small granules on this outer surface allow for a certain degree of interlock with the layer above, yet rendering the exine readily detachable. The radially orientated elements EXPLANATION OF PLATE 60 Figs. 1-12. Azolla prisca, megaspore apparatus and massula. 1-3, float structure. 1, oval float, biconvex in side view, with hairs near apex of inner face, x375. 2, hair base, x 1550. 3, surface showing small pseudocellular cavities, with larger cavities beneath, x 480. 4-7, megaspore proper. 4, proximal surface showing trilete mark, X 180. 5, exine in optical section, x 1875. 6, exine surface at high, and 7, low level of focus, x 1875. 8-T 1, massula. 8, massulae attached to megaspore apparatus, just below collar, x75. 9, massula with anchor-shaped glochidia, x250. 10, anchor-tip showing two recurved prongs and dilation beneath, X 1250. II, massula with microspores and associated funnel-shaped cavities, x940. 12, microspore-containing cavity and associated funnel-shaped cavity opening by a pore to the exterior, X 940. PLATE 60 FOWLER, AzoUa prisca 494 PALAEONTOLOGY, VOLUME 18 give the characteristic striated structure at lower magnification, and is consistent with the sculpture of the exine. The perine is divisible into an inner granular and outer homogeneous layer, the latter stratified into four zones. Its thickness, though variable due to protuberances and elaboration at the proximal surface, is approximately 10-5 ixm, excluding the outer hairy zone. The granular layer, which is approximately 3 i^m thick, has a smooth base and undulating upper surface (PI. 61, fig. 3). Transmission electron microscopy shows that the structural elements within the striated and granular layers are similar, though more haphazardly arranged in the latter (PI. 6 1 , fig. 4). The homogeneous layer is supported above the granular layer by small solid columellae, 0-5-1 ;u,m in height, forming the columellate zone. This passes up into a spongy zone, approximately 4-5 /xm thick, composed of an irregular network of large elements which fuse to form a solid outer covering about 2-5 fxm in thickness. The surface of this outer dense zone is dissected by grooves and pierced by foveae to give the sculpture already mentioned. The outermost zone of the perine is composed of hair-like filaments originating from the dense or spongy zones at the bases of the foveae, or from the reduced spongy zone within the tubercles (text-fig. Ic; PI. 61, fig. 3). The wall of the tubercle is com- posed of an anastomosing network of cylindrical elements developed from the dense zone (PI. 59, fig. 4). At the proximal pole of the megaspore, the perine structure is much modified from that described above, this transformation taking place in the collar region (text-fig. Id; PI. 61, figs. 1, 2). Here, the wall approaches 50 fxm in thickness (exclud- ing the hairy zone), most of this being composed of the greatly thickened and vacuo- lated granular layer. Correspondingly, the homogeneous layer is much reduced in this region, being represented only by the dense and hairy zones. The proximal wall, with an average thickness of 25 nm increasing to 100 |um in the formation of labra, is composed almost entirely of the granular layer. On this proximal surface of the megaspore the homogeneous layer almost completely disappears, remaining only as scattered granules from which hairs may arise. The structure of the proximal wall, with pseudocellular cavities as large as 21 jj.m in diameter, is reminiscent of that of both float and massula. A single layer of small cavities, approximately 4 jxm in diameter, form the outer surface of the proximal wall. EXPLANATION OF PLATE 61 Figs. 1-4. Azolla prisca, megaspore apparatus in thin section. 1, median section through megaspore apparatus, showing two triangular floats covered by cap, oval float beneath with ‘knot’ at centre, partially detached exine, thick perine with tubercles, and vacuolate proximal wall with labra. Megaspore wall has fractured in the collar region, x 200. 2, wall in collar region, showing thickening and vacuolation of granular layer and reduced homogeneous layer represented only by dense zone. Hairs occur on dense zone. Detached exine at bottom of figure, x 1400. 3, wall and tubercle. Outside the detached striated exine, the granular layer supports the homogeneous layer divisible into columellate, spongy and dense zones. Tubercle composed of anastomosing cylindrical elements formed by the dense zone. Within the tubercle the spongy zone appears reduced, giving rise to hair-like structures, x950. 4, transmission electron micrograph showing partially detached exine, granular layer, spongy and dense zones of homo- geneous layer, x 4000. PLATE 61 FOWLER, Azolla prisca 496 PALAEONTOLOGY, VOLUME 18 DESCRIPTION OF MASSULA Numerous massulae of the same type were found associated with, and attached to, megaspore apparatuses of A. prisca. There seems little reason to doubt that both types of reproductive structure belong to the same parent species. Invariably, the massulae are found attached by their anchor-shaped glochidia at, or near, the hairy collar region of the megaspore apparatus (PI. 60, fig. 8). The massulae are vacuolate pseudocellular discoid bodies ranging in maximum diameter, excluding glochidia, from 98-8 to 167-2 [j.m, averaging 136-7 ij.m (fifty specimens) (PI. 60, fig. 9). As in floats, the pseudocellular cavities of the massula range in diameter from approximately 5 /xm at the periphery, to about 25 fxm toward the centre. Occasionally, in both floats and massulae, large cavities may extend to the periphery. Glochidia are rarely seen projecting from the massula, being mainly restricted, and closely adpressed, to the flattened surfaces. The nonseptate glochidia have an average length of 70 ;u,m; the stalk, approximately 5-5 p.m wide in the median region, tapers to about 2-3 ^m at the proximal and distal ends. A slight dilation of the stalk near its distal extremity becomes abruptly constricted again at the Junction with the anchor-shaped tip. Average width of the anchor-shaped tip is 8-4 ^m, and the two prongs of the anchor are recurved (PI. 60, fig. 10). An inverted V-shaped diaphragm, often seen 5-6 fxm beneath the distal dilation, separates what appears to be a tubular stalk from a solid tip. Microspores, averaging 20-8 ;u,m in diameter (range 15-25 |U,m, 150 specimens measured), occupy large pseudocellular cavities within the massula. Six microspores per massula appears usual, though the number ranges from three to nine. Micro- spore walls are laevigate, with a thickness less than 1 jj.m. Each microspore-containing cavity is closely associated with the bulbous base of a funnel-shaped cavity, the neck of which extends to the periphery, opening by a pore to the exterior (PI. 60, figs. 11, 12). The diameter of this pore approximates to that of the small cavities to the outside of the massula. The germinal area of the microspores, represented by both closed and open triradiate sutures, consistently occurs in a position adjacent to the base of the funnel-shaped cavity (PI. 60, fig. 11). An incomplete partition appears to connect these two adjoining cavities. DISCUSSION Most Azolla species with nine floats in two tiers in the swimming apparatus can be included in sections Rhizosperma or Antiqua. Section Antiqua is established on the basis of A. antiqua, a fossil species from the late Eocene and early Oligocene of the U.S.S.R. in which the massulae are unknown (Dorofeev 1959). The nine-floated species A. nana, A. turgaica, and A. ventricosa, described by Dorofeev (1959), and in which the massulae are reported as eglochidiate (Hall and Swanson 1968; Trivedi and Verma 1971), can be included in the Rhizosperma, together with the modern species A. nilotica and A.pinnata. It would seem expedient to include the fossil species A. aspera, A. nikitinii, and A. sihirica, together with yl. antiqua, in the section Antiqua until further information is available on the massulae. Since A. prisca cannot be included in either of these sections of the genus, due to its anchor-shaped glochidia. FOWLER: OLIGOCENE AZOLLA 497 it seems appropriate to establish a new section, Section Trisepta, to accommodate this, and similar species. The columella in fossil and modern Azolla. Most pre-Eocene Azolla species were described between 1969 and 1971, resulting in some synonymy, and confusion in the descriptive morphology of the reproductive structures. The columella, as first recog- nized by Meyen (1836), is well defined by the time Campbell (1893) describes it as a short stalk from which microsporangia develop laterally. Since then, the term has taken on dual usage, being also applied to that part of the swimming apparatus bear- ing floats. Misinterpretation of the structure of the megaspore apparatus in both fossil and modern species has resulted in a confused and inaccurate definition of the term columella. One of the first applications of the term to the megaspore apparatus is made by Eames (1936) in an account of the reproductive structures of modern Azolla species. Here it is regarded as a conical pad of tissue situated, as the name suggests, in a central position between the floats. Hall and Swanson (1968) illustrate this interpretation of the columella with reference to the vacuolate pseudocellular peg-like structure between the floats of the modern A. mexicana. However, in the same work the authors describe the columella of the fossil species A. montana as a hairy, hollow, thimble-shaped structure with attached floats. Further complica- tions arise with the definition by Jain and Hall (1969), given as ‘a peg-like or cone- shaped structure, distally continuous with the perispore and commonly hairy or highly vacuolate’. Even when applied to the megaspore apparatus, the term columella is apparently being used to describe two different structures, features of both having become incorporated within the definition. This study of A. prisca indicates that the vacuolate peg-like structure is best regarded as an elaboration of the proximal wall of the megaspore, and not as part of the hairy superstructure primarily concerned with holding the floats. On the bases of priority and aptness, the term columella should be applied to the peg-like structure. However, as alternative terms may be found for modification of the proximal wall of the megaspore, and since the term has now been widely adopted for the tomentose superstructure in fossil species, it is proposed to retain the term for that particular purpose. A reappraisal of the structure of the columella would seem pertinent, especially as it is the major component of the swimming apparatus in Palaeogene species of Azolla. The columella is essentially a hairy superstructure over the proximal surface of the megaspore, formed from hair-like filaments of the megaspore wall. The swimming apparatus can be composed solely of this one component, forming a structure called a columellate float, as in A. simplex (Hall \969b). Commonly, a second component, the float, is developed. It is generally accepted that true floats are distinguished from the columella by their vacuolate pseudocellular structure and lack of surface hairs. Such distinction should be preserved, to the extent that a term such as columellate float should be abandoned, this type of structure simply being regarded as an undif- ferentiated columella. Similarly, in species such as A. montana, where structures described as floats are hardly distinguishable from the columella, it would seem more appropriate to refer to the structure as a segmented columella. The form of the columella varies in different species, such variation depending on the volume of the swimming apparatus given over to float production, and the size, shape, and number 498 PALAEONTOLOGY, VOLUME 18 of floats. At its simplest, the columella appears to be dome- or cone-shaped, as in A. simplex and many multi-floated species. In A. prisca, and possibly all nine- and three-floated species, modification of the dome-shaped type of columella by float production in three sectors has restricted its development to a thin layer in the form of a triseptate structure. A transverse section of this type of columella, as seen in the Lower Pleistocene species A. tegeliensis, is well illustrated by Kempf (19696, fig. 8). Here, two layers of tomentose material are seen to form each septum dividing float compartments. The suggestion that the basic form of the columella is dome-shaped is an oversimplification. In some species there is a tendency for only the central part of the columella to be hollow, often with a pore-like opening at the apex. A. rnoniana shows such a pore (Jain and Hall 1969), and Hall (19696), commenting on A. simplex, states ‘in many specimens there is a canal in the columellate float, extending from the apex of the megaspore body to the tip of the swimming apparatus’. The canal, though narrow, is present in A. prisca, passing up through the central strand of the columella, the position of the pore being marked at the apex by a small indentation in the apical cap (text-fig. 1a; PI. 59, fig. 3). There is some doubt as to whether the apical cap, so characteristic of A. prisca and other nine-floated species in the Oligocene, is truly part of the columella. According to Rao (1935), describing a similar structure in the modern nine-floated species A . pinnata, it is a remnant of the inner part of the megasporangial wall. However, as can be seen in A. prisca, both the columella and the outer membraneous megasporangial wall would appear to be represented (PI. 59, fig. 1). Scanning electron microscopical examination of megaspore apparatuses of modern nine- and three-floated species, after removal of the enveloping megasporocarp and megasporangial walls, shows that the columella forms a tomentose peltate structure lining the inside of the mega- sporangial wall at the apex of the swimming apparatus. The columella within the swimming apparatus of the modern A. filiculoides, A. pinnata, and A. nilotica has been described by various authors (Bonnet 1957; Campbell 1893; Demalsy 1954; Rao 1935) but its apparent insignificance precluded a term being applied. In these species, representing both the three-floated and nine-floated condition, the peltate part of the columella, which becomes inverted on removal of the megasporocarp and megasporangial wall, is described simply as an abundance of hairs at the apex of the swimming apparatus. The present work indicates that the columella of all nine- and three-floated species, fossil and modern, is both peltate and triseptate. Furthermore, the small tomentose columellar cap seen in fossil species such as A. prisca, was probably more extensively developed in life, having been lost after release from the parent plant. The tomentose cap is not recorded with any degree of certainty before the Oligocene, though Hall (1969u) suggests that this feature may be present in A. intcrtrappea, an Eocene species from India. The author is not aware of a similar structure having been recorded for any megaspore apparatus other than the nine- and three-floated type. There is variation in the extent to which the swimming apparatus, and hence the columella, covers the megaspore in fossil species. Jain and Hall (1969), suggests that the swimming apparatus completely envelops the megaspore in ancestral types similar to AzoUopsis, becoming progressively more restricted to the proximal pole of the megaspore in the course of evolution. FOWLER; OLIGOCENE AZOLLA 499 A. prisca appears to be the first species, chronologically and stratigraphically, in which the triseptate columella is considered of structural and evolutionary significance, hence the use of this feature in naming the section Trisepta. Wall structure. Modification of the proximal pole of the megaspore can be seen in fossil and modern species of Azolla. The earliest example of such modification can be found in the late Cretaceous to Palaeocene species A. schopfi, described by Dijkstra (1961) as having triradiate ridges, 60 pm in height, which are clearly visible when the swimming apparatus is absent. A. distincta, with a similar stratigraphic range, is described as having columella and floats with the ‘same foamy texture’ (Hall and Bergad 1971). Possibly this foamy columella in A. distincta is really the proximal face of the megaspore with vacuolate pseudocellular structure like that of the floats, as in A. prisca. Study of the literature suggests that apart from the above-mentioned species similar modification may occur in extincta, A. montana, A. fragilis, A. velus, A. intertrappea, and indica, and may be a common feature of pre-Oligocene species. In A. prisca structural modification of the proximal surface takes the form of lips bordering the triradiate suture. A transition zone of this sort between sutures and the remainder of the proximal surface, due to increased wall thickness, sculptural modification, or both, is termed a labrum (Couper and Grebe 1961). The term gula, applied by Kempf (19696) to a similar structure in A. tegeliensis, is best retained for a more marked extension of the labra than that seen in A. prisca. Wall stratification in Azolla megaspores is complex and a number of terminologies has been applied. Details of terminologies used, together with suggestions as to various authors’ interpretations of the megaspore wall structure, is not within the scope of this work which is not primarily concerned with developmental history of the wall layers. However, it would be appropriate simply to outline the main termino- logies used for both modern and fossil species. Campbell (1893) recognized two principal layers in the megaspore wall of A. filicidoides, an inner exospore, and an outer epispore which could be sub-divided into two zones. Later workers adopted the same terminology in describing the wall of modern Azolla, though Demalsy (1954) and Bonnet (1957) delimited an innermost endospore from the exospore. By this time, perispore was being used as an equivalent term to epispore. Kempf (1969fl and h) uses the terms exine, instead of endospore and exospore, and perine, instead of epispore and perispore, for both fossil and modern species. In earlier work on fossil species the exine was termed endospore and most of the perine was called exospore, the term perispore being reserved only for the outer hairy zone of the perine (Hall and Swanson 1968; Jain and Hall 1969). Jain (1971), though using the same basic delimitation of layers, termed the hairy zone as perine, and applied the terms endexine and ectexine to the exine and remainder of perine respectively. The terminology adopted for A. prisca, and for fossil and modern species mentioned in this work, is that used by Kempf (1969a and b). Sweet and Hills (1971), describing the megaspore wall of A. pirmata, indirectly make use of the term perine by intro- ducing the terms inperine and experine. Such introduction of new terms is, in the author’s opinion, both unjustifiable and unnecessary. Wall structure of modern species has received little detailed attention, and the development of the wall layers is imperfectly understood. Such information available 500 PALAEONTOLOGY, VOLUME 18 indicates that, as in prisca, the exine is composed of a basement zone and radially striated zone. The inner layer of the perine (equivalent to the granular layer of A. prisca) is described as granulate, reticulate, or foamy, in A. pinnata, A. nilotica, and A. filiculoides respectively, such differences possibly reflecting the degree of vacuolation of this layer in each species. In A. filiculoides it is called the ‘couche ecumeuse’, is characteristically vacuolated and extensively developed, forming eruptions toward the surface (Bonnet 1957). Demalsy (1954), describing structural variation in the megaspore wall of A. nilotica, points out that this inner layer of the perine appears thicker and heterogeneous in some megaspores. However, similar structural differences may be observed in oblique sections of the wall of A. prisca. The outer homogeneous layer of the perine is composed primarily of radially elongated elements in A.pinnata and A. nilotica, that of A. filiculoides appearing to have a denser structure. As in A. prisca, the outermost zone of the homogeneous layer is composed of hairs. Hannig (1911) suggests that in A. filiculoides hairs originate from eruptions into the dense zone of the vacuolate granular layer, a suggestion later accepted by Bonnet (1957). Photographs of the ultrastructure of the megaspore wall of A. fili- culoides, loaned to the author (Pettitt 1974, pers. comm.), would appear to sub- stantiate this. However, it is possible that a very thin layer of homogeneous material is deposited over the granular layer, at the site of the eruption, before hairs form. Hairs certainly appear to originate directly from the surface of the dense zone in the intervening areas, as illustrated by Bonnet (1957, fig. 35). In A. prisca, hairs appear to be composed of the same material as that of the homogeneous layer, and they can be seen to arise from the spongy zone within the tubercle and from the dense zone in the collar region. Hairs which originate in foveae, away from the tubercle, appear to originate from the dense zone, though a connection between the hair base and spongy zone beneath is not discounted. Details of wall structure are now known for several Palaeogene species, with A. prisca furnishing the best example from the Oligocene. Although there is distinct variation in thickness and structure of individual layers or zones, a similar pattern to that seen in modern species is shared by the majority of fossil types. This basic pattern in fossil species can be summarized as follows: An exine, 3-4 /j,m thick, is covered by a two-layered perine. The inner layer of the perine is smooth, granular, or laminated, and between 3-8 |U.m in thickness. It is the outer homogeneous layer which shows most interspecific variation, and it is divided into at least three zones by most authors. There is often a columellate zone supporting a reticulate or clavate zone, the elements of which become fused toward the surface from which hairs arise. As Pettitt (1966) points out, the term perine, and equivalent terms, are indis- criminately used for a variety of exinous and extra-exinous layers of the spore or pollen wall. Erdtman (1952) defines the perine as an outer extra-exinous layer formed by the activity of a tapetal plasmodium. It is acknowledged that use of such terms as exine and perine for A. prisca has developmental implications. However, structural similarities between the vacuolated granular layer, massulae, and floats of A. prisca cannot be disregarded, and suggest that these structures may be homologous. This similarity is even more marked in modern T . /7//cu/o/V/(?5' where the vacuolated granular layer is extensively developed in the megaspore wall, not merely limited to the proximal pole as in A. prisca. As massulae and floats are usually accepted as perinous. FOWLER: OLIGOCENE AZOLLA 501 there seems reasonable justification in regarding the granular and homogeneous layers of A.priscaas perine. Only intensive study of the development of the megaspore wall of modern Azolla will reveal whether a particular layer is exinous or perinous. Structural resemblances between the wall of modern and fossil species suggest the possibility that conclusions reached from study of modern species may also be applied to fossil species. Kempf (1969(3 and b, 1973), equates the perine of megaspore walls with the ektexine of angiosperm pollen grains, emphasizing the presence of foot layer, columellae, and tectum in both. At the same time the spore exine is equated with the endexine of the pollen grain. This would seem unacceptable, as the term perine can only correctly be applied to plants with a periplasmodial tapetum, and which is known to contribute sporopollenin to the pollen grain wall. Though Kempf ’s (1969fl) terminology is used, the author does not hold the view, expressed by Kempf (1973), that all spore walls have perine to the outside, the exine beneath playing no part in surface orna- mentation. The terms adopted here are intended only for species of Azolla. Snead’s (1969) contention that wall structure is sufficiently variable in fossil Azolla to allow species identification from wall fragments would seem to be correct, though it should be applied with caution. More intensive study using ultra-thin sectioning would seem necessary before individual species can be identified with any degree of confidence. The extent of variation within a single megaspore wall, and between spores of the same species must be evaluated. Interpretation of the wall of fossil megaspores found attached to the parent plant may result in description of immature structure, since megaspores become detached at maturity. Development of labra, or similar structures, appears to be linked with a thickening of the megaspore wall to form a collar around the proximal face of the megaspore. The Eocene species A. intertrappea not only provides the earliest example of this association, but is also the earliest species to demonstrate the significant part played by the granular layer in the formation of the proximal wall and labra (Sahni 1941). Such development of the proximal pole is readily seen in A. prisca, where the collar and labra are prominent features of the megaspore. Here, the collar region and proximal wall with labra are composed almost entirely of the thickened vacuolated granular layer, the homogeneous layer becoming reduced to a thin covering of scattered granules which may be associated with hair development. This association of labra and collar, with a prominent granular layer in the proximal wall, probably occurs in other nine-floate(i Oligocene species. After the Oligocene, it can again be seen in the Lower Pleistocene species A. tegeliensis (Kempf 19696) and A. pyrenaica (Florschiitz and Menendez Amor 1960), representing the nine-floated and three- floated condition respectively. The apparent size difference between the gula of A. nana, as illustrated by Kempf (1969(3, pi. 13, fig. 8), and the labrum of A. prisca, may possibly be accounted for by differences in preparation technique. In A. nana, contraction of the megaspore wall in the collar region, with associated infolding of the exine, has also resulted in the extrusion of the vacuolate proximal wall upward between the floats, so giving an exaggerated size to the structure which has been termed a gula. It is conceivable that the apparent size of the gula is partly responsible for the importance attached to this structure by Kempf (19696) with regard to anchor- age of floats, the tomentose columella being considered of minor significance. 502 PALAEONTOLOGY, VOLUME 18 Maximum development of the proximal pole of the megaspore occurs in modern species. Concerning the role of the granular layer, Rao (1935) states that this layer forms the spongy conical structure at the top of the megaspore in A. piimata. The author’s own observations, together with published description and illustration, indicate that modern species have a much enlarged collar, a central conical structure trisected by sutures, and a similar role for the granular layer as that seen in A. prisca (Rao 1935, pi. 19, fig. 45; Demalsy 1954, pi. 10, figs. 201-202; Bonnet 1957, text- fig. 3; Hall and Swanson 1968, fig. 14). Relevance of funnel-shaped cavities. Funnel-shaped cavities occurring in association with microspore-containing cavities is a consistent feature of all massulae of A. prisca examined. The germinal area of the microspore, represented by a triradiate mark, consistently occurs in a position adjacent to the base of the funnel-shaped cavity, which often appears as a thin incomplete partition. The exterior pore and the open- ing in the base of the funnel-shaped cavity are found associated with microspores having both closed and open sutures. The occurrence of uniform funnel-shaped cavities associated with closed sutures, together with the intact nature of the funnel, not appearing to have formed by breakdown of pseudocellular material, would seem to support the suggestion that these structures are features of the primary develop- ment of the massula, and not formed as a result of post-germination prothallial activity. Such organization could conceivably have formed an escape mechanism for spermatozoids, and to the author’s knowledge, no directly comparable structure has previously been recorded for Azolla species. Fames (1936), describing microspore germination in modern Azolla, states that a papilla protrudes through the opened sutures, then differentiates to form a small prothallus on which develops an antheridium producing eight spermatozoids. The gametophyte remains embedded in the massula, spermatozoids being freed by the eventual breakdown of the outer part of the massula. Most accounts of microspore germination in Azolla are similar, there being no mention of funnel-shaped cavities. It seems unlikely that such organization, which would seem to impart distinct bio- logical advantage, was no longer a feature of the massulae of modern species. Pre- liminary examination of massulae of modern A. filiculoides by the author reveals a similar organization to that described for A. prisca. It seems possible, therefore, that such organization may occur in the massulae of all Azolla species, fossil and modern. Evolutionary trends. Pioneering work by Hills and Gopal (1967) led to the con- clusion that the three-floated condition in the swimming apparatus of Azolla is ancestral to the nine-floated condition. This conclusion was based largely on the discovery of A. geneseana, a late Cretaceous species purported to possess three floats from study of a few poorly preserved specimens (Hills and Weiner 1965). Other workers have since failed to establish the presence of three-floated specimens at the type locality (Snead 1969; Jain 1971). Together with A. simplex, the oldest species yet described (Hall 19696), A. geneseana is best considered as possessing a tomentose columella without float diflerentiation. A. primaeva, an Eocene species once erroneously reported as having three floats (Hills and Weiner 1965; Hills and Gopal 1967), is now believed to have a single large vacuolate pseudocellular float- FOWLER: OLIGOCENE AZOLLA 503 like structure on which surface hairs may be present (Hall 1969n). Apart from species just mentioned, the majority of late Cretaceous and Palaeocene species are multi- floated, bearing up to twenty-four floats which may, or may not, have structure different from that of the columella. Readily distinguishable floats probably made their appearance before the close of the Cretaceous, as in A. barbata (Snead 1969; Hall and Bergad 1971). Many multifloated species, however, have little more than a segmented columella, as in A. montana, in which the so-called floats are hardly differentiated from the hairy columella. The float-like structures described in A. distincta, A. fragilis, A. stanleyi, Sind A. veins may represent an evolutionary advancement in float development, in that they lack hairs and are readily removed from the dome-shaped columella (Hall and Bergad 1971; Jain and Hall 1969). Megaspores in which the floats, proximal wall, and collar region are distinctly vacuo- late make their first appearance in the Eocene of India, with A. intertrappea and A. indica. These two species are the earliest recorded as showing the three-floated condition, though this is still a matter for speculation. Hall (1969<7), in a revision of A. intertrappea, accepts the presence of three floats, and describes this species as having a well-developed peltate columella bearing small floats approximately half the size of those of extant three-floated species. Megaspores with three floats, similar to those of extant species do not appear until the Oligo-Miocene (Lancucka- Srodoniowa 1958). Sahni (1941 ) points out that the exact number of floats in A. inter- trappea is difficult to ascertain in longitudinal section, due mainly to the thickness of the sectioned material, the floats being seen at different levels of focus. From such material, interpretation of A. intertrappea as having one or nine floats would appear equally possible, and on stratigraphic evidence, would seem more plausible. A. indica, described by Trivedi and Verma (1971 ) as probably having three floats, furnishes no better evidence for the existence of the three-floated condition in the Eocene. Until further information is available, A. intertrappea and A. indica are accepted as having three floats in the swimming apparatus. These two species are very similar, and may eventually be regarded as con-specific. Main differences reported are number of microsporangia, size of microsporangia and massulae, and structure of the glochidia, which is described as septate in A. indicia and non-septate in A. intertrappea (Trivedi and Verma 1971). Presence or absence of a septum provides the only difference of possible value, though it seems likely that the diaphragm separating the solid glochidial head from the stalk, as seen in A. prisca, may have been interpreted as a septum. Evolutionary development of the swimming apparatus of Azolla seems reasonably clear, and may be summarized as follows. The multifloated condition appears more ancient than the nine-floated and three-floated condition, but due to the presence of A. simplex and A. geneseana in the Cretaceous, it is not known if the most ancient types were multifloated or were without floats. Considering the tomentose columella as the basic component of the swimming apparatus, it seems likely that the dome- shaped columella without floats is the most primitive type. From this type of struc- ture the columella becomes progressively organized into separate areas to form float-like structures of the multifloated condition. At first the columella becomes segmented, as in A. montana, the segments hardly distinguishable from the hairy columella. Some species, like A. distincta, are reported as having foamy floats, imply- ing that true floats appear before the close of the Cretaceous. A number of Cretaceous 504 PALAEONTOLOGY, VOLUME 18 species probably possess floats which, though distinguishable from the columella, do not have the vacuolate structure of later species. Numerous vacuolate float-like structures, readily distinguished and easily removed from the columella, is a feature of some Palaeocene species. Eocene records are scanty and not particularly reliable, though it is evident that the number of floats is reduced, the columella becomes less extensive and floats take up a correspondingly larger volume of the swimming apparatus. Eocene species are known to possess true floats showing smooth surface with vacuolate pseudocellular structure, and the proximal wall of the megaspore is modified to form a collar region and labra, as in /4. inter irappea. In this species, the columella is still a significant feature of the swimming apparatus, the floats are much smaller than those of extant species and undifferentiated columella remains in the form of a dome at the apex. In Oligocene species such as A. prisca, perhaps we see maximum elaboration in the form of the triseptate columella, resulting from float development in three sectors of the swimming apparatus. The columella, though much reduced in volume, is still a significant structure supporting nine floats. The three floats of the upper tier are held together by the cap-like development of the columella at the apex, whilst those of the lower tier are supported in position by the contours of the modified proximal pole and held together by the triseptate columella. Species having three large floats like those of living species first occur, with certainty, in the late Oligocene or Miocene. The structure and role of the columella appears to have remained largely unaltered since the close of the Eocene, despite the develop- ment of the three-floated condition. However, with the development of three large floats, the significance of the columella has possibly been slightly diminished as a result of increased elaboration of the proximal pole, more support for the floats being provided by the development of the collar, labra, gulae, etc. How a species such as primaeva, with a single pseudocellular float, could fit into this basic evolutionary pattern is not known. Its late appearance, in the Eocene, suggests that it might have developed from an ancestor similar to A. simplex, as a result of vacuolation. Evolutionary tendencies are not clear regarding the massulae. High numbers of microspores per massula is a feature of multifloated species, with fifty microspores recorded in the massula of A. extincta, considered by Jain (1971) to represent the contents of a single microsporangium. Less than eight microspores per massula occur in the Eocene species A. indica and the Oligocene species A. prisca, this low number being retained as a feature of post-Oligocene species, both fossil and modern. Mahabale (1963) proposed an evolutionary scheme for Azolla based on structure of glochidia, on the assumption that section Azolla, with septate anchor-shaped glochidia, is primitive. He suggested that these primitive glochidia became reduced, losing both septa and anchor-tip, to become filamentous as in modern A. pinnata and eventually eglochidiate as in modern A. nilotica. Section Azolla is no longer considered primitive, but anchor-shaped glochidia, though found occurring with every known type of megaspore apparatus throughout the stratigraphical range of Azolla, are consistently associated with multifloated megaspores (Jain and Hall 1 969). According to Hills and Gopal ( 1 967), septation is a recently acquired character, not an ancestral one, the earliest record of septate glochidia occurring in the Pleisto- cene. As previously mentioned, there is some doubt concerning the reported presence of septa in the glochidia of the Eocene species A. indica. FOWLER: OLIGOCENE AZOLLA 505 It was Kempf (1969a and b) who provided the basis of our understanding of the structural morphology of the megaspore apparatus of AzoUa species, with particular emphasis being placed on the ultrastructure of the megaspore wall. This present investigation of A. prisca, using modern techniques, further extends this knowledge. Ultra-thin sectioning and transmission electron microscopy of the megaspore wall supports Kempf ’s (1969a) suggestion that wall structure is sufficiently variable as to provide a useful means of taxonomic separation and identification of both modern and fossil types, and provides further information on the origin of the hair-like structures. Furthermore, the significance of the innermost layer of the perine in the formation of the proximal wall of the megaspore and associated labra, gulae, etc., is given more attention than in previous work. Scanning electron microscopy employed in the study of the megaspore apparatus of A. prisca and some modern species, has led to a better understanding of the structure and significance of the columella, the sculpture of the megaspore wall, and the nature of the apical cap. Critical study of the massulae of A. prisca and modern species, has revealed structural organization previously unrecorded. As a result of this investigation on the reproductive structures of A. prisca, this species becomes one of the best known of all species of Azolla, both fossil and modern. Our knowledge concerning fossil Salviniaceae has expanded considerably in recent years, indicating great diversity in reproductive morphology and megaspore wall structure. At one time, the Salviniaceae was regarded as having two living genera, Salvinia and AzoUa, the latter divided into two sections, Azolla and Rhizosperma. We are now aware of the importance of the genus AzoUa in the Upper Cretaceous and Lower Tertiary, from which over thirty species have been recorded and placed in seven sections of the genus. In addition, two new genera, AzoUopsis (Hall 1968) and Parazolla (Hall 1969^), have been established within the Salviniaceae. Acknowledgements. The author is indebted to the Keeper of Palaeontology, British Museum (Natural History) for material of Azolla prisca. My gratitude to Dr. J. M. Pettitt, British Museum (Nat. Hist.) and Dr. K. R. Sporne, Department of Botany, University of Cambridge, for their helpful advice on certain aspects. However, responsibility for opinions expressed, and any errors, rest with the author. Sincere thanks are due to Mrs. P. Palmer for sectioning material, to Diane Irwin and Steve Furtado for assistance with scanning electron microscopy, to Helen Harris for typing the manuscript and to the photography section of the Portsmouth department. Lastly, to Dr. L. V. 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The palaeoenvironment of the Bembridge Marls (Oligocene) of the Isle of Wight, Hamp- shire. Proc. Geol. Assoc. Lond. 84, 83-93. 506 PALAEONTOLOGY, VOLUME 18 DAWSON, J. w. 1890. On fossil plants from the Smilkameen Valley and other places in the southern interior of British Columbia. Trans. R. Soc. Can. 8, 75-91. DEMALSY, p. 1954. Le sporophyte d'Azolla nilolica. La Cellule, 56, 1-60. DUKSTRA, s. J. 1961 . Some Paleocene megaspores and other small fossils. Meded. Geol. Sticht. N.S. 13, 5-11. DOROFEEV. p. I. 1959. New species of Azolla Lam. in Tertiary floras of the U.S.S.R. Bot. Zh. 44, 1756-1763. [In Russian.] DUNCAN, R. E. 1940. The cytology of sporangium development in Azolla filiculoides. Bull. Torrev bot. Club, 67,391-412. EAMES, A. J. 1936. Morphology of vascular plants. Lower groups. McGraw-Hill Book Co., New York, 433 pp. ERDTMAN, G. 1952. Pollen morphology and plant taxonomy. Angiosperms. Stockholm, 539 pp. FLORSCHUTZ, F. 1945. Azolla uit het Nederlandsche Palaeoceen en Pleistoceen. Verb. Geol. Mijnb. Gen. Nederl. KoL, Geol. 14, 191-197. and MENENDEZ AMOR, J. 1960. Une Azolla fossile dans les Pyrenees Orientales. Pollen et Spores, 2, 285-292. GRIFFITH, w. 1844. On Azolla and Salvinia. Calcutta J. Nat. Hist. 5, 227-273. HALL, J. w. 1968. A new genus of Salviniaceae and a new species of Azolla from the late Cretaceous. Am. Fern. J. 58, 77-88. 1969fl. A reappraisal of the megaspores of two Eocene species of Azolla. J. Paleont. 43, 528-531. 19696. Studies on fossil Azolla: Primitive types of megaspores and massulae from the Cretaceous. Am. J. Bot. 56, 1173-1180. 1970. A new section of Azolla. Taxon, 19, 302-303. and BERGAD, R. D. 1971. A critical study of three Cretaceous salviniaceous megaspores. Micro- paleontology, 17, 345-356. and SWANSON, n. p. 1968. Studies on fossil Azolla: Azolla montana, a Cretaceous megaspore with many small floats. Am. J. Bot. 55, 1055-1061. HANNIG, E. 1911. liber die Bedeutung der Periplasmodien. 2. Die Bildung der Massulae von Azolla. Flora Jena, 102, 243-278. HILLS, L. V. andGOPAL, B. 1967. Azolla primaeva and its phylogenetic significance. Can. J. Bot. 45, 1179-1 191. and WEINER, N. 1965. Azolla geneseana, n. sp., and revision of Azolla primaeva. Micropaleontology, 11, 255-261. JAIN, R. K. 1971. Pre-Tertiary records of Salviniaceae. Am. J. Bot. 58, 487-496. and HALL, J. w. 1969. A contribution to the early Tertiary fossil record of the Salviniaceae. Ibid. 56, 527-539. KEMPF, E. K. 1969u. Elektronenmikroskopieder Sporodermis von kanozoischen Megasporen der Wasserfarn- Gattung Azolla. Paldont. Z. 43, 95-108. 19696. Elektronenmikroskopie der Megasporen von Azolla tegeliensis aus dem Altpleistozan der Niederlande. Palaeontographica, B 128, 167-179. 1973. Transmission electron microscopy of fossil spores. Palaeontology, 16, 787-797. LANCUCKA-SRODONIOWA, M. 1958. Salvinia i Azolla w miocenie Polski. Acta Biol. Cracov. Bot. 1, 15-23. MACHiN, J. 1971. Plant microfossils from Tertiary deposits of the Isle of Wight. New. Phytol. 70, 851-872. MAHABALE, T. s. 1963. Evolutionary tendencies in the genus Azolla. J. Indian Bot. Soc. Mem. 4, 51-54. METTENius, G. 1847. Uber Azolla. Linnaea, 20, 259-282. MEYEN, F. J. F. 1836. Beitrage zur Kenntnis der Azollen. Nova Acta Acad. Caesar. Leap. Carol. 18, 505-524. PETTiTT, J. M. 1966. Exine structure in some fossil and recent spores and pollen as revealed by light and electron microscopy. Bull. Br. Mus. nat. Hist. (Geol.), 13, 221-257. PFEIFFER, w. M. 1907. Differentiation of sporocarps in Azolla. Bot. Gaz. 44, 445-454. RAO, ti. s. 1935. The structure and life history of Azolla pinnata R. Brown with remarks on the fossil history of the Hydropteridae. Proc. Indian Acad. Sci. 2, 175-200. REID, E. M. and CHANDLER, M. E. J. 1926. Catalogue of Cainozoic plants in the Department of Geology, I. The Bemhridge Flora. Brit. Mus. (Nat. Hist.), London, 206 pp. .SAHNi, B. 1941. Indian silicilied plants. 1. Azolla intertrappea Sah. & H. S. Rao. Proc. Indian Acad. Sci. B 14, 489-501. - and RAO, H. s. 1943. A silicilied flora from the Intertrappean cherts round Saugar in the Deccan. Proc. natn. Acad. Sci. India, 13, 36-75. SCULFHORPE, c. D. 1967. The biology of aquatic vascular plants. Edward Arnold, London, 610 pp. FOWLER; OLIGOCENE AZOLLA 507 SNEAD, R. G. 1969. Microfloral diagnosis of the Cretaceous-Tertiary boundary, central Alberta. Bull. Alberta Res. Council, 25, 1-148. 1970. A new approach to the classification of Azolla megaspore species (abstract). Geoscience and Man, 1, p. 135. STRASBURGER, E. 1873. Uber Azolla. Jena. 1889. Histologische Beitrdge. 2. Uber das Wachsthum vegetabUischer Zellhaute. Jena. SVENSON, H. K. 1944. The New World species of Azolla. Am. Fern. J. 34, 69-84. SWEET, A. and hills, l. v. 1971. A study of Azolla pinnata R. Brown. Ibid. 71, 1-13. TRiVEDi, B. s. and VERMA, c. L. 1971. Contributions to the knowledge of Azolla indica sp. nov. from the Deccan Intertrappean Series M.P., India. Palaeontographica, B 136, 71-82. WOODWARD, H. 1879. On the occurrence of Branehipus (or Chirocephalus) in a fossil state, associated with Eosphaeroma and with numerous insect remains, in the Eocene Fresh Water (Bembridge) Limestone of Gurnet Bay, Isle of Wight. Q. J! geol. Soc. Land. 35, 342-350. Typescript received 12 August 1974 Revised typescript received 2 December 1974 K. FOWLER Department of Biological Sciences Portsmouth Polytechnic King Henry I Street Portsmouth POl 2DY E LUDLOW BENTHONIC ASSEMBLAGES by J. D. LAWSON Abstract. The communities recently described by Calef and Hancock are considered to provide an inadequate picture of Ludlow faunas and their palaeoecological significance. Alternative assemblages, including the important non-brachiopod benthos, have been compiled from the evidence of published faunal lists. It is here maintained that these four assemblages reflect more accurately than those of Calef and Hancock the faunal distribution within the Ludlow rocks but no special significance is claimed for them; each contains subdivisions which may be more readily explained in palaeoecological terms. It is suggested that the recent emphasis on depth-communities has led to neglect of other very important environmental controls, particularly the nature of the substrate. The concept of continuous regression through the Ludlow is considered untenable in the light of sedimentological evidence. The degree of diachronism of the shelly faunas is assessed. It is concluded that the picture drawn by Calef and Hancock is an over- simplification resulting, perhaps, from the attempt to impose a relatively straightforward Llandovery pattern on to the more complex Ludlow rocks. A RECENT paper in Palaeontology by Calef and Hancock (1974) describes five major marine benthonic communities occurring in clastic (i.e. terrigenous) sediments laid down in areas of increasing depth of water ‘from the shoreline to deep areas in Wales and the Welsh Borderland during Wenlock and Ludlow times’. Only four of these communities are well developed in the Ludlow rocks, mainly on the stable eastern margin of the Welsh basin. They are named after characteristic brachiopod genera as follows; (1) Salopina, (2) Sphaerirhynchia, (3) Isorthis, and (4) Dicoelosia com- munities. They are considered as approximate equivalents of the upper Llandovery depth-communities; (1) Eocoelia, (2) Pentamerus, (3) Stricklandia, and (4) Clorinda, the last-named being the deepest of the four. A fifth, deeper Visbyella community has only been recognized at one locality in the Ludlow rocks. The purpose of this paper is to critically examine some of Calef and Hancock’s conclusions in the light of the very detailed published evidence on Ludlow faunas and sediments. Text-fig. 1 shows the localities mentioned in this paper. RECOGNITION OF COMMUNITIES The statistical description of their communities by Calef and Hancock is most welcome but it is not clear how collections were assigned to a particular community in the first place. Perhaps the allocation was made on the basis of survivors from Llandovery communities but these form a small proportion of the faunas and some genera apparently change their modal communities (Calef and Hancock 1974, Table 12). It is stated that the communities completely intergrade and that the com- munity boundaries are arbitrary lines through a continuum (Calef and Hancock 1974, p. 779). The number of divisions is therefore a matter of practical convenience and ten communities could have been postulated instead of five. The recognition of five communities has proved to be of value in the upper Llandovery and this fact has presumably influenced the choice of five for the Wenlock and Ludlow. Although it is at first reassuring to have the presence percentage and frequency [Palaeontology, Vol. 18, Part 3, 1975, pp. 509-525.] 510 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 1, Map of south-east Wales and the Welsh Borderland showing the outcrops of Ludlow rocks (stippled) and localities mentioned in the text. presence recorded for each fossil in each community it is not clear how a geologist | attempting to use these tables is expected to allocate a particular fauna to one of these communities. For instance, in the Wenlock Salopina community (Calef and Hancock 1974, Table 2) five of the seven prevalent fossils are present in less than one-third of the seventeen localities examined—evidently not prevailing very successfully. ASSEMBLAGES AS LIFE-ASSEMBLAGES Calef and Hancock follow the practice of Ziegler, Cocks and Bambach (1968, p. 3) t in accepting the shell assemblages as reasonably representative of the preservable * LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 511 elements of the communities. This seems well justified in the Llandovery for the following reasons: 1. Analysis of shells suggests only limited post-mortem transport. 2. The faunal associations are so frequently repeated. 3. Life-assemblages of similar composition to the transported assemblages have been recorded. 4. The community belts are about ten miles wide and only extensive shell transport could confuse the basic pattern. Points (1) and (2) apply also to the Wenlock and Ludlow rocks (Calef and Hancock 1974, p. 781) but so far no depth-patterns have been established or life-assemblages described. Although it seems likely that Calef and Hancock’s thesis does apply to most of the shelf Ludlow faunas, it should be accepted with caution until broad dis- tribution belts have been established, life-assemblages recognized, and further analysis of shell wear and distribution carried out. COMPOSITION OF ASSEMBLAGES If, however, the above contention is broadly acceptable it means that previously described Ludlow assemblages may now merit consideration as life-assemblages and deserve close comparison with the communities listed by Calef and Hancock. Straw (1937, p. 411) and Lawson (1960) both described Ludlow faunas but much new information has been published since those papers and it is now possible, using detailed faunal lists, to draw up tables of four major Ludlow benthonic assemblages occupying the main shelf area of the Welsh Borderlands and the English Midlands. They characterize the four Ludlow stages (Eltonian, Bringewoodian, Leintwardinian, and Whitcliffian) on the shelf and, therefore, succeed each other vertically in any particular area. Unlike the intergrading communities postulated by Calef and Hancock three of these four assemblages suflFer abrupt vertical changes in faunal content. This can be most clearly seen in the range charts included in the papers on Usk (Walmsley 1959, p. 490), Woolhope (Squirrell and Tucker 1960, p. 144), Malvern (Phipps and Reeve 1967, p. 354), Wenlock Edge (Shergold and Shirley 1968, p. 135), and in text-fig. 2 of this paper. This apparent distinction between the faunas is prob- ably due to breaks in deposition or slow deposition between the main stratigraphical units. There is a widespread conglomerate at the junction of the Bringewood and Leintwardine Beds, a frequently developed phosphatized fragment-bed at the Leintwardine-Whitcliffe junction and the Ludlow Bone-Bed where the Whitcliffe Beds join the Downton Castle Sandstone. The term ‘assemblage’ is here used in its most general sense to denote those fossils which tend to be found together in the rocks, without drawing any conclusions about the life-assemblages from which they might have been derived or implying any statistically proved separation from an adjacent assemblage. The scope of the word ‘together’ is also important. If only four assemblages are to be recognized in a shelf thickness of over 360 m of Ludlow rocks then the average thickness per assemblage is at least 90 m. If the thickness examined is limited to about 20 m then the collection of fossils occurring ‘together’ has a different composition ; these are here called ‘minor 512 PALAEONTOLOGY, VOLUME 18 assemblages’. If the thickness is restricted to one or two metres the fossil composition is again different and much more limited ; these are here called faunal units and are, perhaps, the associations of Calef and Hancock (1974, p. 796). The signihcance of these distinctions is discussed after the assemblage lists. It must be made clear that no particular significance is claimed in this paper for the four major assemblages described. Calef and Hancock, however, claim that there are four successive intergrading communities related to depth. It is here agreed that four successive assemblages are present and this contention is supported by records from previous papers but it is maintained that there are substantial differences in com- position from the community lists of Calef and Hancock. It is further maintained that only one pair of assemblages intergrade and that their ecological significance is more complex than Calef and Hancock realize. It is agreed that the highest assemblage almost certainly represents much shallower water than the lowest and earliest assemblage but the two intermediate assemblages are more complex and contain subdivisions of considerable palaeoecological significance. The changes in the major assemblages may be due to some major environmental factors, such as changes in late Silurian palaeogeography causing restriction of seas and closing and opening of connections to other regions. The major assemblages listed below have been named after two characteristic genera— not necessarily the most abundant. Although generic names change, they have been preferred to species names which are more likely to be duplicated (e.g. ludloviensis or lewisii). Ideally, both generic and specific names should be used as different species of the same genus may have different ecological preferences. This procedure would make the titles of the assemblages cumbersome and has not been adopted. However, species names have been given in the assemblage lists. The lists have been compiled from faunal lists from the following eight areas on the shelf: May Hill (Lawson 1955), Usk (Walmsley 1959), Woolhope (Squirrell and Tucker 1960), Malverns (Phipps and Reeve 1967; Penn 1969), Aymestrey (Lawson 1973), Ludlow (Holland, Lawson and Walmsley 1963), Leintwardine (Whitaker 1962), and Wenlock Edge (Shergold and Shirley 1968). Three points have been allocated to a fossil recorded as common, two for fairly common, and one for present, giving a pos- sible top score of twenty-four for ‘commonness’. Because the major Ludlow divisions each contain two or three subdivisions, usually with separate recordings of species abundance, average values have had to be taken resulting in non-integers. The figure after the stroke (maximum eight) indicates the number of areas of occurrence. I Only benthonic forms are listed, i.e. graptolites and cephalopods are omitted. These lists differ in intent from those of Calef and Hancock in that non-brachiopod benthos is listed (indicated by an asterisk), and often seems of greater importance than they allow. Fossils collected from the limestones as well as the terrigenous sediments are included and are considered to be essential if an over-all picture of Ludlow palaeo- ecology is required. The brachiopod contents of these assemblages are sufficiently similar to those of the communities of Calef and Hancock to invite closer com- | parison. A more detailed examination, however, reveals some important disparities, , which are briefly discussed. I The author’s name is provided only at the first mention of a species but, in the I interests of clarity, generic names are repeated in subsequent lists. Text-fig. 2 provides !• LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 513 a graphic presentation of these faunal changes. Most of the important fossils are figured in Holland, Lawson and Walmsley (1963, pis. 3-7), and in Calef and Hancoek (1974, pi. 106). BENTHONIC ASSEMBLAGES A. Dicoelosia-Skenidioides assemblage 1. Aegiria grayi (Davidson) 14-3/8 *2. Dalmanites myops (Konig) 13-6/8 Hemsiella maccoyana (Jones) 12-2/7 4. isorthid 10-7/7 5. Atrypa reticularis (Linnaeus) 9-7/8 6. Craniops implicata (J. de C. Sowerby) 9-4/8 7. Shagamella ludloviensis Boucot and Harper 8-0/8 8. Howellella elegans (Muir-Wood) 8-0/6 9. Mesopholidostrophia sp. 6-9/6 10. Dicoelosia biloba (Linnaeus) 6-3I6 11. Protochonetes minimus (J. de C. Sowerby) 6-3/5 *12. Calymene sp. 6-1/8 13. Leptaena depressa (J. de C. Sowerby) 5-9/6 14. 1 1 Strophonella euglypha (Hisinger) 5-8/6 15.J 1 Amphistrophia funiculata (M’Coy) 5-8/6 *16. Leonaspis sp. 5-5/7 17. Skenidioides lewisii (Davidson) 5-2/6 18.1 ' Leptostroplna filosa (J. de C. Sowerby) 5-0/5 19. J 1 Eospirifer spp. 5-0/5 20. Sphaerirhynchia wilsoni (J. Sowerby) A-116 *21. proetid 4-6/6 22. Dalejina cf. hybrida (J. de C. Sowerby) 4-5/4 23. Orbiculoidea rugata (J. de C. Sowerby) 4-4/5 24. Gypidula cf. galeata (Dalman) 4-3/6 25. Glassia sp. 4-1/5 26. Coolinia pecten (Linnaeus) 4-0/5 This list compares well with the Dicoelosia eommunity of Calef and Hancock but contains four trilobites and one ostracod. As they indicate, it is a high-diversity, low- density assemblage of predominantly small brachiopods. Dalejina, Skenidioides, Nucleospira, Cyrtia, and Leangella are more important in their list, perhaps beeause seven (maybe eight) of their nine Dicoelosia localities are in the Lower Elton Beds where these forms are commoner. The Eltonian succession has, therefore, been sampled very unevenly by Calef and Hancock. B. Strophonella-Gypidula assemblage 1. Atrypa reticularis 20-5/8 2. Strophonella euglypha 19-8/8 3. Leptaena depressa 19-3/8 4. Sphaerirhynchia wilsoni 15-5/8 5.1 1 Gypidula lata Alexander 15-0/8 6.J Leptostroplna filosa 15-0/8 7. Shagamella ludloviensis 14-0/8 8. Isorthis orbicularis (J. de C. Sowerby) 13-8/8 *9 solitary trochoid coral 13-5/8 514 PALAEONTOLOGY, VOLUME 18 *10.' Poleumita globosa (Schlotheim) 11-3/8 ♦11. J Dalmanites myops 11-3/8 12. Howellella elegans 11-0/8 13. Amphistrophia funiculata 10-3/8 14. Mesopholidostrophia sp. 10-3/7 ♦15. Hemsiella maccoyana 10-0/7 16. Camarotoechia micula (J. de C. Sowerby) 9-5/8 17. Craniops implicata 9-5/8 ♦18. Favosites spp. 9-3/8 19. Shaleria sp. nov. 8-5/7 20. Coolinia pecten l-Sj! ♦21. Cypricardinia spp. 7-5/7 ♦22. PtUodictya spp. 1-516 23. Kirkidium knightii (J. de C. Sowerby) 6-5/5 24. Eospirifer spp. 6-3/8 ♦25. Protochonetes ludloviensis Muir-Wood 6-3/7 26. Encrinmus sp. 6-3/6 ♦27. Calymene sp. 6-0/8 28. Aegiria grayi 6-0/6 29. Dayia navicula (J. de C. Sowerby) 5-5/6 30. 1 Protochonetes minimus 5-0/6 ♦31. Halysites sp. 5-0/6 ♦32. Rhabdocyclus porpitoides (Lang and Smith) 5-0/4 This is a diverse, high-density assemblage dominated by brachiopods, particularly strophomenids, but with quite a significant variety of other groups, i.e. trilobites, corals, bivalve, gastropod, ostracod, and bryozoan. It most closely resembles the Isorthis community of Calef and Hancock but the order of abundance is very different. At least two of their samples are from Elton Beds which may explain the records of Dalejina, Homeospira, Glassia, and Skenidioides. C. Dayia-Isorthis assemblage 1. Camarotoechia nucula 21-5/8 2. Dayia navicula 17-8/8 3. Protochonetes ludloviensis 16-8/8 4. Sphaerirhynchia wilsoni 14-8/8 5. Isorthis orbicularis 14-6/8 6. A trypa reticularis 14-2/8 1.] 1 Shaleria ornatella (Davidson) 13-3/8 8.J I Shagamella ludloviensis 13-3/8 9. Howellella elegans 13-0/7 10. Salopina lunata (J. de C. Sowerby) 11-7/7 11. Leptaena depressa 10-5/8 12. Whitfieldella canalis (J. de C. Sowerby) 10-3/7 13. Craniops implicata 10-0/8 14. Orbiculoidea rugata (J. de C. Sowerby) 9-5/8 ♦15. Bythocypris siliqua (Jones) 9-2/6 ♦16. Sedgwickia [Fuchsella] amygdalina (J. de C. Sowerby) 8-9/8 ♦17. Calymene neointermedia (R. & E. Richter) 8-4/8 18. Lep tostrophia filosa 8-3/7 19. i 1 Aegiria grayi 7-7/7 ♦20. J 1 Pteronitella retrqflexa (Wahlenberg) 7-7/7 ♦21. Goniophora cymbaeformis (J. de C. Sowerby) 7-6/7 ♦22. Serpulites longissimus (J. de C. Sowerby) 7-5/8 LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 515 *23. Hemsiella maccoyana 7-2/6 *24. Neobeyrichia torosa (Jones) 6-7/7 *25. proetid 6-2/8 *26. //ov<7;7 (J. de C. Sowerby) 6-1/7 *27. Cyclonema corallii 5-2/6 28. Lingula lewisii 5-0/6 This is a diverse, high-density assemblage, still with brachiopods dominant but the non-brachiopod benthos (ostracods, trilobites, bivalves, gastropods, worm) becoming important in the ‘second division’. The brachiopod component compares most closely with the Sphaerirhynchia community of Calef and Hancock. Their list omits Shaleria and Aegiria, presumably because the Upper Leintwardine Beds were not sampled at all. It includes, however, Mesopholidostrophia, Gypidula, Strophonella, and Amphistrophia^-genera. which do not, in fact, occur with an abundance of Dayia, Protochonetes, and Salopina. D. Protochonetes-Salopina assemblage 1. Protochonetes ludloviensis 22-5/8 2. Camarotoechia nucula 21-5/8 3. Salopina lunata 20-0/8 *4 Sedgwickia [Fuchsella] amygdalina 16-7/8 *5. Serpulites longissimus 15-0/7 *6. Neobeyrichia torosa (Jones) 12-3/8 *7. Pteronitella retroflexa 10-8/6 *8. Goniophora cymbaeformis 10-3/6 Cornulites serpularius Schlotheim 9-7/8 10. Orbiculoidea rugata 9-5/6 *11. Nuculites spp. 9-0/6 12. Craniops implicata 8-0/6 13. Howellella elegans 7-3/7 *14.) Loxonema spp. 5-8/6 *15.j Tentaculites tenuis (J. de C. Sowerby) 5-8/6 16. Dayia navicula 5-7/5 *17. Bythocypris siliqua 5-7/4 This is a low diversity, high-density assemblage with three brachiopods dominant but ten of the seventeen commonest fossils are not brachiopods. Bivalves are parti- cularly important. This fauna corresponds reasonably closely with the Salopina community of Calef and Hancock in its brachiopod content but they report Sphaeri- rhynchia and Dayia as being prevalent. This may be due partly to their four samples from the atypical Llandeilo-Llandovery area and partly to their three Leintwardinian localities out of a total of twelve localities. It is difficult to comprehend why these seven samples should be grouped with the five from the Whitcliffian in the first place. Text-fig. 2 presents the same data in graphic form but with more detailed informa- tion on the variation in abundance of the various taxa with time. The following points should be noted : 1. The four assemblage-zones (or, perhaps, concurrent-range zones) correspond with the four main divisions of the Ludlow Series into Elton, Bringewood, Leint- wardine, and Whitcliffe Beds. 2. The chart is confined to benthonic forms so that the graptolites and the cephalo- pods are important absentees. Because of the more refined presentation of the vertical ASSEMBLAGE FOSSILS DIcoelosia - Skenidioides Strophonella • Gypidc'la Doyia - Isorthis Protochonetes - Salopina Dicoelosio bilobo Leonaspis sp. isorthid Dalejina cf. hybrida Skenidioides lewisi i Glassio sp. Gypidgla cf. galeata Profochonefes minimus Coolinia pecfen Eospirifef spp. Halysites sp. Sholerio sp. nov. Gypidula lato Kirkidium knight ij Dalmanites myops Strophonella euglypha Amphistrophio funiculata Mesopholidostrophia Poleumito globoso Favosites spp. solitary trochoid corals Rhabdocyclus porpitoides Cypricardinia spp. Ptilodictya spp. Hemsiella maccoyana Leptostrophia filosa Sphaerirhynchia wilsoni Whitfieldella canalis Neobeyrichia lauensis Aegiria grayi Atrypo reticularis Leptaena depressa Isorthis orbicularis proetids Encrinurus spp. Shagamella ludloviensis Bembexia Iloydii Shaleria ornatella Calymene neointermedia Doyio navicula Lingula lata C rani ops implicata Howellella elegans Calymene spp. Orbiculoidea rugata Lingula lewisii Camarotoechia nucula Pteronitella retroflexa Sedgwickia amygdalina Goniophoro cymbaeformis Nuculites spp. Cornulites serpularius Tentaculites spp. Loxonemo spp. By thocypris si 1 iqua Protochonetes ludloviensis Cyclonema corallji Salopina I una ta Neobeyr ichio torosa Serpulites longissimus TEXT-FIG. 2. Range chart of benthonic fossils in the Ludlow rocks of the Welsh Borderland shelf facies: based on records from May Hill, Usk, Woolhope, Malvern, Aymestrey, Ludlow, Leintwardine, and Wenlock Edge (see p. 515 for discussion). LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 517 variation, the stratigraphically important fossils Neobeyrichia lauensis and Lingula lata become eligible for inclusion on this chart, although not in the assemblage lists. 3. Most of the species and almost all the genera have longer ranges and different abundance patterns outside this region ; in other words, these are mostly local ranges and local acmes due to ecological controls. 4. The common constituents of these assemblages do not necessarily enter and depart, or wax and wane, together, e.g. Howellella elegans is prevalent in four assemblages, Atrypa reticularis in three, Salopina lunata in two, Shaleria ornatella in one, whilst Kirkidium kniglitii and Dicoelosia biloba are dominant only for part of an assemblage. This suggests that these species are not all reacting to one ecological factor, such as depth of water— as is implied in Calef and Hancock’s account. It also seems inappropriate to group species of varying tolerances in the same community; the components of a community should come and go together. 5. There is quite a degree of lateral faunal variation not evident from this chart of vertical abundance; the main contrast is between the inner and outer shelf areas. There are obviously important differences between these two versions of the four major Ludlow benthonic assemblages— even if the comparison is restricted to the brachiopod content. At first sight, it might be thought that the conclusions of Calef and Hancock have the greater objective validity as they have described the com- munities statistically, counting all macrofossils in collections of 100-200 specimens. Their records are therefore more objective and precise than the familiar categories of ‘common’, ‘fairly common’, and ‘present’. On the other hand, presumably because of the time involved in rock-splitting and counting, only 53 localities were collected — usually represented by single beds or up to 20 cm of rock. This means a possible maximum thickness sampled of 10-6 m in a succession at least 360 m thick, i.e. a per- centage of only 3-4 in a series of rocks characterized by many vertical and lateral facies and faunal changes. The four major communities are based on only 44 localities, an average of 1 1 per community. Of these 44, 14 are from the Sawdde Gorge which is just one of the four main sections in the Llandovery-Llandeilo area, where the shelf facies is atypical. In contrast, in the eight areas from which the alternative lists have been compiled, a total of 2600 Ludlovian localities has been examined— an average of 325 per area. Although it is improbable that any single bed was collected and studied as thoroughly as those examined by Calef and Hancock it is certain that a large percentage of these 2600 localities were studied bed by bed in order to establish the faunal succession and subdivisions and to delimit accurately the boundaries between them. A close look at the locality list in their Appendix (p. 810) reveals some important differences in faunal records between Calef and Hancock and previous authors. For instance, they record three examples of Isorthis communities from the Leint- wardine Beds of Ludlow but Holland, Lawson and Walmsley (1963) did not record any occurrences of the supposedly prevalent Isorthis community fossils Meso- pholidostrophia spp., Dalejina, and Amphistrophia in their Leintwardine Beds. The collections from these three localities have now been examined by the present author at the British Museum (Natural History), by courtesy of Dr. L. R. M. Cocks. Locality Lud 2 evidently yielded abundant Kirkidium knightii and is undoubtedly in Upper 518 PALAEONTOLOGY, VOLUME 18 Bringewood Beds and not Leintwardine Beds; it is hardly a very good example of an Isorthis community in that 7 out of the 10 prevalent fossils are missing, the most notable absence being Isorthis itself with its statistically assessed presence percentage of 100. Lud 7 and Lud 8 are, however, correctly assigned to the Leintwardine Beds but are again not very convincing representatives of the Isorthis community. Indeed, Lud 7 yielded only 4 of the 10 prevalent forms of the /sorz/jw community but contained 8 of the 10 prevalent fossils of the Sphaerirhynchia community. This locality is Sunny- hill Quarry, which has recently been studied in detail by Miss Lesley Cherns of Glasgow University. She reports that there are about 15 m of Leintwardine Beds at this exposure of which only 20 cm were sampled by Calef and Hancock (i.e. 1-33%). At this level in the quarry successive bands are dominated by different fossils, e.g. Isorthis, Sphaerirhynchia, Dayia, and Shagamella. Calef and Hancock evidently struck a band rich in Isorthis but if they had collected a metre above or a metre below they might well have hit a Sphaerirhynchia band, and allocated their col- lection to that community. Indeed, Miss Cherns has studied another locality in the Leintwardine Beds of the Ludlow area (4619 7360) where, in a thickness of 3 m, the four community index fossils Lingula, Salopina, Sphaerirhynchia, and Isorthis are all very common, taking it in turn to dominate different bands. Such a faunal pattern might be expected to instil some doubt in the mind of even the strictest devotee of the depth-community religion. Equally anomalous is the record of a Sphaerirhynchia community from the Lower Perton Beds of Woolhope (i.e. Lower Whitcliffe Beds). The prevalent fossils of this community include Sphaerirhynchia wilsoni (with a presence percentage of 100), Whitfieldella and Leptostrophia filosa, none of which are recorded from their Lower Perton Beds by Squirrell and Tucker. This collection has also been examined by the present author and a list of fossils, with numbers present, was submitted to Dr. E. V. Tucker for his expert opinion. He places the fauna in his lowest Lower Bodenham Beds (Lower Leintwardine Beds). He also points out that the locality map reference given by Calef and Hancock appears to indicate a collection from the southern face of the extended Perton Quarry where Perton Beds do not occur at all. The above lists are supported by less complete evidence in the following publica- tions on the areas of Usk (Squirrell and Downing et al. 1 969), Church Stretton (Greig et al. 1968), Tites Point and Newnham (Cave and White 1971), and Gorsley (Lawson 1954). The Llandovery-Llandeilo district has been excluded from this analysis as it repre- sents an unusual and ‘sandy variety of the shelf facies’ (Potter and Price 1965, p. 396) and the faunas display variations which may relate to the sandy, shallow-water facies. Calef and Hancock, however, include fourteen localities from this area in their com- munity analysis based on fifty-three Ludlow localities and this may explain some of the peculiarities in the associations recorded by them. Presumably because of their commitment to brachiopod communities they fail to recognize what is probably the most significant assemblage palaeogeographically in this area. This is a strong molluscan fauna which Potter and Price (1965, p. 390) considered to be ‘well adapted for sandy, shallower and possibly less saline conditions’. It occurs in sandstones of middle Ludlow age and includes the bivalve genera Grammysia and Modiolopsis and the gastropods Loxonema, Platyschisma, and Bucanopsis. Lingula and Orbiculoidea LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 519 also occur in association with this fauna, which resembles that of the Downton Castle Sandstone and also the persistent Palaeozoic linguloid-molluscan community described by Bretsky (1969) as characterizing near-shore sandy and silty environ- ments. Although Calef and Hancock (1974, p. 779) refer to shelly faunas occurring in the basin they record collections only from Builth Wells (four localities) and Denbighshire (one), and none from Clun Forest, Knighton, Long Mountain, and Radnor Forest. They would certainly not have found a simple succession of their four shallowing benthonic communities. In many places, as at Bishop’s Castle, the Dicoelosia- Skenidioides assemblage is well developed at the base of the Ludlow succeeded by Diversograptus nilssoni shales. Above follows a Dayia-Isorthis fauna with some elements of the Strophonella-Gypidula fauna in the more calcareous siltstones (e.g. Gypidula, Poleumita, and Favosites at Builth). Then succeeds a normal Dayia- Isorthis fauna followed by shales with Lingula lata and Saetograptus leintwardinensis. This latter association is very interesting when it is recalled that in the upper Llandovery the Lingula community is in the shallowest belt and the graptolitic beds in the deepest belt. Above this fauna comes the distinctive Aegiria grayi-Neobeyrichia lauensis assemblage, followed by a Dayia-Protochonetes-Fuchsella assemblage and then a typical Protochonetes-Salopina assemblage as on the shelf. This is only a very generalized pattern covering a large area but it serves to demonstrate the limitations of a palaeoecological interpretation based only on brachiopod communities and also includes some distinctive associations not recognized by Calef and Hancock. ASSEMBLAGES AS COMMUNITIES If four major benthonic assemblages are worthy of recognition in the shelf Ludlow it is here maintained that the above lists are a more accurate record of the associations of the fossils than are the lists of Calef and Hancock, even allowing for their restric- tion to brachiopods. The palaeoecological significance of these major assemblages must, however, be questioned. Are they, for instance, communities? In its normal, non-biological usage the term ‘community’ suggests that the com- ponents have something in common, some interdependence, which results in a nucleated gathering. In palaeontology the term has come to be used quite commonly, as in Calef and Hancock’s paper for a completely intergrading life-assemblage. It consists of a number of species inhabiting the same area at the same time. In the case of the major shelf assemblages listed above it should be realized that the forms recorded occur over an area of 12 000 sq km and each assemblage spans at least 30 m of strata, i.e. at least one million years of time. The same applies to the com- munities of Calef and Hancock. They might claim that this is not a serious objection if one is concerned with the regional palaeogeographical picture. There are, however, lateral and vertical faunal variations within these major assemblages which may have greater palaeoecological and palaeogeographical significance than the differences between the major faunal units. An example of significant lateral variation occurs in the Dayia-Isorthis assemblage of Leintwardinian age; the eastern shelf is charac- terized by the common occurrence of Protochonetes ludloviensis and Salopina lunata in the siltier near-shore shallow-water facies (Holland and Lawson 1963, p. 287) 520 PALAEONTOLOGY, VOLUME 18 whereas the shelf-edge area, muddier and perhaps deeper, shows a reduced abundance of these species and the increased importance of Dayia navicula and Shagamella ludloviensis. Vertical variation is well illustrated in the Bringewoodian of the western shelf where the Strophonella-Gypidula assemblage can be divided into a lower Amphistrophia funiculata fauna and an upper Kirkidium-Favosites fauna. Are these minor assemblages communities in the sense that the constituent species inhabited the same place at the same time -in the same depth of water? It is doubtful, for Newall (1966) has subdivided the Kirkidium-Favosites fauna into three units of palaeoecological significance viz. ; 1. Atrypa-Strophonella units formed in conditions of least turbulence. 2. Coral units of tabulate coral colonies formed in the shallow photic zone in conditions of fairly high turbulence. 3. Kirkidium units formed in a high-energy environment and possibly within the breaker zone. Such faunal units, of depth significance, are completely masked by being lumped together in major assemblages or communities. Even the units mentioned above, usually several feet thick, may benefit from refinement. Contrary to the statement by Calef and Hancock (1974, p. 780), Ludlow fossils commonly occur in bands, often dominated by particular fossils. Studies of these bedding-plane assemblages would probably repay study; there may even be more than one community on one bedding plane ! In the Leintwardinian of the eastern shelf successive bedding planes are often dominated by Isorthis, Sphaerirhynchia, and Protochonetes with Salopina in turn; it is surely too much to postulate depth changes every few centimetres through the succession to explain the repetition of Calef and Hancock’s communities. The ultimate degree of refinement is to investigate the palaeoecology of the individual species, paying particular attention to its relationship to the sediment and to the possible functional significance of some of its morphological characters. Mr. John Hurst, of Oxford University, has already derived significant results from some such studies on Silurian brachiopods (Fiirsich and Hurst 1974). BRACHIOPOD COMMUNITIES The community tables published by Calef and Hancock ( 1 974, p. 783) are based solely on the brachiopod fraction of the fauna for two reasons: (1) brachiopods generally make up at least 90% of the total fauna, (2) the taxonomic uncertainty is less with brachiopods than with most other groups. This second reason is particularly uncon- vincing as the trilobites and ostracods have been quite well studied and even the negleeted groups, such as corals, bivalves, gastropods, worms, bryozoa, can often yield information of palaeoecological significance in spite of their nomenclatorial impreeision. The first point, on the dominance of brachiopods, can be seen to be well justified from the lists published here. Nevertheless, non-brachiopods are evidently not unimportant. Indeed, in the Protochonetes-Salopina fauna here listed, ten out of the seventeen fossils are not brachiopods, bivalves being particularly important. It has already been pointed out that there are important coral units on the main shelf LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 521 and a bivalve assemblage in the Llandeilo-Llandovery area during Bringewoodian times. It must, however, be appreciated that the study of brachiopod communities has yielded important ideas on Silurian palaeogeography in recent years. It would be interesting to see to what extent the study of the non-brachiopods will confirm, refine, or contradict these ideas. Corals, stromatoporoids, and algae should certainly be helpful as depth-indicators particularly in the Wenlock and in the carbonate developments. It should be emphasized in this respect that Calef and Hancock’s study is restricted to the clastic rocks. DEPTH COMMUNITIES Calef and Hancock wisely refer to depth-rc/fl/ct/ communities rather than depth- controlled communities. It is difficult to understand how depth can directly control the distribution of organisms in the sea. Nevertheless, most of the controlling factors normally vary with depth— some directly, such as pressure, light, and temperature and some less inevitably such as substrate, sedimentation, turbulence, salinity, and food supply. Muddy substrate and still water are commonest at greater depth but are not uncommon in shallow water; hence the need for caution. The depth-patterns plotted for the upper Llandovery (Ziegler 1965) nevertheless seem convincing proof of the depth-relationship of the communities. Even here there is need for some caution as a progression from onshore to offshore does not always correlate with increasing depth. Indeed, in the case of the middle Ludlow, Alexander (1963, pp. 111-112) adduced evidence that the shell-banks of Kirkidium accumulated on a shelf-edge ridge, i.e. in very shallow water even though far off shore. Calef and Hancock do not, however, produce such depth-pattern maps for the Ludlovian, to demonstrate their communities succeeding each other laterally and basinwards at particular times. The main reason for this (Hancock, pers. comm.) is their uncertainty about precise time-correlations in the Ludlow rocks of the Welsh Borderlands. Presumably, they require lineage zones such as have been established for the upper Llandovery based on the evolution of Eocoelia, etc. These zones did not, however, prove the established graptolite zones to be inadequate or diachronous and it is therefore not clear why the widespread graptolite zones of Diversograptus nilssoni and Saetograptus leintwardinensis are not acceptable in the Ludlovian. If the correlation by Holland, Lawson and Walmsley (1963, p. 150, Table 2) is followed, Calef and Hancock’s communities can be plotted for each of the stages of the Ludlow. No clear patterns emerge, partly because more data are needed and partly because single communities tend to spread over most of the shelf, perhaps because the slope was much more gentle than in the Llandovery. There are also some puzzling anomalies. In the lower Eltonian the south-eastern inkers of Usk, May Hill, and Woolhope display a Dicoelosia community whereas the further offshore area of Wenlock Edge has a ‘shallower’ Isorthis community. In the Bringewoodian the Isorthis community occurs at Ludlow and Wenlock Edge but the ‘deeper-water’ Dicoelosia community is reported from May Hill, which is well on to the shelf. The Leintwardinian plots show an equal mixture of Sphaerirhynchia and Salop ina communities at Usk and 522 PALAEONTOLOGY, VOLUME 18 May Hill— apparently completely, not merely marginally, overlapping. The Isorthis community is reported from Ludlow, which is indeed further offshore in the tradi- tional interpretation. In the Whitcliffian, the Salopina community is widespread, occurring at Usk and May Hill on the inner shelf, at Ludlow on the outer shelf, and at Builth in the basin. At Woolhope, however, on the inner shelf a Sphaerirhynchia community is recorded. The direct interpretation of these communities in terms of depths therefore results in inconsistent and confusing patterns. Calef and Hancock state (1974, p. 797) that ‘no good correlation has been seen between sediment type and community within the clastic facies covered by this paper’. This is contrary to the experience of previous workers who have felt compelled to refer informally to the "Dicoelosia mudstones’ (actually fine siltstones), the ‘strophomenid siltstones’, the "Dayia shales’, and the 'Chonetes flags’. It would be interesting to know whether the Dicoelosia community of Calef and Hancock has ever been found other than in fine olive siltstones with irregular bedding. Nevertheless, the suggestion that the Salopina community normally inhabited shallower water than the Dicoelosia community is not disputed. Also, Calef and Hancock’s use of density and diversity indices to interpret depths is a welcome new approach, to be used with caution. CONTINUOUS REGRESSION Calef and Hancock contend that the upward Ludlow succession represents a single regression and (1974, p. 800) ‘have found no evidence of widespread cyclic trans- gressions and regressions such as those postulated by Phipps and Reeve (1967, fig. 6) for the Malvern Hills area’. It is here maintained that there is adequate evidence from both the sediments and the fauna that the pattern figured by Phipps and Reeve is the regional picture for the shelf area. The Main Outcrop (Wenlock Edge to Aymestrey) confirms this. The Dicoelosia mudstones of the Lower Elton Beds obviously accumu- lated in still water with a muddy substrate; the high faunal diversity and low density lead Calef and Hancock to the conclusion that the water was relatively deep. This seems quite acceptable. The succeeding Middle Elton Beds are characterized by graptolites and orthocones with a very small benthonic fauna. It has usually been considered that these deposits probably represent a further deepening of the sea. Calef and Hancock record a Visbyella community from the Middle Elton Beds of Ludlow and presumably agree on this continued deepening (perhaps to 1000 or 1500 m according to Hancock, Hurst and Fursich 1974) rather than a regression. The graptolitic Upper Elton Beds contain slumps and few benthonic forms. They pass up into the richly benthonic Strophonella-Gypidula calcareous siltstones of the Lower Bringewood Beds which are succeeded by the Kirkidium-Favosites limestones of the Upper Bringewood Beds. Newall (1966) has concluded, from detailed palaeoecological studies, that the tabulate corals lived in moderately turbulent water and that the Kirkidium banks were probably within the breaker zone. Cross-bedding is fairly common (Whitaker 1962, p. 339) and is indicative of current action. Lawson has found algal remains in these beds at Aymestrey (Elliott 1971) suggesting water no deeper than 30 m. These indications of extreme shallowing are confirmed by the widespread occurrence of LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 523 a limestone conglomerate at the base of the succeeding Lower Leintwardine Beds, suggesting actual emergence of most of the shelf area. Ooliths have been found at this level on Wenlock Edge (Shergold and Shirley 1968, pi. 126) and the occurrence there of the large ostracod Leperditia might be taken to indicate extreme shallowing as Berdan (1968) suggests that these ostracods were adapted to temporary subaerial exposure. The dark shales of the Lower Leintwardine Beds at Aymestrey containing a Dayia navicula-Shagamella ludloviensis sub-fauna plus Saetograptus leintwardinensis must therefore represent some degree of deepening as postulated by Phipps and Reeve (1967) not continued regression. This period of emergence in the middle Ludlow is even more convincingly demonstrated by Potter and Price (1965, p. 398) in the Llandovery-Llandeilo area where the Old Red Sandstone facies in the Bringe- woodian Trichrug Beds is succeeded by the fully marine Dayia-Isorthis assemblage (the Sphaerirhynchia community of Calef and Hancock) of the Leintwardinian. There is then general agreement on progressive shallowing up through the Whitcliffe Beds into the Downton Castle Sandstone, with its Lingula-moWusc assemblage. The regional pattern for the shelf is therefore of two periods of maximum trans- gression (Middle Elton Beds and Lower Leintwardine Beds) and two periods of maximum regression (tops of the Bringewood Beds and Whitcliffe Beds), approxi- mately as depicted by Phipps and Reeve (1967, fig. 6). The recognition of this pattern raises serious problems for the believers in depth communities. It means that the same depth of water probably obtained three, or even four, times in the Ludlovian period and yet there is no repetition of Calef and Hancock’s depth-communities. The Dicoelosia mudstones, the strophomenid siltstones, and the Dayia shales may all have been deposited at similar depths and it may have been the difference in sub- strate (or some other factors) which resulted in the differences in faunal assemblage. DIACHRONOUS COMMUNITIES Although Calef and Hancock postulate a succession of regressive benthonic com- munities they do not explicitly suggest that these are diachronous in the way that the upper Llandovery communities are. This reticence may be due to their uncertainty about the precise time correlation of the Ludlow rocks. It has for long been recog- nized that the shelly faunas are largely facies dependent and the present Ludlow correlation from basin to shelf has therefore been based on the occurrences of graptolites, trilobites, and ostracods rather than brachiopods. The internationally recognizable graptolite zones of Diver sograptus nilssoni and Saetograptus leint- wardinensis, although best developed in the basin facies, spread well on to the shelf and interdigitate with the shelly divisions, particularly along Wenlock Edge. Further- more, at the top of the Leintwardinian there occur not only the highest specimens of Saetograptus leintwardinensis but also the short-range species Neobeyrichia lauensis and Calymene neointermedia which occur together at a similar level on the Baltic island of Gotland. If this correlation is accepted some of the brachiopod assemblages are seen to be diachronous. The brachiopods characteristic of the Strophonella-Gypidula assemblage appear in the Eltonian of the basin but in the Bringewoodian of the shelf. The Protochonetes-Salopina assemblage is strongly developed in the Leintwardinian of F 524 PALAEONTOLOGY, VOLUME 18 the southern and eastern shelf but does not reach the basin areas of Kerry and Knighton until Whitcliffian times. Within the main shelf area diachronism of the shelly divisions is less easily demonstrated, perhaps because of fairly uniform condi- tions, including depth, over most of the area. CONCLUSIONS The four successive benthonic assemblages here listed for the Ludlow are considered to give a fuller and more accurate picture of the shelf faunas than the communities listed by Calef and Hancock, which seem to be based on inadequate sampling and are inevitably limited by restriction to brachiopods in clastic sediments. The palaeo- ecological significance of these four major assemblages is not clear. The minor assemblages, characterizing smaller thicknesses of rock, are likely to be closer to the life assemblages. The study of the functional morphology and facies preference of particular species is also a promising approach. The recent emphasis on depth-communities has led to a neglect of other important, and more direct, environmental controls, particularly the nature of the substrate. A consideration of sedimentary evidence demonstrates that Calef and Hancock’s postulation of continuous regression throughout the Ludlow is unacceptable. The present correlation of the Ludlow rocks, based mainly on graptolites, trilobites, and ostracods, is thought to be reasonably sound. Some of the shelly assemblages are, however, markedly diachronous from shelf to basin but not noticeably so on the main shelf. It is concluded that the picture drawn by Calef and Hancock is an over-simplification resulting, perhaps, from an attempt to impose a relatively straightforward Llandovery pattern on to the more complex Ludlow rocks. Acknowledgements. I thank Mr. Nigel Hancock and other members of the Oxford ‘community school’ for the ready access to their writings and for many stimulating and amicable discussions— in spite of the divergence of our scientific views. Professors T. Neville George and C. H. Holland, and Miss Lesley Cherns kindly read and criticized the manuscript. REFERENCES ALEXANDER, F. E. s. 1936. The AymesUy Limestone of the Main Outcrop. Q. Jlgeol. Soc. Land. 92, 103-1 15. BERDAN, J. 1968. Possible paleoecological significance of Leperditiid ostracodes. Geol. Soc. Amer. Prog. Annu. Mtng. North-eastern Sect. Washington D.C., p. 17 (Abstr.). BRETSKY, p. w. 1969. Evolution of Paleozoic benthic marine invertebrate communities. Palaeogeogr., Palaeoclimat., Palaeoecol. 6, 45-59. CALEF, c. E. and Hancock, n. j. 1974. Wenlock and Ludlow marine communities in Wales and the Welsh Borderland. Palaeontology, 17, 779-810. CAVE, R. and white, d. e. 1971. The exposures of Ludlow rocks and associated beds at Tites Point and near Newnham, Gloucestershire. Geol. J. 7, 239-254. ELLIOTT, G. F. 1971. A new fossil alga from the English Silurian. Palaeontology, 14, 637-641. FURSiCH, F. T. and HURST, J. M. 1974. Environmental factors determining the distribution of brachiopods. Ibid. 17, 879-900. GREiG, D. c., WRIGHT, J. E., HAiNS, B. A., MITCHELL, G. H., et al. 1968. Geology of the country around Church Stretton, Craven Arms, Wenlock Edge and Brown Clee. Mem. geol. Surv. U.K. 1-379. HANCOCK, N. J., HURST, J. M. and FURSICH, F. T. 1974. The depths inhabited by Silurian brachiopod com- munities. Jlgeol. Soc. bond. 130, 151-156. LAWSON: LUDLOW BENTHONIC ASSEMBLAGES 525 HOLLAND, c. H. and LAWSON, J. D. 1963. Facies patterns in the Ludlovian of Wales and the Welsh Borderland. Lpool Manchr geol. J. 3, 269-288. and WALMSLEY, V. G. 1962. Ludlovian Classification— A reply. Geol. Mag. 99, 393-398. 1963. The Silurian rocks of the Ludlow district, Shropshire. Bull. Br. Mas. nat. Hist. (Geol.), 8, 95-171. LAWSON, J. D. 1954. The Silurian succession at Gorsley (Herefordshire). Geol. Mag. 91, 227-237. 1955. The geology of the May Hill inlier. Q. J I geol. Soc. Load. Ill, 85-1 16. 1960. The succession of shelly faunas in the British Ludlovian. C.R. Intern. Geol. Congr. 21st Session, Nor den, 7, 114-125. 1973. Facies and faunal changes in the Ludlovian rocks of Aymestrey, Herefordshire. Geol. J. 8, 247-278. NEWALL, G. 1966. A faunal and sedimentary study of the Aymestry Limestone and adjacent beds m parts of Herefordshire and Shropshire. Ph.D. thesis, Univ. Manchester. PENN, J. s. w. 1969. The Silurian rocks to the west of the Malvern Hills from Clenchers Mill to Knightsford Bridge. Ph.D. thesis, Univ. London. PHIPPS, c. B. and REEVE, F. A. E. 1967. Stratigraphy and geological history of the Malvern, Abberley and Ledbury Hills. Geol. J. 5, 339-368. POTTER, J. F. and PRICE, J. H. 1965. Comparative sections through rocks of Ludlovian-Downtonian age in the Llandovery and Llandeilo districts. Proc. Geol. ^455. Lond. 76, 379-402. SHERGOLD, J. H. and SHIRLEY, J. 1968. The faunal stratigraphy of the Ludlovian rocks between Craven Arms and Bourton, near Much Wenlock, Shropshire. Geol. J. 6, 1 19-138. SQUiRRELL, H. c., DOWNING, R. A. et al. 1969. Geology of the South Wales Coalfield pt. 1. The country around Newport (Mon.). Mem. geol. Surv. U.K. 1-333. and TUCKER, e. v. 1960. The geology of the Woolhope inlier (Herefordshire). Q. Jl geol. Soc. Lond. 116, 139-185. STRAW, s. H. 1937. The higher Ludlovian rocks of the Builth district. Ibid. 93, 406-456. WALMSLEY, v. G. 1959. The geology of the Usk inlier (Monmouthshire). Ibid. 114, 483-521. WHITAKER, J. H. MCD. 1962. The geology of the area around Leintwardine. Ibid. 118, 319-351. ZIEGLER, A. M. 1965. Silurian marine communities and their environmental significance. Nature, Lond. 207, 270-272. COCKS, L. R. M. and bambach, r. k. 1968. The composition and structure of Lower Silurian marine communities. Lethaia, 1, 1-27. J. D. LAWSON Department of Geology Typescript received 23 May 1974 University Revised typescript received 22 November 1974 Glasgow G12 8QQ T^’ "I!; • j ;■ ' }_J*151<1, ; .(fi ■•’•*••- "' - ■ ■ 'S ■ I ■• ,<:'*1ii . V •' \ ' i|.\, :i » THE TRILOBITE LEJOPYGE HAWLE AND CORDA AND THE MIDDLE-UPPER CAMBRIAN BOUNDARY by B. DAILY and J. B. jago Abstract. The species and subspecies of the late middle Cambrian agnostid trilobite Lejopyge are reviewed. Lejopyge cos Opik is shown to be a junior synonym of Lejopyge laevigata armata. In Sweden the middle-upper Cambrian boundary is placed at the boundary between the Lejopyge laevigata and Agnostus pisiformis Zones. The reassignment of L. cos to L. 1. armata and other criteria suggest that this boundary in Australia should be drawn within the Mindyallan Cyclagnostus quasivespa Zone between the L. cos and Blackwelderia sahulosa faunas. It is suggested that the middle-upper Cambrian boundary in North America be placed well up into the Cedaria Zone ; in China it is at some as yet undefined position within the Blackwelderia sinensis Zone ; on the Siberian Platform it should be placed between the zones of Lejopyge laevigata armata- Lomsucaspis alta and Agnostus pisiformis- ' Homagnostus fecundus’ and in north-west Siberia between the zones of Maiaspis spinosa-Oidalagnostus trispinifer and Acrocephalella granulosa- Koldiniella prolixa. Various species and subspecies of Lejopyge are important index fossils of the late middle Cambrian of Sweden (Westergard 1946), Utah (Robison 1964^, b), Queens- land (Opik 1961a, 1967), Siberia (Demokidov 1968), and Alaska (Palmer 1968). This paper reviews the status of the species and subspecies of Lejopyge and discusses the intercontinental correlations arising out of this work. The availability of large numbers of latex moulds and silicone-rubber casts of trilobites (especially those illustrated by A. H. Westergard from Sweden), allowed many conclusions to be drawn which otherwise could not have been made from the published literature. Order miomera Jaekel, 1909 Suborder agnostina Salter, 1864 Superfamily AGNOSTACEA M’Coy, 1849 Family agnostidae M’Coy, 1849 Subfamily ptychagnostinae Kobayashi, 1939 Genus lejopyge Hawle and Corda, 1847 Synonymy. Hawle and Corda, 1847,p. 51 ; Kobayashi 1937, pp. 437-447; 1939, p. 131 ; Lermontova 1940, p. 130; Westergard 1946, p. 87; Hupe 1953, p. 61; Pokrovskaya 1958, p. 72; 1960, p. 60; Howell 1959, p. 178; Opik 1961a, p. 85; 1967, p. 93; Robison 1964a, p. 521 ; Palmer 1968, p. 27. Miagnostus iaekel, 1909, p. 401. Type species. Battus laevigatas Dalman, 1828, p. 136. Discussion. Westergard (1946, p. 87) and Opik (1961a, pp. 76, 85) have discussed Lejopyge, its species and subspecies, and its relationships with other genera, especially Ptychagnostus Jaekel. Westergard (1946, p. 75) suggested, and Opik (1961a, p. 85) agreed, that Ptychagnostus (Triplagnostus) elegans (Tullberg), P. elegans laevissimus Westergard (PI. 63, figs. 12, 13), andL. /acv/ga/a (Dalman) ‘constitute an evolutionary series with very small intervals’. [Palaeontology, Vol. 18, Part 3, 1975, pp. 527-550, pis. 62-63.] 528 PALAEONTOLOGY, VOLUME 18 The following species and subspecies have been included in Lejopyge: L. calva Robison, L. cos Opik, L. empozadensis Rusconi, L. exilis Whitehouse, L. laevigata (Dalman), L. laevigata armata (Linnarsson), L. 1. forfex (Brogger), L. 1. perrugata Westergard, L. 1. rugifera Westergard, L. 1. similis (Brogger), and L. obsoletus (Kobayashi). Opik (1961fl, p. 86) suggested that the holotype cephalon of L. exilis belongs in either L. laevigata or L. 1. armata and that the pygidium of L. exilis figured by White- house (1936, pi. 9, fig. 12) belongs in either Phalacromal dubium Whitehouse or Hypagnostus hippalus Opik. This pygidium is very poorly preserved (PI. 63, fig. 11) and cannot be assigned to any species or genus with certainty. In our opinion the border is far too wide to include the specimen in L. laevigata. Westergard (1946, p. 88) suggested that L. 1. similis belongs in Cotalagnostus confusus (Westergard), and that L. 1. forfex resembles the pygidium figured as L. 1. armata by Westergard (1946, pi. 13, fig. 31). The pygidium described by Kobayashi (1935) as Agnostus (Lejopygel) obsoletus was reassigned by him (Kobayashi 1962, p. 30) to Phoida- gnostus limbatus. L.l controversa Kryskov {in Borovikov and Kryskov 1963) belongs in Peratagnostus Opik (1967, p. 35). L. ? sugandensis Kryskov was described in Borovikov and Kryskov (1963, p. 275, pi. 1, fig. 9). However, a footnote (p. 274) indicates reassignment of sugandensis to Phaldagnostus Ivshin. Rusconi (1953, p. 5) described a single pygidium as L. empozadensis. He later redescribed and figured the same specimen (1954, p. 33, pi. 2, fig. 10) as L. empozadense. As far as can be determined from the figure, this species has a much wider border than any described species of Lejopyge. The specimen described and figured by Rusconi (1951, p. 8, fig. 9) as Spinagnostus pedrensis was later assigned by him to L. pedrensis ( Rusconi 1 953). However, the figure given by Rusconi ( 1 95 1 ) is inadequate for either generic or specific identification. Robison (1964a) described L. calva from Utah and Nevada where it is the nominate species of the youngest of the three subzones of his late middle Cambrian Bolaspidella Assemblage Zone. Palmer (1968) described L. calva from Alaska. L. calva is more effaced (PI. 63, fig. 10) than L. laevigata and its subspecies. Robison (1964a, p. 522) reported the occurrence of an unnamed subspecies of L. calva from U.S. Geological Survey Collection 2523-CO from Schell Creek Range, Nevada, characterized by postero-lateral border spines on the cephalon, but not on the pygidium. A pygidium is figured (PI. 63, fig. 9), but none of the available associated cephala show undoubted cephalic spines. Cephala and pygidia from a Lejopyge- coquina from Patterson Pass, Snake Range, East Nevada, are almost entirely effaced and are figured as Lejopyge sp. (PI. 63, figs. 7 and 8) but may well be representatives of L. calva. L. cos was described by Opik (1967, p. 93) from the lower two zones {Erediaspis eretes and Cyclagnostus quasivespa Zones) of the Mindyallan Stage of north-west Queensland, which were placed in the upper Cambrian, thus making L. cos the youngest species of Lejopyge. All other described and authenticated species of Lejopyge come from late middle Cambrian horizons. As concluded below, we believe that L. cos is a junior synonym to L. 1. armata and that it is of late middle Cambrian age. L. laevigata and L. 1. armata are differentiated on the basis of the latter having DAILY AND JAGO: LEJOPYGE 529 cephalic and pygidial spines. However, there are small postero-lateral spines on the pygidium of L. laevigata (Westergard 1946, pi. 13, fig. 25; PI. 62, fig. 10). There are also short spines on the cephalon of L. laevigata (Westergard 1946, pi. 13, fig. 24; PI. 62, fig. 2). L. 1. perrugata and L. 1. rugifera were erected by Westergard (1946) for forms with cephala showing a greater degree of scrobiculation than in either L. laevi- gata or L. 1. armata. However, some of the cephala of L. laevigata and L. 1. armata illustrated by Westergard (1946, pi. 13, figs. 22, 35) are scfobiculate to varying degrees (PI. 62, fig. 3). L. 1. rugifera was differentiated from L. 1. perrugata by Westergard on the basis of the latter having short cephalic spines with no mention of cephalic spines in the diagnosis of L. 1. rugifera. The cephalic spines of the holotype of perrugata are quite large (PI. 63, fig. 1) and the holotype of rugifera also has cephalic spines albeit short (PI. 63, fig. 6). The pygidia (PI. 62, figs. 12, 13 ; PI. 63, figs. 2-4) associated with the holotype cephala of rugifera and perrugata are indistinguishable from pygidia of L. laevigata and L. 1. armata. Westergard noted the great morphological variation within L. laevigata and also the presence of intermediate forms between L. laevigata and L. 1. armata, L. 1. per- rugata and L. 1. rugifera, and between the subspecies (see text-fig. 1). This variation and the presence of intermediate forms indicate that we are dealing with a species complex with the subspecies armata, perrugata, and rugifera representing extreme forms of L. laevigata. Lejopyge laevigata rugifera Lejopyge laevigata armata < > Lejopyge laevigata perrugata TEXT-FIG. 1. Summary of gradations between the species and subspecies of Lejopyge from Sweden. The arrows indicate the presence of gradational characteristics, which include the over-all shape of the cephalon and pygidium, the degree of effacement, the width of the pygidial axis, the presence or absence of cephalic and pygidial spines, the length of spines, and the degree of cephalic scrobiculation. Opik (1967, p. 93) diagnosed L. cos as follows: Leiopyge cos sp. nov. is distinguished by well developed posterior section of the cephalic axial furrows and rather distinct but relatively small basal lobes, short pygidial marginal spines, and two median nodes on the pygidial axial lobe; the additional node is placed on the anterior axial annulation. Opik’s differential diagnosis of L. cos is as follows: The marginal pygidial spines of L. cos are shared by Leiopyge laevigata armata (Linnarsson) but armata has only one node, on the second axial annulation; furthermore, the cephalic spines of armata are long (short in cos, as observed on specimens not illustrated). The specimens figured by Westergard (1946, pi. 13, figs. 28, 29, 30, 31) as L. 1. armata (Linnarsson) fit the diagnosis of L. cos perfectly. (The anterior of the two nodes cannot be seen in Westergard’s figures.) The pygidia of armata (Westergard 530 PALAEONTOLOGY, VOLUME 18 1946, pi. 13, figs. 30, 31 ; PI. 62, figs. 15, 16) have nodes on both the first and second pygidial axial segments in identical positions to the two nodes illustrated on L. cos by Opik (1967, fig. 20). Close examination of the holotype pygidium of L. cos reveals the presence of a faint, but distinct, third node placed at about the centre of the third axial segment (PI. 62, fig. 18). A third node in a similar position is also present on L. laevigata, L. 1. armata, and on pygidia associated with the holotype cephala of L. /. perrugata and L. 1. rugifera and the unnamed subspecies of L. calva of Robison (1964a). Palmer (1968, p. 26) noted that Lejopyge has ‘the posterior axial node on the axial lobe and not at its terminus, comparable to the position in Ptychagnostus' . The presence or absence of pygidial nodes and spines on the various species of Lejopyge is shown in Table 1. Not all pygidia possess a third node; where it is present it is usually small and faint and is not always visible in the photographs. However, in some specimens the node is reasonably prominent (e.g. PI. 62, figs. 7, 8; PI. 63, figs. 3, 9). At least one pygidium of L. laevigata (Westergard 1946, pi. 13, fig. 23; PI. 62, fig. 7) has an anterior axial node as do some of the pygidia associated with the holotype cephalon of L. 1. perrugata. In most pygidia not possessing a definite anterior axial node there is a slight general swelling in the expected position of the node. Thus the presence or absence of the first or third nodes cannot be used to differentiate L. cos, L. laevigata, and L. 1. armata. The pygidium of Ptychagnostus elegans laevissimus (Westergard 1946, pi. 10, fig. 22; PI. 63, fig. 13), the supposed ancestor of L. laevigata, shows no sign of either a first or a third pygidial node. L. eos is also similar to L. 1. armata in its pygidial spine characteristics. In this discussion of spine characters the line diagram of Opik (1967, fig. 20) is referred to rather than his photograph of the holotype of L. cos (Opik 1967, pi. 57, fig. 5; PI. 62, fig. 18), because the border is poorly preserved on the holotype and Opik had access to other unfigured pygidia of L. cos. Opik (1961a, p. 87; 1967, p. 93) maintained that L. 1. armata has long cephalic and pygidial postero-lateral spines. However, Westergard (1946, pi. 13, figs. 28-36) allows great variations in the length of these spines— they vary from quite small to very long. Westergard (1946, p. 89) also notes, when discussing armata that: Forms with shorter spines and more or less distinctly furrowed cheeks connect this long-spined and smooth form on the one hand with the typical laevigata and on the other hand with the subspecies perrugata. This is borne out by a cephalon with short spines (PI. 62, fig. 14) which occurs on the same slab as the pygidia figured as L. 1. armata in Westergard (1946, pi. 13, figs. 30, 31) (see also PI. 62, figs. 15, 16). Further, a cephalon figured as L. /acv/gata (Westergard 1946, pi. 13, fig. 24; PI. 62, fig. 2) has short cephalic spines. The pygidia of L. 1. armata (Westergard 1946, pi. 13, figs. 30, 31; PI. 62, figs. 15, 16) have quite small spines which in fact are smaller than those of L. cos (Opik 1967, p. 93, fig. 20). Thus, as far as cephalic and pygidial spines and pygidial nodes are concerned, L. cos and L. 1. armata are indistinguishable. The over-all shape of the holotype pygidium of L. cos (PI. 62, fig. 18) is similar to the shape of many of the pygidia of L. laevigata and L. 1. armata figured by Westergard (1946). Unfortunately, the only cephalon of L. cos figured by Opik (1967, pi. 57, fig. 6) (see also PI. 62, fig. 17) is a poorly preserved collapsed specimen in which the border has not been preserved. Opik’s diagnosis of L. cos notes the well-developed posterior section of the cephalic axial furrows and the small DAILY AND JAGO: LEJOPYGE TABLE 1 . Pygidial characteristics of the species and subspecies of Lejopyge. 531 Designated name Figuring Figuring in Spine Axial nodes or association herein previous works characteristics 1 2 3 Other remarks Lejopyge laevigata PI. 62, fig. 7 Westergard (1946, pi. 13, fig. 23) Absent 7 P P 5 or 6 pairs of muscle scars. Associated with Dalman's syntype L. laevigata PI. 62, fig. 4 WestergSrd (1946, pi. 13, fig. 26) Absent A P A At least four pairs of muscle scars L. laevigata PI. 62, fig. 10 Westergard (1946, pl. 13, fig. 25) Very small 7 P P L. laevigata PI. 62, fig. 8 Unfigured pygidium on same slab as cephalon figured in Westergdrd (1946, pl. 13, fig. 24) Absent P P P Faint trace of post- axial median furrow L. laevigata PI. 62, fig. 6 Unfigured pygidium on same slab as above specimen Minute A P P Faint trace of post- axial median furrow L. laevigata PI. 62, fig. 9 Westergard (1946, pl. 13, fig. 20) Absent A P P L. laevigata PI. 62, fig. 5 Unfigured specimen on same slab as above specimen Absent P P P Trace of post-axial median furrow L. laevigata PI. 62, fig, 1 Westergard (1946, pl. 16, fig. 9) Absent A P 7 Complete specimen L. 1. armata PI. 62, fig. 15 Westergard (1946, pl. 13. fig. 30) Very small P P 7 L. 1. armata PI. 62, fig. 16 Westergard (1946, pl. 13, fig. 31) Very small P P P Pygidium associated with holotype cephalon of L. 1. perrugata PI. 63, fig. 3 Unfigured Present A P A Broad low ridge posterior to node 2. Spines broken — length indeterminate Largest pygidium PI. 63, fig. 2 Unfigured Present 7 P P Very large spine base associated with holotype cephalon of L. 1. perrugata Pygidium associated PI. 62, fig. 13 Unfigured Large spines P P P with holotype cephalon of L. 1. perrugata Pygidium associated PI. 62, fig. 12 Unfigured Present P P P with holotype cephalon of L. 1. perrugata Pygidium associated PI. 63, fig. 4 Unfigured Absent A P P with holotype cephalon of L. 1. rugifera Holotype pygidium of L. cos PI. 62, fig. 18 Opik (1967, pl. 57, fig- 5) Present P P P L. calva Unfigured Robison (1964, pl. 83, fig. 3) Absent A P A Strikingly effaced in both cephalon and pygidium U.S.G.S. Collection 2523-CO (unnamed subspecies of L. calva, see Robison 1964a, PI. 63, fig. 9 Unfigured Absent 7 P P Wide border. Not all pygidia on this specimen have the third node p. 522) Lejopyge sp. (probably PI. 63, fig. 8 Unfigured Absent A P A All pygidia in these L. calva) from coquina, Patterson Pass, Snake Range. Nevada Plychagnostus elegans laevissimus PI. 63, fig. 13 Westerg^rd (1946, pi. 10, fig. 22) Absent A P A specimens are strikingly effaced Wide axis A ^ absent. P present. ? = indeterminate. 532 PALAEONTOLOGY, VOLUME 18 but distinct basal lobes. However, the basal lobes of all species of Lejopyge are small. The rear part of the cephalic axial furrows of almost all the specimens of L. laevigata and its subspecies figured in Westergard (1946) and herein also have well-developed posterior axial furrows. The facts noted above indicate that L. cos is a junior synonym of L. /. armata. Another point is that the pygidia of L. 1. armata, as illustrated by Opik (1961a, pi. 22, figs. 2, 3, 4) presumably have no node on the anterior axial annulation. Whether this is so or not cannot be clearly determined from the illustrations given by Opik. If, in fact, there is no anterior node on the Queensland middle Cambrian and Passage Zone forms, then this may indicate a difference due to geographical variation. A further point of difference between the Swedish specimens of L. I. armata and those from Queensland illustrated by Opik (1961a, pi. 22, figs. 2-4) is that in the Queensland forms the pygidial spines are posterior to those figured by Westergard (1946). LEJOPYGE THE MIDDLE-UPPER CAMBRIAN BOUNDARY Scandinavia Within the Acado-Baltic province (type province of the Cambrian System) in both the Oslo region and adjacent parts of Sweden, the Cambrian occurs as very markedly condensed platform sequences. Although sections of these seemingly shallow-water deposits contain breaks, the painstaking collection and documentation of the fossils, mainly trilobites, has allowed a reliable and very fine zonation of the System, especially for the middle and upper Cambrian. Westergard (1922; 1946, p. 19; 1947, pp. 20-21) has shown that the most complete sections for the middle and upper Cambrian in Sweden are in Scania. However, even there breaks of varying magnitude are evident. In Scandinavia the middle Cambrian-upper Cambrian boundary is drawn at the top of the Lejopyge laevigata Zone (see Tables 2 and 3). However, when discussing the biostratigraphy of the Swedish middle Cambrian, Westergard (1946, p. 7) pointed out that ‘The boundary is not very well defined, the zone of Lejopyge laevigata merging into that of Agnostus pisiformis'. There are several reasons why this appears to be so : 1. In contrast to the rich and varied fauna of the L. laevigata Zone, only eight trilobite species or subspecies (even one of these questionably) are known in the A. pisiformis Zone in Sweden; three in Norway, where Olenus alpha Henningsmoen constitutes a further species. However, the rare O. alpha is unknown outside of the Ringsaker area (Henningsmoen 1957; 1958). 2. A. pisiformis (Linnaeus) is the only common trilobite in the A. pisiformis Zone, all other species being generally rare or absent in collections from most localities where the zone is recognized. The fossils which occur in black bituminous shales (alum shales) and dark bituminous limestone (stinkstone) were probably specialized planktonic forms that were able to avoid the poisonous bottom habitat ( Bergstrom c/ a/. 1972). 3. Of the trilobites found in the A. pisiformis Zone only A. pisiformis ranges down into the L. laevigata Zone (Table 2). Originally Westergard (1947, p. 22) showed DAILY AND JAGO: LEJOPYGE 533 TABLE 2. Trilobite zonation for the late middle Cambrian-early upper Cambrian of Sweden. The ranges of the majority of Scandinavian trilobites mentioned in the text are presented to facilitate discussion. The thicknesses given for the various divisions are taken from Westergard (1944a, p. 29). The unbracketed figures are for the Andrarum No. 1 borehole; those bracketed are for the Sodra Sandby borehole about 40 km west of Andrarum, Scania. Note that the thickness for the L. laevigata Zone includes the unfossili- ferous interval 10 m (3 0) immediately below the designated A. pisiformis Zone. (P m g (p I z m CP Acrocephalites stenometopus Acrocephalites stenometopus agnostorum Acrocephalites stenometopus olenorum Agnostus pisiformis Agnostus pisiformis subsulcatus Clavagnostus sulcatus Diplagnostus planicauda vestgothicus Drepanura eremita Glyptagnostus reticulatus Glyptagnostus reticulatus nodulosus Homagnostus obesus Hypagnostus sulcifer Lejopyge laevigata Lejopyge laevigata armata Oidalagnostus trispinifer Olenus alpha Peronopsis insignis Phalacroma glandiforme Phalagnostus bituberculatus Proceratopyge conifrons Proceratopyge nathorsti Ptychagnostus (Goniagnostus) spiniger Ptychagnostus (Ptychagnostus) aculeatus Schmalenseeia amphioneura Solenopleura brachymetopa MIDDLE CAMBRIAN UPPER I CAMBRIAN • I TO 3 o o ■J ■J 0) cu (Q IQ 3 3 0 O W W C C U> (/) 1 § cn 5 CP g o 3 O ■g (D c Q} n 3^ >< O ■D CU o' T3 < (Q (Tl QT CD < ID' 0) u 6 3 00 > (Q 3 C cn ■g V) 05 O Is 7 5 s.' N y Q Cfl (/) T3 ■D CD O' o a o ij. to 534 PALAEONTOLOGY, VOLUME 18 Acrocephalites stenometopus (Angelin) in the Agnostus pisiformis and Olenus Zones, but he later (1948) referred forms from each of these zones to the subspecies A. steno- metopus agnostorum and A. s. olenorum respectively (Table 2). Moreover, he regarded the middle Cambrian A. stenometopus and its two upper Cambrian subspecies as con- stituting an evolutionary series which spanned the middle-upper Cambrian boundary. Thus in Scandinavia and elsewhere, rocks with L. laevigata signify the middle Cambrian. 4. Where unfossiliferous intervals occur between rocks containing the L. laevigata and Agnostus pisiformis faunas, there must be an interval of uncertainty concerning the zonal and series boundaries. In practice, the boundary has been drawn either immediately above the barren interval (Westergard 1944a, h) or immediately below it (Westergard 1922, p. 18). Should a convenient reference section for the middle-upper Cambrian boundary be required, the section described by Westergard (1922, fig. 33, pp. 67-68) from Odegarden, Falbygden district in Vastergotland would be suitable, for at that locality the L. laevigata and A. pisiformis Zones are in contact and the ranges of the two nominate zonal species overlap. This unbroken section provides an unambiguous solution to the boundary problem. The Cambrian world exclusive of Scandinavia Australia. Since Lejopyge cos Opik is a synonym of L. laevigata armata (Linnarsson), it is evident that L. 1. armata ranges as high as the Mindyallan Zone of Cyclagnostus quasivespa (see Opik 1967, Table 4, p. 41). Providing the upper limits of the ranges of this subspecies are the same in Queensland and Sweden then part of the C. quasivespa Zone and the top part of the Swedish L. laevigata Zone are correlatives (Table 3). The described specimens of L. cos came from the Mungerebar Limestone at locality G 131 in the Zone of C. quasivespa. In the Mungerebar-Mindyalla area dips are low and outcrops are small and discontinuous so that Opik’s stratigraphic suc- cession was pieced together on faunal evidence rather than on superposition. This has led to uncertainties, for example, Opik (1967, vol. 2, p. 9) commented that the collection from locality G 131 was ‘apparently below G 130’ which among other species contained Blackwelderia sabulosa Opik. As indicated on the collection ; locality map (Opik 1967, fig. 3, p. 12), the G 131 site is not far removed from the \ lower boundary of the zonal limits. An analysis of faunal lists from collecting sites | within the C. quasivespa Zone suggests a clear separation of the G 131 fauna (and its * presumed equivalent the G 10 fauna, see Opik 1967, vol. 2, p. 6) from those contain- { ing B. sabulosa (G 124-G 127 ; G 1 30), which as he suggested are presumably younger. Thus for the Australian region it is advocated that the middle-upper Cambrian | boundary be drawn within the C. quasivespa Zone between the L. cos{ = L. 1. armata) and B. sabulosa faunas (Table 3). In passing, we note that in Australia Blackwelderia was already present in the late middle Cambrian for at locality G 1 19, 5. cf. sabulosa r.i is found in the zone of E. eretes. Moreover, Blackwelderia succeeds Damesella in i Australia as in China. In Australia Damesella first appears in the D. torosa-A. janitrix Zone and D. torosa itself ranges into the E. eretes Zone (Opik 1967, p. 307) where Blackwelderia is present. ' TABLE 3. Correlation chart of late middle and early upper Cambrian trilobite faunas of Scandinavia and other areas discussed in the text. It should be noted that the top and bottom lines of the correlation chart have no temporal significance, e.g. it does not indicate that the top of the North American Aphelaspis Zone corresponds to the top of the Glyptagnostus reticulatus Zone from Australia or that the base of the North American Bolaspidella Zone is equivalent to the base of the Swedish Solenopleura brachymetopa Zone. Chu (1959) uses the term Damesella paronai Zone rather than the D. blackwelderi Zone. DAILY AND JAGO: LEJOPYGE 535 UOH l> « o III m 8 1 i 6 WZIOQH IMSIVhmxrS I aswissns IMSNiaOWVS (fl C WT> np § £ ? i a E 0) 0) O h. 5 <0 a" •n .'ii § ? 5 i NOliVWUOd NVHSn>< O 5 NviHOVQsaya 30V1S NvgysivQi 5 W) « 2 5 S’ s X <5 % S NVnnVAQNIW (Ji W i E < a 2 £ S3TVHS saoo/vuno Nviaawvo Is -I c ^ > sSf C 0) S' ^ s I $ i S3HVHS QNV SlIUO b3ii30NVW Nviyewvo 31QQWN T3 C C3 C o s: c &t) c C3 T3 C c3 C/5 ^ T3 2 Uh «/5 O ■C « O ^ tH 6 S z (D 2 G (/5 ^ & 2 c o c 3 ^ S. ■2 ^ I- ^ as ge laevigoia Lelopyge laevigaia NORTH AMEFBCA Proampyx agrs Ptyctia^xstus cessis laevigata i SIBEFUAN PLATFORM NORTH-WEST SIBERIA Clypiegnostus 3? plSIlorrrUS- HorrofFOSiuS lecuAdus .elopyge laevIgaB I Lomsucaspis a ( Acrocepnaieiia 2 Maiaspts spirosa- Agramos punciatus Notes: 1 and 2. The age of the basal part of the Manceiter Grits and Shales is uncertain and may range within the limits shown. 3 and 4. The relative positions of two important fossils in the Merevale No. 3 Borehole. Notes 5 and 6, The lower boundary of the Maiaspis spinosa-Oidalagnosius irispinifer Zone is shown extending to position 5, well into the Solenopleura brachymetopa Zone. Table 4 which is based mainly on Datsenko et a/. (1968, ‘Atlas’, pp. 28-31) shows that the ranges of Phalacroma glandi/orme and Oidalagnostus irispinifer overlap. Consequently, if it is conceded that P. glandiforme ranges into the Swedish L. laevigata Zone, then this boundary will need to be shifted to approximately position 6, 536 PALAEONTOLOGY, VOLUME 18 The vast majority of all the other trilobites listed in Opik’s Table 4 are endemic species and so have little value for refined intercontinental correlations. However, a check of the non-endemic forms listed suggests that the correlation proposed above is correct. The following species of agnostids listed by Opik deserve comment (reference to Tables 2 and 3 will assist the reader); 1. In Sweden Ptychagnostus {Goniagnostus) spiniger (Westergard) occurs in the ‘Zone of Lejopyge laevigata, basal layer’ (Westergard 1946, p. 82). Opik (1967, p. 90) reported this species from limestone in the Northern Territory (locality T 87) and from the Steamboat Sandstone in Queensland (localities G 106 and D 96). In the discussion of the Australian material Opik (1967, p. 90) stated that P. (G.) spiniger occurs ‘in the upper part of the L. laevigata II and in the laevigata III Zones’. Now the L. laevigata III Zone is shown as the uppermost middle Cambrian Zone in the biostratigraphic chart given by Opik (1961a, %. 15, p. 34). However, from the Devoncourt Limestone (locality D 18, which is a direct correlative of, or at the most one zone older than the T 87 fauna cited above) and the older Roaring Siltstone (locality D 7/15) in Queensland, Opik (1961a, p. 44) reported Ptychagnostus {Ptycha- gnostus) aculeatus (Angelin), a species which in Sweden is confined to the Solenopleura brachymetopa Zone. Thus, the positioning of the D 18 fauna on Opik’s chart (Opik 1961a, fig. 15, p. 34) appears to be too high in terms of the Swedish zonal scale and in the writers’ opinion the Australian L. laevigata II Zone is not younger than the upper half of the Swedish S. brachymetopa Zone. The occurrence of the Swedish Diplagnostus planicauda vestgothicus (Wallerius) in the D 18 fauna also tends to support the correlation of the Australian L. laevigata II Zone with the Zone of S. brachymetopa although in Sweden this form also occurs in the overlying L. laevigata Zone. Thus it appears likely that the L. laevigata III Zone will correlate approximately with the basal part of the Swedish Zone of L. laevigata. In terms of the Swedish Scale we suggest that P. (G.) spiniger in Australia spans the boundary separating the S. brachymetopa- L. laevigata Zones. 2. Opik (1967) showed that Oidalagnostus trispinifer Westergard ranged from the late middle Cambrian L. laevigata III Zone (localities G 121 and G 133) to the Zone of C. quasivespa (locality G 131) where it is associated with L. cos. Further, Opik (1967, p. 1 34) stated that O. trispinifer occurs in the superjacent zone of Glyptagnostus stolidotus in Tasmania. However, the only species of Oidalagnostus from Tasmania known to the writers is indeterminate. Its age is probably the Erediaspis eretes Zone or the C. quasivespa Zone. In Sweden the very rare O. trispinifer has been found only in the upper part of the L. laevigata Zone (Westergard 1946, p. 67). (Dr. Lars Karis, Geological Survey of Sweden (pers. comm.), has found O. trispinifer in a limestone concretion containing faunal elements of the Zone of S. brachymetopa in the Tasjo area, central Swedish Caledonides. Thus the stratigraphic range of this species is more extensive than that shown on Table 2. Consequently, the lower boundary of the Siberian Zone of Maiaspis spinosa-0. trispinifer can now be confidently drawn at position 5 on Table 3.) Thus it seems likely that the lower portions of the C. quasivespa Zone and the top part of the Swedish L. laevigata Zone are correlatives and that the species may in fact cover the full range of the Swedish L. laevigata Zone. This latter suggestion DAILY AND JAGO: LEJOPYGE 537 TABLE 4. Stratigraphic distribution of trilobites important for the correlation of the north-west Siberian middle and upper Cambrian rocks. The relative sizes of the zones and the ranges of the fossils were calculated from Datsenko et al. (1968, ‘Atlas’, pp. 28-31) and Rosova (1968). TRILOBITES Agraulos punctatus Maiaspis spinosa- Oidalagnostus trispinifer Acrocephalella granulosa — Koldiniella prolixa Pedinocephalina— Toxotisc?) Phalacroma glandiforme Maiaspis spinosa Oidalagnostus trispinifer "Homagnostus fecundus’ X Grdnwallia decora X Koldiniella convexa - Nganasella nganasanensis - Acidaspidella limita Pseudagnostus nganasanicus — ■peronopsis insignis” “Clavagnostus sulcatus” X is supported by the common occurrence of O. trispinifer in north-western Siberia in the middle Cambrian Mayanian Stage where according to Datsenko et al. (1968, in ‘Atlas of stratigraphic schemes’, pp. 28-29) it is found in all but the basal part of the Zone of Maiaspis spinosa-Oidalagnostus trispinifer which, in our opinion (see below), marks the top of the middle Cambrian (Table 4). 3. An agnostid cephalon from the Mungerebar Limestone (locality G 119, Zone of E. eretes) figured (Opik 1967, pi. 58, fig. 1) as Agnostus‘1 sp. aff. Agnostus pisiformis subsulcatus Westergard, may belong in our opinion to Westergard’s subspecies which was described by him from the Paradoxides forchammeri beds, although on his range chart (Westergard 1946, p. 102), he indicated that the species occurred only in the L. laevigata Zone. Apart from minor taxonomic differences it would seem that the uncertainty of Opik’s assignment was partly influenced by the belief that the E. eretes Zone was younger than the L. laevigata Zone of Sweden. 4. According to Opik (1967, pp. 131-132) the Proagnostusl sp. from Woodstock, Alabama, U.S.A. (see Palmer 1962), is Connagnostus venerabilis Opik, a species which in Australia is confined to the Glyptagnostus stolidotus Zone. It is one of the few new species of Australian agnostids described by Opik common to both continents. Of even greater significance is its occurrence in Alabama, in the Conasauga Formation, in association with G. stolidotus Opik (Palmer 1962, fig. 4) the nominate zone fossil for the uppermost zone of the Australian Mindyallan Stage. Thus the intercontinental 538 PALAEONTOLOGY, VOLUME 18 correlation of the G. stolidotus Zone with the lower levels of the Crepicephalus Zone in North America and probably an undefined part of the subjacent Cedaria Zone seems assured (Table 3). Further, in both Australia and North America G. stolidotus is succeeded by Glyptagnostus reticulatus (Angelin) (Opik \96\b, 1963; Palmer 1962, Table I, p. 7). G. reticulatus is also present in Sweden where it occurs in the two oldest subzones of the Olenus Zone and its subspecies G. r. nodulosus Westergard passes into the overlying subzone. Therefore it seems that providing the lower part of the C. quasivespa Zone marks the top of the Swedish L. laevigata Zone as indicated above, then the upper part of the C. quasivespa Zone (from the base of the B. sabulosa fauna) together with the overlying G. stolidotus Zone must equate with the Scandinavian A. pisiformis Zone. Thus in Australia the middle-upper Cambrian boundary would occur within the Mindyallan Stage and within the C. quasivespa Zone as shown in Table 3. Great Britain. Until recently the L. laevigata and A. pisiformis Zones were unknown with certainty in Britain but they have now been positively identified from fossils obtained from the Merevale No. 3 Borehole, Warwickshire (Rushton in Taylor and Rushton 1972; Cowie et al. 1972). However, L. laevigata has not yet been found in British rocks. The L. laevigata Zone is present within the Mancetter Grits and Shales. The oldest identifiable fossil within this formation is the bradoriid crustacean Svealuta primordialis (Linnarsson). It was found one-third of the way through the forma- tion but fragments assigned to this species occur almost to its base. In Sweden the species occurs in the L. laevigata Zone (Westergard 1944a, p. 33) and it is ‘abundant in the Zone with Solenopleura brachymetopa' (Opik 1961a, p. 175). Hence it seems EXPLANATION OF PLATE 62 All figures are rubber casts whitened with magnesium oxide prior to photography. All figures are untouched. Figs. 1-10. Lejopyge laevigata (Dalman). 1, complete specimen (Westergard 1946, pi. 16, fig. 9) from Ullavi (boulder), Narke, x7-3. 2, cephalon (Westergard 1946, pi. 13,fig. 24)fromDjupadalen, Vastergot- land, x8-4. 3, cephalon showing scrobiculation (Westergard 1946, pi. 13, fig. 22) from Honsater, Kinnekulle, Vastergotland, X 11-2 (the black hole is a hole in the cast). 4, pygidium (Westergard 1946, pi. 13, fig. 26) from Gudhem, Vastergotland, x 8. 5, small pygidium showing post-axial median furrow (associated with specimen figured PI. 62, fig. 9), Andrarum, Scania, x 1 2-4. 6, minutely spinose pygidium (associated with cephalon figured PI. 62, fig. 2), Djupadalen, Vastergotland, xlO. 7, pygidium (Westergard 1946, pi. 13, fig. 23) from Honsater, Kinnekulle, Vastergotland, x8. Note the very faint third pygidial node and the several pairs of muscle scars on the third pygidial lobe. 8, pygidium (associated with cephalon figured PI. 62, fig. 2), Djupadalen, Vastergotland, x 10. 9, pygidium (Westergard 1946, pi. 13, fig. 20) from Andrarum, Scania, x9-7. 10, pygidium (Westergard 1946, pi. 13, fig. 25) from Djupadalen, Vastergotland, x 8. Figs. 11-18. Lejopyge laevigata armata (Linnarsson). Figs. 11, 12, 13 are of specimens associated with the cephalon (Westergard 1946, pi. 14, fig. 2) figured herein (PI. 63, fig. 1) as the holotype of Lejopyge laevigata perrugata from Karlfors, Billingen, Vastergotland. 11, cephalon with long spines, x8-4. 12, pygidium with long spines, x7-9. 13, small pygidium, x 10. 14, spinose cephalon associated with pygidia of Lejopyge laevigata armata (see PI. 62, figs. 15, 16) from Gudhem, Vastergotland, x 13. 15, pygidium with small spines (Westergard 1946, pi. 13, fig. 30), x7-6. 16, pygidium with small spines (Westergard 1946, pi. 13, fig. 31), x7-5. 17, crushed cephalon (Opik 1967, pi. 57, fig. 6 as Lejopyge cos) from Mungerebar Limestone, Queensland at Lat. 22° 15-5' S., Long. 139° 01' E., x 13-5. 18, pygidium figured (Opik 1967, pi. 57, fig. 5) as holotype of Lejopyge cos, Mungerebar Limestone, Queensland, at Lat. 22° 15-5' S., Long. 139° OF E., x9-4. PLATE 62 DAILY and JAGO, Lejopyge 540 PALAEONTOLOGY, VOLUME 18 likely that the lower third of the Mancetter Grits and Shales could conceivably incorporate part of the S. brachymetopa Zone, rather than all of it belonging to the L. laevigata Zone as suggested by Rushton. Such an uncertainty is expressed in Table 3. Irrespective of its age, the basal part of the formation is a conglomerate (see also Illing 1916, p. 395; Stubblefield 1956, p. 31) which may reflect an erosional event comparable with that of the Exporrecta conglomerate of Sweden. The youngest fossil which can be assigned confidently to the L. laevigata Zone is Hypagnostus sulcifer (Wallerius), found near the top of the formation. Westergard (1946, p. 52) reports this species only from the upper part of the Swedish L. laevigata Zone. The A. pisiformis Zone is contained with certainty in the lower part of the over- lying Outwoods Shales. A. pisiformis and Schmalenseeia cf. amphionura occur together at or near the base of the zone, a 10-m interval below this level remaining unassigned due to lack of diagnostic fossils. An important find about three-fifths of the way through the Mancetter Grits and Shales was Ptychagnostus (Goniagnostus) fumicola Opik (Rushton in Taylor and Rushton 1972, p. 9). However, on the bore log record (ibid., pi. 4) the identification appears to be less certain for there it is given as Ptychagnostus cf. fumicola. Through the kind efforts of Dr. A. Rushton we have examined latex casts of this material and believe that the assignment of P. (G.) fumicola Opik is correct. Now in the Mungerebar area in Queensland, P. (G.) fumicola occurs with Oidalagnostus trispinifer in rocks (locality G 121) referred by Opik (1967, p. 91) to the L. laevigata III Zone. It is also found in the succeeding zone with Damesella torosa and Ascionepa janitrix which Opik called the middle-upper Cambrian zone of passage. However, as pointed out above, O. trispinifer in Queensland is known to range upwards into the C. quasivespa EXPLANATION OF PLATE 63 All figures are photographs of rubber casts, except figs. 7 and 8 which are of the actual specimens. All were whitened with magnesium oxide prior to photography. All figures are untouched. Catalogue numbers are those of the palaeontology collections, South Australian Museum, Adelaide, South Australia. Fig. 1. Holotype cephalon of Lejopyge laevigata perrugata (Westergard 1946, pi. 14, fig. 2) from Karlfors, Billingen, Vastergotland, x 9. Figs. 2, 3. Pygidia associated with the holotype cephalon of Lejopyge laevigata perrugata. 2, pygidium with very large spine base, x 10-8. 3, pygidium with broad low ridge posterior to the second axial node, x 1 1. Figs. 4, 5. Pygidium and rugose cephalon associated with the holotype cephalon of Lejopyge laevigata rugifera from Sjogestad, Ostergdtland. 4, pygidium, x 7-7. 5, cephalon, x 7-4. Fig. 6. Holotype cephalon of Lejopyge laevigata rugifera (Westergard 1946, pi. 14, fig. 3), x 8-4. Figs. 7, 8. Lejopyge sp. (probably Lejopyge calva) from coquina at Patterson Pass, Snake Range, East Nevada. 7, P. 14545, cephalon, x8-8. 8, P. 14546, pygidium, x 10-4. Fig. 9. Pygidium of unnamed subspecies of Lejopyge calva (see Robison 1964a, p. 522) from U.S. Geo- logical Survey Collection 2523-CO, Schell Creek Range, Nevada, x8-5. Note the third pygidial node. Fig. 10. Lejopyge calva Robison, holotype cephalon (Robison 1964a, pi. 83, fig. 1) from 1336 ft above base of the Marjum Formation, Wheeler Amphitheater, House Range, Western Utah, x 10-3. Fig. 1 1. Lejopyge exilis pygidium (Whitehouse 1936, pi. 9, fig. 12) from 8 miles north-east of Duchess, Queensland, x7T. Figs. 12, 13. Ptychagnostus elegans laevissismus Westerg&rd, from Gislovshammer (boulder 18), Scania. 12, holotype cephalon (Westergard 1946, pi. 10, fig. 21), x9-7. 13, pygidium (Westergard 1946, pi. 10, fig. 22), x81. Figs. 14, 15. Drepanura eremita Westergard . 14, cranidium (Westergdrd 1947, pi. 3, fig. 9), locality unknown, x3-5. 15, holotype pygidium (Westergard 1947, pi. 3, fig. 11) from Djupadalen, Vastergotland, x2. PLATE 63 DAILY and JAGO, Lejopyge, Ptychagnostiis, and Drepanura 542 PALAEONTOLOGY, VOLUME 18 Zone where, at locality G 131, it is associated with L. cos Opik ( = L. /. armata) and Svealuta cf. primordialis. The range of the British P. (G.) fumicola is unknown, being found only in one thin bed, just above the mid-point of the interval allotted by Rushton to the L. laevigata Zone. Unfortunately, without further fossil control on the upper and particularly the lower limits of the zone, the value of P. {G.) fumicola for refined intercontinental correlation remains untested. Nevertheless, as the species occurs well below the occurrence of H. sulcifer, which in Sweden seems to have the same range as O. trispinifer, it appears likely that P. (G.) fumicola may be confined to the interval represented by the central portion of the Swedish L. laevigata Zone. North America. In North America L. calva Robison occurs in the uppermost subzone of the late middle Cambrian Bolaspidella Assemblage Zone. Lu (1960, p. 213) and Robison (1964/?) independently proposed that the middle-upper Cambrian boundary in North America be placed at the top of the Bolaspidella Zone. In reaching his con- clusion Robison {\96Ab) assumed that the range of L. calva was contained within the time interval occupied by the Swedish Zone of L. laevigata. However, Palmer (1968, p. 10) has shown that in Canada L. calva is associated with Phalagnostus bituberculatus (Angelin) and Ptychagnostus {P.) aculeatus (Angelin) both of which in Sweden are confined to the S. brachymetopa Zone (Table 2). Palmer (1968, p. 10) also reported L. laevigata from the Hillard Peak area in Alaska within a mile or so of the Canadian occurrence of L. calva. Unfortunately, both species are unknown in the same section in Alaska (or elsewhere), and thus all that can be said presently with any degree of certainty is that L. calva, based on the Canadian occurrence, covers only the lower part of the range of L. laevigata. Thus in North America the middle-upper Cambrian boundary may well lie within the Cedaria Zone rather than at its base as suggested by Robison (1964Z), c). Using the generic range of trilobites. Palmer (1962, fig. 9) was the first to suggest that the Series boundary lay somewhere within the Cedaria Zone. This conclusion is in harmony with our views (Table 3), which, however, are based on more recent information at the species level. Indeed, it is the writers’ view that correlations based on species have the best chances of being correct, for the accuracy of correlation using genera or higher taxa is of a much lower order and should be viewed as such. For example, of the many polymerid species listed by Opik (1967, Table 4), only Corynexochus plumula Whitehouse and Stephanocare richthofeni Monke presently allow for intercontinental correlation. Corynexochus has in the past been regarded as a middle Cambrian genus. However, the anachronistic C. plumula, which succeeds G. reticulatus in all its known occurrences in Australia and elsewhere (Opik 1963; Palmer 1968), is clearly upper Cambrian in age. China. Recently, Kobayashi (1967, p. 476, and fig. 5, p. 477) has discussed and shown the areal distribution of three distinct Cambrian faunas in eastern Asia. Two of these, namely the Hwangho Fauna and the Chiangnan Fauna are of interest here. The Hwangho Fauna is a shallow-sea fauna which contains mainly endemic elements with rare cosmopolitan elements. In contrast, the Chiangnan Fauna is interpreted as a pelagic or offshore fauna preserved in mainly black carbonaceous shales; its facies is similar to the dark-coloured Scandinavian alumshale and stinkstone facies. S. richthofeni, an important member of the Hwangho Fauna, provides a firm correlation of the Australian C. quasivespa Zone with part of the Kushan Formation DAILY AND JAGO: LEJOPYGE 543 sensu stricto, of northern China. There S. richthofeni is confined to the Blackwelderia paronai Zone (elsewhere in the text and Table 3 the term B. sinensis Zone is used in preference to the term B. paronai Zone) and the lower part of the succeeding Drepanura premesnili Zone (Chu 1959). Sun (1948), on the basis of the occurrence of D. eremita Westergard in the Swedish A. pisiformis Zone, argued for an early upper Cambrian age for the Kushan Formation sensu stricto. Opik ( 1 967) assigned both D. eremita and D. ketteleri Monke (note D. ketteleri is confined apparently to the D. premesnili Zone) to Palaeadotes Opik, which in Australia occurs in both the C. quasivespa and G. stoli- dotus Zones. Palaeadotes Opik is, however, a synonym of Bergeronites Sun whose genotype is Drepanura ketteleri Monke (see Kuo 1965, p. 637). We have re-examined D. eremita and believe that although it is close to Bergeronites it should be reassigned to a new genus. For example, its anterior facial sutures are distinctly divergent and not convergent as in Bergeronites and its pygidium has a well-defined border (see PI. 63, figs. 14, 15). Thus, less importance should be accorded this species for inter- continental correlation than has been in the past. In contrast to the paucity of agnostids in the Hwangho Fauna, there is a relative abundance of cosmopolitan agnostids in the Chiangnan Fauna. This fauna occurs in a broad north-easterly trending belt of rocks across south-eastern China and embraces parts of South Korea. Within this belt, on the Hunan-Kueichow border in southern China, Egorova et al. (1963) have reported Drepanura in the Para-Kushan Fauna in association with Proceratopyge conifrons Wallerius, a species confined to the upper part of the Swedish L. laevigata Zone (Table 2). At another locality Drepanura was found with "Glyptagnostus fossus' Pokrovskaya { = G. stolidotus Opik) and G. ret/cM/flto (Kobayashi 1971, Table 13, p. 177). Hence, in terms of the Scandinavian scale, and providing the determinations of the fauna are correct (we have not seen Egorova et al. 1963), Drepanura (or Drepanurinae if the determinations are not precise) would range from the upper part of the L. laevigata Zone to at least the base of the Olenus Zone where G. reticulatus is present in its lower part. Note that in Australia Opik (1961Z), p. 430) reports that G. stolidotus and G. reticulatus ‘overlap for a short interval (represented by a few feet of sediment only)’. This range for the Drepanurinae, therefore, is comparable to that cited above for Queensland. However, in northern China, Chu (1959) has shown that Drepanura and Bergeronites are pre- sumably restricted to the D. premesnili Zone whereas S. richthofeni ranges downwards into the lower levels of the B. sinensis Zone. As Bergeronites aff. dissidens occurs in Queensland in the C. quasivespa Zone with L. laevigata armata [= L. cos] (Locality G131) and with S. richthofeni (Locality G153) it would seem that the B. sinensis and C. quasivespa Zones are correlatives either fully or at least in part and that the D. premesnili Zone must in turn be correlated with the Australian G. stolidotus Zone and the upper part of the Swedish A. pisiformis Zone (Table 3). This agrees with con- clusions cited above. Likewise the Stephanocare Zone below the Drepanura Zone in South Korea will correlate to the C. quasivespa Zone as S. richthofeni is confined to the Stephanocare Zone in that region. Within the Chiangnan faunal belt in China, Kobayashi (1967, pp. 459-461) has reported the occurrence of Lejopyge in the Yanglioukang limestone in west Chekiang and south Anhwei provinces. In west Chekiang L. 1. armata occurs in the upper part of the formation (Kobayashi 1971, p. 176) and below Glyptagnostus beds above. In 544 PALAEONTOLOGY, VOLUME 18 south Anhwei Lejopyge occurs below rocks with Drepanura, Blackwelderia, and Pro- ceratopyge and many other genera, but further pertinent details are unavailable to us. Kobayashi (1967, p. 501) also reports Lejopyge from the dark- and light-grey bedded limestones and shales of the Mehuershan Series in the Eastern Tienshan. Glyptag- nostus occurs in the 25-m thick basal member of the overlying Torsuqtagh Series. In presenting a list of the middle and upper Cambrian trilobites from the Chiangnan faunal belt of central and south China, Kobayashi (1967, p. 462) reported L. 1. armata in the middle Cambrian sequence of the Kueichow-Hunan border region. Its occur- rence is listed together with the Swedish agnostids Ptychagnostus aculeatus (Angelin), P. atavus (Tullberg), and Diplagnostus planicauda bilobatus Kobayashi. We have been unable to check either the original locality data (presumably this is in Egorova et al. 1963) to see if further stratigraphic refinement is possible, or to check the fossil identifications. However, in the Handbook of standard fossils of south China (Chinese Academy of Science, 1964) some of the named species are figured but without accompanying locality and stratigraphic data. We believe the squashed specimen on plate 3, fig. 10 therein is correctly referred to L. 1. armata although we have some reservations about the identity of their P. atavus (pi. 2, figs. 8, 9). The material figured as P. aculeatus (pi. 2, figs. 10, 11) is not Chinese but Swedish material figured by Westergard (1946, pi. 12, figs. 9, 8). Judging the data presented by Kobayashi (1971, pp. 175-177) it seems likely that the listed L. 1. armata is from the west Chekiang occurrence cited above and that it has been inadvertently placed in the list of material from the Kweichow-Hunan border. Until more concrete facts are known concerning the occurrence of L. 1. armata and its relationship to immediately overlying faunas in this part of China, a final decision concerning the Series boundary cannot be given. However, the present evidence seems to favour the drawing of the boundary at some point within the Blackwelderia sinensis Zone rather than at its base as has so often been suggested. This conclusion pertains only to the Hwangho faunal facies belt. Lejopyge is yet unknown in this facies and is seemingly restricted to the Chiangnan Fauna. It is critical that further studies be conducted to find areas of intertongueing of the two faunal belts to prove or negate the above conclusion. U.S.S.R. Three zones, namely the Agnostus pisiformis-^ Homagnostus fecundus', G. stolidotus, and G. reticulatus Zones constitute the early upper Cambrian Tuorski or Tuorian Stage, Siberian Platform (Table 3). Its stratotype occurs in the foothills of the Tuora-Sis Ridge, 6 km below Chekurovka village on the River Lena (Lazarenko 1966; Ivshin and Pokrovskaya 1968). In northern Siberia Demokidov (1968) has referred to the interval covered by the two lower zones as the Sukhanski Horizon. The middle-upper Cambrian boundary is drawn between the Mayanian ( = Maisky) Stage and the overlying Tuorian Stage (Table 3). The uppermost zone of the Mayanian Stage is the Zone of L. armata- Lomsucaspis alta (Table 3). In Lazarenko’s zonal scheme the same zone is called the Zone of ‘L. armata-M. mirabilis'. Presumably, L. 1. armata is not necessarily present, as in the accompanying faunal list 'Lejopyge ex gr. laevigata" is cited. However, elsewhere in Siberia L. 1. armata has been recorded from many sections, for example in northern Siberia (Demokidov 1968) and in the north-western portion of the Siberian Platform, within the upper levels of the Mayanian Stage, in the Gremyakinskaya Anticline and on the River Mokoutey at DAILY AND JAGO: LEJOPYGE 545 the Rylninskii Ledge (Datsenko et al. 1968). Note also that only A. cf. pisiformis has been recorded from the Altay-Sayan fold belt (Romanenko 1972), so it seems invalid to use it as one of the nominate species in a zonal scheme. "Homagnostus fecundus', however, is not yet described and is a nomen nudum (Lazarenko, pers. comm. 1974). The faunal lists for the two oldest zones of the Tuorian Stage stratotype given by Lazarenko (1966, chart opposite p. 34) and by Ivshin and Pokrovskaya (1968, pp. 98-99) are significantly different. It is difficult to make a judgement without figures of the listed species and one might assume that the later of the two lists has updated the earlier one and includes taxa from more recent collections. With this in mind the following comments are offered. Four of the species listed for the A. pisiformis-" H . fecundus' Zone occur outside the limits of the U.S.S.R. In Sweden Damesella{l) eremita { = Drepanura eremita Westergard) and Proceratopyge nathorsti Westergard are known only from the A. pisiformis Zone whereas Acrocephalites stenometopus (Angelin) is confined to the L. laevigata Zone (Westergard 1952 and Table 2 herein). However, in her determination of fossils from the G. stolidotus Zone, Lazarenko (1966) identified A. stenometopus agnostorum Westergard and if this is correct, then the Swedish yI./?/5z/brw A Zone is indicated (Westergard 1948). Lazarenko (pers. comm. 1974) has not only reaffirmed the identification but has pointed out that the subspecies is now known from the A. pisiformis-" H . fecundus' Zone as well as the lower G. stolidotus Zone. We presume that Acrocephalites stenometopus recorded in Ivshin and Pokrovskaya (1968) is in reality the subspecies A. s. agnostorum in which case the base of the A. pisiformis-" H. fecundus' Zone will coincide with the middle- upper Cambrian boundary. If, however, Acrocephalites stenometopus is really present below A. s. agnostorum, then the middle-upper Cambrian boundary would need to be drawn within the zone and not at its base as indicated in Table 3 herein. The fourth species Pseudagnostina contracta was described by Palmer ( 1 962) from the G. stolidotus beds in Alabama, U.S.A., where it is unknown outside that zone. In the Tuorian Stage stratotype P. contracta and Proceratopyge nathorsti pass from the A. pisiformis- "H. fecundus' Zone into the overlying interval referred to as the G. stolidotus Zone thus suggesting that the upper levels of the A. pisiformis-" H . fecundus' Zone may correlate with the lowest parts of the G. stolidotus Zone elsewhere. Such an idea is expressed in Table 3. It should also be emphasized that Ivshin and Pokrovskaya (1968, p. 98) recorded G. reticulatus angelini Resser and Homagnostus obesus (Belt) in the G. stolidotus Zone in addition to the nominate species. In Sweden H. obesus is confined to the Olenus Zone. Thus it appears that the upper part of the Siberian G. stolidotus Zone in the Tuorian Stage stratotype already includes rocks that can be correlated with the lower levels of the Swedish G. reticulatus Zone and consequently the upper boundary of the Siberian G. stolidotus Zone is drawn a little higher than the base of the Swedish G. reticulatus Zone (Table 3). In the middle section of the River Kulyumbe, a tributary of the River Yenisey in north-western Siberia, the listed Swedish agnostids given in Datsenko et al. (1968, ‘Atlas’, Table 3, pp. 6-7) suggests that the Mayanian Stage, as recognized in that region, is represented by the time interval equivalent to that covering the Swedish Zone of Ptychagnostus punctuosus to the top of the L. laevigata Zone (but see below). Its two uppermost zones are the Zone of Maiaspis spinosa-Oidalagnostus trispinifer below and the Zone of Acrocephalella granulosa- Koldiniella prolixa above. All the 546 PALAEONTOLOGY, VOLUME 18 species in the latter zone are endemic to the U.S.S.R. except for Peronopsis insignis (Wallerius) which in Sweden is confined to the upper part of the L. laevigata Zone (Westergard 1946, p. 43). Rosova (1964, fig. 2) has indicated that P. insignis is restricted to the lower and midsections of the Sakhaiski Horizon, the upper- most division of the Middle Cambrian in her stratigraphic scheme. As well, Datsenko et al. (1968, p. 7) included P. insignis in their list of fossils contained in the Acrocephalella granulosa-Koldiniella prolixa Zone which together with the upper levels of the underlying Maiaspis spinosa-Oidalagnostus trispinifer Zone they equated with the Sakhaiski Horizon. However, on their charts Datsenko et al. (1968, fig. 31, p. 31) and Lazarenko and Nikiforov (1968, chart opposite p. 20) have also shown the occurrence of P. insignis in the very basal part of the overlying Pedinoeephalina-Toxotis(l) Zone (Table 4). This seems to support the observation by Lazarenko and Datsenko (1967, chart opposite p. 16) of the presence of P. insignis in both the A. granulosa- K. prolixa and Pedinocephalina-Toxotis{l) Zones. Like Westergard (1946) we regard P. insignis as indicative of a late middle Cambrian age. However, in our opinion the agnostid figured as P. insignis by Lazarenko and Nikiforov (1968, pi. 1, figs. 1-5) is incorrectly assigned because the pygidial axes of the two forms are different and the glabella of the Swedish form is shorter than the Siberian form; likewise for the pygidium figured by Rosova (1964, pi. 13, fig. 16). Also Lazarenko and Nikiforov (1968) charted Clavagnostus suleatus Westergard (known in Sweden only from the upper part of the L. laevigata Zone) as occurring above the form they called P. insignis (Table 4). The pygidia figured as C. suleatus (Lazarenko and Nikiforov, pi. 3, figs. 13, 14) may be incorrectly assigned (Jago and Daily 1974, p. 99). Thus neitW of these two agnostids are important for the boundary problem. However, their ranges are shown herein on Table 4 for comparison with those of other trilobites mentioned in the text. Many of the species recorded in the A. granulosa- K. prolixa Zone range up from the underlying zone. Among the new forms is ' Homagnostus fecundus' Pokrovskaya, the nominate zone fossil in the Siberian A. pisiformis- H . fecundus' Zone of the type Tuorian Stage. Datsenko et al. (1968) have indicated on their stratigraphic tables (p. 7 and Table 13, p. 41) that the A. granulosa-K. prolixa Zone at the top of their Mayanian Stage is middle Cambrian in age. However, as the Swedish agnostid O. trispinifer ranges only to the top of the M. spinosa-0. trispinifer Zone (Table 4), we suggest that the middle-upper Cambrian boundary should be placed at the top of this zone (Table 3) rather than at the top of the succeeding A. granulosa-K. prolixa Zone as suggested by most Soviet workers. Also because of the spot occurrence of ‘//. fecundus' in the latter zone (Table 4) the present authors suggest that this zone would better equate with the A. pisiformis-'H. feeundus' Zone of the type Tuorian Stage, in which case it is upper Cambrian in age (Table 3). The lower levels of the overlying Zone of Pedinocephalina-Toxotisfl) can be correlated with the lower Nganasanski Horizon at the bottom of the Kulyumbeiski Superhorizon or Substage of Rosova (1963, 1964, 1968, 1970) by means of the short- ranging Nganasanella nganasanensis Rosova, Koldiniella convexa Lazarenko, and Groenwallina decora Rosova (Tables 3 and 4). Pseudagnostus nganasanicus Rosova occurs in the same horizon (Rosova 1964, fig. 2). Also of importance for correlation is the reported occurrence of the very distinctive Acidaspidella limita Rosova, the DAILY AND JAGO: LEJOPYGE 547 lower range of which according to Rosova (1964, 1968, 1970) is near the base of the Nganasanski Horizon, although Datsenko et al. (1968, ‘Atlas’, fig. 31, p. 31) and Lazarenko and Nikiforov (1968, chart opposite p. 20) record its first appearance above the upper range of N. nganasanensis. Rosova’s observations for the species’ range are accepted herein (Table 4) particularly as Rosova (1970) has re-emphasized its occurrence near the base of the Nganasanski Horizon. P. nganasanicus and A. limita appear to be endemic to the U.S.S.R. Their occurrence also in the G. stoli- dotus Zone of the Tuorian Stage stratotype (Ivshin and Pokrovskaya 1968) permit reference of both the lower Nganasanski Horizon and the lower part of the Pedinocephalina-Toxotis{l) Zone to the G. stolidotus Zone. Such a conclusion reinforces the view suggested above that the A. granulosa- K. prolixa Zone is to be correlated with the A. pisiformis-" H . fecundus' Zone of the Tuorian Stage stratotype and with the lower part of the Swedish A. pisiformis Zone (Table 3). CONCLUSIONS The present revision of the taxonomic status of L. cos Opik has led to the conclusion that it is a junior synonym of the morphologically variable L. 1. armata Westergard. All known species of Lejopyge are of late middle Cambrian age. In Sweden L. laevigata and its subspecies range through the Solenopleura brachy- metopa Zone and throughout the succeeding Zone of L. laevigata, the top of which marks the middle-upper Cambrian boundary. For Australia, it is advocated that because L. cos Opik is synonymous with L. 1. armata Westergard, the middle-upper Cambrian boundary should be drawn within the Mindyallan Stage and at a level within the Cyclagnostus quasivespa Zone between the L. cos and Blackwelderia sabulosa faunas. Previously the boundary has been drawn at the base of the Mindyallan Stage. L. laevigata is presently unknown from British rocks. In England recent finds of agnostids and other fossils in the Merevale No. 3 Borehole show that the middle- upper Cambrian boundary lies within an unfossiliferous interval between the occur- rence of Hypagnostus sulcifer (Wallerius), found near the top of the Mancetter Grits and Shales, and below the occurrence of Agnostus pisiformis (Linnaeus) and Schmalenseeia cf. amphioneura, found towards the base of the overlying Outwoods Shales (Table 3). In North America the top of the Bolaspidella Assemblage Zone, which contains L. calva, has been regarded as the uppermost zone of the middle Cambrian. However, present evidence from Alaska where both L. calva and L. laevigata are found, sug- gests that the middle-upper Cambrian boundary for North America is more likely to occur within the overlying Cedaria Zone (Table 3). In China L. laevigata is apparently absent within the shallow-water shelf facies of the Hwangho Faunal Facies belt. Existing evidence favours the positioning of the middle-upper Cambrian boundary at some undefined level within the Blackwelderia sinensis Zone rather than at its base. However, elsewhere in China and within the Chiangnan Faunal Facies belt, the occurrence of L. 1. armata and other cosmopolitan agnostids should permit a reliable positioning of the Series boundary. On the Siberian Platform, in the foothills of the Tuora-Sis Ridge, the middle-upper 548 PALAEONTOLOGY, VOLUME 18 Cambrian boundary appears to be correctly drawn between the L. 1. armata- Lomsucaspis alta Zone below, and the A. pisiformis-'' Homagnostus fecundus' Zone above. However, in north-west Siberia evidence presented above suggests that the middle-upper Cambrian boundary should be drawn at the top of the Maiaspis spinosa-Oidalagnostus trispinifer Zone (Table 3) rather than at the top of the succeed- ing Acrocephalella granulosa-Koldiniella prolixa Zone as is presently done by Soviet authors. Acknowledgements. We are indebted to Professor A. R. Palmer, Drs. V. Jaanusson and H. Mutvei, the late Professor F. Brotzen, Professor D. Hill, and Dr. J. Shergold for kindly allowing us to obtain rubber moulds from specimens in their care and to Dr. A. W. A. Rushton who sent us rubber moulds of fossils from the Merevale No. 3 Borehole, Warwickshire. Dr. V. A. Gostin translated some of the Russian literature. One of us (J. B. J.) was supported by a grant from the Australian Research Grants Committee. REFERENCES BERGSTROM, J., LAUFELD, s. and CHRISTENSEN, w. K. 1972. Ekskursion til Skane. Dansk geol. Foren. Arsskr. for 1971, 111-118. BOROVIKOV, L. I. and kryskov, l. n. 1963. Cambrian deposits in the Kendyktas Mountains (South Kazakhstan). Trudy vses. nauchno-issled. geol. Inst. (VSEGEl) N.S. 94, 266-280, 1 pi. [In Russian.] CHERNYSHEVA, N. E. (ed.) 1960. Arthropoda, Trilobitomorpha and Crustacea. In ‘Osnovy Paleontologii’, Gos. nauch.-tekh. Izdat. Lit. geol. Okhr. Nedr. Moskva, 515 pp., pis. 1-18. [In Russian.] CHINESE ACADEMY OF SCIENCE. 1964. Handbook of Standard fossils of south China. Peking, 173 pp., pis. 1-92. [In Chinese.] CHU, CHAO-LING. 1959. Trilobites from the Kushan Formation of north and north-eastern China. Mem. Inst. Palaeont. Acad. Sinica, Nanking, 2, 44-80 [in Chinese]; 81-128 [in English], pis. 1-7. cowiE, J. w., RUSHTON, A. w. A. and STUBBLEFIELD, c. J. 1972. Cambrian— a correlation of the Cambrian rocks in the British Isles. Geol. Soc. Lond., spec. Rep. 2, 42 pp. DALMAN, i. w. 1828. Arsberattelse om nyare zoologiska arbeten och upptackter. Vetensk. Akad. Arsberdtt., Stockholm. 134-135. DATSENKO, V. A., ZHURAVLEVA, I. T., LAZARENKO, N. P., POPOV, YU. N. and CHERNYSHEVA, N. E. 1968. Bio- stratigraphy and fauna of Cambrian layers of the northwestern Siberian Platform. Trudy nauchno-issled. Inst. geol. Arkt. 155, 213 pp., pis. 1-23; ‘Atlas of stratigraphic sections and schemes’, a supplement, 42 pp. [In Russian.] DEMOKIDOV, K. K. 1968. Correlation of Arctic Cambrian strata. Ibid. 153, 141 pp. [In Russian.] EGOROVA, L. L, HSIANG, L. w., LEE, s. c., NAN, J. s. and KUO, C. M. 1963. The Cambrian trilobite faunas of Kueichou and Western Hunan. Bull. Geol. Inst. Surv. China, Sec. B, Stratigraphy and Palaeontology, 3(7). HAWLE, I. and CORDA, A. J. c. 1847. Prodrom einer Monographie der bohmischen Trilobiten. Rozpr. mat.- pfir. K. ceske Spot. Nduk. 5, 176 pp., 7 pis. HENNiNGSMOEN, G. 1957. The trilobite family Olenidae. With description of Norwegian material and remarks on the Olenid and Tremadocian Series. Skr. norske Vidensk-Akad. Mat.-naturv. Kl. 1957, 1, 303 pp., pis. 1-31. |] 1958. The Upper Cambrian faunas of Norway. Norsk geol. Tidsskr. 38, 179-196, pis. 1-7. |j HOWELL, B. F. 1959. Agnostidae. In moore, r. c. 1959. Treatise on Invertebrate Paleontology, Part O, !• Arthropoda I. Univ. Kansas Press and Geol. Soc. Am. 172-186. ] HUPE, p. 1953. Classification des trilobites. Annls Paleont. 39, 61-168 (1- 1 10). i ILLING, V. c. 1916. The Paradoxidian fauna of a part of the Stockingford Shales. Q. J I geol. Soc. Lond. \ 71 (for 1915), 386-450, pis. 28-38. ivsHiN, N. K. and Pokrovskaya, n. v. 1968. Stage and zonal subdivision of the Upper Cambrian. 23rd Int. geol. Congr., Montreal, 9, 97-108. JAEKEL, o. 1909. Uber die Agnostiden. Z. dt. geol. Ges. 61, 380-401. DAILY AND JAGO: LEJOPYGE 549 JAGO, J. B. and DAILY, B. 1974. The trilobite Clavagnostus Howell from the Cambrian of Tasmania. Palaeonto- logy, 17, 95-109, pis. 11-12. KOBAYASHi, T. 1935. The Cambro-Ordovician formations and faunas of South Chosen. Palaeontology, Pt. III. Cambrian faunas of South Chosen with special study on the Cambrian trilobite, genera and families. J. Fac. Sci. Tokyo Univ., sect. 2, 4, 49-344, pis. 1-24. 1937. The Cambro-Ordovician shelly faunas of South America. Ibid. 4, 369-522, pis. 1-8. 1939. On the Agnostids (Part I). Ibid. 5, 69-198. 1962. The Cambro-Ordovician formations and faunas of South Korea. Part IX. Palaeontology VIII. The Machari Fauna. Ibid. 14, 1-152, pis. 1-12. 1967. The Cambrian of eastern Asia and other parts of the continent. The Cambro Ordovician formations and faunas of South Korea. Part X, Section C. Ibid. 16 (3), 381-534. 1971. The Cambro-Ordovician faunal provinces and the interprovincial correlation. Cambro- Ordovician formations and faunas of South Korea. Part X, Section E. Ibid. 18 (1), 129-299. KUO, ZHEN-MiNG, 1965. New material of Late Cambrian trilobite fauna from the Yehli area, Kaiping Basin, Hopei. Acta palaeont. sin. 13 (4), 629-637, 1 pi. LAZARENKO, N. p. 1966. Biostratigraphy and some new trilobites of the Upper Cambrian of the Olenensk Hills and Kharaulekhski Mountains. Uch. Zap. nauchno-issled. Inst. Geol. Arkt. pal. i biostrat. 11, 33-78, pis. 1-11. [In Russian.] and DATSENKO, V. A. 1967. Biostratigraphy of the Upper Cambrian of the northwestern Siberian Platform. Ibid. 20, 13-32. [In Russian.) and NIKIFOROV, N. I. 1968. Complexes of trilobites in the Upper Cambrian layers River Kulyumbe (northwestern Siberian Platform). Ibid. 23, 20-80, pis. 1-15. [In Russian.) LERMONTOVA, E. 1940. Arthropoda. In vologdin, a. g. et al., ‘Atlas of the leading forms of the fossil fauna of the U.S.S.R.’, vol. 1, Cambrian. Vses. nauch. Issled. geol. Inst. (VSEGEI). Moskva, 193 pp., pis. 1-50. [In Russian.) LU, YEN HAO, 1960. Cambrian deposits of China. Sci. Rec. Acad, sin., n.s. 4, 199-216. m’coy, f. 1849. On the classification of some British fossil Crustacea, with notices of new forms in the University collection at Cambridge. Ann. Mag. nat. Hist. (London), ser. 2, 4, 161-179, 330-335, 392-414. MOORE, R. c. (ed.). 1959. Treatise on Invertebrate Paleontology, Part O, Arthropoda I. Univ. Kansas Press and Geol. Soc. Am., 560 pp. OPiK, A. A. 1961fl. The geology and palaeontology of the headwaters of the Burke River, Queensland. Bull. Bur. Miner. Resour. Geol. Geophys. Aust. 53, 1-249, pis. 1-24. 19616. Alimentary caeca of agnostids and other trilobites. Palaeontology, 3, 410-438, pis. 68-70. 1963. Early Upper Cambrian fossils from Queensland. Bull. Bur. Miner. Resour. Geol. Geophvs. Aust. 64, 1-133, pis. 1-9. 1967. The Mindyallan fauna of northwestern Queensland. Ibid. 74, Vol. 1, 1-404; Vol. 2, 1-167, pis. 1-67. PALMER, A. R. 1962. Glyptagnostus and associated trilobites in the United States. Prof. Pap. U.S. geol. Surv. 374-F, 1-49, pis. 1-6. 1968. Cambrian trilobites of East-Central Alaska. Ibid. 559-B, 1-115, pis. 115. POKROVSKAYA, N. V. 1958. Middle Cambrian Agnostids of Yakutia, Part I. Trudy geol. Inst. Akad. Nauk. SSSR, Moskva, 16, 1-90, 5 pis. [In Russian.) 1960. Miomera. In CHERNYSEtEVA, N. e. 1960. Arthropoda, Trilobitomorpha and Crustacea. In ‘Osnovy Paleontologii’. Gos. nauch.-tekh. Izdat. Lit. geol. Okhr. Pp. 54-61. [In Russian.) ROBISON, R. A. 1964a. Late Middle Cambrian faunas from western Utah. J. Paleont. 38, 510-566, pis. 79-92. 19646. Middle-Upper Cambrian boundary in North America. Bull. geol. Soc. Am. 75, 987-994. 1964c. Upper Middle Cambrian stratigraphy of western Utah. Ibid. 75, 995-1010. ROMANENKO, E. V. 1972. New data on Cambrian of the North-Eastern Altay. Izv. Kuzn. Otd. geogr. o-ov. SSSR. Pt. 1, 52-57. [In Russian.) ROSOVA, A. V. 1963. Biostratigraphic scheme for the Late Middle-Upper Cambrian of the north- western Siberian Platform based on trilobites. Geologiya Geofiz. Novosibirsk, 9, 3-19, pis. 1-2. [In Russian.) 1964. Biostratigraphy and description of Middle and Upper Cambrian trilobites from the north- western Siberian Platform. Moskva, Nauka, 1964, 148 pp., 19 pis. 550 PALAEONTOLOGY, VOLUME 18 ROSOVA, A. V. 1968. Biostratigraphy and trilobites of the Upper Cambrian and Lower Ordovician of the northwestern Siberian Platform. Trudy Inst. Geol. Geofiz. sib. Otd. 36, 1-196, pis. 1-17. [In Russian.] 1970. On the biostratigraphic schemes for the Upper Cambrian and Lower Ordovician of the north- western Siberian Platform. Geologiya Geofiz. Novosibirsk, 5, 26-31. [In Russian.] RUSCONi, c. 1951. Mas trilobitas Cambricos de San Isictro, Cerro Pelado y Canota. Revta Mus. Hist. nat. Mendoza, 5, 3-30, 29 figs. 1953. Nuevos trilobitas Cambricos de la Quebrada de la Cruz. Boln paleont. B. Aires, 27, 1-8, text- figs. 1-10. 1954. Trilobitas Cambricos de la Quebradita Oblicua, Sud del cerro Aspero. Revta Mus. Hist. nat. Mendoza, 7, 3-59, 4 pis. SALTER, J. w. 1864. A monograph of the British trilobites. Palaeontogr. Soc. [Monogr.], 1-80, pis. 1-6. STUBBLEFIELD, c. J. 1956. Cambrian palaeogeography in Britain. In El Sistema Cambrico su Paleogeografia y el problema de su base. 20th Int. geol. Congr., Mexico, 1, 1-43. SUN, Y. c. 1948. On the problem of the stratigraphic boundaries in the Cambrian Formation in China. Contr. natn. Res. Inst. Geol., Shanghai, 8, 323-330. TAYLOR, K. and RUSHTON, A. w. A. 1972. The pre-Westphalian geology of the Warwickshire coalfield with a description of three boreholes in the Merevale area. Bull. geol. Surv. Gt Br. 35, 1-152, pis. 1-22. WESTERGARD, A. H. 1922. Svcrigcs olcnidskiffer. Sver. geol. Unders. Afh. ser. Ca. 18, 1-205, pis. 1-16. 1944a. Borrningar genom Skanes alunskiffer 1941-42. Ibid. ser. C. 459, 1-45, pis. 1-3. 1944i. Borrningar genom alunskiflferlagret pa Oland och i Ostergotland 1943. Ibid. ser. C. 463, 1-22. 1946. Agnostidae of the Middle Cambrian of Sweden. Ibid. ser. C. 477, 1-140, pis. 1-16. 1947. Supplementary notes on the Upper Cambrian trilobites of Sweden. Ibid. ser. C. 489, 1-34, pis. 1-3. 1948. Non-agnostidean trilobites of the Middle Cambrian of Sweden. Ibid. ser. C. 498, 1-32, pis. 1-4. 1952. Non-agnostidean trilobites of the Middle Cambrian of Sweden III. Ibid. ser. C. 526, 1-58, pis. 1-8. WHITEHOUSE, F. w. 1936. The Cambrian Faunas of Northeastern Australia. Mem. Qd Mus. 11, 59-112, pis. 8-10. B. DAILY Department of Geology and Mineralogy University of Adelaide G.P.O. Box 498B Adelaide, South Australia 5001 J. B. JAGO School of Applied Geology South Australian Institute of Technology Typescript received 23 April 1974 North Terrace Revised typescript received 29 November 1974 Adelaide, South Australia 5000 THE OSTRACOD PARAPARCHITES MINAX IVANOV, SP. NOV. FROM THE PERMIAN OF THE U.S.S.R., AND ITS MUSCLE-SCAR FIELD by M. N. GRAMM and v. k. ivanov Abstract. The ostracod Paraparchites minax sp. nov., from the early Permian of the Pre-Donetz Depression of the Rostov area of the Soviet Union, is described and figured. Particular attention is paid to the muscle scars, to mandibular and frontal scars and especially to the adductor muscle scars, which are in the form of a cluster of up to 190 spots. An outline of the ontogenetic development of the scars is given. The systematic position of the Para- parchitacea is discussed in the light of outline, inner lamella, dimorphism, and central muscle-scar pattern, with the conclusion that the superfamily is related neither to the Platycopa, nor the Kloedenellidae, and in consequence, a new suborder of the Podocopida, the Paraparchitocopa, is proposed. In the early Permian strata of the Donetz, amongst the commonest ostracods are members of the Paraparchitacea, a preliminary account of which has been given by Ivanov (1964). Particularly well-preserved specimens, including large numbers of the form Paraparchites minax sp. nov., were recovered from a depth of 474-475 m in Asselian stage beds in drillings in the Rostov region (Tatzin district, Skosyr area). Such was the preservation that some thirty specimens showed details of adductor, mandibular, and frontal scars, improving our hitherto scanty knowledge of the muscle-scar patterns of Palaeozoic ostracods. Thus, the main purpose of this paper is to describe and analyse these structures and to discuss the systematic position of the Paraparchitacea. In most earlier works the central muscle-scar field has been studied from internal moulds, or from the inner surface of valves. In the specimens described here the details have been obtained by treating translucent or semi- transparent carapaces with castor oil or sugar solutions and photographing the specimens in reflected light. All specimens referred to in the text under No. 146 have been deposited in the Ukrainian Scientific Research Institute for natural gas (UkrNIIGas), Kharkov. SYSTEMATIC DESCRIPTION Order podocopida Muller, 1894 Suborder paraparchitocopa Gramm, n. suborder .Diagnosis. Dorsal margin straight, ventral margin generally convex. Surface smooth, one or two postero-dorsal spines may be present. Calcified inner lamella narrow. Adductor muscle scar in the form of a cluster, which may contain a large number of spots. Mandibular scar elongate; frontal scar complex. Dimorphism of non- kloedenellid type. One superfamily— Paraparchitacea Scott, 1959. Range: Devonian to Permian. [Paleontology, Vol. 18, Part 3, 1975, pp. 551-561, pi. 64.] 552 PALAEONTOLOGY, VOLUME 18 Superfamily paraparchitacea Scott, 1959 Family paraparchitidae Scott, 1959 Genus paraparchites Ulrich and Bassler, 1906 Paraparchites minax Ivanov, sp. nov. Plate 64, figs. 1-9 1964 Paraparchites humerosus Ulrich and Bassler, 1906, morpha magna Ivanov, 1964, p. 110, pi. 2, fig. \a-c. Derivation of name. ‘Minax’ = prominent (Latin). Holotype. Complete carapace, 146/1. Paratypes. Thirteen complete carapaces (146/2, 3, 4, 5, 146/9-3, 146/10-1, 146/10-2, 146/11-1, 146/11-2, 146/11-4, 146/12-3, 146/13, and one right valve, 146/6). All types are from Borehole 2323, from the Asselian Stage, at 474/475 m, Tatzin district, Skosyr area, Rostov. Material. Eighty carapaces, and over 100 valves. Diagnosis. Carapace large, up to 2800 ij.m, elongate and sub-oval; left valve slightly overlaps right valve along the entire free margin, with reversal of overlap along the hinge margin. In lateral view, anterior and posterior margins evenly rounded, although the former is more fully curved ; dorsal margin short, straight, and somewhat inclined posteriorly ; cardinal angles weakly developed; ventral margin convex, merging smoothly with anterior and posterior margins. Shell surface smooth, with a few scattered pits corresponding to normal pore canals. Parallel to the free margin, and close to it, thin elevated ridges sometimes observed. No internal features other than the central muscle-scar field are known, these consisting of the adductor field located centrally within the valve and made up of up to 190 spots, an elongate mandibular scar, and a frontal scar. Dimensions. Details of type specimens given in Table 1. Ontogeny. The smallest specimens, 725 ptm long, possibly Instar III, differ little morphologically from the holotype (an adult carapace). Changes during growth follow a pattern of regular increase in all basic dimensions relating to shape. There is size increase in the adductor scar field, as well as an increase in number and size of EXPLANATION OF PLATE 64 Figs. 1-5. Paraparchites niina.xlnvdno\,sp. nov. 1, 2, carapace, holotype, no. 146/1. 1, right view; 2, dorsal view. 3, 4, carapace, no. 146/3; 3, right view. 4, dorsal view. 5, carapace, no. 146/4, right view. Rostov region, Skosyr area; Lower Permian. All x 15. Figs. 6-9. Central muscle-scar field of Paraparchites minax Ivanov. 6, 7, larval stages. 6, right side of carapace, VI? instar, L 1400 /xm, no. 146/10-1 ; adductor muscle spots, mandibular spot, and frontal spot are seen. 7, right side of carapace, VI? instar, L=- 1500 ;u,m, no. 146/9-3; adductor muscle spots, mandibular spot, and frontal spot are seen. 8, 9, adults. 8, right side of carapace, L = 2525 jum, holotype, no. 146/1 ; adductor muscle spots and mandibular spot are seen. 9, left side of carapace, L = 2550 jum, no. 146/4; adductor muscle spots, mandibular spot, and frontal spot are seen. Photographs were taken from the outer side in reflected light. L— length of carapace. Rostov region, Skosyr area; Lower Permian. All X 150. Fig. 10. Paraparchites sp., right valve, no. 1 1 16/76-1, internal view in transmitted light; the inner lamella is seen. Leningrad region; Lower Carboniferous, x 30. PLATE 64 GRAMM and IVANOV, Paraparchites 554 PALAEONTOLOGY, VOLUME 18 the spots. There is limited variation in the adult stage, rare specimens showing greater inflation, or concave ventral margins. Other than the inflation mentioned above, no clearly dimorphic features have been observed. Remarks. The new species differs from Paraparchites scotoburdigalensis (Hibbert) from the British Carboniferous in its greater dimensions, and length : height ratio. Some of our specimens are morphologically close to those figured as P. humerosus Ulrich and Bassler by Scott (1959), but these are of much smaller dimensions (length 2000 |Ltm). Ecology. The early Permian paraparchitaceans from the Donetz area appear to have lived in conditions of varied salinity, leading Ivanov (1964) to conclude that they were euryhaline. A similar conclusion was reached by Robinson (1969) and Sohn (1971) who both thought that, although essentially a marine genus, Paraparchites may have tolerated brackish and hypersaline conditions at times. In the Donetz region P. minax sp. nov. occurs in grey and dark-grey argillaceous limestones, accompanied by an abundance of darwinulaceans and carbonitids (Darwinula sp. and Carbonita sp.). Other fauna includes micro-gastropods and bivalves, calcareous worm tubes, stick bryozoan fragments, fish scales, and denticles. Particularly the abundance of darwinulids, and the paucity of marine invertebrates, suggest abnormal salinity conditions, verging upon fresh water. THE MORPHOLOGY OF THE CENTRAL MUSCLE-SCAR FIELD OF PARAPARCHITES MINAX Adductor scar field. On the surface of adult carapaces, 2450-2800 /xm long, the adductor scar field is sometimes evident as a shallow, circular depression located in the centre of the valve. In the adult, the adductor scar field is a circular to elliptical cluster of small spots, the long axis of the cluster aligned dorso-ventrally. The cluster can be 270 /xm in length and 300 ju,m in height. The number of spots within the cluster varies from 128 to 190, and may differ in the two valves of a single carapace. As can be seen from Table 1, there is no close correlation between spot number and size of carapace, indeed, in the right valve of one of the largest specimens examined (2800 length), one of the lowest spot counts, 128, was recorded. The shape of the spots varies from circular or oval to angular, the packing being usually close-set. Any kind of consistent pattern of spots within the scar is difiicult to detect. While details of the ontogenetic development of the scar is scanty, the present material suggests a general increase both in size and number of spots with growth. Thus, in specimens c. 1100 jj.m long, spot counts range from 25 to 35; for specimens c. 1400 /xm long, the count is 40-60; for carapaces greater than 1500 |xm, the count is 46-plus. Mandibular scar. Antero-ventral to the adductor-scar field, there lies an elongate scar which is best interpreted as a mandibular scar. Sometimes visible on the outer surface of the valves, the scar may be horizontal but sometimes slightly bowed. Although the scar might suggest the coalescence of spots, there is no evidence to support this idea. There is a gradual increase in size through ontogeny. Frontal scar. Dorsal to the adductor-scar field, there is an oval frontal scar, 75-90 /xin high in carapaces 1400-1500 /xm long, increasing to 100 in adults. GRAMM AND IVANOV: THE OSTRACOD PARAPARCHITES MINAX IVANOV 555 TABLE 1. Dimensions of Paraparchites minax sp. nov. and details of the central muscle-scar field. Mandibular Frontal Adductor muscle scar scar scar Length Number Length Height Length Height Collection no. (^m) of spots (ium) {^rn) (ium) (;um) 146/12-3 C left view 1100 16 146/11-1 C right view 1200 25 60 146/11-2 C right view 1400 35-40 146/10-1 < \ C right view [ C left view 1400 60 125 125 140 140 175 170 75 90 146/9-2 C left view 1500 46 146/9-3 < f C right view [ C left view 1500 40 40 125 140 150 160 200 200 80 146/10-2 j 1 C right view 1650 170 170 210 50? / C left view 150 160 200 146/10-3 C right view 2050 200 146/7 C right view 2250 250 250 250 146/6 RV 2450 151 225 240 325 146/1 j C right view ^ C left view 2525 190 184 250 250 290 300 250 146/4 j 1 C right view ^ C left view 2550 132 138 225 225 250 250 250 250 100 146/3 j 1 C right view 2650 131 250 250 300 [ C left view 270 300 325 146/5 ^ \ C right view 2800 128 225 250 350 [ C left view 250 250 335 The central muscle field of Paraparchites minax can be homologized with this structure in bairdids, cyprids, and cytherids, the scar representing the points of attachment of muscle and chitin elements of the soft-part anatomy. Its mandibular scar was presumably the attachment point of the chitinous rods springing from the dorsal apex of the basal podomere of the mandible protopodite (Triebel 1960). The presence of two mandibular scars reported by Ivanov (1964) and Robinson (1969), and to be seen in Sohn’s plates (1971), may prompt the idea that these have become fused to form the single scar of P. minax. As Smith (1971) has demonstrated that the dorsal anterior scar in Recent cytherids and cyprids has no direct relationship to the antennae, the term frontal scar is employed for the scars here described. The relative disposition of the scars described by Ivanov (1964), Robinson (1969), and Sohn (1971), together with the present evidence from P. minax, removes any doubt as to the orientation of Paraparchites. Orientation in fact, is as described by Scott (1959). The Paraparchitacean central muscle-scar field. Data as to the central muscle-scar field of Paraparchites is limited, and usually refers to a smooth muscle scar in the centre of the valve (Tschigova 1960), or a central muscle scar with faint marks (Kummerow 1953). The first detailed description appears to be that of Ivanov (1964, p. 110, pi. 2, fig. 4) for P. humerosus morpha oblima. Later, in 1967, Bless described and illustrated fifty discrete spots as the muscle pattern for P. cantelii Bless, 1967, from the Upper Carboniferous of Spain. Robinson (1969) noted that the central muscle-scar field of Paraparchites is essentially the same as that for Bernix, a large H 556 PALAEONTOLOGY, VOLUME 18 patch area covered with clusters of small pits, with one or two linear scars obliquely below. Such scars were figured for Paraparchites sp. from Tournaisian, and for Paraparchites cf. inornalus (M’Coy) from the Visean (Robinson 1969, pi. 3, figs. 3 and 4). The fullest documentation of paraparchitid muscle-scar patterns is to be found in the monographs of Sohn (1971, 1972), in which he specifically mentions the presence of a ‘cyprid adductor muscle scar pattern in some of the genera’ (Sohn 1971, Al, Abstract). According to Sohn’s schematic illustration, the most complete cypridid pattern is that of Shishaella marathonensis (Hamilton, 1942) in which there are some six elongate obliquely arranged adductor scars, and two closely adjoined mandibular scars (Sohn 1971, A5, fig. 2). At the same time the scar pattern in the genus Chami- shaella Sohn, 1971 is described as follows, ‘The subcentral adductor scar consists of a circle of small individual scars’ (Sohn 1971, All). Available data indicate three types of paraparchitid adductor muscle-scar patterns : 1. The pattern of P. minax, characterized by a circular cluster of many spots (up to 190). Close to this type are the patterns of P. sp. and P. cf. inornatus from the Lower Carboniferous (Robinson 1969) and of Cliamishaella (Sohn 1971). P. cantelii Bless, 1967 also has this type of adductor muscle scar, as does Bernix \ and Robinson (1969) has argued persuasively that Bernix belongs to the Family Paraparchitidae. The presence of one or two mandibular scars is also typical, but a frontal scar is, at present, known in P. minax only. 2. The pattern of P. humerosus morpha oblima, consisting of a circular group of a few scars (up to ten?) associated with two mandibular scars (Ivanov 1964). 3. The pattern of Shishaella marathonensis, with six large scars associated with two elongate mandibular scars. This pattern was regarded as being of cyprid type by Sohn (1971). It is difficult to envisage three such strongly dissimilar adductor muscle-scar patterns forming a morphological series within the paraparchitid group. At the moment, the available data, especially for the second and third adductor muscle-scar types, are very limited and any final assessment of the taxonomic significance of the second and third types mentioned above must await further information. (Latest observations on some well-preserved Visean paraparchitids from Novgorod region revealed that in some old individuals on the adductor muscle-scar area an intense calcification took place, due to which the structure acquired a form of a coarse, uneven elevation. May this be the cause of scars which give the impression of a cyprid- like adductor muscle-scar pattern?) THE SYSTEMATIC POSITION OF THE PAR APARCHITACE A In the past, three general views have been widely held: 1. Assigning the genus Paraparchites to the Family Kloedenellidae Ulrich and Bassler, 1923, which in turn would place it within the Order Palaeocopa (Henningsmoen 1953; Mertens 1958), or alternatively within the Platycopa, Podocopida (Pokorny 1958). 2. That of the 1961 Treatise oj Invertebrate Paleontology, placing the Superfamily Paraparchitacea Scott, 1959, within the Suborder Kloedenellocopina Scott, 1961, which in turn belongs to the Order Palaeocopida (Scott, 1961). 3. Amalgamating the Paraparchitacea with the Kloedenellacea and the Cytherellacea within a Suborder Platycopina (opinion of Schallreuter 1968). Other views to record are those expressed in Ostwvy, placing Paraparchites within GRAMM AND IVANOV: THE OSTRACOD P A RA P A RC HIT ES MINAX IVANOV 557 the Family Aparchitidae Jones, 1910 (Orlov 1960) and more recently, Sohn’s defini- tion of the Paraparchitacea as Podocopida incertae subordinis (Sohn 1971). In all these opinions, there appear to have been judgements based upon the following criteria. First, the presence of a form of kloedenellid dimorphism. Second, carapace outline. Third, the presence of what is judged a calcified inner lamella. Fourth, the type of central muscle-scar pattern. Taking these in turn, a presumed kloedenellid dimorphism in Paraparchites has been taken as evidence of affinity to the Kloedenellidae (Pokorny 1958 and Schall- reuter 1968). On the other hand, evidence of dimorphism was regarded as inconclusive by Scott (1961, p. Q86), and of limited value by Griindel (1967, p. 323). Because their possible dimorphic features are so weak, Kniipfer has rejected any relationship of Paraparchitacea to the Platycopina, preferring to regard them as a discrete branch of the Podocopida, equal in status with the Platycopina and Metacopina (Kniipfer 1968). A kloedenellid-type dimorphism in paraparchitids has been completely rejected by some, including Tschigova (1967). The same author has noted a ventral inflation in possible female carapaces (Tschigova 1960; Buschmina 1968), a view repeated by Robinson for Paraparchites and Bernix (1969) and by Sohn (1971, p. A5). In P. minax some forms are ‘inflated’ with obtuse extremities, whereas others are ‘thin or uninflated’ with acute extremities, but no traces of kloedenellid dimorphism have been revealed. All this leads to the conclusion that any sexual dimorphism in paraparchitids would seem to be of non-kloedenellid type, and no basis for allocation of the group within either the Kloedenellidae, or the Platycopa. Carapace outlines do not provide a reliable basis for placing the paraparchitids within the Kloedenellacea or the Platycopa, groups which normally possess a recti- linear or slightly concave ventral margin in contrast to the strongly convex venter of Paraparchites. In P. minax the ventral margin is convex with the exception of a few rare specimens with obvious concave ventral margins. Published information concerning the calcified inner lamella is scanty, and even contradictory. Scott notes that a duplicature is generally absent in the Kloedenelli- copina, but present in the Geisinidae (Scott 1 96 1 , p. Q90 ; Sohn in Scott 1 96 1 , p. Q 1 82). Such observations have been extended more recently by Pollard (1966) and Kniipfer (1968) to include the genera Glyptopleura Girty, 1910, Electia Tschigova, 1960, Hypotetragona Morey, 1935, Knoxites Egorov, 1950, Mennerella Egorov, 1950, IMarginia Polenova, 1952, and others. Data are scarce for the Paraparchitecea. Scott has written of a ‘vestibule’ in P. humerosus Ulrich and Bassler, 1959. Once again Sohn (1971) is our main source of information, recording a narrow inner lamella in the genera Shivaella Sohn, Shamishaella Sohn, Shishaella Sohn, and Shemonaella Sohn. Working with the complete carapaces of P. minax, it has been impossible to confirm such structures, but in well-preserved single valves of Paraparchites from the Lower Carboniferous of the Leningrad region, a clearly visible inner lamella has been found (PI. 64, fig. 10). Thus it can be said that the possession of a calcified inner lamella is a characteristic of paraparchitaceans as well as of some kloedenellaceans, separating both from Platycopa sensu stricto, the latter possessing only rudimentary traces at best (Van Morkhoven 1962). Our total knowledge of the central muscle-scar field of P. minax confirms the opinion of Sohn that, ‘the lateral outline, hingement, calcified inner lamella and 558 PALAEONTOLOGY, VOLUME 18 adductor muscle scar pattern negates this assignment’ (of the Paraparchitacea to the Platycopina: Sohn 1971, p. A5). For the Platycopa, the pattern and its evolution could be said to be well established, changing from the multiserial scar of the Cavellinidae (six rows of from 7 to 10 spots, totalling between 40 and 56 spots, Triebel 1941 and Scott 1944), to the biserial scar of the Cytherellidae (Gramm 1972). In contrast, relatively little is known of the adductor muscle scar of the Kloedenellidae. Nyhamnella from the Lower Silurian, has an oval group of spots (23) somewhat drawn out in a dorsal direction (Adamczak 1966, fig. 1). The Lower Carboniferous genera Geisina and Kloedenellitina have biserially arranged adductor scars with up to 11 spots (Knupfer 1968, also Pollard 1966). With so little evidence, it is impossible to discuss any morphological evolution of the kloedenellid scar, except to observe that the scar type differs considerably from that of the Platycopa, that of the paraparchitids described by Sohn (1971), and that described herein for P. minax. Table 2 summarizes our knowledge of muscle-scar patterns for Ostracoda, TABLE 2. Central muscle-field elements of various ostracod groups. -I- known, — unknown. From data published by the following authors: Sars 1922-1928; Triebel 1941, 1960; Scott 1944, 1951; Schweyer 1949; Swartz 1949; Schneider 1956; Kashevarova 1958; Abushik 1960; authors in Osnovy Paleontologii, 1960; authors in Treatise on Invertebrate Paleontology, Pt. Q, 1961 ; Morkhoven 1962, 1963; Sandberg 1964; Darby 1965; Smith 1965, 1971; Gramm 1970; Gramm et al. 1972; Gramm and Posner 1972; Hartmann 1966; Adamczak 1966, 1968; Benson 1967; McKenzie 1967; Knupfer 1968; Maddocks 1969; Grundel 1970; Bolz 1971 ; Malz 1971 ; Ishizaki 1973; Shornikov and Gramm 1974. Central muscle field Adductor Mandibular Frontal muscle scar scar scar Leperditiida 4 - - Palaeocopida-Beyrichicopa : Scrobicida (possibly Podocopida) 4 — ? Placidea + — — Sulcicuneus, Svislinella, Kielciella + — — Puncia, Manawa + — — Kloedenellacea : Nyhamnella + — — Geisina 7- — . — Kloedenellitina 4- — — Myodocopida : Myodocopa -f — — Cladocopa -4 — — Podocopida Platycopa : Cavellinidae + — — Cytherellidae f — — Metacopa : Healdiidae f + + Podocopa : Darwinulacea L + — Bairdiacea ■f + + Cypridacea i + + Cytheracea * + + Sigilliidae t — + GRAMM AND IVANOV: THE OSTRACOD PARAPARCHITES MINAX IVANOV 559 requiring it to be said that data relating to several important Palaeozoic groups are very limited. CONCLUSIONS On the basis of the absence of kloedenellid dimorphism, aspects of outline, the nature of the central muscle-scar field and its pattern, it is apparent that the Paraparchitacea cannot be united with either the Kloedenellacea or the Platycopa. The presence of a calcified inner lamella moves the superfamily still further from a relationship to the Platycopa, while the development of the same structure in some kloedenellids may be regarded as instances of evolution in parallel. On the possible criteria for a more refined taxonomic judgement upon the Paraparchitacea, that which appeals most is consideration of the central muscle-scar field. Such structures are, we believe, important, because the scars are intimately associated with the soft-body anatomy of the Ostracod, and in fossil carapaces provide as Smith said, ‘one of the common meeting grounds between the palaeontologic and zoologic systems of classification’ (Smith 1965, p. 1). Of course, it is necessary to take other criteria into consideration, but many internal structures in Palaeozoic ostracods are very poorly known and ideas and opinions are frequently based on insufficient evidence. As a result, the importance attached to certain features for taxonomic purposes varies, and the same features may have varying significance in different groups’ ability to recognize homologous structures of independent origin, which is crucial for phylogenetic systematics. As our discussion has shown, the central muscle-scar field of the Para- parchitacea can best be compared with that of the Podocopa— a view strengthened by the record of the elongate mandibular scar. Thus in taxonomy, serious attention should be given to the close relationship with the Podocopida postulated by Sohn (1971). As, however, aspects of shape and outline, the absence of radial pore canals coupled with the rudimentary nature of the duplicature, and special features of the scar pattern, do not allow the assignment of the Paraparchitacea to any of the recog- nized Suborders of the Podocopida, we feel that it is necessary and appropriate to propose a new Suborder Paraparchitocopa to accommodate this group. Acknowledgements. Thanks are due to many colleagues cited in this paper for sending literature, and to Dr. Alan Lord, Professor P. C. Sylvester-Bradley and especially Dr. Eric Robinson for help with the manu- script. Mrs. O. G. Gein kindly typed the paper. REFERENCES ABUSHIK, A. F. 1960. Silurian ostracodes of Siberian Platform. Trud. vsesoyuz. nauch.-issled. geol. Inst. (VSEGEI), Leningrad, 39, 131 pp. [In Russian.] ADAMCZAK, F. 1966. On kloedenellids and cytherellids (Ostracoda, Platycopa) from the Silurian of Gotland. Acta Univ. Stockholm, 15, 7-21. 1968. Palaeocopa and Platycopa (Ostracoda) from Middle Devonian rocks in the Holy Cross Mountains, Poland. Stockholm Contr. Geol. 17, 109 pp. BENSON, R. H. 1967. Muscle-scar patterns of Pleistocene (Kansan) ostracodes in Paleontology and strati- graphy. R. C. Moore commemorative volume. Univ. Kansas Dept. Geol. Special Publ. 2, 211-241. BLESS, M. J. M. 1967. 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New Late Mississippian Ostracode genera and species from Northern Alaska. U.S. Geol. Survey Prof. Paper, 71 1-A, 24 pp. 1972. Late Paleozoic ostracode species from the conterminous United States. Ibid. 71 1-B, 15 pp. SWARTZ, F. M. 1949. Muscle marks, hinge and overlap features and classification of some Leperditiidae. J. Paleont. 23, 306-327. TRiEBEL, E. 1941. Zur Morphologie und Okologie der fossilen Ostracoden. Mit Beschreibungen einiger neuer Gattungen und Arten. Senckenbergiana, 23, 294-400. 1960. Die taxionomische Stellung und die Gattungen der Unterfamilie Macrocypridinae (Ostracoda). Senckenbergiana biologica, 41, 109-124. TSCHiGOVA, V. A. 1960. Age relationship of Rakovka and Lower Malinovka deposits of Kama-Kinel depression according to the data of ostracod studies. Trud. vsesoyuz. neftegas. nauch.-issled. Inst. (VNII), Moscow, 30, 169-233. [In Russian.] 1967. Ostracodes in boundary beds of Devonian and Carboniferous deposits of Russian Platform. Ibid. 49, 256 pp. [In Russian.] M. N. GRAMM Institute of Biology and Pedology Far East Scientific Centre USSR Academy of Sciences 690022 Vladivostok, U.S.S.R. Typescript received 3 April 1974 Revised typescript received 25 October 1974 V. K. IVANOV Ukrainian Scientific-Research Institute for Natural Gases Kharkov, U.S.S.R. ‘ , ''. 1(1 ,:• ;..,if' ■■ '''''■ 'W^': ' d||tif4!#fe'i!!^-V :%■:>■ f J ■, /., '^r i ’. ■•, -.'j-,!jl( V ■■ ' ‘•■- ='.^'’’>vr' • 'V ^ ■■■• ; '-r,,'^;.^ J • ' ' ■ ■; . I ,/ ■ V If i. j.' ■ 1 I'' ’ ' ' «,;'''. V - ■■• ■' » , .. ... ..’m.'.^‘ '■ ,' '‘.I, '• ■ <■■■••« 1 ,,' ' j , •■ - ■ :’■ .*.•' '.■;' 1 , ^ . 'I, i I - - .( ;, ■' , -'f," •. .. ', ; 'i-Ti;-';^', ' ' ■ . 1 : ■ ■ : ’ ' ' ■'■ ■ ' ■ .i fldWtfjffi " , :■ '!■•.( -..^ ".j-^a'4.i, tv'*'' •< ■ '■■ •,, I 'i i, ‘ ,s - '• ^* ‘*v-j ■* 'v ,:'ii.;„: ft , THE BRADYCNEMIDAE, A NEW FAMILY OF OWLS FROM THE UPPER CRETACEOUS OF ROMANIA by c. J. o. HARRISON and c. a. walker Abstract. The only bird hitherto known from the upper Cretaceous (supposed Maestrichtian) of Transylvania is the pelecaniform Elopteryx nopscai Andrews (1913), based on the proximal half of a femur; referred material includes the distal ends of three tibiotarsi from the same beds. Re-examination of these tibiotarsi, however, shows that they belong to the owls (Strigiformes); they represent the oldest owls known and are described and named as two species in new genera, Bradycneme and Heptasteornis. The posterior side of the condylar region in both genera differs so much from that of the tibiotarsi of Recent owls as to warrant the separation of these Cretaceous forms into the new family Bradycnemidae. Andrews(1913) described a large bird Elopteryx nopscai from the upper Cretaceous of Transylvania, Romania, the holotype being the proximal half of a femur (A 1234). He placed the new genus in the Pelecaniformes, an assignment which is confirmed by our re-examination of the specimen. Andrews also referred to his new species, albeit tentatively, the distal end of a tibiotarsus from the same locality for which he found no parallel among other birds; indeed he may have thought it to belong to the same individual, for he gave it the same register number, though it is now re-registered A 4359— all material is in the British Museum (Natural History). When Lambrecht (1929) discussed bird fossils from this region, and subsequently (1933) included them in his handbook, he referred to this species a further proximal end of a femur (A 1235) and also the distal ends of two more tibiotarsi (A 1528 and A 1588). Of the three distal ends of tibiotarsi A 1588 is wide distally, with a large intercondylar hollow. A 4359, described and figured by Andrews (1913), has condyles of similar diameter but is much narrower. Since it has a median fracture it was first thought that the middle region might have been lost through lateral pressure, but the third specimen, A 1528, which is worn and has some small accretions of hard matrix, does not show similar signs of damage and confirms the general size and shape of the second specimen. Since the differences are not of a kind which could be attributed to sexual dimorphism it would appear that two related forms are involved, one represented by A 1588 and the other by A 4359 and A 1528. The characters shown by these two forms, however, cannot be reconciled with those of known pelecaniform birds and it is evident that there are no grounds for referring them to the genus Elopteryx which is therefore represented only by the femora. A search was therefore made for other avian taxa with which they might show affinities. The broader specimen, A 1588, showed some general similarities to falconi- form species and a particular similarity to Ealco rusticolus (Falconidae) in the shape and position of the condyles and in the development of the external ligamental prominence (text-fig. 1). The Falconidae, however, have a complex tendinal bridge over the tendinal fossa which is absent from the fossils; the resemblance of the [Palaeontology, Vol. 18, Part 3, 1975, pp. 563-570, pis. 65-66.] 564 PALAEONTOLOGY, VOLUME 18 fossils to Falco is therefore more likely to be the result of convergence than evidence of affinity. In features such as the absence of a tendinal bridge, the size and shape of the tendinal fossa, the size of the peroneus groove, the proximally placed prominence for muscle attachment on the internal side of the anterior face of the shaft, and the pit just proximal to the anterior face of the internal condyle, these distal ends of tibiotarsi resemble those of owls, Strigiformes; this particular combination of characters is not found in any other order of birds. These fragments appear to repre- sent the earliest known owls; they are earlier than the genera Eostrix and Protostrix, family Protostigidae (Eocene of North America), and the earliest species of the family Strigidae, a family which is still extant, is from the upper Eocene or Oligocene of France. They differ from Recent owls, however, in lacking any marked posterior projection of the condyles. In modern forms the condyles project posteriorly to a greater distance; the intercondylar groove is deep and extends back to a hollow just proximal to the condyles on the posterior surface of the shaft, exaggerating the degree to which the condyles appear to project. The absence of posteriorly projecting condyles might be either primitive or secondary. The accompanying text-fig. 1 shows the condition in a Recent owl (u), in the two fossils {b, c) and in two Recent falconids {d, e); the distal views show very clearly that only in (a) do the condyles project a K* TEXT-FIG. 1 . Anterior and distal views of right tibiotarsi : a, Strix varia (Strigidae) ; b, Heptasteornis andrewsi gen. et sp. nov. (left tibiotarsus reversed); c, Bradycneme draculae gen. et sp. nov. ; d, Falco msticolus (Falconidae); e, Polyborus plancus (Falconidae). Various magnifications. posteriorly. The fact that these fossils differ consistently in this respect from Recent owls, more so than the tibiotarsi of the two Recent owl families differ from each other, appears to justify their segregation into a new family; and the structural dif- ferences between the two fossil forms suggest that they represent separate genera. Order strigiformes Family bradycnemidae nov. Type genus. Bradycneme nov. Diagnosis. Large owls much larger than any described species. Distal end of tibio- tarsus flattened. Condyles not projecting posteriorly; external condyle projecting distally beyond internal condyle; intercondylar groove shallow. Anterior tendinal HARRISON AND WALKER: CRETACEOUS OWLS FROM ROMANIA 565 fossa well defined, broad, fairly deep, its distal margin partly undercutting inter- condylar region and external condyle. BRADYCNEME gen. nov. Type species. B. draculae sp. nov. Diagnosis. Distal end of tibiotarsus broad and antero-posteriorly flattened. Distal projection of external condyle beyond internal condyle very marked. Internal and external condyles projecting anteriorly to same extent ; projection of internal condyle also directed internally to some extent. Anterior intercondylar fossa transverse, deep. On external side well-developed groove terminating at large external ligamental prominence, proximally situated on external surface of external condyle. Bradycneme draculae sp. nov. Plate 65, figs. 1-5 Etymology. The generic name is formed from the Greek bradys ( heavy or massive), cneme (= leg) and is feminine. The specific name is derived from the Romanian word dracul meaning evil one. Material. Holotype only. The distal end of a right tibiotarsus, A 1588. Collected and presented by Lady Smith- Wood ward, 1923. Occurrence. Szentpeterfalva, Hatszeg, Transylvania, Romania. Beds attributed previously to the Danian (now of the Palaeocene period) but according to Jeletzky (1962) and other modern authors the reptilian forms associated with the deposits indicate a Maestrichtian upper Cretaceous age. The dating problem is now under review by Finnigan. Description. The specimen is a distal end of a right tibiotarsus with a short portion of shaft. It is in fairly good condition, but damaged in places along the proximal external edge, and with small areas of crushing elsewhere. The proximal part of the shaft shows a ridged and roughened surface. The shaft and head are antero-posteriorly flattened, the shaft being thickest along the internal side. The external condyle projects further distally than does the internal condyle, and is distally tilted towards the internal side. The internal condyle projects internally, its distal edge and the distal edge of the intercondylar groove forming a level transverse surface. Posteriorly the bone is flattened, with smooth curving edges, the central portion of its surface merging smoothly at its distal end with the intercondylar region. Distally and posteriorly the inner edges of the condyles are little in evidence, the intercondylar groove curving smoothly upwards laterally to the outer edges of the condyles. The latter are only slightly prominent posteriorly. Distally the condyles are widely spaced and most prominent at their outer edges, the intercondylar groove being deeper where it borders the external condyle. Anteriorly the condyles have prominent rounded surfaces projecting beyond the line of the anterior surface of the shaft. On the anterior surface of the intercondylar groove there is the deep transverse groove of the anterior intercondylar fossa ; the part of the intercondylar region between this and the tendinal fossa of the shaft forming a narrow lip. The anterior part of the outer surface of the external condyle is hollowed, but there is a large, projecting, external ligamental prominence towards the proximal edge of the condyle. A deep groove extends along the anterior side of the external edge of the shaft, ending abruptly at the external ligamental prominence, at a level with the distal edge of the tendinal fossa. Posterior to this groove a narrow ridge extends along the middle of the internal surface of the shaft. The anterior surface of the shaft is rela- tively smooth, a large rounded tendinal fossa occupying most of the distal end of the shaft. This fossa is nearer the external side and leaves a thick ridge on the internal side extending to the proximal base of the internal condyle where it bears a small elongated pit. The fossa tapers a little towards the proximal end where it is shallowest and distally deepens to a point just proximal to the condyles. Small areas within the fossa appear to have been crushed, and detail is more satisfactory on the other species, but there is a small 566 PALAEONTOLOGY, VOLUME 18 rounded hollow at the distal internal corner, slightly undercutting the intercondylar region bordering the internal condyle, and another broader and more shallow just undercutting the internal side of the proximal edge of the external condyle. The edge of the fossa is rounded on the internal side but a narrow ridge borders it on the external side, slanting externally towards the external ligamental prominence and separating the fossa from the peroneus groove. From comparison with the other specimen it appears that this ridge should form a thick structure, its upper surface slanting internally, just proximal to the external condyle, but on the present specimen crushing has produced a double ridge with a hollow between. There is also a small area of crushing towards the proximal external end of the main narrow ridge. The internal side of the shaft is rounded but much thicker than the external side, and this thickness increases proximally to a point where, on the tibiotarsi of strigiform species, a prominence is present on the anterior internal edge. The shaft of the present specimen appears to have been broken at the point where this prominence occurs. Measurements. Length from proximal end to distal tip of external condyle 68-7, to internal condyle 60-5. Width across posterior edges of condyles 33-5, across distal ends 35-2, across anterior edges 37-8. Distal/ proximal depth of internal condyle 16-9, of external condyle 16-4. Anterior/posterior thickness of internal condyle 20-9, of external condyle 2 TO. Length of anterior intercondylar fossa 121. Distal end of shaft, internal to external edges 21-7, thickness on internal side 12-6, on external side 8-7, greatest length of tendinal fossa 24 0, greatest width 21-4. Height of external ligamental prominence 4-5 mm. HEPTASTEORNis gen. nov. Type species. H. andrewsi sp. nov. Diagnosis. Distal end of tibiotarsus less broad and less flattened antero-posteriorly than in Bradycnemis. Distal projection of external condyle beyond internal condyle very small. Internal condyle projecting much further anteriorly than external condyle. Anterior intercondylar fossa less marked than in Bradycnemis. Heptasteornis andrewsi sp. nov. Plate 65, figs. 6, 7; Plate 66, figs. 1-7 Etymology. The generic name is formed from the Greek hepta{ = seven), asty- ( = town), and ornis ( = a bird) in reference to the name of the area of origin, and is feminine. It is named after C. W. Andrews. Diagnosis. The only known species of its genus. Material. Holotype: distal end of a left tibiotarsus A 4359, presented by Baron von Nopcsa, 1913. Paratype: another distal end of a left tibiotarsus, A 1528. Presented by Baron von Nopcsa, 1922. Occurrence. Szentpeterfalva, Hatszeg, Transylvania, Romania. Maestrichtian (upper Cretaceous). (See eomments under previous species.) Description. The holotype is a distal end of a left tibiotarsus, broken off before the proximal end of the tendinal fossa. The surfaces are in good condition but the external edge is broken away to the external ligamental prominence, and the specimen had been irregularly fractured along the median axis. The surface EXPLANATION OF PLATE 65 Bradycneme draculae gen. et sp. nov. Holotype: distal end of right tibiotarsus (A 1588). Stereopairs, x^. Fig. I, anterior; Fig. 2, external; Fig. 3, posterior; Fig. 4, internal; Fig. 5, distal. Heptasteornis andrewsi gen. et sp. nov. Paratype: distal end of left tibiotarsus (A 1528). Stereopairs, xf. Fig. 6, anterior; Fig. 7, internal. PLATE 65 HARRISON and WALKER, Cretaceous owls 568 PALAEONTOLOGY, VOLUME 18 of the bone shows some very fine ridging and irregular texturing. The posterior surface is flat and smooth, rounded at the edges. The posterior edges of the condyles show only a very slight prominence along the outer edges, and the posterior condylar surfaces continue smoothly from the posterior side over the distal end, with only a shallow intercondylar groove between them. Distally the external condyle projects slightly beyond the internal condyle, but shows the converse condition to that of Bradycneme in that the distal surface of the external condyle is shorter and more rounded distally. Anteriorly both condyles are pro- minent, with a deeper groove between them. The internal condyle projects further anteriorly than does the external condyle, and the anterior ends of both show some internal deflection. The internal side is smooth and flat, slightly rounded at its edges; and the internal side of the condyle shows a hollow towards the anterior edge. On the external side there is some evidence of a projecting ridge which has broken away. There is a portion of a deep, tapering groove. There is a worn area where a ligamental prominence might have been, and a hollow on the anterior side of the outer condylar surface. On the anterior intercondylar fossa, but proximal to it the surface of the groove forms a narrow prominent lip above the distal end of the anterior tendinal fossa which undercuts it. The broad ridge formed by the anterior surface along the internal side of the tendinal fossa terminates at the proximal base of the internal condyle. It bears an elongated pit which appears to have been enlarged by erosion. On the external side of the anterior shaft surface the floor of the tendinal fossa forms a similar ridge with an inward-slanting surface, the floor of the fossa deepening markedly in the central part of the shaft. The distal end of the fossa shows a small rounded hollow in the proximal side of the intercondylar region adjacent to the inner side of the internal condyle, and a similar hollow proximally undercutting the inner side of the external condyle. The referred second specimen is worn and eroded over much of the surface and elsewhere shows small accretions of matrix which obscure detail. Apart from confirming the general configuration of the holotype it adds little except that, having a longer portion of shaft, it shows the outline of the tendinal fossa, tapering to a point proximally near the external edge of the shaft. Measurements. Holotype. Length on internal side 30T, on external side 35-7. Greatest width at distal end 32-5. Distal/proximal depth of internal condyle 13-9, of external condyle 15-7. Anterior/posterior thickness of internal condyle 19 0, of external condyle 17-8, of external side of shaft 11-3, of internal side 12-6 mm. Paratype. Length on internal side 5 10, on external 54-9, greatest width at distal end 33-8, width of proximal end of shaft 17-2. Distal/proximal depth of internal condyle 18 0, of external condyle 16-3. Anterior/posterior thickness of internal condyle 19-7, of external condyle 181, of internal side of shaft 1 I T, of external side of shaft lOT. Greatest length of tendinal fossa 27-9 mm. Discussion. Apart from the flattened condition of the posterior condylar region, the specimens resemble the tibiotarsi of Recent owls such as Strix. The existence of giant forms at a period when the other known fauna consists of a huge aquatic bird and a number of large reptiles would not be surprising. In general, in Recent diurnal raptors, the broader, more flattened distal end of the tibiotarsus is associated with species which are relatively sedentary and rely on a rapid flight and swift seizure with the feet to capture their prey, the narrower bone being usually associated with species which walk or run more frequently. The difference in shape of the specimens discussed here might be the result of similar selective pressures. EXPLANATION OF PLATE 66 Heptasteornis andrewsi gen. et sp. nov. Paratype: distal end of left tibiotarsus (A 1528). Stereopairs, xf. Fig. 1, posterior; Fig. 2, external; Fig. 3, distal. Heptasteornis andrewsi gen. et sp. nov. Holotype: distal end of left tibiotarsus (A 4359). Stereopairs, x^. Fig. 4, anterior; Fig. 5, internal; Fig. 6, posterior; Fig. 7, external; Fig. 8, distal. PLATE 66 HARRISON and WALKER, Cretaceous owls 570 PALAEONTOLOGY, VOLUME 18 REFERENCES ANDREWS, c. w. 1913. On some bird remains from the Upper Cretaceous of Transylvania. Geol. Mag. (5) 10, 193-196. JELETZKY, j. A. 1962. The allegedly Danian dinosaur bearing rocks of the globe and the problem of the Mesozoic-Cenozoic. J. Palaeont. 36, 1005-1018. LAMBRECHT, K. 1929. Mesozoische und tertiare Vogelreste aus Siebenbiirgen. C.R. 10th Congr. Int. Zool. Budapest 1927. Sect. 8, 1262-1275. 1933. Handbuch der palaeornithologie. xix^ 1024 pp., 209 figs. Berlin. C. J. O. HARRISON Subdepartment of Ornithology British Museum (Natural Elistory) Tring, Herts. C. A. WALKER Department of Palaeontology Original typescript submitted 24 April 1974 British Museum (Natural History) Revised typescript submitted 20 November 1974 London SW7 5BD A NEW 7BRYOZOAN FROM THE CARBONIFEROUS OF EASTERN AUSTRALIA by BRIAN A. ENGEL Abstract. Revision of Australian Carboniferous cryptostome fenestrate bryozoans has resulted in the recognition of a new genus, Septatopora, which has been defined on the basis of nine species, four of which, 5. flemingi, S. gloucesterensis, S. nodosa, and 5.(?) williamsensis, are new, with the remaining five species having been previously assigned to Fenestella Lonsdale or Polypora M’Coy. The existence of eight apertural septa and an additional orifice on the branch surface proximal to each aperture, place the affinities of the genus in doubt. Grouping with either bryozoans or octocorals is suggested, with the con- clusion being drawn that greatest affinities lie with the contemporary genera of fenestrate bryozoans. A new family, doubtfully positioned close to the Family Fenestellidae King, 1850, is erected to contain the new genus. A BiosTRATiGRAPHiCAL, taxonomic, and evolutionary study of Australian Carboniferous fenestrate bryozoans, has led to the recognition of a new, morpho- logically distinct group of species, previously described members of which have been distributed generically between Fenestella Lonsdale and Polypora M’Coy. Division of Australian species between these two taxa, based largely upon the number of rows of zooecial apertures per branch, has been found to be impractical. There exists a distinct evolutionary trend throughout the Carboniferous Period for all initially two-rowed fenestrate species to develop a third row of apertures at an increasing distance proximal to each branch bifurcation. One result of this is that it is no longer possible to decide if some Mid to Upper Carboniferous species are basically two- or three-rowed forms. This problem has already been raised in the case of Fenestella{l) altinodosa Campbell (Campbell 1961) where that author sug- gests his species could equally well be placed in Polypora M’Coy. As a result of an extensive statistical survey in the present study of numerous Australian Carboniferous fenestrate specimens it became apparent that there were variations in apertural form, in conjunction with several other features, which pro- vided a more satisfactory grouping of the Australian material. In particular, three basic types of aperture were recorded, namely : 1. Fenestellid type— a simple, weakly exserted, circular aperture with a narrow peristomal rim. Mean apertural diameter lies between 0 08 and 0T5 mm. 2. Polyporid type— a larger, simple aperture with a broad, low, peristomal collar which may become horseshoe-shaped in some species. Mean apertural diameter is usually about OT 4-0-23 mm. 3. Septate type— a circular, strongly exserted aperture with a thin, high peristome within which there are eight radially disposed septa surrounding a very small central orifice. Mean apertural diameter ranges between 0 07 and 013 mm. This last group was also found to share several additional morphological features which together define the new genus described here as Septatopora gen. nov. [Palaeontology, Vol. 18, Part 3, 1975, pp. 571-605, pis. 67-70.] I 572 PALAEONTOLOGY, VOLUME 18 The geological range of this new genus commences in strata which can be cor- related, on the basis of other fauna, with the Tournaisian-Visean boundary. It extends up through the remainder of the Australian Carboniferous sequence but has not yet been recorded from the overlying Permian strata. For purposes of brevity the following morphological discussion will refer to low, mid, and high zonal dis- tribution, each of which correlates approximately with Lower Visean, Upper Visean- Namurian, and Westphalian-Stephanian respectively. More specific stratigraphic data are given with the systematic descriptions. A total of nine species, two of which are of dubious relationship, are here assigned to the new genus : Septatopora pustulosa (Crockford) 1949 Septatopora flemingi sp. nov. Septatopora isaacsensis (Campbell) 1961 Septatopora stellaris (Campbell) 1961 Septatopora(l) sulcifera (Crockford) 1947 Septatopora gloucesterensis sp. nov. Septatopora acarinata (Crockford) 1947 Septatopora nodosa sp. nov. Septatopora(l) williamsensis sp. nov. [= Polypora pustulosa] [= Polypora isaacsensis] Fenestella stellaris] [= Polypora sulcifera] [= Fenestella acarinata] The stratigraphic distribution of these species is illustrated in text-fig. 2. DIAGNOSTIC MORPHOLOGY OF SEPTATOPORA Apart from the fact that all species have a standard cryptostome fenestrate mesh- work with a normal zooecial chamber/vestibule arrangement, the following are the four major, additional generically-distinguishing morphological features: Septation. All apertures are strongly exserted and contain eight apertural septa which commence on the sides of the vestibule from where they taper upwards and inwards towards the axis to leave only a small circular opening in the centre of the external aperture. Each aperture also bears a narrow, elevated peristomal collar which gives it a cup-like form very similar to the calice of some solitary corals. Auxiliary tube. In low zonal species the proximal side of the exserted aperture has a small opening or gap on to the obverse branch surface. This detail is quite difficult to observe in the very fine meshwork of these older species. Upper zonal species have an obvious small, conical or slit-like depression situated some distance proximal to each aperture on the branch surface. This depression bears the surface ornament of the branch and is connected by a narrow auxiliary tube to the proximal region of the elongated vestibule just anterior to the hemiseptum. Position and orientation of the auxiliary tube vary according to the form of the zooecial chamber. Ovicellular structures. Most species have additional large, irregularly spaced, hemi- spherical depressions on the branch surface. When present, they are situated adjacent to the proximal rim of an aperture where they obliterate the smaller conical depres- sion. The surface of these larger depressions is smooth and they are also connected ENGEL: CARBONIFEROUS SEPTATOPORA 573 TEXT -FIG. 1. A, B, side-sectional diagrams along one row of zooecial apertures in a branch showing zooecial chambers, hemisepta, septate vestibules, auxiliary tubes, and surface ovicellular depressions, (a, Septatopora flemingi, x 75; B, Septatopora acarinata, x 60.) c, D, E, reverse views of the method of packing of zooecial chambers immediately beneath the back wall of the branch, c illustrates a low zonal species with only one additional aperture appearing at bifurcation, d is a mid-zonal species with a third row of apertures appear- ing some distance before bifurcation, e demonstrates the change in zooecial packing in the late Carboni- ferous forms, (c, Septatopora acarinata, x 25; D, Septatopora ghucesterensis, x 25; E, Septatopora flemingi, x20.) to the lower vestibule by the auxiliary tube. They may be the sites of former external ovicellular chambers. Ornamentation. Most species lack carina and are ornamented with fine, pustulose, sinuous, longitudinal striations of distinctive appearance. The above features define a morphologically compact species group dilferent from other fenestrate taxa. Several other variable features have proved also to be of con- siderable stratigraphic value. They are detailed in the comparative discussion which follows the description of each species. BRYOZOAN OR OCTOCORAL? The classification of Septatopora gen. nov. presents numerous difficulties which can- not be resolved on the basis of evidence at present available. The novel occurrence of eight septa in the vestibule of a form with a fenestrate bryozoan habit combines aspects of both bryozoan and possibly octocorallian affinities, a final decision between which must await further detailed thin section study. Unfortunately, with rare exceptions, Eastern Australian Carboniferous fenestrate species are preserved in fine clastic sediments as either internal or external moulds, the original calcareous skeleton having been leached away or perhaps replaced by structureless secondary mineral deposition (calcite or hydrous silica). Consequently, almost no information is available on skeletal microstructure. Despite this serious deficiency, it is possible to reconstruct from the moulds many of the important struc- tural details, some of which would be quite difficult to observe on complete specimens. 574 PALAEONTOLOGY, VOLUME 18 Amongst the rare material suitable for thin section work, all sections made so far have revealed a standard fenestellid microstructural arrangement (Tavener-Smith 1969; Tavener-Smith and Williams 1972). Unfortunately most of these sections have not been identifiable generically, and hence it is not possible to be certain that specimens of Septatopora have been included, although by their frequency, this is thought to be quite probable. Some internal moulds of Septatopora exhibit short skeletal rods which extend from the base of the zooecial chambers out to the side and reverse walls of the branch. These rods are almost certainly a replacement of the skeletal rods which occur normally in the laminated wall tissue of all fenestellids, lending further support to the supposition that the microstructure of Septatopora is of the fenestellid type. Despite the major problems which will arise consequent upon the decision, the writer is of the opinion that Septatopora must be classified with its contemporary fenestellids. In recognition of its distinct morphology, the genus has been placed herein in a separate family and, with slight reservation, grouped most closely with the Family Fenestellidae pending the resolution of the generic microstructural details of the new genus. Some of the reasons for this decision are given below. Growth habit. Where known, species of Septatopora have a broadly funnel-shaped or flared zoarium structurally identical with contemporary fenestellids. Apertures are arranged in regular rows along the branches on the inner surface of the cone. Exact equivalence of so many structural aspects is so great that an explanation of similarity based upon convergence from separate phyla is regarded as being highly improbable. Both FenesteUajPolypora and Septatopora also exhibit the same evolu- tionary trends throughout the Carboniferous in the development of their zoaria, some details of which are discussed later. In Lower Carboniferous species septation is the major visible distinguishing feature, and in the case of poor preservation of this aspect, it is not possible to make a generic decision between Septatopora and Fenestella. It is only in the much larger, late Carboniferous species that the septation and auxiliary tube become readily evident, but even there the similarity of form is still very clear. Growth habit in the octocorals is of extremely wide variation and a fenestrate form is known in a number of groups (e.g. gorgonids). No examples have been observed of the regular funnel-shaped zoarial form, and, although of limited significance, size differences between this group and Septatopora are of quite major proportions. Septation. The existence of eight apertural septa is considered to be the main argu- ment against a bryozoan origin for Septatopora. Modern ideas of the lophophore and gut of a bryozoan would appear to be incompatible with septation. It is not possible to argue this matter without further details of the skeletal microstructure of the vestibular region. It should be pointed out that the septation is generally much shorter (longitudinally) than the vestibule in which it is housed and there appears to be no difficulty with the protrusion of the tentacles between the septa. In their fully extended mode, the tentacles would fill the calice-like external aperture and raise the mouth to a position beneath the central orifice in the base of the calice. To do this requires some slight invagination of the tentacle ring which in turn would provide a suitable secreting I ENGEL: CARBONIFEROUS SEPTATOPORA 575 surface for the septal development. Such possible modifications to the lophophore require further investigation. An additional aspect of septation concerns the type species of Polypora M’Coy {P. dendr aides M’Coy) which has been redescribed by Miller ( 1 963 ) as having apertures with ‘fifteen or sixteen short thin internal projections resembling the septa of corals’. Although of only slight form, their presence and number is highly suggestive, and lends some possible support to the argument that Septatopora should be grouped with these fenestrates. Internal form. In spite of a lack of thin-section detail it is possible to establish that, internally, Septatopora is quite different from most octocorals of comparable arborescent form. All species of Septatopora have a calcified skeleton in which the body chambers are regularly packed in contact with each other in rows adjacent to the thin reverse wall in a fashion identical with that of the fenestellids. These body chambers almost fill the branch having some variable skeletal thickening surrounding them. In the space available in each branch it is quite impossible to develop an inner coenenchymal (medullar or axial) zone with an outer layer in which the chambers are shallowly embedded, as is a common condition in the gorgonid octocorals. It would appear that there is a variety of similar basic structural differences between Septatopora and most arborescent groups of living and fossil octocorals which would make their combination improbable. Finally, all zooecia in Septatopora are distinctly subdivided into a body chamber and a vestibule separated by a marked hemiseptum. This dual chamber arrangement appears to have no modern analogue in the octocorals but is a well-established bryozoan feature. Septation remains the most difficult aspect of the new genus to encompass within modern ideas on bryozoans. Despite this problem, the case has been argued above that Septatopora is basically inseparable from its contemporary fenestellids with which it closely approximates in both structure and form. It would seem that if Septatopora is unacceptable within the Phylum Bryozoa, then further close investiga- tion must be made of the systematic position of the Family Fenestellidae. FUNCTIONAL MORPHOLOGY Whilst lacking any clear understanding of the reasons behind the development of apertural septation in all species of Septatopora, it is readily evident that the polypide was greatly restricted in its ability to extrude out of the zooecial cavity. In the fully extended mode, the tentacles would have been placed between the septal partitions and the mouth must have been located beneath the small central opening in the base of the calice-like depression. Of necessity, the tentacle ring or lophophore was thus contained within the vestibule. Assuming the genus was a normal ectoproct, this means that the anus, being outside the lophophore, would also have been enclosed within the vestibule. To overcome this major problem, the development of a separate anal opening would seem to have been an essential requirement. In low zonal species with their globular zooecial chamber close to the obverse surface it is postulated that this was initially achieved by the simple development of 576 PALAEONTOLOGY, VOLUME 18 a breach in the side of the exserted vestibule, or by the construction of a short, narrow, horizontal connection from the base of the vestibule to the branch surface on the proximal side of the aperture. In high zonal species the chamber became elongate oval in form and located quite close to the reverse branch surface. This required the elongation of both the vestibule and the auxiliary ‘anal’ tube, each of which then developed as quite separate structures situated perpendicular to the branch surface. From the simple expedient solution of a lateral breach in the side of the exserted aperture, changes in chamber shape and position would thus have inevitably resulted in the need for the elaborate auxiliary tube as can be observed in the late Carboni- ferous representatives of the genus. It is perhaps not surprising that such a complex arrangement apparently did not survive beyond the Carboniferous Period. It also appears reasonable to postulate that the reproductive system would have used this auxiliary tube for the release of fertilized ova which were then stored in enlarged spherical chambers on the branch surface, prior to final release. This would explain the coincidence of the auxiliary tube opening with the frequent, large hemi- spherical depressions observed on the branch surface adjacent to the proximal rim of selected fertile polypides in most zoaria. The assignment of such an alimentary/reproductive role to the auxiliary tube presents several major difficulties. It is customary to extrapolate backwards from modern functional morphology to fossil morphology and unfortunately there appears to be no modern equivalent which can lead to the above interpretation. Modern calcified bryozoans have a budding pattern in which the anus is distally placed in the tentacular crown and given this information it is quite difficult with the budding pattern in Septatopora to postulate a proximal anus. Study of all species of Septatopora makes it quite evident that the auxiliary tube connects to the base of the vestibule adjacent to the hemiseptum making it obligatory to propose a proximal anus if the above proposed theory is to have any substance. In addition, modern species have their coelomic pores for egg extrusion placed distally and the transfer of eggs to the distally positioned brooding cavities requires a great deal of movement and manipula- tion on the part of the tentacle crown, a process clearly not possible from the base of the vestibule. Finally, external proximal ovicells are unknown in modern forms although little doubt is held that this is the only likely interpretation of these large, spherical, proximally situated structures in the fossil species. From the above discussion it is apparent that an alimentary/reproductive role for the auxiliary tube requires a major reversal of the polypide construction from fossil to modern species. Although the proposition remains attractive, the absence of skeletal detail makes it impossible to arrive at a positive conclusion. A second suggestion that the auxiliary tube served an hydrostatic function, with the surface opening being analogous to an ascopore is possible. This structure is defined by Bassler (1953) as a ‘median small opening in the frontal wall of some cheilostomes leading to the compensatrix, located proximally with reference to the aperture’. There is a close similarity with this cheilostome feature and the opening found in Septatopora making it necessary to propose an hydrostatic function as an alternative explanation. However, since the polypide was unable to move very far because of the septation, it is unlikely to have developed the need for any great degree of compensation. The term ‘ascopore’ has been used for several non-homologous ENGEL: CARBONIFEROUS SEPTATOPORA 577 systems in bryozoans and it is possible that other hydrostatic functions than that of compensation may have been the role of the auxiliary tube. Although of major significance to the interpretation of the new genus, a lack of thin-section data and modern analogous structures means that a satisfactory explana- tion has yet to be achieved for the biological function of the apertural septation and its closely associated, proximally situated auxiliary tube. Abbreviations. The following abbreviations are used in the statistical treatment of fenestrate mesh. FL = fenestrule length (centre to centre of dissepiments) ; FW = fenestrule width (centre to centre of branches) ; BW = branch width ; DW = dissepiment width ; ZD = zooecial diameter ; Z-Z = zooecial aperture spacing (centre to centre of apertures); N-N = nodal spacing; F/10 = number of fenestrules in 10 mm; B/10 = number of branches in 10 mm; Z/5 = number of zooecial apertures in 5 mm; N/5 = number of nodes in 5 mm ; Z/F = number of zooecial apertures per fenestrule ; m = arithmetic mean value of dimension ; s = standard deviation; OR = observed range of dimension; N = number of measurements recorded. Repositories. All specimens have had their catalogue number prefixed by the letter ‘F’, preceded by the following Museum coding: QU = Queensland University; QGS = Queensland Geological Survey; NEU = University of New England; NU = University of Newcastle; SU = Sydney University. Most specimens recorded by Crockford (1947, 1949) in the University of Queensland Catalogue have had new numbers allocated since their original publication. Fossil localities. Localities are recorded, wherever possible, with the prefix NUL, followed by a number, all of which refers to the University of Newcastle Fossil Locality Index. Localities not present in that index are given in descriptive detail in the text. NUL9— 3 km east of Booral, N.S.W. (Campbell 1961); NUL39— Cameron’s Bridge, Rouchel Brook, N.S.W. (Crockford 1947); NUL258— Barrington, N.S.W. (Cvancara 1958); NUL361— Glen William, north of Clarencetown, N.S.W. (Crockford 1947); NUL372— Hilldale, N.S.W. (Crockford 1947); NUL390-Oaky Creek, N.S.W. (Campbell 1962); NUL4 14- Barrington Guest House, N.S.W. (Crockford 1947); NUL448— Raglan property, east of Dungog, N.S.W.; NUL454— Isaacs Road, Dungog 1 mile Military Map (Grid Reference 019840), N.S.W. (Campbell 1961); NUL472 — Ridgelands 1 mile Military Map (Grid Reference 194827), Queensland (Fleming 1969). Photographic methods. Because most specimens used in this study occur as external moulds, it was generally necessary for photographic purposes to prepare latex casts which were firstly painted with a uniform black coating over which a thin grey-white layer of ammonium chloride was deposited. Depending upon the size of the specimen and the magnification required, photographic negatives were produced with a stand- mounted, close-up camera, or with a camera attached to a stereobinocular microscope. SYSTEMATIC DESCRIPTIONS Phylum ?BRYOZOA Order ?cryptostomata Shrubsole & Vine, 1882 Family septatoporidae fam. nov. Type genus. Septatopora gen. nov. Family diagnosis. ?Cryptostomata with zoaria of a broadly flared funnel shape with obverse surface on inner side of cone; composed of sub-parallel to radiating non- carinate branches connected by non-celluliferous dissepiments into a regular fenestrate meshwork; branches with two to four rows of small to medium-sized, strongly exserted calice-like apertures; apertures bear eight septa which taper upwards and inwards from the sides of the vestibule, converging in the base of the external aperture on a small central orifice ; branch surface with fine pustulose, striate ornament ; nodes present or absent, but when developed, irregularly placed on the distal rim of some 578 PALAEONTOLOGY, VOLUME 18 apertures; hemiseptum distinct; base of vestibule connected to branch surface where a second opening is located on the proximal side of each aperture. Geological range. Upper Tournaisian to Stephanian. Remarks. This family has been erected solely for the reception of the new genus Septatopora which cannot readily be combined with any other existing taxon. For reasons outlined in the previous discussion, the new family is regarded as belonging to the Order Cryptostomata Shrubsole & Vine, 1882, and is doubtfully grouped closest to the Family Fenestellidae King, 1850, with which it would appear to share the greatest number of common features. Genus septatopora gen. nov. Type species. Septatopora pustulosa (Crockford) (= Polypora pustulosa Crockford, 1949). Generic diagnosis. See family diagnosis given above. Generic description. Septatoporid with zoaria of a flared funnel shape (where known) with obverse surface on inner side of cone; fine to medium-sized fenestrate mesh composed of narrow to wide, finely striated, pustulose branches, each having a rounded, non-carinate cross-section; fenestrules oval to sub-rectangular being moderately to strongly indented by zooecial apertures; apertures small to medium- sized, circular, septate, strongly exserted, being surrounded by a thin, high, complete peristome of calice-like form; apertures in two to four rows per branch with increase in number before, and decrease after, each branch bifurcation; nodes absent or irregularly developed adjacent to the distal or disto-central rim of some apertures in any zooecial row ; arrangement may appear more regular in branches with only two rows of zooecia. Zooecial chambers globular to elongate oval in form, being joined on their distal margin to curved or L-shaped vestibules respectively; distinct hemiseptum at base of vestibule ; each vestibule with eight short, radially disposed septa extending upwards and inwards from the sides of the vestibule to converge on a narrow axial opening in the centre of the external aperture, which thus assumes a rosette pattern on the base and sides of the calice-like depression. Additional small, funnel-shaped depressions located on the branch surface, proximal to each aperture; a narrow tube connects this orifice to the base of the vestibule just anterior to the hemiseptum; irregularly disposed, larger, smooth, hemispherical depressions may occur on the branch surface where they replace the funnel-shaped depressions and abut against the proximal rim of an aperture. Reverse surface of rounded, pustulose branches joined by narrower, near level, sometimes inclined dissepiments; some reverse branches may also bear numerous, irregularly arranged spines. Zooecial bases irregularly pentagonal in lateral rows and rhomboidal in central rows; with increase in the number of zooecial rows they become elongate oval with little overlap between rows. Geological range. Upper Tournaisian to Stephanian. Generic comparisons. The reasons for excluding Septatopora from either Fenestella ENGEL: CARBONIEEROUS SEPTATOPORA 579 Lonsdale or Polypora M’Coy have been discussed previously. No other genus of comparable form has been observed in the literature. It is possible that the species discussed by Miller (1963) as Polypora(l) verrucosa (M’Coy) could be assigned to this genus. In his revision of Polypora M’Coy, Miller excluded this species on the basis of its stalk-like apertures, but was not prepared at that stage to designate a new generic category until similar morphology had been observed on further material. In its apertural form, the species is quite similar to Septatopora, but until further examination of the original material is made it is not possible to confirm its inclusion. Septatopora piistulosa (Crockford), 1949 Plate 67, figs. 1-9 1949 Polypora pustulosa Crockford, p. 426, text-fig. 9. 1949 Polypora tenuirama Crockford, p. 428, text -fig. 1 1. 1961 Polypora septata Campbell, pp. 462-463, pi. 58, figs. 1-2. 1962 Polypora cf. septata Campbell, p. 47, pi. 13, fig. 8a-c. 1972 Polypora pustulosa Crockford; Fleming, pp. 6-7, pi. 3, fig. 8; pi. 4, figs. 1-6; text-figs. 1-2. Revised diagnosis. Septatopora with wide pustulose branches ; mesh open, medium- sized, with sub-oval to sub-rectangular fenestrules; apertures septate, strongly exserted, distantly spaced, with frequent, proximally associated, auxiliary pits and hemispherical depressions; zooecia in three rows per branch; carina and nodes lacking; reverse branch profile rounded; zooecial bases elongate oval. Revised description. Zoarium : gently radiating to sub-parallel branches of maximum radius 90 mm; orientation unknown. Obverse surface, {a) Branches. Wide, normally with three rows of zooecia (m.BW 0-49 mm) ; two-rowed branches medium to narrow (~0-3 mm) and four- to five-rowed branches very wide (~0-8 mm); branch cross- section rounded, becoming oval at bifurcations; ornament of distinctive pustules arranged along slightly wavy, faint, longitudinal ribbing, {b) Dissepiments. Medium to wide (m.DW 0-21 mm); expanded gently outwards from centre to branch junction in a broad curve; level with or slightly below branches; most dissepiments inclined towards base of colony; ornament as on branches, (c) Fenestrules. Sub-oval to sub- rectangular; medium-sized mesh moderately regular but varied by regions of wide pre-bifurcation, and narrow post-bifurcation branches; fenestrules wider than branches, resulting in an open-mesh appearance; fenestrules medium length (m.FL 1-68 mm), medium to wide (m.FW 1-03 mm), {d) Carina. Absent, {e) Nodes. Absent. if) Zooecial apertures. Medium size, circular (m.ZD 0- 1 1 mm) ; strongly exserted being surrounded by high peristome; apertures bear eight radially disposed septa surrounding a narrow axial opening which widens downwards towards the zooecial chamber; erect or laterally inclined apertures arranged in straight rows with alter- nating positions in adjoining rows; marginal apertures strongly indent fenestrules and are not stabilized with respect to the dissepiments ; apertures in each row medium to distantly spaced (m.Z-Z 0-43 mm) with from three to five zooecia per fenestrule (m.Z/F 3-9); usually three rows per branch with increase to four (rarely five) rows up to 2 mm before, and decrease to two rows up to 2 mm after bifurcation, (g) Addi- tional features. Proximal to each aperture there is a small, funnel-shaped pit which 580 PALAEONTOLOGY, VOLUME 18 bears normal, slightly deflected branch ornament; a narrow tube connects the bottom of this pit to the base of the vestibule; some specimens also bear irregularly dis- tributed, smooth, hemispherical depressions (diam. 0-25-0-35 mm) on the obverse branch surface, situated so that the distal rim of the depression is in contact with the proximal margin of an aperture; an opening at the base of the depression may be visible, being the site of the tubular connection. Reverse surface, {a) Form. Broadly rounded branches joined by medium width, level dissepiments; both branches and dissepiments bear fine, pustulose striations. {b) Zooecial bases. Elongate oval with little or no overlap between adjoining rows of zooecia. Material. Holotype QUF24980; topotype QGSF10910 (For. 2v. Ph. Stan well); others QGSF11920, QGSF10936 (Neerkol Creek); QGSF10905, QGSF10988- 10989, QGSF10889 (Malchi Creek); QUF24954-24955 (Malchi Creek); NEUF4708D, NEUF4715C/D, NEUF4734C/D (NUL9); NEUF5632-5634 (NUL390). Further material from various localities in New South Wales and Queens- land has been placed in the University of Newcastle Collection. Remarks. Fleming (1972) first proposed that the three species P. pustulosa Crockford, P. tenuirama Crockford, and P. septata Campbell should be combined into the one species. Concurrent and subsequent detailed mesh studies by the present writer strongly support this decision. However, the work of Miller (1963) clearly indicates that the Australian material cannot be assigned to the genus Polypora M’Coy, and hence a new genus is proposed here for its reception. Based upon Queensland specimens, Crockford (1949) erected both her species in the one paper, but made no comparative remarks. Distinction appears to have been based upon absolute differences in mesh size and zooecial spacing. No mention was made of apertural septation in P. pustulosa, no doubt because of the very poor state of preservation of the type material. Campbell (1961) erected the third species P. septata upon specimens from New South Wales, and hesitantly distinguished it from P. tenuirama because of small dif- ferences in mesh dimensions and apertural septation. Further specimens from another New South Wales locality (Campbell 1962) were referred to P. cf. septata because of their weak development of apertural septation, a reduced branching frequency, an EXPLANATION OF PLATE 67 All figures of latex casts except fig. 7. Figs. 1-9. Septatopora pustulosa (Crockford). 1-4, obverse surface of holotype of Polypora septata Campbell, NEUF4708D, x 20, x 30, x 30, x 50 respectively. Note auxiliary openings proximal to each aperture on figs. 1 and 2 and strongly exserted, septate form of apertures together with the distinctive pustulose ornament on branch surfaces in figs. 3 and 4. 5, 6, obverse surface of holotype of Polypora tenuirama Crockford, QUF24955, x20, x 10 respectively. Note frequent occurrence of proximal ovicellular pits. Weaker occurrence of surface ornament is due to preservation. 7, reverse view of zooecial chamber infillings of P. tenuirama Crockford showing skeletal rods extending between chamber and walls, QUF24955, x5. 8, obverse surface of QGSF10988, x5. 9, obverse surface of QGSF11920, x 5. (Figs. 1-4 from locality NUL9, Booral, N.S.W.; figs. 5-9 from Malchi Creek, Queensland.) PLATE 67 ENGEL, Septatopora 582 PALAEONTOLOGY, VOLUME 18 increase to five, rather than four zooecial rows before bifurcation, and the develop- ment of surface hemispherical depressions not previously observed on P. septata. Detailed measurement by the present writer on a wide variety of specimens from both states, including all type material, has established that all three species belong to the one continuously expanding mesh series, and that there are no grounds for subdivision upon this basis. Furthermore, all material bears the diagnostic obverse features of pustulose ornament, apertural septation, and separate auxiliary orifices, and is therefore considered to be conspecific. All authors have recorded the occurrence of surface hemispherical depressions (?ovicell sites) but Fleming (1972) also noted a few of the smaller openings on one specimen (holotype of P. tenuirama) and described them as incompletely formed ovicellular structures. Close examination of most specimens reveals this structure to be associated with all apertures as a basic functional feature. Septatopora pustulosa (Crockford) has been chosen as the type species of the new genus because of its widespread, common occurrence in Eastern Australia. Further, it is generally of sufficiently coarse mesh to enable easy recognition of the diagnostic features of the genus. Stratigraphy. S. pustulosa (Crockford) has a wide geographic and stratigraphic range through the Levipustula levis Zone in Australian Upper Carboniferous sediments. It is found intermittently through the whole thickness of the Neerkol Formation (2100 m) near Rockhampton, and in the Poperima/Rands Formations (Maxwell 1964) in the Yarrol Syncline of Queensland. Occurrences in New South Wales are more restricted but are found at various uncorrelated levels in the Booral Formation (2000 m) and in the Kullatine Formation as recorded by Campbell (1962). The age of the L. levis Zone is generally considered to be Westphalian but no evidence exists for more precise correlation. Septatopora flemingi sp. nov. Plate 68, figs. 4-8; text-fig. 1a, e Diagnosis. Septatopora with very wide, weakly pustulose branches; mesh closed. EXPLANATION OF PLATE 68 All figures of latex casts except figs. 6-8. Figs. 1-3. Septatopora{l) williamsensis sp. nov. 1, 2, obverse surface of holotype showing lateral position of partly exserted apertures and the wide expanse in centre of branch without carina or nodes, NUF2421a, locality NUL414, x 10, x30 respectively. 3, reverse surface of holotype, NUF2421b, x 10. Figs. 4-8. Septatopora flemingi sp. nov. 4, obverse surface of holotype showing weakly exserted apertures together with their prominent adjacent auxiliary openings which form a longitudinal furrow between apertures in each row, NUF2357, locality NUL472, x 10. 5, obverse surface of NUF2362a, locality NUL472, X 5. 6, 7, oblique reverse view of an eroded zoarium with reverse wall removed. Visible is a complete internal mould of one chamber. In fig. 7 the upper vestibule is partly obscured by fenestrule infilling and only the curved and lower horizontal portion can be seen leading back to the distinct hemi- septum. Immediately below the hemiseptum, the vertical auxiliary tube (shaded) connects the lower vestibule to the obverse surface below. The body chamber extends to the right of the vestibule where its termination tends to merge with adjacent infillings, NUF2358, locality NUL472, x 20, X 40 respectively. 8, vertical view of same showing one complete chamber infilling from the reverse with adjacent infillings being broken off to leave the septate moulds of the upper vestibules, NUF2358, x40. PLATE 68 ENGEL, Septatopora 584 PALAEONTOLOGY, VOLUME 18 medium-sized with sub-oval to sub-rectangular fenestrules; apertures septate, moderately to weakly exserted, distantly spaced with very strong development of proximal auxiliary pits; hemispherical surface depressions rare; zooecia in three or four rows per branch ; carina and nodes absent, but with pseudo-carinal relief between zooecial rows; reverse branch profile rounded; zooecial bases elongate oval. Description. Zoarium: moderately radiating to sub-parallel branches of maximum radius 40 mm; zoarial margins crenulate; orientation unknown. Obverse surface, {a) Branches. Wide to very wide (m.BW 0-54 mm), straight, usually with three to four rows of zooecia; branch cross-section round to oval, well-preserved branches bear sinuous, faintly pustulose, longitudinal ribbing of moderate elevation; large auxiliary orifices in the form of strongly depressed elongated pits extend between adjacent apertures ; each apertural row appears to be located in a linear furrow and separated from adjoining rows by a weak carinal rise. This relief effect is more apparent on deflated branch surfaces, {b) Dissepiments. Medium to wide (m.DW 0-3 mm) with gradual expansion to branch junction in a gentle curve; level with or below branches, they are inclined with the obverse face being directed proximally; ornament as on branches, (c) Fenestrules. Sub-oval to sub-rectangular ; mesh medium- sized, generally regular except in regions where several adjacent branches bifurcate; fenestrule openings narrower than branches resulting in a closed-mesh appearance; fenestrules of medium length (m.FL 1-65 mm) and medium width (m.FW 0-91 mm). {d) Carina. Absent, (e) Nodes. Absent. (/) Zooecial apertures. Medium size, circular (m.ZD 0T3 mm) moderately exserted being surrounded by an entire, low peristome; each aperture bears eight septa which taper down the sides of the vestibule ; apertures are erect or laterally inclined, and arranged in three to four rows per branch with increase to five (rarely six) pre-bifurcation, and decrease to three (rarely two) post- bifurcation ; apertures alternate in adjacent rows only slightly indenting the fenestrule margin and are not stabilized with respect to the dissepiments; spacing between apertures medium to distant (m.Z-Z 0-38 mm) with from three to five zooecia per fenestrule (m.Z/F 4-3). (g) Additional features. Elongate, proximally directed oval- shaped zooecial chambers are located close to the reverse surface wall. The long vestibule is geniculate in form with a short horizontal section being joined by a longer vertical section. Septa commence above the geniculation, and taper upwards and inwards towards the axis. The auxiliary tube extends vertically from the horizontal section of the vestibule immediately anterior to the strong hemiseptum, to join the branch in a deeply depressed slit-like surface pit of dimensions comparable with those of the adjacent aperture. Only rare hemispherical surface pits have been observed. Reverse surface, (a) Form. Branches broadly rounded joined by medium width, near level or slightly depressed dissepiments both of which generally lack much ornament; some specimens bear strong, ribbed attachment spines, {b) Zooecial bases. Narrow, elongate oval in form, with little or no overlap between adjacent rows. Material. Holotype NUF2357 (NUL472); paratypes NUF2358, 2360a/b, 2361, 2362a/b, 2365, 2366 (NUL472); others NUF2359a/b, 2363, 2364 (NUL472). Remarks. Although quite similar to S. pustulosa in most mesh dimensions these ENGEL: CARBONIFEROUS SEPTATOPORA 585 specimens display sufficient morphological differences to justify the erection of a new species. Major differences between the two species are that S.flemingi has (a) an extra row of zooecial apertures in only slightly wider branches. Zooecia are more closely packed and apertures can be located low on the sides of the branches; (b) apertures which are somewhat larger but more closely spaced, and less exserted, resulting in reduced fenestrule indentation; (c) auxiliary tube openings very strongly developed being sub-equal to the apertures in size. This results in a crowded branch surface of distinctly different aspect to S. pustulosa where the auxiliary tube openings are still quite small. The strong depression of the auxiliary tube openings between apertures in S.flemingi results in linear furrows along the zooecial rows not seen in the other species. The opposed relief effect of apparent carinae between zooecial rows is another feature not observed on S. pustulosa. Stratigraphy. S. flemingi sp. nov. is known only from the top 300 m of the Neerkol Formation as recorded by Fleming (1969) in association with the Cancrinella levis Zone. Because of lack of stratigraphic continuity it is not possible to be certain of the exact age of this late Carboniferous zone. However, the occurrence of an associated brachiopod-bivalve fauna of late Carboniferous-early Permian aspect would sug- gest that the C. levis Zone is at least of late Westphalian to Stephanian age. The zone is known only from localities in the Stan well- Ridgelands and Yarrol districts of Queensland. Septatopora isaacsensis (Campbell), 1961 Plate 69, figs. 7-8 1961 Polypora isaacsensis Campbell, pp. 463-464, pi. 63, fig. la-e. Revised diagnosis. Septatopora with wide, weakly pustulose branches; mesh closed, medium to fine with oval to sub-oval fenestrules; apertures septate, moderately exserted, medium spaced with frequent, proximally associated, hemispherical depres- sions obliterating most auxiliary pits ; zooecia in three rows per branch ; carina absent ; blunt nodes distantly spaced; reverse branch profile tapered, with ornament of numerous irregular spines; zooecial bases oval. Revised description. Zoarium : large zoarium of gently radiating, strongly crenulate branches; maximum radius of specimen 50 mm; obverse surface faces upwards on the interior of a broadly flattened cone-like zoarium. Obverse surface, {a) Branches. Wide (m.BW 0-47 mm), straight, broadly rounded to flattened with weak pustulose ornament, fb) Dissepiments. Medium to wide (m.DW 0-26 mm); growth expands from centre to branch junction in a semi-circular curve ; level with, or just below, branches; no ornament observed, (c) Fenestrules. Oval to sub-oval; medium to small, moderately regular mesh with small fenestrule openings resulting in a closed appearance; short to medium length, medium width fenestrules (m.FL 0-91 mm; m.FW 0-75 mm), {d) Carina. Absent, (c) Nodes. Medium size, circular, blunt nodes very poorly developed due to large number of hemispherical depressions present ; irregularly spaced when present (m.N-N 0-94 mm); usually located on distal rim of an aperture. (/) Zooecial apertures. Medium size, circular to slightly oval (m.ZD 586 PALAEONTOLOGY, VOLUME 18 012 mm); exserted with distinct peristome; eight septa in each aperture with a rela- tively large central opening; apertures erect, with slight fenestrule indentation, not stabilized with respect to dissepiments; apertures in each row of medium spacing (m.Z-Z 0-32 mm) with two to three zooecia per fenestrule (m.Z/F 2-8); three rows per branch increasing up to five pre-bifurcation, (g) Additional features. Obverse surface largely covered with many hemispherical depressions (diam. 0-2-0-25 mm) although smaller auxiliary tube pits can be observed at a few locations. Reverse surface, (a) Form. Branches tapered becoming narrowly rounded and sub- equal to near level dissepiments; ornament of strong, variable-size spines arranged irregularly near the centre line of the branch, {b) Zooecial bases. Form not clear but have a well-rounded to oval form near the basal plate. Material. Holotype NEUF4744A/C (NUL454). Remarks. This species is known only by the holotype. No further material from the type locality has been found. 5. isaacsensis (Campbell) is the smallest Upper Carboniferous member of the new genus and can be grouped with S. stellaris (Campbell) and S', gloucesterensis sp. nov. on the basis of their common development of strong obverse nodes. Stratigraphy. S. isaacsensis (Campbell) occurs only at one locality in the Isaacs Formation as described by Campbell (1961). By its association with rare specimens of Levipustula levis it is considered to be situated high in that zone, but unfortunately there are no overlying marine faunas at this locality which can be used to fix its position with any degree of accuracy. The brachiopod fauna, with which S. isaacsensis is associated, is located about 1500 m above the profuse but vertically restricted development of the L. levis fauna near the base of the Booral Formation. On rather tenuous grounds therefore, the fenestrate species is considered to be of late Westphalian age. Septatopora stellaris (Campbell), 1961 Plate 69, figs. 2-4 1961 Fenestella stellaris Campbell, pp. 456-457, pi. 58, fig. 4a-d. Revised diagnosis. Septatopora with medium width, finely pustulose branches; mesh uniform, medium to fine, with oval to sub-oval fenestrules ; apertures septate, strongly EXPLANATION OF PLATE 69 All figures of latex casts except fig. 1. Fig. 1. Septatopora{l) sulcifera (Crockford). Obverse surface of holotype, QUF14909, locality For. 21/22, Ph. Malmoe, Queensland, x 10. Figs. 2-4. Septatopora stellaris (Campbell). 2, obverse surface of holotype, NEUF4716A, locality NUL9, X 10. 3, 4, reverse surface of holotype showing tapered branches with equal width to that of the dissepi- ments in a polygonal mesh. Note reverse surface spines, x 10, x 10 respectively. Figs. 5-6. Septatopora gloucesterensis sp. nov. 5,6, obverse surface of holotype, NUF2398, locality NUL258, x20, X 10 respectively. Figs. 7-8. Septatopora isaacsensis (Campbell). 7, 8, obverse and reverse of holotype, NEUF4744A/B, locality NUL9, x 30, x 10 respectively. PLATE 69 : » % % % ENGEL. Septatopora 588 PALAEONTOLOGY, VOLUME 18 exserted, medium spaced, being associated with profuse, proximal, hemispherical depressions; zooecia in two to three rows per branch; carina absent; nodes large, irregular, distantly spaced ; reverse branch profile tapered, with ornament of irregular spines; zooecial bases unknown. Revised deseription. Zoarium'. flattened, funnel-shaped expansion with a very small cone of attachment; maximum radius 55 mm; obverse surface faces upwards or to the interior of the funnel. Obverse surface, (a) Branches. Medium width (m.BW 0-36 mm), straight, broadly rounded with some deflation; ornament of fine ribbing and faint pustules, fb) Dissepiments. Medium width (m.DW 0-14 mm); growth expands from centre to branch junction in a semi-circular curve; level with branches; ornament of fine ribbing, (c) Fenestrules. Sub-oval to oval; medium to fine mesh; regular distally but variable proximally ; fenestrule openings of about branch width resulting in a uniform appearance; short to medium length, medium width fenestrules (m.FL 0-95 mm; m.FW 0-63 mm), {d) Carina. Absent, (e) Nodes. Large, circular (diam. 0-15 mm), erect or slightly inclined distally; spacing irregular (m.N-N 0-95 mm) where present, but large areas nodeless; situated distal to an aperture resulting in zigzag placement on two-rowed branches but centrally placed in three- rowed branches. (/) Zooecial apertures. Medium size, circular (m.ZD 01 3 mm); strongly exserted with high peristome; each aperture with eight septa and strong axial tube; erect apertures moderately indent the fenestrules and are not stabilized with respect to the dissepiments; medium spacing (m.Z-Z 0-33 mm) with from two to three zooecia per fenestrule (m.Z/F 2-9); two rows of zooecia per branch with three rows developing up to half-way between successive bifurcations, but normally only for about one-third of this distance, (g) Additional features. Obverse surface covered by profuse hemispherical depressions (diam. 0-2-0-28 mm) situated between apertures and projecting into the fenestrule margin. Reverse surface, {a) Form. Branches taper in width to become acutely rounded and equal in dimension to the near level dissepiments. Reduced branch width is accom- panied by a wavy to zigzag branch outline which results in an irregular mesh of rectangular-polygonal fenestrules with no thickening at branch-dissepiment junc- tions; branch and dissepiment width about 0-2 mm; ornament of fine, longitudinal ribbing with a pustulose overgrowth; numerous irregularly disposed spines occur with large variation in size, position, and attitude; most are distally inclined. {b) Zooecial bases. Poorly preserved in type material, being of oval form some little distance above the basal plate. Material. Holotype NEUF4716A/B (NUL9); paratype NEUF4717 (NUL9). Addi- tional material in the University of Newcastle Collection. Remarks. Campbell (1961) noted the very different morphology of this species as compared with other Carboniferous fenestellids, but was guided by the widespread development of two rows of apertures into placing it in the genus Fenestella Lonsdale. It is removed here from that genus on the basis of its distinctive apertural features. There is a considerable degree of similarity between S. isaacsensis (Campbell) and S. stellaris (Campbell), but they can be readily distinguished by the number of rows ENGEL: CARBONIFEROUS SEPTATOPORA 589 of zooecial apertures per branch at which taxonomic level this feature is given its greatest significance. Stratigraphy. This species comes from low in the Booral Formation, where it is associated with the principal occurrence of Levipustula levis. To date it has only been found at localities of similar age in the Stroud-Gloucester Syncline, N.S.W. On this basis it can only be assigned a probable early Westphalian age. Septatoporaip.) sulcifera (Crockford), 1947 Plate 69, fig. 1 1947 Polypora sulcifera Crockford, pp. 15-16, pi. 1, fig. 2; text-fig. 13. Revised diagnosis. Septatopora-\ike species with medium to wide, pustulose branches ; mesh open, medium sized, with oval to sub-rectangular fenestrules; apertures small, strongly exserted, closely spaced, without visible septation; carina and nodes absent; reverse branch profile rounded; zooecial bases unknown. Revised description. Zoarium : small fragment of radiating branches from base of the zoarium; orientation unknown; maximum radius 6-5 mm. Obverse surface: {a) Branches. Medium to wide (m.BW 0-41 mm), straight, slightly flattened (depth 0- 36 mm); ornament of fine, pustulose ribbing, (b) Dissepiments. Small to medium width (m.DW 0-2 mm); centrally straight with slight expansion at branch junction; slightly depressed below branch level; pustulose ornament, (c) Fenestrules. Elongate oval proximally becoming sub-rectangular distally; proximal mesh, medium size, irregular with an open appearance; fenestrules of medium length and width (m.FL 1- 36 mm; m.FW 0-74 mm), {d) Carina. Absent, (e) Nodes. Absent. (/) Zooecial apertures. Small (m.ZD 0 07 mm); circular; strongly exserted; no internal structure preserved; narrow peristome; apertures closely spaced (m.Z-Z 0-29 mm) with from three to six zooecia per fenestrule (m.Z/F 4-7) but distal portions indicate a dis- tribution of five to six per fenestrule ; three rows per branch with two or three post- bifurcation and three to five pre-bifurcation. Reverse surface, {a) Form. Rounded branches joined by narrow, near level dissepiments, both of which bear pustulose ornament, {b) Zooecial bases. Unknown. Material. Holotype QUF14908 (formerly QUF5768c) Riverleigh Limestone For. 21/22, Ph. Malmoe, 8 km NW. of Mundubbera, Queensland. Remarks. The only known specimen is the holotype which comprises two small, silicified fragments dissolved from the Riverleigh Limestone near Mundubbera, Queensland. Both fragments are very close to the base of the zoarium indicating little significance for the accompanying dimensions. Despite further solution of limestone no other samples have been recovered from the type locality. Since morphological details of apertural structures, zooecial bases, and distal zoarial form are unknown, generic assignment must be conjectural. Based upon the occurrence of small, strongly exserted apertures on nodeless branches which bear only a fine ornament of pustulose striations, this species has been provisionally grouped with Septatopora. This assignment is subject to confirmation by the recovery of distally located, better-preserved specimens. 590 PALAEONTOLOGY, VOLUME 18 Stratigraphy. The Riverleigh Limestone, located in an isolated fault block, has been previously correlated with beds which lie just below the Rhipidomella fortimuscula Zone (Hill 1934; Driscoll 1960). More recent studies by McKellar (1967) and Jull (1968, 1969) indicate an older age which would correlate either with the Delepinea aspinosa Zone, or perhaps with the Orthotetes australis Zone. Experience in New South Wales would indicate this latter age is too old, since extensive sampling has failed to reveal any multi-rowed fenestrates in beds belonging to that zone. For the present, a D. aspinosa age is preferred, but no conclusive evidence for this age exists. Septatopora gloucesterensis sp. nov. Plate 69. figs. 5-6; text-fig. Id Diagnosis. Septatopora with medium width, weakly pustulose branches; mesh open, fine, with sub-oval to sub-rectangular fenestrules; apertures small, septate, strongly exserted, associated with numerous proximal, hemispherical depressions; zooecia in two to three rows per branch; carina absent; nodes small, irregularly placed, moderately spaced, situated on disto-central rim of some apertures; reverse branch profile rounded ; zooecial bases irregularly pentagonal and rhomboidal. Description. Zoarium: shallow, cone-shaped zoarium of radiating branches; obverse surface on interior of cone; maximum radius 20 mm. Obverse surface: {a) Branches. Straight, narrow to medium width (m.BW 0-3 mm); obverse acutely rounded with prominent apertures ; ornament of fine pustules and very weak longitudinal ribbing. (b) Dissepiments. Medium to wide (m.DW 0T8 mm); centrally straight with moderate expansion to branch junction; profile tapers obversely so as to appear slightly carinate, (c) Fenestrules. Fine, slightly irregular, open mesh of sub-oval to sub- rectangular, medium to short length, narrow fenestrules (m.FL 1T2 mm; m.FW 0-58 mm), {d) Carina. Absent, (c) Nodes. Small, erect, irregularly developed, moderately spaced nodes (m.N-N 0-51 mm) situated adjacent to an aperture on its distal or central rim; most nodes placed near to centre of branch when present. (/) Zooecial apertures. Small, circular (m.ZD OT mm); strongly exserted; narrow, entire peristome ; apertures bear eight septa which radiate from a central perforation ; erect apertures arranged in straight rows with moderate fenestrule indentation; mostly stabilized with respect to the dissepiments, on to which they commonly encroach; zooecia closely spaced (m.Z-Z 0-27 mm) with from four to five zooecia per fenestrule (m.Z/F 4T); usually two to three rows per branch with increase to four rows up to 3 mm before bifurcation, (g) Additional features. Hemispherical depres- sions developed on branch surface between apertures and projecting into fenestrules; auxiliary tube connection to vestibule visible at base of depression; pronounced hemiseptum developed in most zooecial chambers. Reverse surface, (a) Form. Rounded branches joined by slightly narrower dissepi- ments near branch level; ornament of fine pustules over longitudinal striations. (b) Zooecial bases. Elongate, irregularly pentagonal in two-rowed branches, becoming shorter where three or four rows occur; central rows rhomboidal in shape. Material. Holotype NUF2398 (NUL258); paratypes NUF2383 (NUL258), NUF2425 (NUL414). ENGEL: CARBONIFEROUS SEPTATOPORA 591 Remarks. This new species has the distinctive apertural features of the genus Septato- pora. Further, it has considerable, more or less equal, areas of either two or three rows of apertures per branch, making it transitional from the older two-rowed species to the younger three-rowed forms. The existence of occasional nodes in a near central row is a further characteristic of this species. Stratigraphy. S. gloucesterensis occurs in the Delepinea aspinosa and Rhipidomella fortimuscula Zones in New South Wales. As such it is the first occurrence of a multi- rowed fenestrate in the Australian Carboniferous sequence, and it is joined in the R. fortimuscula Zone by the first representative of the genus Polypora M’Coy. The incoming of these multi-rowed fenestrates is thus considerably younger than their development in other parts of the world, but their appearance in the Australian record is of maximum zonal value. Septatopora acarinata (Crockford), 1947 Plate 70, figs. 6-8; text-fig. 1b, c 1947 Fenestrellim acarinata Crockford, p. 36, pi. 4, fig. 3; text-fig. 45. 1968 Levifenestella acarinata (Crockford) Wass, p. 87. Revised diagnosis. Septatopora with narrow, straight to zigzag, pustulose branches; mesh open, fine, with sub-oval to sub-rectangular fenestrules; apertures small, septate, closely spaced, strongly exserted with frequent, proximally associated hemi- spherical depressions; zooecia in two rows per branch; carina and nodes absent; reverse branch profile rounded; zooecial bases irregularly pentagonal. Revised description. Zoarium: shallow, cone-shaped zoarium of radiating branches; obverse surface on interior of cone; maximum radius 20 mm (holotype 6 mm). Obverse surface, {a) Branches. Narrow, straight or slightly zigzag; rounded profile without carina; ornament of very fine, pustulose, longitudinal striations (m.BW 0-21 mm), {b) Dissepiments. Medium width centrally with gradual expansion to branch junction in an expanding curve; some dissepiments inclined from vertical plane; level with or slightly below branches; ornament of fine striations (m.DW Oil mm), (c) Fenestrules. Fine, irregular mesh of sub-oval to sub-rectangular short, narrow fenestrules (m.FL 0-75 mm; m.FW 0-48 mm), {d) Carina. Absent, (c) Nodes. Absent. (/) Zooecial apertures. Small, circular (m.ZD 0 08 mm); strongly exserted; narrow, raised, entire peristome; apertures bear eight septa radiating from a minute axial tube ; mostly erect with some lateral apertures moderately indenting the fenestrule margin ; apertures generally stabilized with respect to dissepiments on to which they commonly encroach; zooecia closely spaced (m.Z-Z 0-25 mm) in each row, with from three to four zooecia per fenestrule (m.Z/F 3 0); two rows per branch with a third row appearing at or immediately prior to branch bifurcation, (g) Additional features. Large, hemispherical branch depressions located adjacent to the proximal rim of some apertures; horizontal lateral connection between exserted portion of vestibule and proximal branch surface occurs with all apertures; distinct hemiseptum visible on casts of most zooecial chambers. Reverse surface, (a) Form. Branches and dissepiments rounded with the latter depressed 592 PALAEONTOLOGY, VOLUME 18 slightly below branch level ; reverse wall very thin ; ornament of longitudinal striations. (b) Zooecial bases. Irregularly pentagonal. Material. Holotype SUF7402 (NUL372); paratypes SUF7406 (NUL372); SUF6438 (NUL36 1 ) ; others NUF2478, NUF2483-2485 (NUL448) ; NUF25 1 8-252 1 (NUL39) ; NUF2402-2403 (NUL414). Remarks. S. acarinata (Crockford) has long been known as an aberrant species of Fenestella in that it lacks the generically diagnostic, nodose carina and has septate apertures. Wass (1968) placed the species in Levifenestella Miller, but this seems inappropriate, in view of the importance of the nodeless carina of that genus. As at present defined, S. acarinata extends over a wide range covering much of the Visean interval. It should be noted that the specimens from the lowest zone have a much narrower branch profile which appears to zigzag between apertures which thus dominate the obverse surface. By contrast, specimens from later zones have a more robust, rounded branch profile on which the apertures appear to have been superimposed. This variation in branch width has not been given taxonomic status at this time, although it results in specimens with quite dissimilar appearance. Because S. acarinata is a very fine-meshed species, it is quite difficult to observe the auxiliary opening in the side of the exserted vestibule on most specimens. Certainly the type material is too poorly preserved to enable the description of such features. Stratigraphy. The species first appears in the Schellwienella cf. burlingtonensis Zone at Raglan (NUL448) and other stratigraphically similar localities. It is of common occurrence in the Pustula gracilis Zone at Rouchel Brook (NUL39) where the thin, zigzag branch form is most common. The species is plentiful in the Orthotetes australis Zone at Glen William (NUL361) and the type material comes from Hilldale (NUL372) which is situated low in the Delepinea aspinosa Zone. The final occurrence of the species is in the Barrington Guest House fauna (NUL414), a little higher in the above zone, where its range overlaps with the first occurrence of the two- to three- rowed species, S. gloucesterensis sp. nov. EXPLANATION OF PLATE 70 All figures of latex casts except fig. 2. Figs. 1-5. Septatopora nodosa sp. nov. 1, obverse surface of holotype exhibiting an ill-defined central carina, NUF2386, locality NUL258, x 10. 2, obverse mould of the base of a fan-shaped zoarium showing early branches bending away from the mesh to anchor the colony to the surface of a brachiopod, NUF2431a, locality NUL258. x 5. 3, reverse surface with spherical ovicells attached to the sides of the branches and projecting above the reverse surface level, NUF2525, locality NUL39, x 5. 4, obverse surface of NUF2524 illustrating strong development of a central carina in a low zonal form, locality NUL39, x 10. 5, obverse surface of NUF2523 showing multiple lateral branches developed from the side of a marginal branch in the positions normally occupied by dissepiments, locality NUL39, X 5. Figs. 6-8. Septatopora acarinata (Crockford). 6, obverse surface of NUF2519 exhibiting large spherical ovicells positioned adjacent to the proximal rim of some apertures. Note also the zigzag obverse appear- ance of this low zonal form, locality NUL39, x 10. 7, obverse surface of a funnel-shaped zoarium, NUF2519, locality NUL39, x 5. 8, enlarged obverse surface of NUF2519 showing strong exsertion of septate apertures and the absence of a central carina and nodes, locality NUL39, x20. PLATE 70 ENGEL, Septatopora 594 PALAEONTOLOGY, VOLUME 18 Septatopora nodosa sp. nov. Plate 70, figs. 1-5 Diagnosis. Septatopora with narrow, straight to zigzag, pustulose branches; mesh open, fine with sub-rectangular to rectangular fenestrules; apertures small, septate, closely spaced, strongly to moderately exserted with proximally associated hemi- spherical depressions and/or spherical bodies which project into fenestrules and on to reverse surface; zooecia in two rows per branch; carina weakly developed or absent; nodes small, closely spaced in a central row; reverse branch profile rounded, with spiny ornament ; zooecial bases broadly triangular to pentagonal. Description. Zoarium : radiating fan-shaped, gently undulose to laminate fragments of unknown orientation; some zoaria grow rapidly outwards in a fan shape from the base of the colony, in which specimens several of the outside branches droop away from the mesh to become recumbent sterile spine-like supporting anchors ; maximum radius 50 mm. Obverse surface, (a) Branches. Straight or broadly curved, narrow (m.BW 0-25 mm); rounded with no carina or with low, indistinct median ridge between closely set nodes; profile strongly modified by apertural exsertion; orna- ment of fine, pustulose striations. (b) Dissepiments. Narrow (m.DW 009 mm); centrally straight with gradual expansion close to branch junction; slightly depressed below branch level; ornament of fine, pustulose striations. (c) Fenestrules. Sub- rectangular to rectangular; mesh fine, moderately regular, of even appearance; fenestrules short and narrow (m.FL 0-92 mm; m.FW 0-5 mm), {d) Carina. Lacking or represented by ill-defined ridge produced by narrowing of the branch profile; development variable within each zoarium. (e) Nodes. Small, erect, pointed nodes with rounded or slightly elongated bases; closely spaced (m.N-N 0-28 mm) with linear distribution in a central row; each node associated with an aperture on its disto-central rim. (/) Zooecial apertures. Small, circular (m.ZD 0-1 mm), strongly to moderately exserted; peristome narrow, raised, entire; apertures with eight septa surrounding a fine axial perforation; septa extend for only a very short distance down into the vestibule; erect apertures situated on branch shoulder and showing some slight lateral inclination; apertures indent fenestrule margin and may be stabilized with respect to the dissepiments on to which they frequently encroach; closely spaced (m.Z-Z 0-26 mm) with from three to five zooecia per fenestrule (m.Z/F 3-6); zooecia in two rows with a third appearing only in the fork at each bifurcation, (g) Additional features. A short horizontal tube proximally connects the upper exserted vestibule to the branch surface; ovicellular structures uncommon but when present they are usually located on the branch side in the fenestrule where they may also project around above the level of the reverse surface. Some specimens bear strong, ribbed, spine-like projections (diam. c. 0-2 mm) standing erect on the obverse surface at distant intervals. Reverse surface, {a) Form. Branches and dissepiments rounded to slightly tapered with dissepiments at or below branch level; surface of branches and dissepiments longitudinally striate; high zonal specimens also bear numerous large pustules or small spines irregularly developed along the striations. {b) Zooecial bases. Broadly triangular; irregularly pentagonal on wider branches. ENGEL: CARBONIFEROUS SEPTATOPORA 595 Material. Holotype NUF2386 (NUL258); paratypes NUF2388a/b, NUF2431a/b, NUF2445 (NUL258); NUF2523-2525 (NUL39); others NUF2432a/b, NUF2436- 2438, NUF2385, NUF2387, NUF2389a/b, NUF2390-2391 (NUL258); NUF2404, NUF2424 (NUL414); NUF2488 (NUL448); NUF2522, NUF2526 (NUL39); NUF2412 (NUL361). Remarks. The most distinctively different aspect of this species is its regular develop- ment of nodes. All other species of Septatopora either lack nodes or have them placed adjacent to some apertures in a generally irregular pattern. In S. nodosa they are associated with apertures but, because of the narrow branch width, they have assumed a linear, or slightly zigzag arrangement. In total appearance the species is not a good representative of the genus to which it has been attached with some misgivings. Were it not for the apertural septation, this species could be grouped readily with Fenestella Lonsdale. The distinctively septate apertures and the proximo-lateral branch connection with an auxiliary tube form the basis of its assignment here to Septatopora. However, because of the short vestibular septa, mould infillings of the apertures do not always appear obviously septate and very close study is needed for correct generic assign- ment. As in S. acarinata (Crockford), which shares a similar low zonal range with the present species, the oldest specimens have a very narrow branch profile which appears to zigzag between the exserted apertures. Subsequent material assumes a wider branch profile which eliminates this effect. Coupled with this, there is a reduction in the height of the low Carina which becomes scarcely apparent, if at all. A few specimens of S. nodosa have been found attached to the surface of brachiopods in the Rhipidomella fortimuseula Zone, where they use recumbent basal branches as an additional attachment device. Comparisons. S. nodosa is the only species assigned to the new genus which can be reasonably compared with existing species of Fenestella Lonsdale. Generally, the distinction is readily based upon the development of apertural septation in 5. nodosa. Fenestella wilsoni Roberts occurs within a part of the range of S. nodosa and they share an identical mesh configuration. Because of a crystalline silica coating on all the type specimens of F. wilsoni it is difficult to observe apertural details, but it does not appear to be septate, and hence can probably be distinguished on this basis. Should better-preserved material of F. wilsoni be found, it may be possible to show that these two species are identical, but for the present they have been retained as separate taxa. Other Lower Carboniferous species of Fenestella in Australia are readily dis- tinguished on mesh grounds alone, quite apart from the apertural details. Stratigraphy. S. nodosa first appears rarely in the Schellwienella cf. burlingtonensis Zone at Raglan (NUL448). It is of common occurrence in all subsequent zones up to and including the Rhipidomella fortimuseula Zone, thus spanning a range com- parable with much of the Visean interval. 596 PALAEONTOLOGY, VOLUME 18 Septatopora{l) williamsensis sp. nov. Plate 68, figs. 1-3 Diagnosis. Septatopora-\i\.Q species with straight, narrow, pustulose branches ; mesh open, medium to fine, with sub-rectangular to rectangular fenestrules; apertures small, weakly septate, medium spaced being arranged on the extreme margin of the branch where only the fenestrular rim is weakly exserted; zooecia in two rows per branch; carina and nodes absent; reverse branch profile rounded; zooecial bases quadrate to pentagonal. Description. Zoarium: small, radiating fragments of unknown orientation ; maximum radius 20 mm. Obverse surface, {a) Branches. Straight to broadly curved, narrow (m.BW 0-22 mm); narrowly rounded without carina; ornament of fine, pustulose, longitudinal striations. {b) Dissepiments. Very narrow (m.DW 0-08 mm), centrally straight with moderate expansion at branch junction; situated well below branch level; ornament of longitudinal striations. (c) Fenestrules. Sub-rectangular to rectangular; regular mesh of medium size and open appearance; fenestrules of medium length, narrow width (m.FL 1-29 mm; m.FW 0-57 mm), {d) Carina. Absent. (e) Nodes. Absent. (/) Zooecial apertures. Small, circular (m.ZD 0-09 mm); weakly exserted with indistinct, low peristome developed only on the fenestrule margin of the aperture; apertures bear radiating septal plates which extend only half-way towards the axis and which do not extend far down into the vestibule; apertures situated low on the sides of the branch where they project weakly into the fenestrules with their low peristomal margin; inner apertural margins depressed into side of branch resulting in apertures which have a slight proximal and lateral inclination towards the fenestrule; moderately stabilized with respect to the dissepiments; zooecia medium spaced (m.Z-Z 0-32 mm) with from three to five zooecia per fenestrule (m.Z/F 4-0); apertures in two rows with a third row developing in the fork at each bifurcation. Reverse surface, {a) Form. Rounded branches joined by narrower level dissepiments; ornament of fine, pustulose striations, identical to those of the obverse surface. {b) Zooecial bases. Quadrate to pentagonal in form being arranged in weakly over- lapping rows. Material. Holotype NUF2423 (NUL414); paratypes NUF2421-2422 (NUL414). Remarks. The generic status of this species is somewhat doubtful. On the basis of its partly septate apertures and distinctive branch ornament it has been placed here with Septatopora. However, the lack of strongly exserted apertures and the absence of any auxiliary tube means that it lacks some of the essential diagnostic features of that genus. As a relative of Septatopora, it would appear that the recessed apertures and short radial septa of this species produced only a partial constriction of the vestibule. This would mean it was still possible to extend both tentacles and lophophore perhaps making the development of an auxiliary tube unnecessary. The stratigraphic occur- rence of 5.(?) williamsensis, which correlates approximately with Mid-Visean pre- cludes any suggestion of an evolving sequence, since other species of Septatopora with ENGEL: CARBONIFEROUS SEPTATOPORA 597 Strongly developed apertural exsertion and septation are known from late Tournaisian onwards. As it is outside the morphological limits of Septatopora, this new species really deserves its own generic category. However, until much more material of com- parable form is found, it is not considered appropriate to propose such a taxon. Another notable morphological aspect of S'.C?) williamsensis is the wide expanse of central, obverse branch surface which lacks carina, nodes, and apertures. Indeed, both reverse and obverse surfaces are so similar that careful inspection of the apertural form is necessary to determine which surface is being examined. No existing species of Septatopora or Fenestella in the Australian Carboniferous resemble this distinctive species. Stratigraphy. S.p.) williamsensis has been found only at the Barrington Guest House locality (NUL414) where it is associated with S. nodosa, S. acarinata, and S. glou- cesterensis. On the basis of the whole brachiopod-bryozoan fauna, this horizon has been placed in the lower parts of the Delepinea aspinosa Zone which correlates approximately with a Mid-Visean age. COMPARISON OF SPECIES OE SEPTATOPORA Descriptive and statistical aspects of all nine species of Septatopora have been given in Tables 1 and 2. From a study of information so displayed it is possible to indicate the general nature of variation present within the genus. Features which show very little varia- tion include : ( 1 ) A standard zoarial form with only slight changes in fenestrule outline (oval to sub-rectangular). (2) A lack of any central carina on the branches (excluding S. nodosa sp. nov.). (3) Development of surface ornament in the form of distinctive pustulose striations. (4) Apertural septation. (5) Strong apertural exsertion with a high peristome forming a calice-like depression on each aperture. (6) Common surface development of hemispherical depressions proximal to some apertures in each zoarium. By contrast the following features display considerable variation: (1) Increase in mesh size. (2) Increase in the number of zooecial rows per branch. (3) Increase in branch width and changes in branch profile. (4) Irregular nodal development. (5) Increase in apertural size and spacing. (6) Change in zooecial chamber form and auxiliary tube. (7) Variations in reverse surface ornament. Each of these aspects is detailed below with reference to the appropriate species and to the interval over which they have maximum zonal potential. 1 . Increase in mesh size. Mesh dimensions reveal a progressive increase from small- to medium-sized species. Low zonal forms {S. acarinata, S. nodosa) are rather delicate compared with the larger species found in the high zones. Mesh variation is indicated by the large changes in fenestrule dimensions, shown in Table 2. 2. Zooecial rows per branch. A general trend throughout the Carboniferous in Australia is for all species of Septatopora to increase the number of zooecial rows per branch from two to four. Low zonal species {S. acarinata, S. nodosa) are basically composed of two rows 598 PALAEONTOLOGY, VOLUME 18 TABLE 1 . A descriptive comparison of the important morphological features of the fenestrate mesh of all species of Septatopora. Mesh Branch Width Form Prof i le Fenestrules Nodes Apertural Size & Spacing Zooecial Rows Zooecia per Fenestrule Zooecial Bases Branch Reverse Post Norm Pre bif. -al bif. S. acarinata fine, open narrow; straight or zig-zag; narrowly rounded sub-oval to sub-rectangular; short ; narrow small; close 2/2/3 3-4 irregularly pentagonal rounded S nodosa fine; open narrow; straight to zig-zag; rounded sub-rectangular to rectangular; short ; na r row close; central row small ; close 2/2/3 3 - 4 broadly triangular to pentagonal rounded; spiny S.l?) williamsensis medium; open narrow; straight; narrowly rounded sub-rectangular to rectangular; medium length; narrow - small; medium 2/2/3 3 - 5 quadrate to pentagonal rounded S. gloucesterensis fine; open narrow to medium ; straight; rounded sub-oval to sub-rectangular; medium to short narrow medium spacing small; close 2 /2-3/4 4 - 5 irregularly pentagonal and rhomboidal rounded S.C’l sulcifera medium; open medium to wi de: straight; oval oval to sub-rectangular; medium length; medium width small, close 2-3 / 3 / 3-5 13)5-6 7 rounded S. stellaris medium to fine; even medium ; straight ; rounded oval to sub-oval ; medium to short; medium width distant spacing medium; medium 2 / 2-3 / 3 2 -3 (?) oval tapered; spiny S. Isaacsensis medium to fine; closed wide ; straight; oval oval to sub-oval; medium to short; medium width distant spacing medium ; medium 3 / 3 / 4-5 2 -3 oval ; no overlap between rows tapered ; spiny S pustulosa medium; open wide, straight ; round -oval sub-oval to sub- rectangular; medium length, medium width medium; distant 2 / 3/4-5 3-5 elongate oval no overlap between rows rounded S Uemingi medium; closed wide to very wide; straight, oval sub-oval to sub-rectangular; medium length; medium width “ medium ; distant 2-3/3-4Z5-6 3-5 elongate oval; no overlap between rows rounded per branch with additional apertures appearing only at bifurcation. S. gloucesterensis in the Delepinea aspinosa and Rhipidomella fortimuscula Zones has about equal development of two and three rows of zooecia between successive bifurcations. In the Levipustula levis Zone, S. stellaris continues in the trend of S. gloucesterensis but it is associated with S. pustulosa and S. isaacsensis which are dominantly three-rowed ENGEL; CARBONIFEROUS SEPTATOPORA 599 TABLE 2. A statistical summary of the principal mesh dimensions of all species of Septatopora. Species known by only one specimen have only the mean and observed range recorded. Explanation of the abbrevia- tions are given in the text. FL FW BW DW ZD z-z N-N N9 F/10 B/10 Z/5 Z/F S. acarinata m s OR mm 0-748 0-123 0-44-1-08 mm 0-484 0-068 0-34-0-64 mm 0-213 0-026 0-16-0-28 mm 0-106 0-037 0-06-0-18 mm 0-078 0-011 0-06-0-10 0-246 0-021. 0-20-0-32 mm 140 13-8 20-7 20-4 3-0 S. nodosa m s OR 0-912 0-150 0-56-1-46 0-504 0-073 0-34-0-70 0-244 O-OU 0-14-0-36 0-092 0-019 0-04-0-14 0-095 0-011 0-06-0-12 0-258 0-02i. 0-20-0-34 0-281 0-040 0-18-0-38 360 11-1 20-0 19-4 3-5 S.(?l williamsensis m s OR 1-289 0-23i 0-86-1-84 0-574 0-079 0-40-0-72 0-223 0-017 0-18-0-26 0-075 O-OU. 0-04-0-10 0-087 0-010 0-08-0-10 0-319 0-020 0-28-0-38 - 60 7-8 17-4 15-7 4-0 S gloucesterensis m s OR 1-116 0-080 0-96-1-28 0-581 0-106 0-44-0-86 0-297 0-030 0-24-0-36 0-183 0-027 0-14-0-26 0-098 0-009 0-08-0-12 0-272 0-019 0-22-0-30 0-512 0-089 0-34-0-64 40 9-0 17-3 18-4 4-1 S.(?) sulcifera m OR 1-358 0-76-2-24 0-742 0-70-0-76 0-411 0-35-0-50 0-200 0-14-0-22 0-069 0-04-0-08 0-288 0-24-0-32 - 20 7-4 13-5 17-4 4-7 S. stellaris m s OR 0-953 0-079 0-70-1-10 0-633 0-092 0-50-0-86 0-361 0-053 0-28-0-46 0-140 0-029 0-10-0-24 0-128 0-013 0-10-0-16 0-333 0-031 0-28-0-42 0-951 0-150 0-60-1-22 40 10-5 15-8 15-0 2-9 S. isaacsensis m OR 0-914 0-82-1-00 0-747 0-60-0-96 0-470 0-34-0-60 0-263 0-18-0-40 0-120 0-10-0-16 0-324 0-26-0-38 0-937 0-70-1-20 20 10-9 13-4 15-4 2-8 S. pustulosa m s OR 1-684 0-305 1-00-2-60 1-030 0-192 0-60-1-50 0-491 0-092 0-32-0-74 0-212 0-039 0-14-0-36 0-106 0-012 0-08-0-14 0-433 0-055 0-30-0-60 - 200 6-1 9-8 11-6 3-9 S. flemingi m s OR 1-652 0-U.8 1-20-2-12 0-905 0-158 0-60-1-40 0-541 0-097 0-36-0-86 0-300 0-065 0-16-0-46 0-128 0-015 0-10-0-16 0-381 O-Oi.3 0-28-0-50 - 140 6-1 11-0 13-1 4-3 species. Finally, in the Cancrinella levis Zone S. pustulosa is joined by S. flemingi which is dominantly four-rowed with pre-bifurcation increase up to five (rarely six) rows. Both increase in mesh size and number of rows of apertures are universal trends which affect all Australian Carboniferous fenestrates. Increase is progressive in both cases and is not readily divided into arbitrary sub-groups. 3. Branch width and profile. Extra rows of zooecia, up to three rows, are accommodated in increasingly wider branches. Increase to four rows as in S. flemingi is, however, achieved by change in chamber arrangement which enables the extra row to be con- tained in branches which have not greatly increased in width. Increase in branch width is also accompanied by a reduction in relative size of the fenestrule openings resulting in open-meshed forms changing to a closed-mesh appearance. 600 PALAEONTOLOGY, VOLUME 18 Variation in branch profile is considerable. As noted previously zigzag profiles of the low zonal species {S. acarinata, S. nodosa) change to a rounded profile in the Orthotetes australis Zone beyond which the profile gradually becomes more oval in form. 4. Nodal development. Some species of Septatopora lack any obverse nodes whereas others have irregular nodes adjacent to the distal or disto-central rim of some apertures. There appears to be no stratigraphic control over this feature which has resulted in three species groups. (fl) Nodeless: S. acarinata, S'.(?) williamsensis, S.{1) sulcifera, S. pustulosa, S. flemingi. {b) Irregular nodes: S. gloucesterensis, S. stellaris, S. isaacsensis. (c) Regular nodes : S. nodosa. No major importance above the species level can be given to the position and occurrence of these nodes. The absence of thin-section detail makes it unlikely that further functional significance will become known, and without this it is not possible to assess the weighting which should be given to this morphological feature. Even within node-bearing species some branches can be found which lack nodal development. It is of some interest to note that most Australian species referrable to Polypora M’Coy also bear similar, randomly distributed nodes which differ in position from those of Septatopora, being placed adjacent to the proximal or proximo-central rim of an aperture rather than in the equivalent distal position. 5. Increase in apertural size and spacing. Low zonal species have slightly smaller apertures (mean range 0-07-0T mm) compared with the medium-sized apertures (mean range 011-0T3 mm) in the higher zones. In parallel with this variation the apertures change from closely spaced (mean range 0-25-0-29 mm) to distantly spaced (mean range 0-33-0-44 mm) over the same stratigraphic interval. 6. Zooecial chambers and associated structures. Chambers in two- or two to three- rowed species are globular in form and almost entirely fill the thickness of the branch. This form results in a very short vestibule beginning quite close to the obverse surface and extending up into the exserted aperture. In this case the auxiliary tube is only a breach in the side of the vestibule or a very short horizontal connection to the branch surface on the proximal side of the aperture. As such it is quite difficult to observe. With zigzag packing of globular chambers, the zooecial base form is irregu- larly pentagonal with considerable overlap between rows. Central rows of apertures appear rhomboidal in shape between the lateral rows. With increase in the number of rows of apertures in the high zonal species (iS. pustulosa, S. isaacsensis, S. flemingi), the chambers are necessarily packed much closer. They therefore assume an elongate, compressed-oval form with little or no overlap between rows. In addition, the ffatter chambers are now located close to the reverse surface of the branch and this requires considerable changes in the shape of the vestibule. It is lengthened into an L-shaped or geniculate form with the auxiliary tube being connected to the short, posterior, horizontal section and extending up to the obverse surface in parallel with the longer anterior section of the vestibule. As ENGEL: CARBONIFEROUS SEPTATOPORA 601 two quite separated structures they are now clearly visible on the obverse surface in their respective positions. Primarily as a result of changes in branch width, the larger hemispherical depres- sions can also vary their position. On wide branches in the higher zones the branch width and zooecial spacing are sufficient to allow full development on the obverse branch surface. However, in the low zonal species the branch width tends to be very narrow and the apertures quite close together so that the spherical (?)ovicells are attached more to the side of the branch where they protrude into the fenestrules, or they can even continue around on to the reverse side of the zoarium where they may extend above the reverse surface level. 7. Reverse ornament. All except two species of Septatopora have a broadly rounded branch profile, joined by narrower dissepiments on the reverse surface. Normal ornament consists of distinctive pustulose striations similar to that developed on the obverse surface. By contrast, two closely related high zonal species, S. stellaris (Campbell) and S. isaacsensis (Campbell) have a narrow, tapered reverse branch profile. Branches are joined by equal width, level dissepiments in a distinctive regular or proximally- polygonal mesh. The branches also bear a near central, very irregular array of numerous spines which are inclined distally. Some features of reverse ornament are probably the product of exceptionally good preservation or are of some ecological significance. For example, all fenestrate genera from one locality (NUL258, Barrington, N.S.W.) have the same network of very fine spines or large thorny pustules over their reverse surface. This particular form of ornament has not been observed at any other locality. AUSTRALIAN STRATIGRAPHIC DISTRIBUTION OF SEPTATOPORA From the foregoing discussion, it is apparent that variation in the species of Septa- topora makes it a most useful local zonal indicator. Text-fig. 2 sets out the range of all nine species in terms of the brachiopod zones of Campbell and McKellar (1969), Roberts and Oversby (1972), and Jones, Campbell and Roberts (1973) with which there is a strong parallel. Tournaisian-earliest Visean Tulcumbella tenuistriata and Spirifer sol Zones have not yielded species referrable to the new genus. However, outcrops are few, and as other fenestrates are known from this level, it is quite possible that representatives will be found. Schellwienella cf. burlingtonensis and Pustula gracilis Zones contain the first repre- sentatives of the new genus, namely Septatopora acarinata and S. nodosa. At this stratigraphic level, examples of both species have very narrow branches which zigzag between alternating apertures in a most distinctive pattern. Visean Orthotetes australis Zone contains the same two species, but at this higher level both have developed wider, straight branches in which the apertures no longer are the dominating element. 602 PALAEONTOLOGY, VOLUME 18 EASTERN AUSTRALIAN FAUNAL ZONES STRATIGRAPHIC DISTRIBUTION OF SEPTATOPORA EUROPEAN STAGES /ZONES Cancrinella levis of c r S to ^ c STEPHANIAN Levipustula levis O to o « 5 51 a QiU \ " Vll Sif i/j ll t/) WESTPHALIAN NAMURIAN Oriocrassatella compressa to Marginirugus barringtonensis -a s 10 -Si Cu IIip-8 CunioA VISEAN Rhipidomella fortimuscula ifera amser ouces Delepinea aspinosa ILfl 3 Orthotetes australis D o c Q nodosa t4 uo Cull S ] [DI r Pus tula gracilis O O t^ cuim Schellwienella cf. burlingtonensis t/i CuIIoc TOURNAISIAN Spirifer sol Tulcumbella tenuistriato Cl I TEXT-FIG. 2. Stratigraphic distribution of the various species of Septaiopora in terms of the Eastern Australian Carboniferous zones. Tentative correlation with equivalent European zonation is also included. Delepinea aspinosa Zone contains representatives of the two previous species plus 5.(?) williamsensis, and the first of the two- to three-rowed forms S. gloucesterensis and 5.(?) sulcifera. Rhipidomella fortimuscula Zone contains S. gloucesterensis and S. nodosa with all other prior species having disappeared. Late Visean-Narnurian-earliest Westphalian Marginirugus barringtonensis Zone is dominated lithologically by coarse detrital sedimentary units within which no bryozoan remains have been preserved. Most brachiopods occur as reworked detrital shell deposits indicating a medium quite unsuited to delicate bryozoan preservation. The same observations are true for the Oriocrassatella compressa Zone (new) where large banks of heavy bivalve shells dominate the fossil record. Westphalian -Stephanian Levipustula levis Zone includes no species of Septatopora from lower stratigraphic ENGEL: CARBONIFEROUS SEPTATOPORA 603 levels, although some generalized species of Fenestella (e.g. F. osbornei Crockford) do appear to have continued across the coarse sedimentary interval noted above. The fauna in this zone consists of S. stellaris (two to three rows), S. pustulosa (three rows), and S. isaacsensis (three rows) of which the three-rowed species are by far the most abundant forms. Cancrinella levis Zone (new) includes the final species S.flemingi (three to four rows) together with S. pustulosa. The new species S.flemingi is the most common bryozoan at this level in a zone which is known only from regions of Carboniferous outcrop in east-central Queensland. The type locality for this newly defined zone is placed in the Stanwell-Ridgelands district where Fleming (1969) has published a geological map together with a description of some of the other elements of this late Carboniferous fauna. It appears that Septatopora did not continue into overlying strata, for a literature survey of Australian Permian species referred to Fenestella Lonsdale and Polypora M’Coy has failed to reveal any probable members of the new genus. It is possible, however, that apertural septation has not been observed because of the generally poor state of preservation, in very coarse sandstones, of many Permian species. It should be noted also that the degree of apertural exsertion is slightly reduced in the final Carboniferous species, indicating that this may not be an obvious aspect in any Permian successors. Finally, it is of some value to indicate that most Australian Permian species of Polypora M’Coy have five or more rows of apertures, thus con- tinuing the general trend noted in all Carboniferous fenestrates. Correlation of the above assemblage zones with the European succession is diffi- cult. Controls used by the previously mentioned authors in the definition of their Eastern Australian assemblage zones depend not upon the nominate, long-ranging brachiopod species, but upon the associated goniatites, a rare and often confusing component of the local faunas. Initial correlation (Campbell and McKellar 1969) assumed that the standard German goniatite sequence was continuous. With the discovery by various European conodont workers including Rhodes et al. (1969, 1971) and Matthews (1969a, b, 1970a, b) that the Lower Carboniferous European goniatite sequence contains several major time gaps, the need arose to recorrelate the Eastern Australian zones. A definitive statement of the revised position is given by Jones et al. (1973) who give detailed arguments for their currently adopted position. Assessment of the magnitude of the time breaks in the European sequence continues to present difficulties, making even the most recent efforts only very tentative. Conodont studies presently being undertaken by Dr. H. Jenkins and colleagues (University of Sydney) would suggest that the correlations adopted in text-fig. 2 must be revised so that the Rhipidomella fortimuscula Zone is of an early rather than late Visean age, with the position of the Tournaisian-Visean boundary remaining unaltered within the Schellwienellaci. bur lingtonensis Zone. Changes of this magnitude in the Lower Carboniferous will obviously also vary the Upper Carboniferous correlations and hence it is not possible to offer confident comparisons at this stage. A study of the brachiopod content of the Cancrinella levis Zone reveals, however, a fauna of distinctively Permian affinities and it is with some confidence L 604 PALAEONTOLOGY, VOLUME 18 that the range of Septatopora is extended up to the level of the late Westphalian or Stephanian age. It is therefore concluded on present evidence that Septatopora ranges from late Tournaisian to Stephanian, at which point it appears to have become extinct. GEOGRAPHICAL DISTRIBUTION In Australia the pre-Carboniferous record is generally poor in fenestrates, so that no suitable ancestral material has yet been described. With the possible exception of Polypora(l) verrucosa (M’Coy) no other described fenestrate has been observed in the literature, at present available to the author, which could be placed in Septatopora. The only other record of the genus outside Australia would appear to be in the Upper Carboniferous of Argentina, where Amos and Sabattini (1969) and Mrs. N. Sabattini (pers. comm.) have listed the occurrence of several fenestrate species, originally described by Campbell (1961), some of which have been transferred here to the genus Septatopora. Dependent upon further published descriptive details by Mrs. N. Sabattini, it would appear that Septatopora is another of the many genera shared in common by these two continents during Upper Carboniferous times. Acknowledgements. I am indebted to Professor B. Nashar of the University of Newcastle and Dr. K. S. W. Campbell of the Australian National University for their continued guidance and support during the course of this project. Thanks are also due to Emeritus Professor D. Hill, University of Queensland, Mr. G. Fleming, Queensland Geological Survey, Mr. G. Foldvary, University of Sydney, Dr. B. Runnegar and Mr. G. Brown, University of New England, and Dr. A. Ritchie, Australian Museum, for their generous provision of access to, or loan of, type material from their respective collections. The writer is especially grateful for the constructive comments given freely by Dr. R. S. Boardman, Smithsonian Institution, Emeritus Professor D. Hill, University of Queensland, and Dr. P. L. Cook and Dr. B. R. Rosen of the British Museum (Natural History) upon the problems of classification and func- tional morphology of the new genus. Provisional assignment to the Phylum Bryozoa, however, remains the responsibility of the author and does not necessarily reflect the opinion of these distinguished contributors. Finally, thanks are recorded for the support given by Mrs. N. Morris and a number of honours students at the University of Newcastle, whose field studies have allowed me to gather together a very large quantity of bryozoan material in the University of Newcastle collections. REFERENCES AMOS, A. j. and sabattini, n. 1969. Upper Palaeozoic faunal similitude between Argentina and Australia. Gondwana Stratigraphy, I.U.G.S. Symposium in Buenos Aires, 1-15 Oct. 1967, UNESCO Earth Sciences Publication, 2, 235-248, 1 table. BASSLER, R. s. 1953. In MOORE, R. c. (ed.). Treatise on invertebrate paleontology. Part G, Bryozoa. Geol. Soc. Amer. and University of Kansas Press. G1-G253. CAMPBELL, K. s. w. 1961. Carboniferous fossils from the Kuttung rocks of New South Wales. Palaeontology, 4, 428-474, pis. 53-63. — 1962. Marine fossils from the Carboniferous glacial rocks of New South Wales. J. Paleont. 36, 38-52, pis. 11-13, 4 figs. - - and MCKELLAR, R. G. 1969. Eastern Australian Carboniferous invertebrates: sequence and affinities. In CAMPBELL, K. s. w. (ed.). Stratigraphy and Palaeontology. Aust. Nat. University Press, Canberra, 77-119. ENGEL: CARBONIFEROUS SEPTATOPORA 605 CROCKFORD, J. M. 1947. Bryozoa from the Lower Carboniferous of New South Wales and Queensland. Proc. Linn. Soc. N.S.W. 72, 1-48, pis. 1-6. 1949. Bryozoa from the Upper Carboniferous of Queensland and New South Wales. Ibid. 73, 419- 429, 4 figs. CVANCARA, A. M. 1958. Invertebrate fossils from the Lower Carboniferous of New South Wales. J. Paleont. 32, 846-887, pis. 109-113. DRISCOLL, E. G. 1960. Geology of the Mundubbera District. Pap. Dept. Geol. Univ. Qd, 5, 5-27, figs. 1-3. FLEMING, p. J. G. 1969. Fossils from the Neerkol Formation of Central Queensland. In Campbell, k. s. w. (ed.). Stratigraphy and Palaeontology. Aust. Nat. University Press, Canberra, 264-275, pis. 16-17. 1972. Redescription of fenestellid species from the Upper Carboniferous of Eastern Australia. Pubis. geol. Surv. Qd, 354, Palaeont. Pap. 29, 1-8, pis. 1-4. HILL, D. 1934. The Lower Carboniferous corals of Australia. Proc. R. Soc. Qd, 45, 63-1 15. JONES, p. J., CAMPBELL, K. s. w. and ROBERTS, J. 1973. Correlation chart for the Carboniferous System of Australia. Aust. Bur. Miner. Resour. Rec. 69, 1-80. JULL, R. K. 1968. The Lower Carboniferous limestones in the Monto-Old Cannindah district; a brief description and a proposed name. Qd Gov. Min. J. 69, 199-201. 1969. The Lower Carboniferous corals of Eastern Australia, a review. In Campbell, k. s. w. (ed.). Stratigraphy and Palaeontology. Aust. Nat. University Press, Canberra, 120-139, pis. 9-10. MCKELLAR, R. G. 1967. The Geology of the Cannindah Creek area, Monto District, Queensland. Pubis, geol. Surv. Qd, 331, 1-38, figs. 1-8. MATTHEWS, s. c. 1969a. A Lower Carboniferous conodont fauna from East Cornwall. Palaeontology, 12, 262-275, pis. 46-50. 19696. Two conodont faunas from the Lower Carboniferous of Chudleigh, South Devon. Ibid. 276-280, pi. 51. 1970a. A new cephalopod fauna from the Lower Carboniferous of East Cornwall. Ibid. 13, 112-131. 19706. Comments on palaeontological standards for the Dinantian. Congr. Avanc. Etud. Stratigr. Garb., 6th, Sheffield, 1967, 3, 1159-1163. MAXWELL, w. G. H. 1964. The geology of the Yarrol Region, Part 1, Biostratigraphy. Pap. Dept. Geol. Univ. Qd. 5, 1-65, pis. 1-14. MILLER, T. G. 1963. The bryozoan genus Polypora M’Coy. Palaeontology, 6, 166-171, pis. 23-24. RHODES, F. H. T. and AUSTIN, R. L. 1971. Carboniferous conodont faunas of Europe. Mem. geol. Soc. Amer. Ml, 317-352. and DRUCE, e. c. 1969. British Avonian (Carboniferous) conodont faunas and their value in local and intercontinental correlation. Bull. Br. Mus. nat. Hist. Geol. Supp. 5, 1-313, pis. 1-31. ROBERTS, J. and oversby, b. s. 1972. The Lower Carboniferous geology of the Rouchel District, New South Wales. Aust. Bur. Miner. Resour. Rec. 119, 1-59, pis. 1-19, figs. 1-16. TAVENER-SMiTH, R. 1969. Skeletal structure and growth in the Fenestellidae (Bryozoa). Palaeontology, 12, 281-309, pis. 52-56. and williams, a. 1972. The secretion and structure of the skeleton of living and fossil bryozoa. Philos. Trans. R. Soc. Lond. 264 (859), 97-159, pis. 1-32. WASS, R. E. 1968. Permian polyzoa from the Bowen Basin. Bull. Aust. Bur. Miner. Resour. 90, 1-135, pis. 1-18. BRIAN A. ENGEL Department of Geology University of Newcastle Typescript received 20 May 1974 Newcastle, N.S.W. 2308 Revised typescript received 10 October 1974 Australia Addendum : The author has very recently been shown fenestrate specimens from the Middle Permian of the Bowen Basin, Queensland, which have strongly exserted apertures bearing eight apertural septa. This discovery thus extends the probable range of Septatopora gen. nov. into Permian strata in Eastern Australia. As an oversight during manuscript preparation, reference has not been made to Polypora stenostoma Tavener-Smith (1971) which shares some aspects of morphological similarity with the new genus. TAVENER-SMITH, R. 1971. Polypora stenostoma: a Carboniferous bryozoan with cheilostomatous features. Palaeontology, 14, 178-187, pi. 25. 1.. •'4^ iW ■ . :. *«. ■ 'f r • J5i“* '■ ' - f. -' .,--v =-’' ^'' . ■?. - '*^'4 r^r.. >s V • :,. ■ ■'■' ' , -■■■ -■ 'ui . , i*. ^ , ' ('‘i.yj,'' I*. , ( i , i • V.. 'V ,^ • -. ♦" . .^''.4* ' N., K- K«*.H -.• ■ ■' ■ .f "rtHtWf* ’■ . o^- ■ ‘f.-v ' • ^ • ■.-, ; •.•. ..>,» — ■ '•, '’ . - •^d) to typical rhodocrinitid types (text- fig. 3c) where the basals are large, in lateral contact, and support the radials and inter- brachials. Transitional crinoids are also known. Note that small basals (relative to size of the infrabasals and radials) are associated with the zygodiplobathrid condition and large basals with the normal rhodocrinitid or eudiplobathrid base. Ubaghs (1950, p. 120) notes that two of the radials of Paulocrinus biturbinatus Springer (1926/?, p. 21, pi. 4, figs. 5, 5a-c) lie on truncated infrabasals whereas the other three rays have the normal rhodocrinitid condition. As in Rhipidocrinus crenatus, the relatively large infrabasals and small basals are associated with the zygodiplobathrid type base. These examples clearly support Ubaghs (1950) and Breimer (1960) in their contention that zygodiplobathrids and normal dicyclic camerates are both variants of the same basic organization. It also implies that one was probably ancestral to the other. These variations within rhodocrinitids are believed to indicate genetic instability with respect to this character, at least in certain species. On the other hand, the proximal structure of the cup seems to be stabilized in zygodiplobathrid taxa. Although these crinoids are rare and do not seem to have been successful, moderately large 642 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 3. Origin of Dimerocrinites pentlandicus sp. nov. a, lateral view of holotype ; note shape of primi- brachs, structure of interbrachials, and zygodiplobathrid base, x3-4. b-d, sketches showing probable ontogeny of rhodocrinitids with eudiplobathrid base and zygodiplobathrids. b, ‘larva’ of dicyclic camerate crinoid with interbrachials separating the radials; note that the plates are still separated by tissues; during later ontogeny, these join to form a rigid mosaic of plates; reconstructed by analogy with living crinoids, based on the growth sequence of plates and statistical data of Brower (1973, pp. 292-328); height of larval calyx is about 0-5 mm. c, D, bases of mature crinoids simulated by growth of the ‘larva’, c, eudiplobathrid base of rhodocrinitid, growth rates of height and width of the plates relative to total size of the calyx: infrabasals 014, basals 0-43, radials 0-43. d, zygodiplobathrid base, relative growth rates of height and width of the plates: infrabasals 0-62, basals 013, radials 0-25. e-g, sketches showing postulated ontogeny of zygodiplobathrid base seen in D. pentlandicus sp. nov. and normal dimerocrinitids. e, ‘larva’ of dicyclic camerate crinoid in which the proximal interbrachials are at the level of the primibrachs, reconstructed as before, f, g, bases of mature dimerocrinitids simulated by growth of the ‘larva’, f, eudiplobathrid base of normal dimerocrinitid, relative growth rates for plates: infrabasals 014, basals 0-43, radials 0-43. G, zygodiplobathrid base of D. pentlandicus sp. nov., relative growth rates for plates: infrabasals 0-62, basals 013, radials 0-25. All relative growth rates of plates are approximate averages for both height and width. Symbols: radials black, interbrachials stippled. BROWER; SILURIAN CRINOIDS FROM SCOTLAND 643 samples are available in Cleiocrinus laevis Springer (191 1, p. 44). Examination of five to ten calyx bases discloses no variation. The oldest zygodiplobathrid is the bizarre Cleiocrinus from middle Ordovician rocks of North America (Springer 1905; Ubaghs 1950, pp. 116-120; 1953, p. 691). In Cleiocrinus, the combined radial-basal circlet overlaps and hangs down over the infrabasals. Except for the CD interray, there are no interbrachials and the adjacent ray plates join one another above the radials and basals. The calyx is large because of the numerous fixed-brachials and all calyx plates are pierced by complex sutural pores which are interpreted as respiratory devices connected to body coeloms. The free arms are composed of uniserial pinnulate brachials. The evolutionary history of Cleiocrinus is unknown because there are no known connecting links between the genus and any known Ordovician archaeocrinids or rhodocrinitids. Nevertheless, Cleiocrinus is believed to have been derived from an archaeocrinid or rhodocrinitid stock. The Devonian zygodiplobathrid Spyridiocrinus is less obscure (see detailed dis- cussion in Ubaghs 1950). Aside from the large basal concavity and a reduced number of interbrachials, intersecundibrachs, etc., the over-all crown habit of Spyridiocrinus is ‘typical rhodocrinitid’. Comparison of Cleiocrinus and Spyridiocrinus shows only one similarity— the zygodiplobathrid base. Consequently the two crinoids are not considered closely related. Obviously, the bizarre Cleiocrinus was not ancestral to Spyridiocrinus. The large time gap between the two taxa is certainly consistent with this belief. The total morphological similarities between Spyridiocrinus and Silurian- Devonian Rhodocrinitidae seem much greater than those between Spyridiocrinus and Cleiocrinus. The most similar rhodocrinitid genera are : Anthemocrinus Wachsmuth and Springer (1881, p. 208 (382)), Wenlock. Paulocrinus Springer (1926^, p. 22), middle or upper Silurian. Condylocrinus Eichwald (1860, p. 612), Devonian. Pre- sumably the ancestral stock of Spyridiocrinus is within one of these genera. At any rate, rhodocrinitid ancestry is postulated for Spyridiocrinus with little doubt. If these considerations are correct, then the two zygodiplobathrid genera had independent evolutionary histories regardless of the origin of Cleiocrinus. Thus zygodiplobathrids were probably polyphyletic. If the ancestry of Cleiocrinus can be clarified, it seems advisable to drop the suborder Zygodiplobathrina and group the two genera within the Eudiplobathrina along with the most closely related families. As previously mentioned, the zygodiplobathrid base is associated with relatively small basals and large infrabasals whereas the reverse characterizes eudiplobathrids. This suggests that one type can be derived from the other by means of ‘mutations’ which affected the growth of the youngest crinoids; these ‘mutations’ would increase or decrease the growth rates of the height and width of the basals relative to those of the surrounding plates. [The word ‘mutations’ is used in a highly general sense, namely to include gene changes, chromosome additions, translocations, etc. ; a detailed dis- cussion of this concept is given by Brower (1973, p. 328 et seq.).] In order to test this hypothesis, a series of hypothetical crinoids was drawn based on statistical data (text-fig. 3b-g). A simulated rhodocrinitid larva is pictured in text-fig. 3b; this was reconstructed based on analogy with living crinoids, using the statistical data and plate-growth sequences for camerate crinoids (Brower 1973, pp. 292-328). The subsequent growth of this ‘larva’ was simulated in two ways. In Case I the growth ■ 644 PALAEONTOLOGY, VOLUME 18 rates of the basals are large compared to those of the infrabasals and radials. In Case II the basals are characterized by relatively small rates of growth. Note that the growth rates are only approximate averages for height and width and that the growth rates are listed as proportions. The data are ; Case Approximate values of subsequent growth Type of base rates for height and width of the listed plates produced relative to total height of the larval calyx Infrabasals Basals Radials 014 0-43 0-43 Rhodocrinitid- eudiplobathrid (text-fig. 3c) 0-62 013 0-25 Zygodiplobathrid (text-fig. ’id) Text-fig. l>b-d indicates that the simulation is geometrically feasible and thus zygodiplobathrids can be derived from eudiplobathrids by a decrease in the growth rates of the basals relative to those of the surrounding plates. Comparison. Assignment to the Dimerocrinitidae seems probable because the Pentland crinoid is basically a dicyclic camerate crinoid with many fixed-brachials and radials in contact within the lateral interrays. For reasons discussed above, the presence of a zygodiplobathrid base is not thought to be a fundamental character. Considering the affinities of the Pentland species within the Dimerocrinitidae, the most closely allied crinoids should have; (1) four arms per ray with axillary secundi- brach 2; (2) primitive structure of the fixed-brachials. In D. pentlandicus primibrach 1 has eight sides and the primaxil eight or nine sides. The most closely related dimero- crinitid should exhibit a similar structure, probably consisting of hexagonal primi- brach 1 and septagonal primaxil. (3) Slender calyx. (4) Relatively high infrabasals. Only a few Ordovician and Silurian dimerocrinitids fit these specifications. These include Ptychocrinus parvus (Flail) (Wachsmuth and Springer 1897, p. 199) and several species of Dimerocrinites with four arms in each ray; i.e. specimens from the Wenlock of Gotland and Dudley, England, labelled D. quinquangularis (Angelin), D. ornatus (Angelin), and D. speciosus (Angelin). These crinoids were described by Angelin (1878), but unfortunately the original figures are not reliable because many are probably composites of several crinoids which are not always conspecific; hence, emphasis is placed on specimens seen by the writer. These crinoids are easily separated from D. pentlandicus by the shapes of the primibrachs, the nature of the adjacent interbrachials, and the type of cup base present. The Pentland crinoid has primibrachs with eight or nine sides whereas those of the other taxa bear from four to nine sides. Due to the structure of the primibrachs, D. pentlandicus has four ranges of inter- brachials below the proximal secundibrachs but only one, two, or three ranges are found in the other forms. As mentioned above, the Pentland species has a zygodiplobathrid-type base whereas the other crinoids have eudiplobathrid bases, and Ptychocrinus parvus has more prominent median-ray ridges than in D. pentlandicus. Phylogeny. The most likely ancestor for D. pentlandicus is an Ordovician or lower Llandovery dimerocrinitid or ptychocrinid with four arms in each ray. Two main evolutionary changes were involved. First is the development of a zygodiplobathrid BROWER: SILURIAN CRINOIDS FROM SCOTLAND 645 from a eudiplobathrid base. This probably occurred in roughly the same way that Spyridiocrinus was derived from the Rhodocrinitidae, by means of a growth ‘mutation’ which reduced the growth rates of height and width of the basals relative to those of the sub- and superjacent infrabasals and radials. Variation of this sort is unknown within the Dimerocrinitidae, but precedent for such evolution is shown by variation within various rhodocrinitids such as Rhipidocrinus crenatus and the Carboniferous inadunate Woodocrinus gravis Wright (1950-1954, pi. 25, cf. figs. 2, 3, 5, 6, 9). Where the basals are small, they are not in lateral contact and the radials rest on the truncated infrabasals. If the basals are large, they are in lateral contact and the radials are fully separated from the infrabasals. Small basals are rectangular like those of D. pentlandicus but the large basals are hexagonal like those of normal dimero- crinitids. The simulated crinoids in text-fig. 3e-g show that such a change is at least geometrically plausible. The second change is the divergence in the structure of the primibrachs and inter- brachials. Increase in the number of sides of the primibrachs probably began when the plates formed early during ontogeny. The shape changes were achieved through adjustments of the various growth rates of widths of the primibrachs (see Brower 1973, pp. 401-407 for outline of similar evolution in patelliocrinids). An increase in the supply rate of interbrachials in conjunction with the shape changes of the primi- brachs mentioned above would be sufficient to develop the interbrachial areas of D. pentlandicus from the ancestral type. Subclass INADUNATA Wachsmuth and Springer, 1885 Order disparida Moore and Laudon, 1943 Superfamily homocrinicae Ubaghs, 1953 Family pisocrinidae Angelin, 1878 PISOCRINUS de Koninck, 1858 Type species. P. pilula de Koninck, 1858. Pisocrinus campana Miller Plate 74, figs. 1, 2, 4; text-fig. 4 1891 Pisocrinus campana Miller, p. 32, pi. 11, figs. 4, 5. 1892 Pisocrinus campana Miller, p. 642, pi. 11, figs. 4, 5. 1897 Pisocrinus sp., Wachsmuth and Springer, pi. 8, fig. 10. 1915 Pisocrinus campana Miller; Bassler, p. 980. 1926fi Pisocrinus campana Miller; Springer, p. 76, pi. 24, figs. 6-27. 1943 Pisocrinus campana Miller; Bassler and Moodey, p. 612. 1952 Pisocrinus cf. campana Miller; Lament, p. 29. Scottish material. A crown and a cup (RSM 1970.42.3, 4) occur on a small slab. Unfortunately, the original has been lost and the two crinoids are only represented by latex casts. Two other crowns, RSM 1970.42.2, 1970.43. Part and counterpart of a cup, Hunterian Museum (HM) 3173a, b. Type locality. Upper Llandovery or Wenlock; Salamonie Dolomite; Wabash, Indiana, U.S.A. Other American localities. Upper Llandovery; Osgood Formation; St. Paul and adjacent areas in southern Indiana. Lower Wenlock; Laurel Limestone; St. Paul, Indiana. Lower Ludlow; Brownsport Formation; various localities in Wayne, Perry, and Decatur Counties, Tennessee. 646 PALAEONTOLOGY, VOLUME 18 Scottish locality. Plectodonta Mudstones, lower part of River North Esk, about 220 yd north-east of the North Esk Reservoir. Diagnosis. A species of Pisocrinus with moderately high cup which shows wide varia- tions in shape, height/width ranges from 0-75 to 1-2; walls of cup slightly rounded; basals high relative to radials regardless of cup shape; radial processes weakly developed ; plates of cup smooth. Arms long and slender, arm length/height of cup ranges from 4 0 to 8 0, arms of mature crinoid consist of about five brachials. Dorsal sides of brachials rounded or distinctly triangular. Stem round, composed of only one order of plates; distal columnals nodose. Description of Scottish specimens. Cup moderately high; height/width ranges from 0-85 to 10; sides of cup slightly rounded; basals high relative to cup height; height of basals/cup height equals about 0-41 ; surfaces of cup smooth, may be faintly rugose in one specimen. Basals five, three pentagonal and two rectangular (A ray, BC interray); pentagonal basals larger than rectangular ones, height/width of pentagonal basal is 0-8 to 1 -0 ; same for rectangular basal equals 0-5. Large inferradial occurs under B and C ray radials, septa- gonal, height/width about 10. B and C ray superradials basically pentagonal, height/width 0-7. A and D ray radials largest plates in cup, pentagonal to septagonal, height/width ranges from 0-8 to 1 0. E ray radial not seen. Radial facets wide, about two-thirds width of radials, faintly curved with small radial processes. Tegmen unknown. Arms large, massive, blade-like, consist of uniserial, non-pinnulate brachials; each arm has from three to eight brachials ; most of arm tapers gently ; at distal arm tips, the taper angle increases and the last brachial is bullet-shaped; arm length/cup height varies from 4 0 to 5-5. Primibrach 1 small, rectangular, much wider than high, partially set inside of radial processes; higher primibrachs much larger and more massive, sutures obscure; height/width variable, ranges from 10 to 16; dorsal sides of brachials are more or less strongly triangular. Large part of column observed, round with small round axial canal; entire column consists of only one order of columnals; column tapers distally from below calyx to mid- distal region of stem; distal-most stem plates become wider than those of mid-distal region. Proximal columnals wide relative to height, shaped like thin discs with slightly nodose edges. Comparison. Despite the recent monographic treatment of pisocrinids by Bouska (1956), the American species remain in need of revision. For example, P. campana Miller (see Springer 1926Zt, p. 76) and P. benedicti Miller (1891, p. 29; Springer 1926/t, p. 77) commonly occur together; the former is separated by a cup with straight or slightly curved walls which is high relative to width whereas the latter is lower and more globose. Springer noted intergradations between the two species (1926Z), p. 76): 'As stated, with the expanding and bell shaped forms the identifica- tion is easy, but those with a lower calyx, ovoid to globose, are confusing; if they have EXPLANATION OF PLATE 74 Figs. 1, 2, 4. Pisocrinus campana Miller, note blade-like arms, relatively high cup with straight walls and high basals, figured specimens, Plectodonta Mudstones, lower part of River North Esk, about 220 yd north-east of the North Esk Reservoir. 1, crown with rugose markings on plates of cup and relatively short arms, /I, B, and Cray view of RSM 1970.42.1, x6-4. 2, poorly preserved crown with tumid plates and cigar-like arms, lateral view of RSM 1970.43, x7 0. 4, left, relatively wide and globose cup with smooth plates, A and B ray view of RSM 1970.42.3; right, crown with comparatively high cup with smooth plates and long arms, lateral view of RSM 1970.42.4, x 5-3. Fig. 3. Ptychocrinus longibrachialis sp. nov., note long slender arms composed of elongate brachials, C ray view of holotype. Grant Institute of Geology 134, mudstone layer, just above top plantation on Gutterford Burn, x2-8. Fig. 5. Dimerocrinites pentlandicus sp. nov., note small basals and zygodiplobathrid-type base of cup, shape of primibrachs and structure of interbrachials, lateral view of holotype RSM 1885.26.78h, ‘Starfish Bed’, Gutterford Burn, x3-8. PLATE 74 BROWER, Scottish Silurian crinoids 648 PALAEONTOLOGY, VOLUME TEXT-FIG. 4. Figured specimens of Pisoaimis campana. Note slender calyx with high basals and long blade-like arms, a, lateral view of crown, RSM 1970.42.4, X 5-3. B, A and B ray view of cup with a partial arm, RSM 1970.42.3, x 5-3. c, A, B, and C ray view of partially disarticulated crown, RSM 1970.42.1, X 5 0. D, lateral view of RSM 1970.43, x 5-3, the plate structure of the cup is conjectural. Symbols: radials and superradials black, inferradials are ruled horizontally. fairly high basals, we may call them campana, while those with basals but little visible will have to go into benedicti. Thus there will be an intermediate zone in which the distinction is shadowy.’ This is shown by measurements made on the specimens in the Springer Collection, United States National Museum, in which the height/width ratios of the cup of specimens assigned to P. campana by Springer ranges from 0-75 to 1 -2 while that of P. benedicti varies from 0-60 to 1 -2. The figures overlap and further data are required to either recombine or fully define the two species. Pending restudy, the specimens with the higher cups having high basals and straight or nearly straight walls are assigned to P. campana while those with lower and more globose cups with shorter basals are placed in P. benedicti. Thus P. campana is a highly variable species which ranges from the upper Llandovery to the lower part of the Ludlow. The specimens from the Pentland Hills differ from typical North American individuals in several respects. Most American crinoids have well-developed radial processes although these grade into individuals with faint radial processes (Springer \92bb, pi. 24). The Scottish specimens are characterized by shallow radial processes like some of the end-member crinoids from America. The Pentland specimens range much smaller. The largest crown is about 13 mm high whereas Springer (1926/?, pi. 24, figs. 7, 8) illustrated crowns about 65 mm high. Both the Pentland and the BROWER. SILURIAN CRINOIDS FROM SCOTLAND 649 American crinoids possess comparable numbers of brachials in each arm. The fact that crinoids develop new brachials at the arm tips throughout life indicates the Pentland crowns were probably not juveniles. These are believed to be adults which exhibited reduced growth rates of size with respect to time compared with typical American individuals. Nevertheless, the high cup with slightly rounded walls and large basals in conjunction with the long blade-like arms and nodose columnals in the stem indicate that the Scottish crinoids should be referred to P. campana. P. campana is also closely related to P. pilula de Koninck (see Bather 1893, p. 27 ; Bouska 1956, pp. 13, 62, 104) of the Wenlock and Ludlow of England, Gotland, and Bohemia. Both species are long ranging and widespread and both vary in the height/ width ratio of the cup and the nature of the radial processes. P. campana can be separated from P. pilula by several characteristics. Better-developed radial processes are seen in P. pilula. The distal columnals of P. pilula exhibit smooth sides whereas the columnals of P. campana are nodose. Also the proximal stem of P. pilula appears to have been secondarily thickened, a feature which is not known in P. campana. The basals of P. pilula are always low while those of P. campana are much higher rela- tive to the height of the cup. The cup walls of P. campana are commonly rounded but those of P. pilula are generally straight. P.pocillum Angelin (1878, p. 21 ; Bather 1893, p. 33; Springer 19266, p. 80) from the Silurian of Gotland, P. ubaglisi Bouska 1956 and P. mofinensis Bouska 1956 both from the Ludlow of Bohemia, have higher cups (height/width ranges from 1-3 to 1-7) with straight and angular sides in contrast to the lower cup with straight or slightly rounded walls of P. campana. Superfamily iocrinicae Ubaghs, 1953 Family myelodactylidae Miller, 1883 HERPETOCRiNUS Salter, 1873 Type species. H. ftetcheri SaAiQX 1873. Herpetocrinus parvispinifer sp. nov. Plate 73, figs. 3, 5 Holotype. RSM 1897.32.285, a terminal coil with part of the straight portion of the stem, in which the crown is only represented by the distal parts of the arms. The lack of the cup and most of the crown does not preclude definite generic and specific placement because all Myelodactylidae can be classified on stems alone: the crowns are only known in three of the five genera assigned to the family by Moore (1962, pp. 40-44). Paratypes. Straight stem segments with cirri; RSM 1885.26.78e (part and counterpart), 1897.32.286 (part and counterpart). A partial terminal coil and straight stem segment: RSM 1897.32.287 (part and counter- part). A partial terminal coil: RSM 1897.32.288 (part and counterpart). Derivation of name. From the short spines on the distal margin of each cirral. Type locality. Gutterford Burn Flagstones, ‘Starfish Bed’, Gutterford Burn. Diagnosis. A species of Herpetocrinus with characteristic cirral ornamentation; distal end of cirral expanding outward to form small angular rim-like process; typically the rim bears two to six short spines; rarely, the rim is absent or weakly developed but such cirrals always show traces of spines. Column with crescent- shaped cross-section, concave part of crescent faces the outside of the coil of the stem, convex side of crescent located on the inside of the coil. 650 PALAEONTOLOGY, VOLUME 18 Description. Proximal part of stem coiled in an S-shaped bend which is followed by another half-circle of coil, distal part of stem nearly straight. Proximal portion of stem round, about 14 mm long, diameter increases from 1 -2 to 1 -6 mm in distal direction, lacking cirri ; longitudinal sutures well developed in middle of stem. Columnals nodose, with parallel sides in straight parts of column; where the column bends, the columnals become slightly wedge-shaped, height/average width of proximal columnals about 0T8. Next part of stem with crescentic cross-section, convex part of crescent occurs on the inside of the coil, concave part of crescent on outside of the coil, diameter of this stem segment increases from 1-8 to 2-8 mm distally, cirri lacking, longitudinal sutures obscure. Columnals slightly nodose, somewhat wedge-shaped, ratio of average height/width ranges from 0-5 to 0-36 with distal columnals having the lowest values. Third region of stem similar to previous part, having crescentic cross-section, diameter of stem segment decreases distally from 3-2 to 2-4 mm, several cirri present in distal part of stem segment, adjacent nodals separated by one or two columnals, longitudinal sutures are poorly developed. Columnals not nodose, proximal columnals slightly wedge-shaped but distal ones have parallel sides, average height/width of columnals ranges from 0-25 to 0-35, internodals lacking cirri; nodals with cirri, portion of nodal with cirrus scar expands, this constricts the adjacent part of the internodal; articular facet for cirrus round, somewhat protuberant. Distal portion of stem almost straight, with crescentic cross-section, width varies from 2-0 to 3 0 mm, cirri generally present, adjacent nodals usually separated by one columnal, longitudinal sutures obscure. Columnals not nodose, like those in previous part of stem except that the sides are parallel and the columnals are not wedge-shaped, average height/width of columnals ranges from 0-35 to 0-30. Cirri long and slender, longest known cirrus is incomplete, observed length about 30 mm, consisting of forty-one plates. Cirrals with round cross-section, sides expanding distally to form rim-like process which bears two to six short spines, some cirrals lack rims but some spines are always present. Crown only known from distal brachials; brachials uniserial, lacking pinnules, ranging from equidimensional to higher than wide. Distal part of column not observed. Comparison. The Pentland species is most closely related to H.fletcheri Salter (1873, p. 118; Bather 1893, p. 46; Springer 19266, p. 86; 1926a, p. 10; Moore 1962, p. 42) from the Wenlock of Great Britain and Gotland. In H.fletcheri the cirrals are evenly nodose whereas those of H. parvispinifer generally possess small angular distal rims which commonly bear two to six short spines or spine bases. The Pentland individuals exhibit some variability in the nature of the cirrals while the distal rims range from prominent to weakly developed or absent, but these are normally seen. The number of spines varies in increments of two, either two, four, or six. When four or six are present, the two spines lying within the plane of stem coil are generally the best developed. H. parvispinifer is distinguished from the Gotland H.flabellicirrus Bather, 1 893 by the shape of the individual cirrals, these being nodose in the Gotland form and rim and spine bearing in the Pentland animal. Also, the cirri of H. flabellicirrus are ponderous and expand distally whereas those of H. parvispinifer are more slender and taper evenly distally. The Pentland species differs from Myelodactylus in the cirri, which in myleodactylids are elongate and unornamented, but the cirrals of the Pentland herpetocrinid are wider and either nodose or rim and spine bearing. Also, the longitudinal sutures are well developed throughout the stem of H. parvispinifer whereas they tend to disappear on the distal end of the column of Myleodactyhis. Order cladida Moore and Laudon, 1943 Suborder dendrocrinina Bather, 1899 Family dendrocrinidae Miller, 1899 DENDROCRINUS Hall, 1852 Type .species. D. longukiclylus HM, 1852. BROWER: SILURIAN CRINOIDS FROM SCOTLAND 651 Dendrocrinm extensidiscus sp. nov. Plate 75, figs. 1-3; text-fig. 5 Holotype. A well-preserved crown of a young specimen with an attached stem segment on RSM 1897.32.289. Paratypes. Young crowns: RSM 1897.32.290, 291. Long stem segment with partial cup of a young crinoid on RSM 1897.32.289. Cup of mature specimen with a long stem segment : RSM 1885.26.78g. Stem segment with attached cirrus roots: RSM 1897.32.301. Derivation of name. In allusion to the relatively high columnals. Type locality. Gutterford Burn Flagstones, ‘Starfish Bed’, Gutterford Burn. Diagnosis. A species of Dendrocrinus with relatively slender cup, brachials high with respect to width; column round; distal columnals have relatively large ratios of height/width compared to most dendrocrinids. Description. Cup conical with straight walls, height/width ranges from 0-8 to 10. Plates of cup convex with depressed sutures, otherwise smooth. Infrabasals high, pentagonal, higher than wide, infrabasal circlet occupies from 17 to 24% of the cup height. Basals large, lateral interray basals hexagonal, higher than wide, height of basal circlet ranges about 50% of the cup height. CD interray basal septagonal, largest plate in cup, distally truncated for reception of anal X. Radials basically pentagonal, equidimensional or wider than high, radial circlet generally represents about 30% of the cup height. Radial facets smooth, narrow, horseshoe-shaped, sloping outward, width of facet varies from 45 to 60% of the width of the radial. Radianal poorly known, large, lying under C ray radial. C ray radial pentagonal with wide radial facet, located above radianal and between anal X and B ray radial. Anal X five-sided, occurring between C ray radial, radianal, and D ray radial and above truncated CD interray basal. Arms only known in young crinoid, slender, branching isotomously, once or twice; usually six primibrachs present, rarely five or seven plates occur, distal primibrach is axillary; number of secundibrachs uncertain, twelve plates present in unbranched arm segment, branched arm segment probably has roughly the same number of secundibrachs ; from one to three tertibrachs present. Brachials uniserial, nonpinnulate, smooth, slender, with round or sharp backs. Nonaxillary primibrachs rectangular; primibrach 1 is shortest primibrach, height/width ranges from 0-7 to 1-2; other nonaxillary primibrachs much higher, height/width varies from 1-7 to 4 0; axillary primibrach pentagonal, spear-shaped, height/width ranges from 1-6 to 2-3. Secundibrachs higher than wide, height/width equals from 2 0 to 3-3. Column round, composed of smooth columnals that are high relative to width compared to other species of Dendrocrinus, column lacking cirri, only one order of columnals can be differentiated. Proximal columnals which are immediately below the calyx disc-shaped, much wider than high, height/width varies from 0-2 to 0-5. Distal columnals of young specimens much higher than wide, height/width ranges from 1-7 to 4 0. Distal columnals of adult have height/width ranging from 0-25 to 0-8. Columnals near rooting device have strongly crenulate sutures, height/width of columnals is about 0-5. Rooting device partially known, consisting of at least two heavy cirri, each of which branches several times. Remarks. This species is represented by cups which fall into two height intervals. The largest crinoid has a cup height of 8 0 mm. The smaller crowns range from I T to 2 0 mm in cup height. The large specimen is considered conspecific with the smaller ones because of similarities in outlines of the cup and its component plates and because all specimens have similar convex plates with depressed sutures. The main differences between the young and mature specimens are in the column. Distal columnals of the smaller specimens are much higher than wide and the height/width ratios of these plates range from 1 -7 to 4 0. The equivalent ratios for the adult crinoid vary from 0-25 to 0-8 indicating columnals that are wider with respect to height. The columnals of the mature crinoid are higher than in the young specimens. The dif- ference in shape of the columnals between the young and adult specimen is attributed o 652 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 5. Dendrocrinus extensidiscus sp. nov. A, B, D and B ray views of holotype, counterpart and part, respectively; note relatively long and slender arms with elongate brachials; the cup is crushed so that the plates appear wider than in uncrushed specimens ; if the crinoid is interpreted correctly, the C ray radial is located above the radianal and well above the other radials, this is higher than in normal specimens and the holotype is considered abnormal in this respect, x 4-9. c, d, lateral ray view of external mould and CD interray view of internal mould, paratype RSM 1885.26.78g, X 3. The radials are black. to progressive growth. In most crinoids the height/width ratios of columnals decrease as the columnals become older and larger (Brower 1973, pp. 298, 299). The arms are not known in the larger crinoid and these cannot be compared with those of younger specimens. Comparison. D. extensidiscus is only remotely related to the Wenlock age species from North America. These include: (1) Z). longidactylus Hall (1852, p. 193) which has a cup with slightly rounded walls and more numerous arm branches; (2) D. celsus Ringueberg (1888, p. 132) which shows eleven primibrachs (compared to about six in this form), more arm branches, and a column which expands near the calyx; and EXPLANATION OF PLATE 75 Figs. 1-3. Dendrocrinus extensidiscus sp. nov., note relatively high columnals and slender arms consisting of elongate brachials, ‘Starfish Bed’, Gutterford Burn. 1, D ray view of holotype RSM 1897.32.289 (counterpart, a well-preserved young crown with long stem segment) and paratype RSM 1897.32.289 (crushed cup of young specimen with long stem segment showing well-preserved columnals, located on right side of photograph), x4-2. 2, C ray view of holotype RSM 1897.32.289 (part), x4-2. 3, lateral view of a mature specimen, paratype RSM 1885.26.78g, x 1-4. Figs. 4, 5. Macrostylocrinus silurocirrifer sp. nov. 4, stem segment with well-preserved cirri, paratype RSM 1897.32.293, ‘Starfish Bed’, Gutterford Burn, x2-4. 5, lateral view of immature crinoid, paratype GSE 12791, Deerhope Burn Flagstones, River North Esk, at bend 935 yd N. 30° W. of North Esk Cottage, x4-8. PLATE 75 BROWER, Scottish Silurian crinoids 654 PALAEONTOLOGY, VOLUME 18 (3) the peculiar Z).? nodobrachiatus Ringueberg (1890, p. 303) which is probably not referable to Dendrocrinus because either ramules or pinnules are present according to Ringueberg : also the cup is wider and there are only two main arms per ray with primibrach 3 forming the axillary. In addition, D. extensidiscus differs from all other Silurian species by the relatively long and slender columnals and brachials. Only two other species of Dendrocrinus, D. rugocyathus Ramsbottom (1961, p. 16) and D. granditubus Ramsbottom (1961, p. 15), are known from Britain; both are upper Ordovician. They are characterized by stellate plates in the cup and a pentalo- bate stem. In D. extensidiscus smooth calyx plates and a round stem are observed. The two British Ordovician species are closely related to the American upper Ordovician D. casei Meek (1871, p. 295; 1873, p. 28). This American form has very similar calyx ornament and shape, stem type, and general stem and crown habit to the British Ordovician crinoids. The most similar crinoids consist of a series of middle and upper Ordovician forms from North America. In general, these and the Pentland animal resemble each other in having round stems which are non-nodose, similar calyx shapes with smooth plates and slender arms which branch two to four times. Middle Ordovician forms in this category are: (1) D. acutidactylus Billings (1857, p. 266; 1859, p. 37); (2) D. gregarius Billings (1857, p. 265; 1859, p. 36); and (3) D. gracilis (Hall) (1847, p. 84). Upper Ordovician species are: (1) D. navigiolum Miller (1880, p. 235) and (2) /).? sp. nov. aff. D.l navigiolum Brower (1973, p. 457). Of all the above species, D. acutidactylus is judged the closest with respect to over-all morphology. D. extensi- discus is separated from all the above species by the higher, relative to width, columnals and brachials. Therefore the affinities of the Pentland crinoid lie closer to Ordovician forms than to Silurian ones. Acknowledgements. I cordially thank the following for loan of specimens: Dr. C. D. Waterston (Royal Scottish Museum, Edinburgh), Dr. W. D. I. Rolfe, Dr. J. K. Ingham, and Miss Sylvia Jackson (Hunterian Museum, Glasgow), Dr. R. Wilson and Mr. P. Brand (Institute of Geological Sciences, Edinburgh), Professor G. Y. Craig and Miss Helen Nisbet (Grant Institute of Geology, Edinburgh), and Dr. P. M. Kier (United States National Museum). Dr. A. Lamont generously donated several important specimens to the Royal Scottish Museum. Most of this work was completed on academic leave from Syracuse University, at the Royal Scottish Museum during 1969-1970, where I was kindly helped by Dr. C. D. Waterston and his staff. The specimens were developed and cast by Mr. Robert Rieke of the Museum. Problems of strati- graphy, correlation, and palaeoecology were discussed with Dr. Waterston, Dr. Rolfe, Dr. P. Toghill, and Dr. L. R. M. Cocks. REEERENCES ANGELIN, N. p. 1878. Iconographia crinoideorum in stratis sueciae Silwicis Fossilium. Holmiae, 62 pp., 29 pis. BASSLER, R. s. 1915. Bibliographic index of American Ordovician and Silurian fossils, vols. 1 and 2. U.S. Nat. Mas. Bull. 92, vii +1221 pp., pis. 1, 2. and MOODEY, m. w. 1943. Bibliographic and faunal index of Paleozoic pelmatozoan echinoderms. Geol. Soc. Am., Spec. Pap. 45, 734 pp. BATHER, F. A. 1 893. The Crinoidea of Gotland Part 1 . The Crinoidea Inadunata. Kongl. Svenska Vetenskaps— Akad. Handlingar, Bd. 25, no. 2, 199 pp., 10 pis. BILLINGS, E. 1857. New species from Silurian rocks of Canada. Canadian Geol. Surv., Kept. Progress 1853- 1856, 256-345. 1859. Canadian organic remains. Decade IV, Crinoidea of the Lower Silurian rocks of Canada. Geol. Surv. Canada, Decade IV, 66 pp., 10 pis. BROWER: SILURIAN CRINOIDS FROM SCOTLAND 655 BOUSKA, }. 1956. Pisocrinidae Angelin ceskeho siluru a devonu, Czechoslovakia. Ustfed., Ustav Geol., Rozpr. 20, 134 pp., 6 pis. BREiMER, A. 1960. On the structure and systematic position of the genus Rhipidocrimis Beyrich, 1879. Leidse Geol. Mededel. 25, 247-260, 1 pi. BROWER, j. c. 1973. Crinoids from the Girardeau Limestone (Ordovician). Palaeontogr. Am. 7, 263-499, pis. 59-79. CARPENTER, p. H. 1884. Report on the Crinoidea collected during the voyage of H.M.S. Challenger, during the years 1873-1876. Part 1, general morphology, with descriptions of the stalked crinoids. Challenger Rept., Zoology, 11 (26), xii + 442 pp., 62 pis. CLARK, H. L. 1915. The comatulids of Torres Strait: with special reference to their habits and reactions. Carnegie Inst. Washington Pub. 212, 97-125. 1917. The habits and reactions of a comatulid, Tropiometra carinata. Ibid. 251, 111-119. COCKS, L. R. M., HOLLAND, c. H., RICKARDS, R. B. and STRACHAN, T. 1971. A Correlation of Silurian rocks in the British Isles. Jl Geol. Soc. Lond. 127, 103-136. EICHWALD, E. DE. 1860. Lethaeo Rossica, Vol. /, Ancienne Periode. E. Schwiezerbart, Stuttgart, xix+681 pp., 59 pis. FELL, H. B. 1966. Chapter 2, Ecology of crinoids. In boolootian, r. a. (ed.). Physiology of Echinodermata. Interscience Pub., New York, pp. 49-62. HALL, J. 1847. Palaeontology of New York, Volume I containing descriptions of the organic remains of the Lower Division of the New York System. C. Van Benthuysen, Albany, New York, xxiii + 339 pp., 87 pis. 1852. Palaeontology of New York, Volume II containing descriptions of the organic remains of the Lower Middle Division of the New York System. C. Van Benthuysen, Albany, New York, vii + 362 pp., 83 pis. 1 867. Descriptions of some new species of Crinoideae and other fossils from the Lower Silurian Strata, principally of the age of the Hudson River Group. New York St. Mus. Nat. Hist., Ann. Rept. 20, 304. HOWELL, H. H. and GEIKIE, A. 1861. The Geology of the neighbourhood of Edinburgh. First edit. Mem. Geol. Surv. Great Britain, 151 pp., 2 pis. JAEKEL, o. 1918. Phylogenie und System der Pelmatozoen. Palaeontologischen Zeitschrift, Band III, Heft. 1, 128 pp. KONiNCK, L. G. DE, 1858. Sur quelques crinoides Paleozoiques nouveaux de I’Angleterre et de I’Ecosse. Acad. Roy. Belgique, Bull. (ser. 2), 4, 93-108, pi. 2. LAMONT, A. 1947. Gala-Tarannon beds in the Pentland Hills, near Edinburgh. Geol. Mag. 84, 193-208, 289-303. 1952. Ecology and correlation of the Pentlandian— A new division of the Silurian System in Scotland. Int. Geol. Cong., Rept. 18th Session, Great Britain, 1948, Pt. X, pp. 27-32. 1954. New lamellibranchs from the Gutterford Burn Flagstones (Gala-Tarannon) of the Pentland Hills, near Edinburgh. Proc. R. Soc. Edin. (b), 65, 271-284, 1 pi. MEEK, F. b. 1871. Article 37. —On some new Silurian crinoids and shells. Amer. J. Sci. (ser. 3), 2, 295-302. 1873. Fossils of the Cincinnati Group. Geol. Surv. Ohio, I, pt. II, Palaeont. 175 pp., pis. 1-14, 3 bis. MILLER, s. A. 1880. Description of four new species and a new variety of Silurian fossils. J. Cincinnati Soc. Nat. Hist. 3, 232-236, pi. 7. 1883. Glyptocrinus redefined and restricted, Gaurocrinus, Pycnocrinus and Compsocrinus established and two new species described. Ibid. 6, 217-235, pi. 11. 1891. 1892. Palaeontology. In 17th Ann. Rep. Geol. Surv. Indiana. 103 pp. (pp. 611-705), 23 pis. Advance publication 1891 ; report published 1892. MOORE, R. c. 1952. Crinoids. In moore, r. c., lalicker, c. g. and fischer, a. g. Invertebrate fossils. McGraw- Hill, New York, pp. 604-652. 1962. Ray structures of some inadunate crinoids. Univ. Kansas, Paleont. Contrib., Echinodermata, Art. 5, 47 pp., 4 pis. JEFFORDS, R. M. and miller, t. h. 1968. Morphological features of crinoid columns. Ibid. 8, 30 pp., 4 pis. MYKURA, w. 1960. The North Esk Inlier. In mitchell, g. h., walton, e. k. and grant, d. (eds.). Edinburgh geology, an excursion guide. Oliver and Boyd, Edinburgh and London, pp. 162-174. and smith, j. d. d. 1962. Chapter II, Ordovician and Silurian. In mitcfiell, g. h. et ai. The geology of the neighbourhood of Edinburgh (3rd edn.). Mem. Geol. Surv. Scotland, pp. 10-22. 656 PALAEONTOLOGY, VOLUME 18 PEACH, B. N. and HORNE, J. 1899. The Silurian rocks of Britain, Vol. 1, Scotland. Mem. Geol. Siirv. U.K. iv+ 749 pp., 27 pis. PHILLIPS, J. 1839. Silurian encrinites. In murchison, r. i. The Silurian System, Part 2. London, pp. 670-675, pis. 17, 18. RAMSBOTTOM, w. H. c. 1961. A monograph of British Ordovician Crinoidea. Palaeontog. Soc. [Monogr.], y'or 1960], 36 pp., 8 pis. RINGUEBERG, E. N. s. 1888. Some new species of fossils from the Niagara Shales of western New York. Proc. Acad. Nat. Sci. Philadelphia, pp. 131-136, pi. 7. 1890. The Crinoidea of the Lower Niagara Limestone at Lockport, New York, with new species. Ann. N.Y. Acad. Sci. 5, 301-306, pi. 3. SALTER, J. w. 1873. A Catalogue of the Cambrian and Silurian fossils contained in the Geological Museum of the University of Cambridge. Cambridge Univ. Press, 204 pp. SHUMARD, B. F. 1855. Dr. Shumard’s report. Missouri Geol. Surv. Ann. Kept. II, 137-208, pis. A-C. SPRINGER, F. 1905. Cleiocrinus. Mem. Mus. Comp. Zool. Harvard, 25, 93-114, 1 pi. 1911. On a Trenton echinoderm fauna at Kirkfield, Ontario. Canada, Dept. Mines, Geol. Surv. Br., Mem. 15-P, 47 pp., 5 pis. 1926a. Unusual forms of fossil crinoids. Proc. U.S. Nat. Mus. 67, art. 9, 137 pp., 26 pis. 19267;. American Silurian crinoids. Smithson. Inst. Pub. 2871, 1-143, 167-239, 33 pis. STORMER, L. 1935. Dictyocaris, Salter, a large crustacean from the Upper Silurian and Downtonian. Norsk Geol. Tidsskr., Bd. 15, 265-298, 3 pis. UBAGHS, G. 1950. Le genre Spyridiocrinus Oc\\\qv\.. Ann. Paleont. 36, 105-122, pi. 1. 1953. Classe des Crinoides. In piveteau, j. (ed.). Trade de Paleontologie. Masson et Cie, Paris, pp. 658- 773, 166 hgs. WACHSMUTH, c. and SPRINGER, F. 1881. Revision of the Palaeocrinoidea, Pt. II. Proc. Acad. Nat. Sci. Philadelphia, vol. for 1881, pp. 178-411, pis. 17-19. 1885-1886. Revision of the Palaeocrinoidea, Pt. Ill, Sec. 1 and 2. Ibid. vol. for 1885, pp. 226-360, 64-227, pis. 4-9. 1897. The North American Crinoidea Camerata. Mus. Comp. Zool., Mem. 20, 21, 897 pp., 83 pis. WILSON, R. B. and smith, j. d. d. 1962. Appendix II, table of fossils collected by the Geological Survey from mudstones and siltstones of the North Esk Silurian Inlier— 1950-59. In mitchell, g. h. et al. op. cit. pp. 138-140. WRIGHT, J. 1950-1954. A Monograph on the British Carboniferous Crinoidea, Vol. I. Palaeontogr. Soc. [Monogr.], xxx+ 190 pp., 47 pis. J. C. BROWER Department of Geology Heroy Geological Laboratory Syracuse University Syracuse, New York, U.S. A. Original typescript received 2 September 1974 Revised typescript received 6 January 1975 A NEW CARINATE PH YLLOCERATID AMMONITE FROM THE EARLY ALBIAN (CRETACEOUS) OF ZULULAND, SOUTH AFRICA by H. C. KLINGER, J. WIEDMANN and W. J. KENNEDY Abstract. The early Albian sediments of Zululand yield abundant specimens of a keeled phylloceratid, Carino- phylloceras collignoni gen. et sp. nov., superfically homeomorphous with the desmoceratid Damesites. Investigation of the suture line confirms the phylloceratid affinities of the genus, which is an independent Cretaceous relative of the P. ( Hypophyllocems) velledae (d’Orbigny) group, and unrelated to the keeled Jurassic phylloceratids HarpophyUoceras Spath, 1927 and Menegheniceras Hyatt, 1900. The early Albian deposits of Zululand (Kennedy and Klinger 1972, 1974) yield rich ammonite faunas consisting of abundant douvilleiceratids, Lyelliceras lyelli (d’Orbigny), L. pseudolyelli (Parona and Bonarelli), Neosilesites, Phylloceras {Hypo- phylloceras) ^ Beaudanticeras\ 'Cleoniceras\ and ^ Sonneratm species, Rosallites, Ammonoceratites, abundant Anagaudryceras sacya (Forbes), Eubrancoceras aff. aegoceratoides (Steinmann), and Oxytropidoceras species. Accompanying this assemblage are abundant specimens of a keeled oxyconic ammonite resembling the desmoceratid genus Damesites Matsumoto, 1942, and referred to as such in a previous publication (Kennedy and Klinger 1975). Subsequent investigation of the external and internal suture of this form revealed it to be more appropriately referable to the ammonite subfamily Phylloceratinae, as a new genus and species, Carinophylloceras collignoni. Location of specimens. The following abbreviations indicate repositories of specimens : SAS— South African Geological Survey Collections, Pretoria, UPE --University of Pretoria (Boschoff Collection). BMNH— British Museum (Natural History). Full details of locality numbers cited are given by Kennedy and Klinger (1975). SYSTEMATIC DESCRIPTION Subclass AMMONOIDEA Zittcl, 1884 Order phylloceratida Arkell, 1950 Superfamily phyllocerataceae Zittel, 1884 Family phylloceratidae Zittel, 1884 Subfamily phylloceratinae Zittel, 1884 Genus carinophylloceras gen. nov. Type species. Carinophylloceras collignoni gen. et sp. nov. Diagnosis. Phylloceratid ammonites with fastigate to distinctly keeled venters. Whorl section ovoid, higher than wide, with maximum width at umbilical margin; [Palaeontology, Vol. 18, Part 3, 1975, pp. 657-664, pis. 76-77.] 658 PALAEONTOLOGY, VOLUME 18 narrowly umbilicated. Ornament typically phylloceratid, consisting of biconcave striae. Suture phylloid, with lituid 7, trifid L, saddles EjL asymmetrically diphyllic, Lj U2 asymmetrically tetraphyllic. Saddles in C/3 asymmetrically diphyllic. Carinophylloceras collignoni sp. nov. Plate 76, fig. [a-h\ Plate 77, figs. 1-3; text-figs. 1-3 Derivation of name. The species is named for General Maurice Collignon. Holotype. SAS A1577 from the Mzinene Formation, Stream Cliff section along the Mzinene River 1200 m NE. of the Farm Amatis, north of Hluhluwe, Zululand, South Africa, 27° 58' 03" S., 32° 18' 34" E. Locality 35 of Kennedy and Klinger (1974). Paratypes. Thirty-nine specimens; SAS UMS/2, SAS A1133, and BMNH C78639, C78644, C78647- C78648, C78767, C78769, C78770 from Locality 35, on the Mzinene River; BMNH C78640-C78643, C78645-C78646, C78651, C78768 from Locality 36, also on the Mzinene River. SAS H 93D/1, SAS H 93/1, SAS H 93/2, SAS H 93/3, SAS H 93/5 from Locality 142, Nxala Estate, southern part of Mkuze Game Reserve, Zululand. SAS EM 91, SAS EM 92, SAS EM 77 from the Msunduzi Pan at 26° 57' 25" S., 32° 12' 40" E. ; UPE B 33 from the same area at 26° 57' 10" S., 32° 12' 45" E. SAS EM 245a, b, c, SAS EM 93, SAS EM 244, SAS EM 1 14 from the Ndumu region, northern Zululand at 26° 55' 55" S., 32° 12' 55" E. SAS LJE 134A, UPE B 463, UPE B 464, UPE B 41 1, and BMNH C78649-C78650 from Locality 174; BMNH C78766 and C78771 from Locality 171, Mlambongwenya Spruit, northern Zululand. UPE B 23 from Aloe Flats Estate, northern Zululand at 26° 59' 50" S., 32° 11' 50" E. All specimens are from the Mzinene Eormation of late early Albian age, Albian III of Kennedy and Klinger (1975). Dimensions. All measurements are in millimetres; figures in parentheses are percentages of total diameter. D = diameter, Wb = whorl breadth, Wh ^ whorl height, U = umbilical diameter. Specimen D Wb Wh Wb/Wh U Holotype SAS A1577 149 60-5(41) 88-5(59) 0-68 8-5(6) Paratypes SAS EM24c 123-5 44-5(36) 68-0(55) 0-65 80(6-5) SAS H98/1 77-5 32-5(41) 44-5(58) 0-73 6-0(8) SAS H93/3 108 40-5(37) 63-5(58) 0-64 7-5(7) SAS UMS/2 132-5 47-0(36) 77-5(58) 0-60 9-0(6-8) Description. Coiling is moderately involute with a narrow funnel-shaped umbilicus (6-8% of diameter). Whorl section is subtrigonal with a fastigate to distinctly keeled venter. Maximum width is at the umbilical edge. In juvenile stages the venter is fastigate, but in the adult a distinct keel is developed. The keel is of the floored type, and, depending on the mode of preservation, may either be present or absent on internal moulds. Ornament consists of pronounced biconcave striae which arise at the umbilical wall, are bent forwards at first, then sweep gently backward near the middle of the flanks, finally being strongly projected on the outer part of the flanks. They are bundled at their origin, and much stronger on the outer part of the whorls and venter, producing a chevron-like ventro-lateral and ventral ornament. On internal moulds the ornamentation is still present, though very much subdued. Suture line as for genus. Auxiliary saddles in are triphyllic. EXPLANATION OF PLATE 76 Fig. \a~h. Carinophylloceras collignoni gen. et sp. nov. Holotype, SAS A 1577. PLATE 76 KLINGER et al., Carinophylloceras 660 PALAEONTOLOGY, VOLUME 18 E t TEXT-FIG. 1 , Sutures of Carinophylloceras collignoni gen. et sp. nov. a, external suture of UPE B464, X 2. b, external suture of UPE B33, x 2. Discussion. In the description of the stratigraphy of Natal and Zululand (Kennedy and Klinger 1975), the present specimens were referred to the desmoceratid genus Damesites because of the presence of a ventral keel. Homeomorphy with Damesites is, indeed, very close. Not only the whorl section and the presence and shape of the keel, but also the degree of shell involution, the course of the ornamentation, and even the external suture line show such similarities that the genera can scarcely be dis- tinguished. Examination of the suture line, especially the internal part, reveals that EXPLANATION OF PLATE 77 Figs. 1-3. Carinophylloceras collignoni gen. et sp. nov. \a-h, paratype BMNH C78644, showing details of ornament and keel and deep lituid internal lobe in section (arrowed). 2, paratype SAS EM 1 14, showing lituid internal lobe, x2. 3a-/), paratype BMNH C78768, showing juvenile ornament and fastigate venter. PLATE 77 KLINGER et al., Carinophylloceras 662 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 2. Carinophylloceras coUignoni gen. et sp. nov. External suture of UPE B33, x 2. TEXT-FIG. 3. Carinophylloceras col- lignoni gen. et sp. nov. Internal sutures of SAS EMI 14, showing overlapping lituid lobes, x 12-5. KLINGER ET AL.: A NEW CARINATE PH YLLOCERATID 663 it is typically phylloid with a lituid internal lobe, characteristic of all phylloceratinids (Wiedmann 1968, p. 115; Kullmann and Wiedmann 1970, pp. 11-14). The internal lobe of Dame sites as figured by Matsumoto (1954, fig. 11, reproduced here as text- fig. Ab), is intensively frilled, and of desmoceratid type; indeed, no desmoceratids known possess a lituid internal lobe. Text-fig. 4 shows Damesites sutures for com- parative purposes. TEXT-FIG. 4. a, external suture lines of Damesites damesi (Jimbo), after Matsumoto 1954, fig. 10, x4. b, external and internal sutures of a juvenile D. damesi at D = 8-5 mm. After Matsumoto 1954, fig. 1 1. Keeled phylloceratids occur in the Jurassic, i.e. Harpophylloceras Spath, 1927 and Menegheniceras Hyatt, 1900. There are, however, no Cretaceous taxa referable to these genera and affinities of Carinophylloceras with these forms may be ruled out. The suture line of Carinophylloceras, with an asymmetrical diphyllic saddle EjL and asymmetrical tetraphyllic L/t/2, the ornamentation, degree of evolution, and to a lesser extent whorl section point to affinities with the Albian/Cenomanian Phylloceras (Hypophylloceras) velledae {sensu Wiedmann 1964), and to the Albian/ Aptian Ph. {H.) cy pris cyprisY dWoi and Termier (Wiedmann 1964, fig. 50, pi. 13, fig. 3, etc.). Apart from the keel, the whorl section is intermediate between Ph. (H.) velledae velledae and Ph. (//.) velledae morelianum. The presence of a keel, however, clearly separates Carinophylloceras collignoni from these forms. It is interesting to note that within the Tetragonitaceae an analogous development of a keel occurs in Carinites Wiedmann, 1973, thus also mimicking a desmoceratid exterior to a certain extent. Carinophylloceras provides a further example of homeomorphy within the Ammonoidea, and demonstrates how consideration of the sutural formula can clarify relationships which are obscure when only external features are taken into account. 664 PALAEONTOLOGY, VOLUME 18 Acknowledgements. We are grateful to Professor J. Visser (Pretoria University) for placing material from the Boschoff Collection at our disposal and to Mr. D. Phillips and Dr. M. K. Howarth of the British Museum for assistance and discussion. The paper is published by permission of the Director of the South African Geological Survey, Pretoria. REFERENCES ARKELL, w. J. 1950. A classification of the Jurassic ammonites. J. Palaeont. 24, 354-364. HYATT, A. 1900. Cephalopoda, pp. 502-604. In zittel, k. a. von, 1896-1900. Textbook of Palaeontology. Eastman & Co., London. KENNEDY, w. J. and KLINGER, H. c. 1972. Hiatus concretions and hardground horizons in the Cretaceous of Zululand. Palaeontology, 15, 539-549, pis. 106-108. 1975. Cretaceous faunas from Zululand and Natal, South Africa. Introduction, Stratigraphy. Bull. Br. Mus. nat. Hist. (Geol.), 25, 266-312. KULLMANN, J. and wiEDMANN, J. 1970. Significance of sutures in phytogeny of Ammonoidea. Univ. Kansas Palaeont. Contrib. 47, 1-32. MATSUMOTO, T. 1954. Selected leading Cretaceous ammonites in Hokkaido and Sakhalin, pp. 243-313, pis. 17-36. In MATSUMOTO, T. (ed.). The Cretaceous System in the Japanese Islands. Jap. Soc. Prom. Sci., Tokyo. SPATH, L. E. 1927-1933. Revision of the Jurassic cephalopod faunas of Kach (Cutch). India Geol. Survey Mem., Palaeont. Indica, N.s. 9, mem. 2, pts. 1-6, 945 pp., 130 pis. WIEDMANN, J. 1964. Unterkreide-Ammoniten von Mallorca. 2. Lief. Phylloceratina. Abh. Akad. Wiss. Lit. Mainz. Math.-naturw. KL, 1963, nr. 4, 157-264, 64 figs., 21 pis. 1968. Neue Vorstellungen uber Stammesgeschichte und System der Kreideammoniten. Proceed. IPU, XXIII d' International Geol. Congress, 93-120, 1 pi. 1973. The Albian and Cenomanian Tetragonitidae (Cretaceous Ammonoidea) with special reference to the circum-indic species. Eclogae geol. Helv. 66, 586-616, 8 pis. ZITTEL, K. A. VON. 1884. Handbuch der Paleontologie. 1. Abt. II, Lief. Ill, Cephalopoda, pp. 329-522. Munchen & Leipzig. H. C. KLINGER Geological Survey of South Africa Private Bag XI 12 Pretoria 0001 South Africa J. WIEDMANN Geologisch-Palaontologisches Institut Universitat Tubingen Sigwartstrasse 10 D 74 Tubingen Germany W. J. KENNEDY Department of Geology and Mineralogy Parks Road Oxford, 0X1 3PR Typescript received 7 October 1974 Final typescript received 28 November 1974 S>'- ■■ "■* - ~-.V6»*^-i-- • • • • n ■■ -.• • . ij'o . ■ .,, ■ f " ' j®’ ■ ■ - '--i ' ,;4. ■> , >• . -t^fr S*^4' ' • I , haf - * = '• r'^^T'r ' PIT! ■^‘^'. i' , - I - <• V .<• . V KJ I / ?; ( = 5? THE PALAEONTOLOGICAL ASSOCIATION The Association was founded in 1957 to further the study of palaeontology. 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Hudson, Department of Geology, The University, Leicester, LEI 7RH Treasurer'. Dr. J. M. Hancock, Department of Geology, King’s College, Strand, London, WC2R 2LS Membership Treasurer: Dr. E. P. F. Rose, Department of Geology, Bedford College, Regent’s Park. London, NWl 4NS Secretary: Dr. C. T. Scrutton, Department of Geology, The University, Newcastle upon Tyne, NEl 7RU Editors Dr. L. R. M. Cocks, Department of Palaeontology, British Museum (Natural History), Cromwell Road, London, SW7 5BD Dr. C. P. Hughes, Department of Geology, Sedgwick Museum, Cambridge, CB2 3EQ Dr. J. W. Murray, Department of Geology, The University, Bristol, BS8 ITR Dr. C. B. Cox, Department of Zoology, King’s College, Strand, London, WC2R 2LS Other Members of Council Dr. D. D. Bayliss, Llandudno Dr. M. C. Boulter, London Dr. C. H. C. Brunton, London Dr. J. C. W. Cope, Swansea Dr. G. P. Larwood, Durham Dr. C. R. C. Paul, Liverpool Dr. J. E. Pollard, Manchester Dr. R. E. H. Reid, Belfast Dr. R. B. Rickards, Cambridge Dr. A. W. A. Rushton, London Dr. E. B. Selwood, Exeter Professor D, Skevington, Galway Dr. P. Toghill, Church Stretton Dr, P. G. Wallace, London Overseas Representatives Australia : Professor Dorothy Hill. Department of Geology. University of Queensland, Brisbane Canada : Dr. B. S. Norford, Institute of Sedimentary and Petroleum Geology, 3,t03-33rd Street NW., Calgary, Alberta India: Professor M. R. Sahni, 98 Mahatma Gandhi Marg. Lucknow (U.P.). India New Zealand: Dr. G. R. Stevens, New Zealand Geological Survey, P.O. Box 30368, Lower Hutt West Indies and Central America : Mr. John B. Saunders, Geological Laboratory, Texaco Trinidad, Inc., Pointe-a-Pierre, Trinidad, West Indies Western U.S. A.: Professor J. Wyatf Durham, Department of Paleontology, University of California, Berkeley 4, California Eastern U.S. A. : Professor J. W. Wells, Department of Geology, Cornell University, Ithaca, New York South America: Dr. O. A. Reig, Departamento de Biologia, Universidad de Los Andes, Merida, Venezuela Palaeontology VOLUME 18 ■ PART 3 CONTENTS Palaeoecology of a bituminous shale— the Lower Oxford Clay of central England K. L. DUFF 443 Megaspores and massulae of Azolla prisca from the Oligocene of the Isle of Wight K. fowLer 483 Ludlow benthonic assemblages J. D. LAWSON 509 The trilobite Lejopyge Hawle and Corda and the middle-upper Cambrian boundary B. DAILY and J. B. JAGO 527 The ostracod Paraparchites minax Ivanov, sp. nov. from the Permian of the U.S.S.R., and its muscle-scar field M. N. GRAMM and V. K. IVANOV 551 The Bradycnemidae, a new family of owls from the upper Cretaceous of Romania C. J. O. HARRISON and C. A. WALKER 563 A new ?bryozoan from the Carboniferous of eastern Australia B. A. ENGEL 571 The Hauterivian ammonite genus Lyticoceras Hyatt, 1900 and its synonym Endemoceras Thiermann, 1963 C. W. WRIGHT 607 Two Triassic fish from South Africa and Australia, with comments on the evolution of the Chondrostei P. HUTCHINSON 613 Silurian crinoids from the Pentland Hills, Scotland J. C. BROWER 631 A new carinate phylloceratid ammonite from the early Albian (Cretaceous) of Zululand, South Africa H. C. KLINGER, J. WIEDMANN and W. J. KENNEDY 657 Printed in Great Britain at the University Press, Oxford by Vivian Ridler, Printer to the University Published by The Palaeontological Association ■ London Price €5 THE PALAEONTOLOGICAL ASSOCIATION The Association publishes Palaeontology and Special Papers in Palaeontology. Details of member- ship and subscription rates may be found inside the back cover. PALAEONTOLOGY The journal Palaeontology is devoted to the publication of papers on all aspects of palaeontology. Review articles are particularly welcome, and short papers can often be published rapidly. A high standard of illustration is a feature of the journal. 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Ingham as the symbol lor the Symposium on the Ordovician System, Birmingham. 1974. Based on silicihed material collected by Dr. R. Addison Irom limestones of Upper Llandeilo age from Wales. KIRKLANDIA TEXANA CASTER- CRETACEOUS HYDROZOAN MEDUSOID OR TRACE FOSSIL CHIMAERA? by F. T. FURSiCH and w. j. Kennedy Abstract. A re-examination of Kirklandia texana Caster, 1945 described originally as a medusoid hydrozoan, revealed stratinomic, preservational, and morphological features incompatible with interpretations as a body fossil. An alternative interpretation, with the ‘bell’ of Kirklandia as a feeding trace of Gyrophyllites type and the ‘arms’ as fecal-pellet-lined burrows comparable with Granularia, satisfactorily explains these anomalous features. The genus Kirklandia and the family Kirklandidae should be removed from the Coelenterata and the medusoid hydrozoans (order Trachylinida) thus have no unequivocal fossil representatives. The last hundred years has seen the description of a variety of actual or supposed fossil hydrozoan medusae. These range from mere stellate impressions on the top surfaces or soles of sandstones, through lobate concretions and composite moulds to material retaining details of internal organs, tentacles, and umbrellar ornament (Riiger and Riiger-Haas 1925; Kuhn 1937; Riiger 1933; Kiderlen 1935; Lorcher 1931; Huene 1901; Caster 1945; Kolb 1951; Sprigg 1947, 1949; Harrington and Moore 1956; Glaessner 1961, 1962, 1966; Glaessner and Wade 1966; Wade 1968). These fossils have in turn been used to draw conclusions on topics as distant as coelenterate phylogeny (e.g. Ruger 1933; Caster 1945) and intertidal exposure (Ruger 1933). In the Treatise (Harrington and Moore 1956) some eight fossil genera are tentatively classed as hydrozoan medusae. Of these, Beltanella Sprigg, 1947 and Ediacaria Sprigg, 1947 from the late Precambrian Ediacara fauna of South Australia are undoubted medusoids, but cannot be referred with confidence to any of the coelen- terate classes (Glaessner and Wade 1966). Acalepha Beyrich, 1849, Acraspedites Haeckel, 1869, and Hydrocraspedota Kolb, 1951 are doubtfully classed as Trachylinid medusae, whilst Atollites Maas, 1902 and Palaeosemaeostoma Riiger, 1933 are definitely trace fossils (Seilacher 1955, 1962; Vialov 1968; Hantzschel 1970 with references; Grubic 1970 with references). Thus only the genus and species Kirklandia texana Caster, 1945 remains as a hitherto undisputed fossil record of the medusoid hydrozoans, the Trachylinida, and the sole member of the Family Kirklandidae Caster, 1945. This species is known from scores of individuals from the Albian Paw Paw Formation of Texas, and there is an additional doubtful record of the genus from the German Dogger (Lorcher 1931). The Cretaceous material occurs typically as sharp sandstone external moulds preserved in full relief. Caster recognized a remarkable degree of structure interpreted as a lobate body typically divided by eight adradial sulci, petaloid stomach pouches, genital sacs with paired gonads, a quad- rate, functional mouth, and eight apparently rod-like tentacles covered in pustules, interpreted as nettling structures. During the summer of 1974 we had the opportunity of studying the holotype and [Palaeontology, Vol. 18, Part 4, pp. 665-679, pis. 78-80.] A 666 PALAEONTOLOGY, VOLUME 18 paratype material preserved in the Smithsonian Institution, Washington, D.C., and a large number of additional specimens housed in that institution and the Texas Memorial Museum, Austin, Texas. With the paratype material preserved in the University of Cincinnati Museum, Princeton University Museum, and other collec- tions (Caster 1945, p. 186) over a hundred individuals are available for study. They suggest that, on the basis of preservation and morphology, Kirklandia is not a medu- soid, but rather a chimaera— a chance association of a feeding burrow of Gyrophyllites type and a fecal-pellet-lined or stuffed hmro'w-Granularia. THE MATERIAL Preservation. The Kirklandia material studied here consists predominantly of depressions— described as natural moulds by Caster (1945)— on the top surfaces of thin-bedded, ripple cross-laminated fine sandstones with a calcareous cement. The sandstone slabs are generally less than 10 cm in thickness, and laminations are generally well preserved, although showing some biogenic disturbance. These are cylindrical burrows both normal and sub-parallel to bedding, some being empty (although originally clay infilled), others with meniscus-like back fills. Escape struc- tures are frequent. Bottom surfaces bear common sole markings; some of these are of inorganic origin, while others are meandering and branching burrows preserved in positive hyporelief. Top surfaces are often covered in diverse burrows in addition to Kirklandia (Caster 1945, p. 186, pi. 4, fig. 6). There are also three supposed natural casts of Kirklandia preserved as ellipsoidal sideritic and pyritic concretions (Caster 1945, pi. 5, figs. 1-5). Occurrence. The bulk of the Kirklandia material originates from the area around Roanoke in Denton County, Texas. The supposed natural casts are from Gaines- ville, Texas. The former region coincides with what Sellards et al. (1966) describe as their second facies of the Paw Paw, a blackish lustrous clay with ironstone and jasper-like concretions and occasional sandstone ledges. The facies around Gaines- ville is somewhat similar (Hill 1901). The sandstones occur interbedded with clays which yield an extensive normal marine fauna, including diverse ammonites (Adkins 1920, 1928 ; Clark 1965). The whole is interpreted as representing a relatively offshore environment. Morphology. Caster (1945) provides a lengthy description and extensive illustrations of Kirklandia and only an outline is therefore needed here. Kirklandia consist of scalloped depressions, generally from 40 to 100 mm in diameter and up to 35 mm depth. There is, in our view, no consistent symmetry other than radial. Up to three EXPLANATION OF PLATE 78 Fig. 1 a-h. The holotype of Kirklandia texana Caster, la, the negative epirelief, from the Paw Paw Formation (Albian), 2 miles west of Roanoke, Denton County, Texas, USNM 136131a. \h, silicone mould of same, OUM KT 8/P. Fig. 2. Silicone mould of a specimen from the Paw Paw Formation (Albian) at USGS Mesozoic Locality 22258. Blue Mound, 5 miles south of Haslet, Tarrant County, Texas. OUM KT 9/P. Fig. 3. A further specimen, preserved as a negative epirelief, from the same locality. PLATE 78 FURSICH and KENNEDY, Kirklandia 668 PALAEONTOLOGY, VOLUME 18 cycles, each with from five to sixteen lobes, are present within the structure (Plate 78, figs. 1-3; Plate 79, figs. 1-3; Plate 80, fig. 3; text-fig. 1), six or seven being the com- monest lobe number. Lobes vary enormously in relative development within cycles, and may be equal or highly unequal. The divisions between lobes, preserved as tapering walls of sandstone (Caster’s radial sulci), are likewise variable in develop- ment, whilst the depressions between vary from deep and narrowly rounded (Plate 78, fig. \a-b) to the shallowest of scoops (Plate 78, fig. 2; Plate 79, fig. 2; text-fig. 2). One of the most critical features of these lobes is that many are associated with definite overhangs— partial roofs of sandstone (text-fig. 2). The outermost cycle of lobes is in general the shallowest and most poorly dilfer- entiated. The intermediate, generally deeper, cycle consists of two lobe types. There are elongate petaloid structures extending to the centre of the disc (Caster’s insert lobes) and those which are reduced, triangular, and peripheral (Caster’s exsert lobes ; see text-fig. 1). The lobes of the innermost cycle are deep inflated structures corre- sponding approximately with the position of the longer petaloid ‘insert’ lobes of the middle cycle. Lobe surfaces commonly show distinct, subparallel concretic striations (Plate 79, figs. 2-3). Caster regarded these as wrinkles resulting either from desicca- tion shrinkage prior to burial, or rigor mortis contraction (Caster 1945, pp. 176, 180). In the centre of the disc there may be depressed areas with a conical protuberance and an axial and tubular pit (Plate 78, fig. \a-b\ Plate 79, figs. 2-3). The ‘arms’ of Kirklandia described by Caster are tubular, sometimes branching cavity systems extending through the sandstone slabs (Plate 80, fig. la-b), or mere depressions on top surfaces (Plate 80, fig. 6). The tubes are about 10 mm diameter, and their surfaces are covered in randomly orientated ellipsoidal depressions up to 1-5 mm in length (Plate 79, fig. 5 and Plate 80, figs. 6 and 7 show silicone rubber moulds of these). THE MEDUSOID INTERPRETATION The original view. Text-fig. \a-b shows Caster’s original interpretation of Kirklandia as natural moulds of the oral or subumbrellar surfaces of trachylinid medusae. The outer cycle of lobes are interpreted as the peripheral zone of the umbrella, the central cycle as the gastric lobes, and the inner cycle as gastrogenital sacs. Obscure structures on some specimens are interpreted as paired gonads within genital sacs. The central area, conical protuberance, and central pit are interpreted as the mouth and associated EXPLANATION OF PLATE 79 Fig. \a-b. A paratype of Kirklandia texana Caster, la, the negative epirelief, USNM 136131b, from the Paw Paw Formation (Albian), 2 miles west of Roanoke, Denton County, Texas, lb, silicone mould of same, OUM KT 11/P. Fig. 2. A silicone mould of Kirklandia texana, from the Paw Paw Formation of USGS Mesozoic Locality 22258, Blue Mound, 5 miles south of Haslet, Tarrant County, Texas. OUM KT 13/P. Fig. 3. Same locality as fig. 2, preserved as a negative epirelief. Fig. 4. Surface details of a specimen of the fecal-pellet-iined burrows Granularia from the Atherfield Clay Series (Lower Aptian), Atherfield, Isle of Wight, Hampshire. BMNH A6208 (Stinton Collection), x2. Fig. 5. Surface details of a silicone mould of the ‘arms’ of Kirklandia texana from the same locality as fig. 2; compare with the Granularia shown in fig. 4, OUM KT 12/P, x 2. PLATE 79 FURSICH and KENNEDY, Kirklandia, Granularia 670 PALAEONTOLOGY, VOLUME 18 organs, the mouth being quadrate (text-fig. \a). The granules on the ‘arms’ are interpreted as stinging cells. Objections. 1. Preservation potential of medusoids. There are three chief situations in which medusoids can become fossilized. (1) In the intertidal zone, (2) associated with very fine grained sediments in restricted environments and burial by special mechanisms, as is the case of the Solnhofen Limestone and Burgess Shale occurrences, and (3) as a result of rapid burial by clastic influx in exceptional conditions, as at Ediacara. Observations on the preservational potential of medusoids, albeit brief, are wide- spread. The early studies and experiments of Walcott (1898) are now classic; there are more recent observations by Trusheim (1937), Wagner (1932), Schafer (1941), Lincke (1956), Muller (1970), experiments by Hertweck (1966), and extensive bio- stratinomic discussion by Schafer (1962, pp. 212-216; available in English translation 1972, pp. 157-190, pis. 31b-39a). Medusoids can be preserved only as moulds, and exposure and desiccation are a prerequisite; they cannot occur as body fossils. The mould is produced by body and organs within a few hours of stranding, and the precise organs identifiable on moulds depend on sediment grain size, water content, and rate of decomposition amongst other factors. As the buried bell decays and subsides the overlying sediment collapses, and all that remains is a composite mould, perhaps picked out by a thin clay veneer, above which is a region of disturbed and crumpled lamination. In some cases the gastrovascular cavity and genital pouches can fill with sediment, either passively, or as a result of inadvertent ingestion during pumping motions as the stranded organism tries to escape. These ‘stomach stones’ have preservation potential, and indeed Walther (e.g. 1910) and others have described such objects. The second category of fossilization again results in the preservation of the medu- soid as a composite mould, or mere film of organic material. The best-known examples are the Solnhofen Limestone, Germany (Barthel 1964, 1970; Van Straaten 1971) and Burgess Shale, Canada (Whittington 1971; Piper 1972a, b). In both cases the medusoids (and indeed other fauna) were buried in very fine-grained material, apparently by turbiditic mud clouds (microturbidites) in local euxinic basins. The Ediacara occurrences of Australia (Wade 1968; Goldring and Curnow 1967) are in relatively coarse-grained sediment. Medusoids occur as moulds in two situa- tions. The commonest is in positive relief on the bottom of sandstone laminae; after rapid burial tissues decayed, and sediment collapsed into the void to produce a species of composite mould. If a clay lamina was present between quartzitic laminae, a counterpart mould may also occur on the subadjacent lamina (Wade 1968, figs. 7, 9, 11). In all cases the mould has an extremely low relief. 2. Comparisons with Kirklandia. The Kirklandia material shows none of the features of preservation and preservational environment seen in undoubted fossil medusoids. The fauna, sedimentology, and palaeogeographic setting of the Paw Paw in the area yielding the specimens studied are offshore, normal marine, with no evidence of inter- tidal exposure, nor of restricted bottom conditions nor burial in fine-grained sedi- ment. The material occurs with full three-dimensional relief on the top surfaces of FURSICH AND KENNEDY: KIRKLANDIA 671 Rr TEXT-FIG. 1. The medusoid interpretation of Kirklandia. a, oral or sub- umbrellar view showing the basic four-part symmetry. According to Caster, the mutability of the species is attained by asymmetrical centri- petal insertion of exsert lobes and perhaps by splitting of the canaliculate radii. B, axial section through the restored disc of Kirklandia. Known features are shown in solid outlines; all others inferred from similarities to the trachyline hydrozoa. Ar, adradius; Cd, central disc; Cm, delicate circular corrugations or rugae of the peripheral zone (possibly ring-muscles or velar muscles); Ex, exsert lobes; G, inferred internal gonads; Ggs, gastrogenital sacs on the radial canals ; Gu, implied gelatinous umbrella ; Gw, gastric wall or shrunken residue of gelatinous umbrella; In, insert lobe; Ir, interradius; Mg, low carina between ovoid depressions on the swollen protuberances; Pd, paired depressions on the swollen pro- tuberances (perhaps indications of the gonads within the gastro-genital pouches); Pf, peripheral field (subumbrella or velum); Pr, perradius; Uc, umbral concavity of aboral surface (modified from Caster 1945, fig. 1 and fig. 4). 672 PALAEONTOLOGY, VOLUME 18 sandstones and therefore cannot be compared with the Ediacara material. Further- more, sections show the Kirklandia cutting across laminations, rather than distorting laminae, which suggests a post-depositional emplacement. Perhaps the most serious objection to a medusoid origin is the presence of overhangs in many sections (text- fig. 2). These could survive only if cementation occurred prior to decomposition of TEXT-FIG. 2. Cross-sections of Kirklandia lobes (after Caster 1945, fig. 5). Note overhanging rims and partial roofs of sediment to lobes in many specimens. the coelenterate tissue. In the environment indicated for the Paw Paw, such de- composition would take only hours or days; there is none of the petrographic evidence of early cements reviewed by Bathurst (1971), whilst the distortion by compaction of some burrows and the obvious cross-cutting relations of others suggest a relatively late date for cementation. Finally, if these indeed are medusoids, the absence of material preserved on bottom surfaces is curious. The supposed EXPLANATION OF PLATE 80 Figs. 1-2. "Caulerpa carruthersi' —Gyrophyllites preserved in three dimensions. Fig. 1 is BMNH 25 (Damon Collection) a section normal to bedding; fig. 2 is BMNH V 2546 (Damon Collection) a section parallel to bedding. These specimens have been preserved by early diagenetic cementation of the clay matrix they were excavated in (compare text-fig. 3a). Kimmeridge Clay (Kimmeridgian) of Sandsfoot, Dorset, x2. Fig. 3. Kirklandia texana Caster. Specimen preserved as a negative epirelief on the upper surface of a sand- stone slab from the Paw Paw formation (Albian) of USGS Mesozoic Locality 22258, Blue Mound, 5 miles south of Haslet, Tarrant County, Texas. Fig. 4. Granularia sp. BMNH A789 (Wethrell Collection) from the London Clay (Yprisian) of Chalk Farm, London. Fig. 5. Granularia sp. BMNH A6154, a club-shaped specimen from the Atherfield Clay Series (Lower Aptian) of the Lower Greensand, Atherfield, Isle of Wight, Hampshire. Compare with fig. 6 of this plate. Figs. 6, la~b. Moulds (6, Ih) and silicone impression (7a; OUM KT 10/P) of Kirklandia arms from the Paw Paw formation (Albian) of USGS Mesozoic Locality 22258, Blue Mound, 5 miles south of Haslet, Tarrant County, Texas. PLATE 80 FURSICH and KENNEDY, Kirklandia, Granularia 674 PALAEONTOLOGY, VOLUME 18 ‘natural casts’ of Kirklandia are equally unlikely to be medusoids, since all other workers have concluded that body fossils of medusoids cannot be preserved. We stress that the depositional environment of the Paw Paw, where Kirklandia is found, is neither one of fine-grained substrate and rapid burial under restricted conditions, nor is it intertidal. In addition there is no stratinomic or petrographic evidence to suggest that these were body fossils buried in sediment and preserved in three-dimensions by rapid cementation ; they are a post-deposition phenomenon and their matrix was cemented at a relatively late date. The biological problems of accepting Kirklandia as a medusoid were discussed by Caster (1945, pp. 187 et seq.). Thus his genus not only mingles features of the Narco- medusidae and Trachymedusidae, but also includes many unique traits, the most striking of which is the enormous variation in the number of body lobes and sym- metry. KIRKLANDIA AS TRACE FOSSILS What we believe to be the true nature of Kirklandia is suggested by Caster’s (1945, p. 184) comment, where he notes two specimens which ‘show either arms or worm burrows emanating from the central area of the mould. In one the burrow-like structure enters the rock, and its termination is unknown. In the illustrated specimen, the two “burrows” terminate in large fusiform expansions, unlike anything seen on any of the worm spoor interlacing the matrix of most slabs.’ We have sectioned a number of specimens, and some of these clearly show an open, or sediment filled, vertical cylindrical burrow extending down into the sandstone slab from the centre of the ‘mouth’ of Kirklandia. This feature recalls the relationship demonstrated by Hantzschel (1970, p. 207, pi. 2) in very similar stellate depressions on the top surfaces of Lower Jurassic sandstones. Hantzschel interpreted these structures as a surface trace, produced by the surface grazing of an animal dwelling in the central tube. The difficulty in applying this interpretation to Kirklandia is that it does not explain the overhangs associated with many of the deeper lobes, the presence of several cycles of lobes, or the observation that a central burrow is not always present. We would therefore suggest that Kirklandia in fact represents the preservation of the distal parts of a much more extensive feeding burrow of Gyro- phyllites type. Gyrophyllites consists of a vertical shaft from which arise rosettes of short, simple, tear-shaped lobes, interpreted by Seilacher (1955) and Hantzschel ( 1 962) as feeding structures. Some typical ‘three-dimensional’ Gyrophyllites are shown in Plate 80, figs. 1-2 and schematically in text-fig. 3. The preservation potential of Gyrophyllites {text-fig. 3). The preservation of a burrow in the sedimentary record depends mainly on the following factors; (a) the nature of the infilling, (b) the sedimentary interfaces through which the trace fossils cut, and (c) the subsequent diagenetic history of the sediment. The Gyrophyllites animal seems to have preferred fine-grained substrates, pre- sumably because of their high organic content. A large percentage of the known occurrences of Gyrophyllites are therefore in mudstones, silts, or even clays. In these cases the burrow fill usually does not differ a great deal from the matrix, and after diagenesis the burrows will be difficult to pick out, especially as compaction will FURSICH AND KENNEDY: KIRKLANDIA 675 endorelief TEXT-FIG. 3. The preservation potential of Gywphyllites. a, reconstruction of the complete burrow; b, c, three-dimensional preservation of the burrow or parts of it by early diagenetic mineralization. The forma- tion of concretions can be confined either to the burrow fill (6) or to the surrounding sediment (c) ; d, preser- vation as compacted endoreliefs in fine-grained sediments as in most Flysch and Molasse occurrences; e, preservation as negative epirelief at clay/sandstone interfaces. largely destroy their three-dimensional nature. If the fill differs from the matrix, thin impressions of rosettes can be found on the upper or lower surfaces of slabs— the common preservation of Flysch and Molasse specimens (text-fig. 3d). To guarantee a three-dimensional preservation of Gyrophyllites differential diagenesis must take place. This can either be an early cementation of the infilling, resulting in a concretion whilst the surrounding sediment remains uncemented (text-fig. 3b). Such seems to have been the case in, for instance, the three-dimensional specimen of Medusina liasica of Ruger and Riiger-Haas (1925). Alternatively, the matrix can have been cemented early in diagenesis, while the burrow infillings remained soft. Damon’s (1888) specimens of Caulerpa carruthersi from the Kimmeridge Clay of Dorset illustrate the latter case (text-fig. 3c; Plate 80, figs. 1-2). Here, calcareous/sideritic mudstone concretions formed around the burrows which are filled with soft clay. Finally, parts of the Gyrophyllites system can be preserved at sedimentary interfaces, usually at clay/sand junctions. This is the mode of preservation of the bulk of the ^ Kirklandia’ and many other fossil ‘medusoids’. In these cases, parts of the burrow system. 676 PALAEONTOLOGY, VOLUME 18 especially the more or less horizontal rosettes of lobes, are found as negative epireliefs on sandstone surfaces (text-fig. 3c), which usually seem to have set the lower limit of sediment penetration. Kirklandia as Gyrophyllites. As a deposit feeder, the producer of Gyrophyllites mined the sediment for food, probably inhabiting a vertical shaft from which the sediment was explored in a radial fashion. The preservation of Gyrophyllites at a sedimentary interface suggests the burrows were excavated primarily in clays. These were exploited for food by the animals shifting their burrows downwards when a rosette was completed to start a further series of radial excavations at a lower level (text-fig. 4). When a clay/sand interface was reached, mining generally terminated, for the sands were low in nutrients due to their larger grain size. In some cases a probing shaft was extended down into the sand (text-fig. 4c), but always abandoned; the ‘bell’ of Kirklandia thus represents the lowest rosette or rosettes of tunnels pro- duced immediately before abandoning the excavation. Text-fig. 4 illustrates how the great variety of Kirklandia can be explained by a combination of slight variations in burrowing behaviour and by preservational phenomena associated with the position of the rosette/rosettes of feeding lobes relative to the clay/sand interface. The size of the central ‘disc’ depends on the position of the axial tube of the burrow system (text-fig. 4), from where the radial feeding lobes originate, relative to the buried sedimentary interface. When well above the interface (text-fig. 4a), only the distal parts of the feeding lobes reach the sand, and the result is a large central ‘disc’. As the distance decreases (text-fig. Aa-b) the central A TEXT -FIG. 4. Generalized features of Kirklandia interpreted as a feeding burrow of the Gyrophyllites type. Vertical sections are reconstructions; only the negative epireliefs are preserved. Horizontal shading is clay, stippling is sand. FURSICH AND KENNEDY: KIRKLANDIA 677 disc becomes smaller, and the lobes deeper and their more proximal parts are also preserved (text-fig. Ab). If the animal extended an exploratory shaft down into the sandstone, then the specimen will bear a central sandstone plug and associated features— Caster’s (1945) manubrial apparatus (text-fig. Ac). The presence of two or three rosettes suggests that lobes were in some cases closely stacked ; this is clearly an efficient means of exploiting the sediment (text-fig. Ad-e), whilst crowding may also have been produced by final intense exploitation of the clay above the top of the sand layer before the burrow system was abandoned. The variation in relative development of rosettes can be explained by the position of the termination of the axial tunnel to clay/sand interface (compare text-figs. Aa and 3e), whilst shape and depth of lobes depend on the angle between the axis of feeding lobes and the central shaft. With an angle of 90°, the lobes will be very elongate (text-fig. Aa-b) ; as the angle decreases the lobes become deeper, increasingly circular in section, and, in general, will lack their proximal portions (text-fig. Ad-e). By combining these variables, it is thus possible to generate the variety of structures described in the original account of the ‘bell’ of Kirklandia. Kirklandia "arms' as Granularia. The nature of the ‘arms’ of Kirklandia is equally explicable in trace-fossil terms; they are simple or branched burrows which were lined or stuffed with clay pellets, referable to the ichnogenus Granularia Pomel, 1849. The ‘utricating structures’ of Caster (1945) are no more than individual pellets. The association with Gyrophyllites is thus no more than chance; we do not regard them as necessarily products of the same animal. Specimens of Granularia from the English Eocene and Cretaceous are figured for comparison in Plate 79, fig. 4 and Plate 80, figs. 4, 5a-b. The remaining Kirklandia material can also be interpreted as trace fossils. The supposed natural casts (Caster 1945, pi. 5) represent no more than concretions developed around Gyrophyllites systems (text-fig. 5b). Apart from Kirklandia, it is clear that the supposed medusoid Palaeosemaeostoma geryonides (von Huene) is also part of a Gyrophyllites, preserved at a sedimentary interface. The overhanging rim of the lobes in the type species (Kiderlen 1935, fig. 3) suggests that an origin at a sediment /water interface is unlikely. Lorcher’s (1931, pi. 1, figs. 1-3) Medusina, from the German Dogger a, referred to Kirklandia in the Treatise (Harrington and Moore 1956, p. 870) is again part of a Gyrophyllites, preserved as a negative epirelief at a clay/sand junction. Identical "Kirklandia' stellate traces in the same preservation in interbedded clay/sandstone successions of Car- boniferous age from central Texas have been shown to us by Professor J. E. Warme of Rice University. CONCLUSIONS On the basis of stratinomic considerations and morphological criteria, we therefore regard the interpretation of Kirklandia texana Caster, 1945 as a fossil medusoid as untenable. We prefer to interpret it as a trace-fossil chimaera, the ‘bell’ being the distal parts of a feeding burrow of Gyrophyllites type, while the ‘arms’ are fecal-pellet- lined burrows of Granularia type. This interpretation satisfactorily explains preserva- tional and morphological aspects of the structures described by Caster which are inconsistent with a medusoid origin. 678 PALAEONTOLOGY, VOLUME 18 The genus Kirklandia Caster, 1945 and the Family Kirklandidae Caster, 1945 should be removed from the Coelenterata ; Kirklandia should be tentatively classed as a synonym of Gyrophyllites Heer, 1841 (non Wiedmann 1962, Cretaceous Ammo- noidea). There is therefore no known fossil record of the medusoid hydrozoa (Order Trachylinida Haeckel, 1877). Acknowledgements. We thank Dr. E. G. Kauffman and Mr. F. Collier of the Smithsonian Institution, Washington, D.C. and Dr. C. Duerden of the Texas Memorial Museum, Austin, Texas for allowing us to study collections in their care. Professor A. Seilacher, Tubingen, provided useful discussion. Financial support from the Lindemann Trust (W. J. K.) and the Sonderforschungsbereich 53 ‘Palokologie’, Tubingen (F. T. F.) is gratefully acknowledged. 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KENNEDY Original typescript received 3 March 1975 Department of Geology and Mineralogy Revised typescript received 20 April 1975 Parks Road, Oxford V ' • 'I I * i k'j » *iSJ AN OUTLINE HISTORY OF SEAGRASS COMMUNITIES by M. D. BRASIER Abstract. The primary ecological role played by seagrasses results from their ability to modify the physical environ- ment. Trapping and binding of nutrient-enriched sediments encourages deposit and suspension-feeding invertebrates. Leaves provide a substrate and shelter for flourishing populations of bacteria, algae, protozoans, coelenterates, molluscs, bryozoans, and echinoderms which in turn contribute CaC03 to the sediment, forming strata with a good preservation potential. The seagrass community is best developed in tropical and subtropical regions, especially where alternative nutrient sources are limited. The geological history of seagrass communities is traced with the aid of foraminifera. Gradual encroachment of seagrasses into the sublittoral of the late Cretaceous or early Caenozoic was followed in the Miocene by a rapid dispersal of Thalassia and associated biota, arriving for the first time in the Caribbean and mid Pacific. Few palaeoecologists would doubt that marine vegetation has played a significant role in the ecostystems of the past. Unfortunately, this role must remain largely enigmatic because of the general lack of non-calcified plant material in the fossil record. The basis for this paper was laid in 1970 when the writer examined recent seagrass associated biota (especially foraminifera) around the Caribbean. It was evident from these studies (e.g. Brasier 1973, 1975a, 1975/?, 1975c) and from the con- siderable work of others, that seagrasses exert great influence over both sedimentation and ecology in shallow-water habitats. Their first appearance in the sublittoral might therefore have been marked by a significant change in community structure, and hence of biofacies. The intention of this paper is to examine briefly the present-day ecological role of seagrasses and then to trace their geographic dispersal through time, leading to an assessment of their probable palaeoecological and evolutionary significance. SEAGRASS ECOLOGY Adaptive features. Seagrasses (‘eel’, ‘turtle’, ‘widgeon’, or ‘manatee’ grass) are the only group of angiosperms known to have successfully invaded the sea. Their means of attachment to the substrate, propagation, and nutrient absorption {s.l.) differ considerably from those of marine algae. It is for these reasons that the group has a more marked effect upon water movement, sedimentation, fauna, and flora. Sea- grasses somewhat resemble true grasses in mode of growth but are more closely allied to the freshwater monocotyledons. Den Hartog (1970) has reviewed the main features of the group, noting that it is not yet certain whether marine forms evolved from freshwater forms or vice versa. However, genera adapted to either habitat are known from within the several families so that seagrasses form an ecological rather than a taxonomic group. Most seagrass genera have adapted to the aquatic medium by the development of hydrophilous pollination (Den Hartog 1970). Certain seagrass fruits also float, thus [Palaeontology, Vol. 18, Part 4, 1975, pp. 681-702.] B 682 PALAEONTOLOGY, VOLUME 18 aiding plant dispersal (Opurt and Boral 1964). The principal method of increase is, however, by rhizomatous growth, leaves sprouting at regular intervals along the rhizome. The size and shape of these rhizomes and leaves varies greatly between genera and is well reflected in their ecology. Forms with large strap-like leaves and extensive rhizomatous growth such as Thalassia, Cymodocea, and Posidonia are the ones with most interest for the palaeoecologist for these have the greatest effect on the environment and biota. Habitat conditions. Generalizations concerning the physical factors controlling sea- grass distribution are difficult to make. Most are found below mean low water and above 12 m depth. Some of the larger forms (e.g. Thalassia, Cymodocea, Posidonia) are tolerant of hypersaline conditions (see Brasier 1975a; Logan and Cebulski 1970). However, differing tolerances of dessication, turbidity, current agitation, sediment thickness, grain size, and humic content are amongst the factors which cause ecological zonations of seagrasses in the sublittoral (e.g. Scoffin 1970; Davies 1970; Thomassin 1971 ; Pichon 1971). Furthermore, light intensity and periodicity, as well as tempera- ture, may affect the latitudinal distribution of species (see Marmelstein et al. 1968). Influence of seagrass. Seagrass is notable for its ability to influence the character of the sediment substrate. This results from four more or less independent factors. In the first place it supplies biogenic CaC03 to the substrate in the form of epibionts and shells from invertebrates and calcareous algae. Secondly, the dense plant growth encourages the sedimentation of suspended particles by reducing current velocities (‘baffling’) and/or trapping the material on the blades. Thirdly, none of these would be significant were it not for the rhizomes which stabilize the accumulated sediment and bind it together. Fourthly, it may modify the chemical environment. Seagrass photosynthesis and respiration are thought to cause variation in the O2 and CO2 content of seawater, which in turn may influence the rate of fixation of CaCOj by marine organisms (Davies 1970). Seagrasses can also exert a direct control on the interstitial environment by the reducing action of exudates from plant cells (which probably arise from bacterial action). The role of these factors in sedimentation has already been discussed in some detail by Davies (1970). Their significance is a function of the density of plant growth, the size of the plants, and the width of the leaves, being greatest where all three are maximal. Seagrasses are, indirectly, important producers of biogenic CaCOj because their epibionts are often very dense. Foraminifera and coralline algae may contribute as much as 5100 gm/m^ per year (see Land 1970; Patriquin 1972; Brasier 1975a), productivity of both being higher on shallow, turbulent shores. Furthermore, cal- careous green algae (e.g. Penicillus) which thrive between the blades are copious producers of aragonitic lime mud (Perkins et al. 1972). In many areas the net result of these processes is the formation of carbonate banks (see Moulinier and Picard 1952; Scoffin 1970; Davies 1970; Farrow 1971). SEAGRASS COMMUNITIES A simplified model of community energetics for tropical seagrass communities is outlined in text-fig. 1 , compiled from the extensive literature and the author’s observa- BRASIER: SEAGRASS COMMUNITIES 683 TEXT-FIG. 1 . Generalized diagram of the energy flow in a seagrass community. B = bacteria ; f = foraminifera and other microherbivores ; a = microscopic algae. tions. A review or synthesis of the ecology of seagrass communities is beyond the scope of this study. The comments below are of necessity generalized, with emphasis on forms likely to be preserved in ancient strata. Primary producers. Most workers on seagrass communities have commented on the associated algae (e.g. Scoffin 1970; Taylor and Lewis 1970; Davies 1970) which pro- vide shelter for many animals. Calcareous algae are common and include benthic codiaceans and corallines (e.g. Penicillus, Halimeda, Goniolithon, Lithothamnion) and encrusting epiphytic corallines (e.g. Leptoporolithon = " Melobesia' of many workers). Abundant non calcified algae (e.g. Laurencia) may also cause entrapment of sediment, adding to the growth of a seagrass bank. The primary food source for much of the food web is not seagrass or macro-algae but populations of benthic and epiphytic unicellular algae and bacteria (see Lee et al. 1966; Lipps and Valentine 1970) or the accumulated detritus (Taylor and Lewis 1970). Epizoans. Feeding upon these epiphytic ‘blooms’ and detritus are a diverse population of epizoans, most significant of which (in terms of numbers and diversity) are the foraminifera. Brasier (1975a) has divided these into primary weed dwellers and secondary weed dwellers, the latter being facultative forms from sediment substrates. Primary weed dwellers include many forms of discoidal shape and sessile habit (e.g. Sorites, Amphisorus, Marginopora, Cyclogyra, Planorbulina) some of which are 684 PALAEONTOLOGY, VOLUME 18 extremely large in size (5 mm + ). Morphological criteria for recognizing other kinds of weed-dwelling foraminifera have been discussed by Brasier (1975Z?). Micro- carnivores may include the paradoxostomatid ostracods (McKenzie 1971 ; Maddocks 1966). Organisms using the leaves as a firm substrate for suspension feeding include annelids (e.g. Spirorbis), bivalves (e.g. Pteria, Barbatia), coelenterates, bryozoans, and sponges. Detritus feeders (e.g. Cerithium) also flourish on the leaves. Substrate fauna. The lime mud and decaying organic material trapped and bound by dense plant growth are an encouragement to bacteria and these together with micro- algae and detritus may form the staple diet of benthic foraminifera (Lee et al. 1966; Taylor and Lewis 1970; Lipps and Valentine 1970). Many of these comprise thin- shelled, elongate miliolids of the genus Cycloforina (see Brasier \915b). Foraminifera, algae, and bacteria are in turn a major dietary component of suspension and deposit feeders (Newell 1965; Lipps and Valentine 1970). Gastropods are abundant and diverse (e.g. Cerithium, Strombus, Cypraea, Olivella, Bulla) and an abundance of small gastropods may be one criterion for the detection of the former presence of seagrass (Moulinier and Picard 1952; Davies 1970). Scleractinian corals may also abound, especially forms tolerant offluctuating salinity and pH (e.g. Porites, Manicina, Siderastrea). Dead coral skeletons comprise much of the framework of some seagrass mounds, affording a hard substrate for colonization by epiphytes and epizoans. Echinoids (e.g. Diadema, Tripneustes, Lyteclmus, Toxaneustes, Clypeaster) have adapted to grazing on seagrass leaves and may also be used as palaeoecological indicators (Kier and Grant 1965). Infauna. Infaunal deposit and suspension-feeding bivalves of seagrass communities are often tolerant of low pH and low oxygen supply (Taylor and Lewis 1970; Taylor 1971) and may increase in diversity with increasing organic content (Thomassin 1971). They include lucinoids, tellinids, and pinnids. The deposit-feeding holo- thurians, polychaetes, and sipunculids thrive in the nutrient-enriched sediments around seagrass, whilst suspension-feeding crustaceans (e.g. Neaxius and Calianassa) utilize the organic rich seston (see Farrow 1971 ; Aller and Dodge 1974). The carni- vorous gastropod Conus is also found in the seagrass community, attracted by the plentiful food supply and protective canopy (Taylor 1971). Jackson (1972) and Levinton and Bambach (1975) have discussed the molluscan ecology of tropical and temperate seagrass communities. Diversity. Various studies (e.g. Logan and Cebulski 1970; Taylor 1971; Brasier 1975fl, 1975c) have shown that diversity, biomass, standing crop, and productivity are strikingly greater in seagrass communities than in those of surrounding waters. This is essentially because of the wide variety of habitats afforded to the fauna and flora by seagrass. For example, the variety of foraminiferal tests found around Alli- gator Reef, south of Jamaica, is significantly higher in the vicinity of seagrass (text- fig. 2). A similar temporal example has been described from Abu Dhabi Lagoon (Murray 1 970) in which recent colonization by seagrass greatly improved foraminiferal diversity and standing crop. Conversely, annihilation of the backreef seagrass stands of Buccoo Reef, Tobago, by Hurricane Flora in 1963, resulted in a towering of foraminiferal diversity and standing crop (Dr. S. Radford, pers. comm. 1972). The BRASIER; SEAGRASS COMMUNITIES 685 Textulorio ogglutinons T. candeiana Bigenerina irregularis Valvulino oviedoiona Vertebralina cassis Spiroloculina antillarum Cornuspiramio ontillarum Quinqueloculino agglutinans Q bicostata Q. bidentota 0 candeiana Q cuvieriana Q lomarckiana Q. poeyana 0 polygona 0 quadriiateralis 0 steliigera Q subpoeyona Q triconnota Triloculma carinota T linneiana T oblonga T rotundo T trigonula Pyrgo subsphoerica Sigmoilina orenata Schlumbergerina alveoliniformis Miliolinella circularis Houerina bradyi H ornatissima Articulina mexicana — •=10-20’/. □ =>20’/. A mucronata Archoios angulatus Sorites marginalis Amphisorus hemprichii Peneroplis bradyii P pertusus P profeus Monalysidium pohtum Borelis pulchrus Bulimina marginota Botivina sp. Neoconorbina orbicularis Oiscorbis spp indet. 0. bertheloti 0 tloridana D volvulata Volvulinerio candeiana Astengerina carinota Siphonina pulchra Ammonia beccarii var tepida Rotorbinetla mira R rosea Elphidium discoidale E poeyonum Amphistegina gibboso Cibicides tobatulus C pseudoungerianus Ranorbulino acervalis Cymbaloporetta squammosa Florilus grateloupi DIVERSITV ( V volue ) (58) ED @ i [m 17 I 20 I 4 ' 38 ^ TEXT-FIG. 2. Distribution of recent foraminiferid tests in samples from Alligator Reef, Jamaica; 1 52 = unvegetated backreef calcarenite (depth 1 m); 153 = backreef muddy calcarenite from Thalassia meadow (1 m); 155 = muddy calcarenite from Thalassia- colonized inter-reef channel (2 m); 1 57 = unvegetated inter-reef Halimeda sand (3m); 159 = carbonate-rich terrigenous muds from Thalassia meadow on open shelf (c. 12 m). Sample numbers refer to H.M.S. Fox/U.C.L. Geology Dept, programme, CICAR 1970. 686 PALAEONTOLOGY, VOLUME 18 epidemic infection of the temperate seagrass Zoster a in the 1930s was also accom- panied by a lowering of community diversity (see the review by Johnson 1964). Ancient seagrass assemblages might therefore be expected to show increases in diversity compared with neighbouring biofacies. Community dispersal. Before discussing the distribution of the seagrass community in space and time it is worthwhile to consider the available dispersal mechanisms. Here the concern is primarily the way in which benthonic organisms have crossed wide oceanic barriers such as the tropical Atlantic and the mid Pacific. Some of the possible mechanisms are illustrated in text-fig. 3, none of which can be ruled out on the basis of chance because of the extremely long time period involved. TEXT-FIG. 3. Diagram of dispersal mechanisms available to tropical shallow-water benthos for crossing ocean barriers in the northern hemisphere. Oceanic islands serve as staging posts. The equatorial surface current (east to west) and undercurrent (west to east) are important. Although dispersal by atmospheric phenomena (e.g. hurricanes) or by birds and marine vertebrates need not be insignificant. For certain organisms planktonic larvae are the major means of dispersal. Scheltma (1968) has shown that such larvae make it possible for some marine species to breach faunal barriers and colonize new regions. He found that stenothermal tropical larvae are distributed not only throughout the westerly travelling Equatorial Current but also throughout the easterly travelling Equatorial Undercurrent, which runs around the equator. Scheltma concluded that both currents can account for the amphi- Atlantic distributions of much of the tropical shallow-water benthos between West Africa and South America. Although these various currents are of value to invertebrates with lengthy plank- tonic larval stages, those with short ones, such as the foraminifera, stand little chance of reaching their destination. Hence Vaughan (1933) suggested that foraminifera were dispersed by rafting as individuals or small colonies upon seaweed, and Bock (1969) specifically mentioned Thalassia as the means of their dispersal throughout BRASIER: SEAGRASS COMMUNITIES 687 the Caribbean region. But whilst many types of foraminifera can live on anchored seagrass, only those firmly adherent and encrusting forms such as Planorbulina, Sorites, Amphisorus, Marginopora, discorbids, cibicidids, and phytal miliolids were found alive and abundant by Brasier (1975c) on grass blades floating on the sea’s surface. Forms that are better adapted to a sediment-dwelling niche, such as Archaias, were not only rare or absent on floating seagrass but also on populations of floating Sargassum and filamentous algae. From this one may expect that rafting on weed, including seagrass, is an unlikely mechanism of dispersal for forms ill-adapted for attachment, although not impossible. That adherent foraminifera are more widely dispersed is evident from studies of recent forms. Stenothermal ‘phytal’ foraminifera have a more or less pantropical distribution today, whilst relatively eurythermal phytal forms are almost pandemic (see Brasier 1975a, \915b). Conversely, typically sediment-dwelling foraminifera of the tropics, such as Archaias and the alveolinids, are endemic to certain provinces. Very isolated islands such as Midway Atoll in the mid North Pacific have been colonized by the firmly adherent Sorites and Marginopora rather than by the loosely adherent or free-lying Baculogypsina and Calcarina, genera which have not yet made the journey successfully (see Cole 1969). The pelagic and pseudopelagic dispersal of these organisms is greatly dependent on the current velocity, the length of the journey, and the ecological stresses encountered en route. Because of the nature of the oceanic surface currents, migration is also more difficult from west to east in the tropics and from east to west in high latitudes. However, these constraints may be overcome with the aid of very mobile vertebrates (especially turtles, birds, and man) or special atmospheric and oceanic phenomena (e.g. hurricanes). All such journeys may have their chances of success improved by ‘staging posts’, volcanic and coral islands for example. The role of some of these factors will be considered in special cases below. DISTRIBUTION IN TIME AND SPACE Several lines of evidence can be pursued to indicate the origin and evolution of sea- grass and its associated biota. The plant remains themselves are naturally of prime importance but are usually rare and indifferently preserved (see Den Hartog 1970). Unless the reproductive parts have been fossilized, the remains are not easily dis- tinguished from other monocotyledons, causing dissent as to how meaningful many of the so-called fossil seagrasses are. Therefore only those recognized by Den Hartog (1970) are considered here. Unfortunately, the pollen of seagrass lacks exine and is therefore not preserved. Hence less direct methods must be considered. It is possible to use elements of the rest of the seagrass community such as fora- minifera, molluscs, echinoids, and crustaceans as indices of seagrass in earlier seas. Furthermore, Farrow (1971) and others have shown that the sediments which accumulate around seagrass communities are distinctive and, if they escape channelling and other forms of erosion associated with the biotope, they stand a first-class chance of preservation. A final and most valuable clue to the history of seagrass and its community lies in studies of present-day biogeography, especially that of seagrass, which Den 688 PALAEONTOLOGY, VOLUME 18 Hartog (1970) has recently discussed. Examination of those data reveals that sea- grass distributions fall generally into three associations: the Zostera association (which may be taken to include Heterozostera, Phyllospadix, Amphibolis, and Posi- donia) is predominantly of temperate water forms with a more or less bipolar distribu- tion (text-figs. 4 and 5) ; the Cymodocea association (including also Thalassodendron and Enhalus) is mostly tropical but is notably absent from the Neotropics and tropical West Africa (text-fig. 5); the third or Thalassia association (including Halophila, TEXT-FIG. 4. Recent distribution of Zostera (Zostera) (shown as stipples) and Heterozostera (shown in black). Modified from Den Hartog (1970) with ocean surface currents after Sverdrup et al. (1942). Syringodium, and Halodide) is also tropical but differs basically in being present in the Neotropics but absent from most of the Mediterranean (text-fig. 6). It should be noted here that seagrasses are, significantly, absent from the coasts of South America excepting the tropical Atlantic region and single records from Chile and Argentina (Den Hartog 1970). These interesting distributions are remarkably similar to the faunal realms of shallow-water benthic foraminifera. This need be no surprise for they have most probably evolved side by side throughout most of the Cainozoic. The ecological requirements of certain foraminifera have become almost dependent upon seagrass, especially those of the larger soritids (‘peneroplids’). Hence Peneroplis planatus parallels the Cymodocea association in its distribution (text-fig. 4) and is known to live attached to that genus (Blanc-Vernet 1969; Davies 1970). Other living larger foraminifera such as Alveolinella, Calcar ina, Baculogypsina, and Operculina are further restricted to the Indo-West Pacific. Conversely, Amphisorus hemprichii and Sorites marginalis appear to parallel the Thalassia association in their distribution BRASIER: SEAGRASS COMMUNITIES 689 (text-fig. 6) and are known to live as epifaunas on Thalassia (Bock 1969; Brasier 1975a, 1975c). Phytal microfaunas on Zostera are not welt known but appear to be dominated by the smaller hyaline forms Rosalina, Discorbis, Cibicides, and Planor- bulina (J. Scott, pers. comm. 1970). These are equally common on other plants and hard surfaces both in and out of the tropics and therefore do not constitute a specially adapted seagrass faunule. Soritids and other larger tropical foraminifera are usually absent from temperate Zostera communities. TEXT-FIG. 5. Recent distribution of Posidonia (dashed lines), the 'Cymodocea association’ (stippled), and records of the foraminiferid Peneroplis planaius (black circles). Data from Den Hartog (1970) and others. Whilst Other invertebrate groups are similarly associated, the advantages of fora- minifera as palaeoecological indices are well known and numerous (e.g. Brasier \915b). Nevertheless they can only, at best, be an indication of the presence of sea- grass and further finds of plants remains themselves or other corroborative evidence should be looked for. Cretaceous The oldest seagrass-like fossils are protozosteroids and cymodoceoids (Den Hartog 1970). These have been found as imprints and silicified remains in the upper Cretaceous rocks of Japan and northern Europe (Koriba and Miki 1931, 1960; Oishi 1931 ; Voigt and Domke 1955). Posidonioids are also known but Den Hartog considered all these Cretaceous forms to be but poorly adapted to marine conditions. Furthermore, the numerous other truly terrestrial angiosperms and cycads found in the Japanese beds must question the validity of referring to the examples as ‘sea- grasses’. Hence they may have been of little significance to the marine biota of that 690 PALAEONTOLOGY, VOLUME 18 time. However, contemporaneous foraminiferal faunas contain a few questionably seagrass-adapted forms such as the peneroplinid Vandenbroeckia and meandrop- sinids such as Broeckina, Edomia, Qataria, and Pseudedomia. These all have a dis- tinctive Tethyan (i.e. Mediterranean to Indo-West Pacific) distribution (text-fig. 7), similar to that of the Cretaceous ‘alveolinids’, but the latter are more likely to have flourished in unvegetated backreef-type sands, as do their descendants. These alveolinids, peneroplinids, and meandropsinids are absent from neotropical strata, and suggest that the Americas were effectively isolated from Africa and Europe in the late Cretaceous (Dilley 1971, 1973). The present bipolar distribution of the Zostera association nevertheless suggests that seagrasses were evolving in Cretaceous times and have since become isolated by continental drift and by the expansion of a more specialized tropical seagrass flora (Den Hartog 1970). The occurrence of the primitive Heterozostera both around South Australia and at an isolated locality in Chile (Van Steenis 1962) suggests, like the marsupial evidence (Cox 1973), an archipelagic link between South America and Antarctica in the late Cretaceous. The genus is unrecorded from New Zealand although Zostera occurs there. Kennedy and Juignet (1974) have recently described possible seagrass bioherms from the upper Cretaceous of Normandy, although the inferred water depth would seem to be greater than tolerated by seagrasses today. Palaeocene- Eocene Fossil seagrasses of the Cymodocea association are first known from the lower Eocene of the Paris Basin where Cymodocea occurred with Posidonia (Den Hartog 1970). Significantly their appearance is accompanied more or less contemporaneously by that of the large foraminifer Orbitolites, whose living, close relatives Marginopora and Sorites are unquestionable seagrass dwellers. In the Ypresian limestones of Corbieres, southern France, the analogy with recent seagrass sediments is supported by foraminifera (especially Orbitolites, Valvulina, and thin-shelled miliolids) together with burrowing crustaceans and lithological evidence (Plaziat and Secretan 1971). These fossil seagrass beds even pass laterally into sand blanket calcarenites with the foraminifer Alveolina and the crustacean Calianassa, much as they do today in the tropics. This Orbitolites-Alveolina-Calianassa assemblage has also been described from the Eocene of Somalia (Silvestri 1939). It is clear from biofacies and lithofacies that some of the later Calcaire Grossier accumulated under similar conditions. Wright and Murray (1972) have further deduced from foraminiferal evidence that seagrass stands (presumably of Cymodocea and Posidonia) were widespread in the middle and upper Eocene of the English Channel and this is supported by finds of Posidonia in the Bracklesham Beds of Selsey Bill, associated with an unusually diverse phytal fauna of miliolids, bryozoa, and molluscs (Curry 1965). As mentioned above, the alveolinid sand facies of the Eocene occurred also in the late Cretaceous tropical regions, excepting those of the Americas. This provincialism was maintained, but the niche of Alveolina may have been occupied in the Eocene of the American region by Archaias (as it is today) and also by the extinct Yaberinella. It must also be emphasized that Orbitolites never reached the Neotropics and that TEXT-FIG. 6. Recent distribution of the 'Thalassia association’ (stippled) with records of the foraminiferids Sorites, Amphisorus, and Marginopora (black circles). Data mainly from Den Hartog (1970) and Wright and Murray (1972). TEXT-FIG. 7. Land, seas, and oceans in late Cretaceous times, with records of fossil cymodoceoids (c) and protozosteroids (z). Black circles show records of possible seagrass-dwelling foraminiferids (peneroplinids, meandropsinids, Praeosorites). Stipples represent inferred distribution of ‘tropical’ seagrasses. Palaeo- geography and palaeocurrents modified from Cox et al. (1973) and Gordon (1973). 692 PALAEONTOLOGY, VOLUME 18 the Cymodocea association is not in evidence there at present, both facts strongly suggesting that seagrass did not succeed in colonizing this region during the Eocene (see text-fig. 8). None the less, seagrasses are likely to have had a complete Tethyan distribution in the early Eocene because Orbitolites occurred at that time as far east as West Pakistan (Nutall 1925) and has been reported from Tibet and Hyderabad (Davies and Pinfold 1937). Other foraminifers which might have been seagrass dwellers are Pseudorbitolites and 'Taberina daviesi from the Palaeocene of the Middle East (Henson 1950; Morley-Davies 1971). Rhipidionina, a middle Eocene soritid from Istria and the Middle East, and Saudia, a dicyclinid from the Palaeocene to middle Eocene of northern Iraq and Arabia, could also be included here. TEXT-FIG. 8. Land, seas, and oceans in Eocene times, with records of fossil Posidonia (p) and Cymodocea (c). Symbols show records of possible seagrass-dwelling foraminiferids: black circles = Orbitolites\ stars = Saudia-, crosses = Rhipidionina. Stipples represent inferred distribution of ‘tropical’ seagrasses. Palaeo- geography and palaeocurrents modified from Cox et al. (1973), Gordon (1973), and Ramsay (1973). It might therefore be concluded that the present-day Mediterranean-Indo-West Pacific distribution of the Cymodocea association was initiated at least by early Eocene times and probably during the Palaeocene. The late Cretaceous soritids mentioned above might have heralded the advent of this association of tropical sea- grasses for their distribution is remarkably similar, but there are no plant remains to support this speculation. BRASIER: SEAGRASS COMMUNITIES 693 Oligocene The extinction of Orbitolites and similar forms before the end of the Eocene and their lack of replacement is not easily explained. It was concurrent with the extinction of many other Palaeogene larger foraminifera (Adams 1973) and may perhaps be connected with a contraction of the tropical belt in the Oligocene as shown by palaeoclimatology (Haq 1973). This would have resulted in a scarcity of suitable habitats. Furthermore, Orbitolites may have had a life cycle extending over three or four years, as do recent Marginopora (Ross 1972) and the consequent lack of adaptability may have rendered it vulnerable to fluctuations of trophic source, habitat, and climate. It is therefore more difficult to suggest what the distribution of seagrass com- munities may have been during the Oligocene. Cymodocea has been recorded from the Oligocene of Bembridge, Isle of Wight (Chesters et al. 1967) which may indicate that this genus maintained its distribution after the demise of its specialized epifauna. No details of stratum, locality of preservation are given, however. The miliolid and rotaliid foraminifera recorded from the Headon Beds of that area were thought by Bhatia (1957) to indicate the presence of vegetation and do in many respects resemble those from recent lagoonal seagrass beds in the tropics (Brasier 1975a). The present distribution of Cymodocea suggests hardiness compared with the other tropical genera, which concurs with its presence in the English Oligocene. Backreef sediments of the tropical Americas during middle and late Oligocene times, contained flourishing ‘microfaunas’ of Miogypsina and Miogypsinoides. These large, lenticular, complexly structured foraminifera spread rapidly to other tropical regions, migrating (like the deeper-water Lepidocyclina) to the Indo-West Pacific via West Africa and the Mediterranean sea (Adams 1967, 1973). Migration in the opposite direction was apparently difficult at this time. There is, therefore, little to suggest that seagrasses or their biota were able to reach the Neotropics during the Oligocene. None the less, Chesters et al. (1967) mention macrofossil records of Cymodocea from the Oligocene of Florissant, U.S.A., but unfortunately give no citation. Until there is better evidence this unfigured occurrence may be treated with caution because Cymodocea is otherwise unknown around the Americas. The fossil (if a seagrass) would more likely have been of Thalassia, Halophila, or Zostera (?). Miocene At the end of the Oligocene and in the early Miocene, the seas began to withdraw from the Near and Middle East (Savage 1967). This effectively isolated the Mediter- ranean from the Indo-Pacific province, an event which was further accentuated by the junction of the Betic peninsula of Europe with Africa in the middle Miocene (Berggren 1972). Somewhat paradoxically it is at the same time that a pantropical expansion of certain shallow-water foraminifera took place, and especially it would appear, of seagrass-dwelling forms. These included Sorites, Amphisorus, Marginopora, and Peneroplis, some of which are very similar in appearance to Orbitolites (see text-fig. 9). They occur in the lower Miocene limestones of the Caribbean region and appeared at about the same time in the Mediterranean and Indo-West Pacific Region (Adams 1967) and Mid Pacific (Cole 1969) where they still occur today. Equally remarkable 694 PALAEONTOLOGY, VOLUME 18 is the fact that the sediment-dwelling Borelis became, at the same time, the first alveolinid to reach the Neotropics. Spiroclypeus also made a unique appearance outside of the Indo-Pacific realm at this time (Adams 1973) and McKenzie (1967) records that the paradoxostomatid ostracods, which are phytal in habit, appeared and spread very widely in the Miocene. Furthermore, certain coralline algae, other- wise unknown from the Neotropics, arrived in the Caribbean from the Indo-Pacific in middle Miocene times (Brasier and Mather 1975). This new or improved connection between the tropical Americas and the Indo- West Pacific province in the early Neogene is likely in part to be correlated with the invasion of the Neotropical area by the Thalassia association. Although largely TEXT-FIG. 9. Land, seas, and oceans in Miocene times, with the distribution of fossil Cymodocea (c). Black circles show the wide distribution of the seagrass-dwelling foraminiferids Sorites, Amphisorus, and Margino- pora. Stipples represent the inferred, almost pantropical, distribution of the Thalassia association. Palaeo- geography modified from Cox et al. (1973), palaeocurrents conjectural. absent from the Mediterranean it is unique in being present at isolated localities around the west coast of Africa (text-fig. 6). This is consistent with a colonization via the south cape of Africa at a time when the Suez isthmus was closed. Geological evidence can substantiate this. According to Haq (1973) a climatic amelioration of 5-8 °C occurred in the higher latitudes of the southern hemisphere during early and middle Miocene times. The probable net northward movement of the African continent during the Tertiary (Newell 1971) may in combination have made it possible for Indo-West Pacific shallow-water biotas to ‘round the cape’ and establish along the west coast of Africa. Closure of the Suez isthmus and Persian Gulf BRASIER: SEAGRASS COMMUNITIES 695 could also have diverted warm Indian Ocean water down the east coast of Africa rather than through the Mediterranean as before, rendering the southern cape more tropical. That the temperatures were unusually suitable in the early and middle Miocene is supported by otherwise unprecedented records of Lepidocyclina and Miogypsina from Angola (Lemoine and Douville 1904), Miogypsina from Brazil (Closs 1966), and Miogypsinoides from Nigeria (Adams 1973). The present-day occurrence of the Indo-West Pacific colonist Borelis, around the Atol das Rocas, off Brazil (Tinoco 1965) and also around the Cape Verde and Ascension Islands (Adams 1967) suggests that these mid-Atlantic islands served as ‘staging-posts’ on the westward route. Briggs (1974, pp. 90-11 1) has pointed out that the (probably) Miocene island of St. Helena, Ascension Islands, has a mixed American Indo-West Pacific fish fauna. The latter, he suggests, arrived on surface currents via the Cape of Good Hope. One may add that one of the two living species of seagrass shared by the Caribbean with the rest of the tropics {Halodule wrightii) is the only species extant along the coast of tropical West Africa but is absent from the Pacific and Mediterranean (Den Hartog 1970). Other than this, the Caribbean and Indo-West Pacific share ‘twin-species’ of Thalassia, Syringodium, and Halodule (ibid.). It is reasonable, therefore, to infer that the Thalassia association of seagrass, together with other flora and fauna, progressed around the south cape and west coast of Africa during the warmer spell in the early and middle Miocene, to be the first to arrive in the hitherto isolated Neotropical waters. After the onset of cooler late Miocene conditions this southern migration route may have become impassible. Tropical and subtropical faunas certainly show evidence of climatic restriction at this later date (Bandy 1968; Newell 1971). As shown in text-fig. 6, the Thalassia association is widely dispersed at present in the North Pacific, Halophila reaching as far as Hawaii and Tuamotu (D. R. Stoddart, written comm. 1974). The seagrass-dwelling foraminifer Marginopora first appeared in this region during the Miocene and others have arrived since (Cole 1969). This suggests that this spread of the Thalassia association (especially Halophila) may also have occurred primarily at that time. Plio-Pleistocene Climatic deterioration probably prevented the relatively stenothermal Thalassia association from colonizing the higher latitudes of North and South America so that these may have been, as yet, unvegetated by seagrass. Den Hartog (1970) has suggested that colonization of the north Atlantic shores by Zostera (Zosterella) took place in the Plio-Pleistocene from the north Pacific (see text-fig. 10). This was pre- sumably achieved via the ‘arctic’ shores of Canada, including Hudson Bay where a relict flora remains. The late Pliocene molluscs of England, Iceland, and New England also share strong north Pacific affinities, which suggests that a two-way migration of biotas took place across North America before the onset of the Pleisto- cene glaciations (Ekman 1953, p. 122). Also in the late Pliocene, the Panama isthmus became closed, isolating the Pacific and Atlantic communities. This limited the flow of warm water along the west coasts 696 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 10. Recent distribution of the seagrass Zostera (Zosterella) and a Pleistocene record (z). of the tropical Americas which once had flourishing Neotropical faunas. The presently restricted distribution of the Thalassia association (text-fig. 6) on the west side of Panama attests to this. DISCUSSION Perhaps the major paradox to arise from the foregoing is the suggestion that tropical seagrass communities were expanding their geographic range in the Miocene, when it is generally held that coral-reef communities became more isolated and impoverished at about that time (see Newell 1971). Both changes may largely have been brought about by Alpine earth movements which reached a climax in the Miocene, uplifting many of the Tethyan continental margins. This must have resulted in a concomitant increase in the input of terrestrial material, causing in places greater turbidity and more highly fluctuating levels of nutrients (especially nitrates and phosphates) than occurred before. According to Tappan (1971) and Valentine (1971) such changes would have ‘rejuvenated’ the coral community ecosystem, causing a reduction in diversity. As the seagrass community is apparently more tolerant of great fluctuations in nutrient levels, acidity, and oxidation, it need not have been adversely affected by the increased ‘continentality’. The east to west dispersal of the Thalassia association across the Atlantic in the Miocene could well help to explain the unusual migratory behaviour of Chelonia mydas, the seagrass-eating green turtle. Carr and Coleman (1974) recently accounted for its yearly migration from Brazil to the Ascension Islands as a product of seafloor spreading. They have suggested that the breeding grounds on the Mid-Atlantic BRASIER: SEAGRASS COMMUNITIES 697 Ridge gradually spread further and further away from the South American feeding grounds, starting at least in the early Caenozoic. As a result C. mydas now swims WNW.-ESE. against the prevailing equatorial current for nearly eight weeks. It breeds around the Ascension Islands, lays eggs from which juveniles hatch and drift back with the current to Brazil. For this behavioural pattern to develop they imply that the home breeding grounds of South America became inexplicably unsuitable at some stage. Whilst remaining good for feeding, only the mid-ocean volcanic islands provided suitable beaches for egg laying. Bearing in mind the extremely conservative breeding behaviour of past and present amphibians and primitive reptiles, one wonders how Chelonia evolved the above- mentioned exploratory breeding behaviour whilst retaining conservative feeding behaviour. The reverse seems to be more in keeping with present evidence. Firstly, Chelonia is not recorded before the Miocene (Carr and Coleman 1974). Secondly, other evidence indicates that seagrass (the food source) did not reach the Americas from the Indo-West Pacific until the Miocene. Thirdly, no such behaviour is known in green turtles from the Indian Ocean (which would have been inherited if they had American origins). It is therefore more likely that Chelonia arrived in the Atlantic like many other organisms, via the Cape of Good Hope during Miocene times. It would have found the new American feeding grounds by passively drifting across the equatorial Atlantic, colonizing the Ascension Islands on route. At breeding time instinctive behaviour still leads them eastwards to the Ascension Islands, their original base (Brasier 1974). One should now consider why it was not possible for the Eocene Cymodocea com- munity to cross the Atlantic from east to west in a similar way. Paradoxically, the Atlantic is thought to have been narrower in the Eocene (Smith et al. 1973). The answer may therefore lie in the complex and conflicting evidence for palaeocurrents, especially that for the Atlantic’s North Equatorial Current which is the one which could have acted as the requisite agent. Interestingly, this is thought to have been weaker than the Equatorial Undercurrent and Counter Current in the Eocene (Ramsay 1973). A warm current from the Indian Ocean into the Mediterranean may also have pertained at that time, produced by north-east trade winds which then had a more northerly sphere of influence (Schwarzbach 1963). The deflection of this current by closure of the eastern end of the Mediterranean may then have helped to extend the tropical zone to the southern cape of Africa, as previously discussed. The closure of the western end of the Mediterranean in the middle Miocene could also have improved the return of the north Atlantic water down the west coast of Europe and North Africa to form a cooler branch of the North Equatorial Current. This cooler water effectively isolated the Mediterranean from the Neotropics and West Africa, as indicated by fossil faunas (Ekman 1953; Berggren 1972). A final point arises out of the foregoing observations: that the nature of ocean surface currents and the availability of migration routes can be more important than geographical proximity in controlling the similarity of shallow-water benthos. Reconstruction of past continental configurations by analysis of faunal and floral similarity should therefore be viewed with some caution (see Jell 1974). c 698 PALAEONTOLOGY, VOLUME 18 SOME PALAEOECOLOGICAL IMPLICATIONS The gradual encroachment of seagrasses into the sublittoral in late Cretaceous and Tertiary times may be surmised from recent studies to have been a significant ecological event. The resultant eutrophication of sediment substrates would have encouraged the development of deposit-feeding organisms, especially prosobranch gastropods and miliolid foraminifera. These two groups have certainly diversified greatly since the Mesozoic. Seagrasses also provide shelter for coralline algae, which likewise have diversified in the Caenozoic (Wray 1971). One may further suggest that those organisms feeding on herbivores and detritus feeders, such as teleosts and rays, have benefited from the innovation. The archaic turtles could have survived their marine reptile contemporaries after the Mesozoic because of their gastropod and seagrass diet. Mosasaurs were probably used to a cephalopod diet— hence were ill-adapted to exploit such a trophic innovation (see Nicol 1961). The more rapid encroachment of seagrasses into Neotropical waters in the Miocene must also have been a significant event. At a time when land barriers were making biotic exchange with the rest of the Tethyan tropics increasingly difficult, seagrasses could have aided the dispersal of sessile organisms across the Atlantic and probably to islands in the mid North Pacific. Such relatively sudden innovations are thought to cause rejuvenation of the ecosystem, threatening specialized tropical organisms with extinction (Tappan 1971). The forms most likely to suffer in the Miocene of the Neotropics were those endemics adapted to lower nutrient levels or to coarser and less stable substrates. Hence it may be no coincidence that the specialized, sedi- ment (?) dwelling Neotropical foraminifera Miogypsina and Lepidocyclina became extinct in their own province during the middle Miocene and not long after in other regions. Their extremely large size, structure, and palaeoecology suggests that they cultured symbiotic algae, which often indicates a relatively low but steady external food supply. If the food supply was increased and trophic stability was upset by the rejuvenation of continental margins and oceanic islands, together with the encroach- ment of seagrasses, these foraminifera would have had difficulty in adapting, especially if they had long life cycles (see Tappan 1971 ; Valentine 1971). Other endemics, such as scleractinian corals, seem to have suffered in a like manner (see Newell 1971). Unfortunately, it is not yet possible to say to what extent the above speculations are justified but they point to some interesting lines for future research. CONCLUSIONS The distributions of Recent and fossil seagrasses are similar to the distributions of Recent and fossil seagrass-dwelling foraminifera. The latter may therefore be used as indices (only) of the geographical dispersal of seagrass communities through time. The suggested dispersal patterns are biased towards tropical seagrass communities because tropical foraminifera indices are more distinctive than temperate ones and are therefore more reliable. Seagrass communities were probably present in the shallow sublittoral waters of the Tethys in late Cretaceous times and almost certainly in Eocene times. BRASIER: SEAGRASS COMMUNITIES 699 The gradual encroachment of seagrasses into the sublittoral in late Cretaceous to early Tertiary times can be surmised from recent studies to have resulted in three significant modifications of the ecosystem: (i) increase in habitat diversity; (ii) eutrophication of sediment substrates; (iii) additional means of dispersal for sessile organisms (i.e. rafting). The more or less contemporaneous radiation of deposit feeding and epiphytic gastropods and miliolid foraminifera (including soritids) in the late Cretaceous and Tertiary could be attributed in part to these factors, particularly in tropical waters. A more rapid colonization of the relatively isolated Neotropical and mid-Pacific sublittoral waters by seagrass communities seems to have occurred during the Mio- cene. Seagrasses, epibionts, and associated faunas (including the green turtle Chelonia) were probably dispersed by oceanic surface currents from the Indian Ocean via the Cape of Good Hope and the islands of the Mid-Atlantic Ridge. Earth movements may also have aided dispersal at this time by the provision of broader shelves and new islands. The Miocene earth movements and seagrass dispersal could likewise have con- tributed to the extinction of specialized endemic faunas such as Lepidocyclina and Miogypsina. The ecological effects were and are most marked in tropical carbonate environ- ments where the influence of land masses (‘continentality’) is low and alternative sources of organic and inorganic nutrients are few. 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Comparisons of modern and Palaeogene foraminiferid distributions and their environmental implications. Mem. Bur. Rech. geol. minier. 79, 87-96. M. D. BRASIER Typescript received 20 June 1974 Revised typescript received 1 3 December 1 974 Geology Department The University Cottingham Road Kingston upon Hull, HU6 7RX THE BIOSTRATIGRAPHY OF THE UPPER ORDOVICIAN AND LOWER SILURIAN OF SOUTH-WEST DYFED, WITH COMMENTS ON THE HIRNANTIA FAUNA by L. R. M. COCKS and d. price Abstract. Late Ordovician and early Silurian beds around Haverfordwest, South-west Dyfed (Pembrokeshire), Wales, are remapped and their faunas reviewed. Five formations are defined, representing a fairly continuous succession from mid Ashgill (Cautleyan) to late Llandovery (Telychian). New faunal evidence places the local Ordovician-Silurian boundary higher than has been previously suggested, within the Haverford Mudstone Forma- tion. The world-wide late Ashgill Hirnantia fauna is reviewed, and the conclusion reached that it represents a diachronous animal life assemblage and that it need not necessarily represent the latest local Ordovician fauna. Rock successions spanning the Ordovician-Silurian boundary are not common and with the current world-wide reassessment of late Ordovician and early Silurian rocks, their correlation, faunas, and ecology, it is desirable to review and evaluate the more important sections available. One such section occurs in South-west Wales. Here a series of large thrust-faults separate blocks of various Palaeozoic ages and the upper Ordovician and lower Silurian are exposed together within one of these blocks around the town of Haver- fordwest. Our field-work there, together with work on museum collections, provides new faunal and stratigraphical evidence in the light of which earlier accounts of late Ordovician and early Silurian strata in Pembrokeshire need revision. We attempt also to rationalize the stratigraphical terminology and we review the position of the Ordovician-Silurian boundary within the area. PREVIOUS WORK Marr and Roberts (1885) first recognized and determined a detailed succession within Ordovician and Silurian rocks in the neighbourhood of Haverfordwest. They regarded the ‘Slade Calcareous Shales’ (the highest unit of the " Trinucleus seticornis Beds’ of their succession) as forming the summit of the Ordovician System. These shales were succeeded by their ‘Conglomerate Series’, represented at Haverfordwest by the unit to be subsequently designated the Cethings Sandstone, and elsewhere by conglomerate or grit or both. The relationship of the Conglomerate Series to higher horizons was not entirely clear to them, but in the Cethings railway cutting at Haver- fordwest the sandstone mentioned above was succeeded by strata which graded upwards into the fossiliferous horizons near Haverfordwest gasworks, which they regarded as of definite lower Llandovery age. Outcrop patterns elsewhere supported this relationship. Provided the position of the Conglomerate Series was as this evidence suggested, they argued (1885, p. 489) that it formed ‘a satisfactory base to [Palaeontology, Vol. 18, Part 4, 1975, pp. 703-724, pis. 81-84.] 704 PALAEONTOLOGY, VOLUME 18 the Silurian rocks of this area’ and that it should be included within the lower Llan- dovery. The horizon was lithologically compared with the Mulloch Hill Con- glomerate (now Lady Burn Conglomerate, Cocks and Toghill 1973) of the Girvan district, Scotland (Lapworth 1882). The Geological Survey (Strahan et al. 1914) accepted this conclusion and followed Marr and Roberts in regarding the Slade (and Redhill) Beds as the youngest of the Ordovician formations. The succeeding strata the Survey termed the ‘Basement Beds’, comprising at Haverfordwest the Cethings Sandstone (named for the first time) with shale units above and below it. Elsewhere conglomerates were variably developed within or at the base of the shales beneath the sandstone. For Strahan and his colleagues the problem of delimiting the local Ordovician- Silurian boundary was primarily one of mapping the junction between the Basement Beds and the Slade and Redhill Beds, a task in which the Cethings Sandstone played an important part as a marker horizon. It was on this basis that the rich faunas collected by V. M. Turnbull from localities near St. Martin’s Cemetery, Haverford- west, were placed within the Silurian (Reed 1906), even though Reed (1905, pp. 98, 103) had earlier regarded them as of ‘Upper Bala’ age. There was some palaeonto- logical evidence for the lower Silurian age, mainly from the misidentifications of graptolites found in the succession (see p. 714), but it is clear, particularly from the accounts written by Cantrill (1907 and in Strahan et al. 1914, p. 101), that the chief reason for reconsidering the age of the St. Martin’s Cemetery faunas was their occurrence above the Cethings Sandstone marker horizon. Strahan et al. (1914) also comprehensively described the succeeding Silurian horizons. Since the publication of the Survey Memoir, and also following Jones (1925, p. 354), the horizon yielding the St. Martin’s Cemetery fauna has been widely regarded as of lowermost Llandovery age. Recently, however, Ingham and Wright (1970, p. 240) recognized elements of the Hirnantia fauna amongst the brachiopods and trilobites recorded from this horizon and suggested for it a Hirnantian age. STRATIGRAPHY AND FAUNAS Due to various palaeontological and stratigraphical misconceptions, outlined below, the previous rock terminology is in several parts unsatisfactory and we have found it necessary to present a revised succession for the Haverfordwest area (Table 1). Geological maps of the area are shown in text-figs. 1 and 2. Each rock unit and its fauna is now reviewed in turn. Slade and Redhill Mudstone Formation Lithostratigraphy. The ‘Redhill Shales’ and ‘Slade Calcareous Shales’ of Marr and Roberts (1885) were grouped by the Geological Survey into a single formation, their ‘Slade and Redhill Beds’, since in certain developments of their ‘northern type’ (Strahan et al. 1914, pp. 55-56) they had been unable to map the two divisions separately. Price (1973) has considered these beds in part and also found that dis- tinctions between various levels within them are not consistent over any area and that even where broad lithological distinction between an upper and a lower level can be made, the boundary region is very vague. We therefore propose that these COCKS AND PRICE: ORDOVICIAN AND SILURIAN BIOSTRATIGRAPHY 705 TABLE 1. Stratigraphical terminology within the Haverfordwest area. Standard Scale IDWIAN a >- YOUNGER q: LU > C5 Q < _l 1 RHUDDANIAN HIRNANTIAN tP X CO < RAWTHEYAN a OLDER Strahanetat, 1914 This paper Fbsitions of selected localities and faunas UZMASTON BEDS ( Lower part of ) GASWORKS SANDSTONE GASWORKS MUDSTONES CARTLETT BEDS MILLIN MUDSTONE FORMATION (Lowest part of) GASWORKS SANDSTONE FORMATION (85 metres) HAVERFORD MUDSTONE FORMATION (370 metres) basement CethingsSondstone BEDS PORTFIELD 'Cuckoo Shale Member Cethings SarxJst. Member FORMATION (65metres) (Scotchwel! Shale MemI iber SLADE a REDHILL BEDS (Highest part of) SLADE a REDHILL MUDSTONE FORMATION (Highest part of) • M Clonnda undata, Eocoelia curtisi, Eoplecfodonta penkiHensis, Leptaena purpurea Sc. Rich shelly Rhudtjanian faunas with Catymene, Dalmanites, Ctorinda, Stncktandia Sc. R Stricktandia Q — CHmacograptus cf norma! is Faunas with Mucronaspis mucronato, Anisopieureiio ^ gracilis, Eospirigerina, Eopiectodonta, Leptaena ac — ■P—'! CHmacograptus norma iis St Marlin’s Cemetery horizon, localities A,D,EandN; Hirnantia fauna — ? OnnieUa F Tretaspis %^^Eochonetes, Plectothyrella Tretaspis, Stenopareia, Diacaiymene I Chasmops ^Z-,PhoHdostrophia horizons should be regarded as a single formation formally designated the Slade and Redhill Mudstone Formation. The type development should be taken as the outcrop strip immediately north-west of Haverfordwest, which includes both Marr and Roberts original localities along the B4330 road and also the outcrops along the A487 road between St. Martin’s Cemetery and the school near Pelcomb Cross, which are much more continuous and include exposures near both base (Grid Ref. SM 9140 1820, loc. 1 of Price 1973) and summit (Grid Ref. SM 9463 1575, see text-fig. 2) of the formation. Fauna. Price (1973) has dated the lower parts of the formation, which is diachronous within the Cautleyan Stage at its base, and reviewed the trilobite fauna. In this paper we consider only the youngest part of the formation. The stratigraphically highest diagnostic fauna from the Slade and Redhill Mudstones known so far comes from locality I on text-fig. 2, a disused quarry on the west bank of the Western Cleddau (Grid Ref. SM 953 162). As well as brachiopods (pp. 706, 709) and other shelly fossils, the following trilobites occur: Calyptaulax sp. (PI. 81, fig. 6), Chasmopsci. >7rarri (Reed, 1894) (PI. 81, fig. 4), "Diacaiymene' cf. marginata Shirley, 1936 (PI. 81, figs. 1-3) (for discussion of the genus see Temple 1975, pp. 146-149), Remopleurides sp. (PI. 81, fig. 5), Stenopareia bowmanni Salter, 1848 (PI. 81, fig. 7), Tretaspis cf. hadelandica St0rmer, 1945 brachystichus Ingham, 1970 (PI. 81, figs. 8, 9). 706 PALAEONTOLOGY, VOLUME 18 Tretaspis hadelandica brachystichus ranges up to Rawtheyan Zone 6 in the north of England (Ingham 1970) and its probable descendant, T. latilimbus (Linnarsson) distichus Ingham, appears in Zone 7. When histograms of fringe characters are plotted separately for forms from Zones 5 and 6 (Ingham 1970, text-fig. 10) there are differences indicating a gradual change towards T. 1. distichus. The fringe characters of the Slade and Redhill Mudstone specimens are like those of the Cautley forms from Zone 5 and also like those of specimens from the highest part of the underlying Sholeshook Limestone (probably Cautleyan Zone 3), but it is not known whether the changes in Welsh populations exactly paralleled those seen in the north of England. All that can yet be said is that the Slade and Redhill specimens are earlier than Zone 7 and most likely to be low to mid Rawtheyan, an age consistent with the rest of the fauna. Cocks (1968, p. 304) reported a specimen of Tretaspis from a temporary exposure near St. Martin’s Cemetery (locality F on text-fig. 1, Grid Ref. SM 9434 1570), in an area marked on the Survey map as early Silurian. The specimen (BM It. 13243) is certainly a Tretaspis, although it is too incomplete to allow specific determination, but our recent remapping, with the aid of many new exposures in the foundations of a housing estate, shows the locality to be unequivocally within the highest Slade and Redhill Mudstones. Thus, as far as is known, there is still no authenticated record of Tretaspis from rocks of Silurian age. The brachiopod faunas of the Slade and Redhill Mudstone Formation are much in need of exhaustive collecting and systematic revision. The assemblages differ much from place to place. The temporary exposure mentioned above (locality F) just west of St. Martin’s Cemetery, was dominated by Eochonetes aff. advena Reed, 1917 (PI. 83, figs. 7, 9, 12), a genus hitherto unknown outside its type area at Girvan, Scotland, which was in late Ordovician time on the further side of the lapetus Ocean. Eochonetes made up of 84% of the collection (n = 287), with Plectothyrella at 8% the next most common element. (The method of calculating percentages follows Ziegler et al. 1968, p. 4.) Topographically close, but over 50 m lower in the formation, a temporary exposure at SM 942 158 (locality G on text-fig. 2) yielded a quite different assemblage dominated by Eostropheodonta (43%, n ^ 181), amongst thirteen different EXPLANATION OF PLATE 81 Figs. 1-3. "Diacalymene' cf. marginata Shirley, x 3. 1, SM A53047a, internal mould of enrolled exo- skeleton, dorsal view of anterior part. 2, SM A85288a, internal mould of distorted enrolled specimen, cranidium in dorsal view. 3, SM A3 1207, internal mould of cranidium in dorsal view. Fig. 4. Chasmops cf. marri (Reed). SM A30961, internal mould of incomplete pygidium, dorsal view, x 2. Fig. 5. Remopleurides sp. SM A30966, internal mould of pygidium, dorsal view, x 8. Fig. 6. Calyptaulax sp. SM A30960b, cast from external mould of right free cheek, dorso-lateral view, x 3. Fig. 7. Stenopareia howmcumi (Salter). SM A30943, internal mould of incomplete cranidium, dorsal view, X 2. Figs. 8, 9. Tretaspis cf. hadelandica St0rmer brachystichus Ingham. SM A53049a, b, internal mould and cast from external mould of cephalon, dorsal views, x 5. All specimens from the high Slade and Redhill Mudstones of locality I on text-fig. 2. Originals of figs. 1, 8, and 9 collected by Mrs. M. R. Cave, originals of figs. 2 and 4-6 collected by V. M. Turnbull, original of fig. 3 collected by D. P., original of fig. 7 collected by J. E. Marr. PLATE 81 COCKS and PRICE, Ordovician trilobites 708 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 1. Geological map of the area between Little Cuckoo and St. Martin’s Cemetery, west of Haverfordwest. Lettered localities are those referred to in the text. COCKS AND PRICE; ORDOVICIAN AND SILURIAN BIOSTRATIGRAPHY 709 brachiopods and nine species of other groups. The Sowerbyella present here at 3% is of interest in that it appears morphologically indistinguishable from the Eochonetes mentioned above from higher strata, apart from the lack of perforations along the hinge-line, and suggests an ancestor for the aberrant Eochonetes stock. Another assemblage, from the old quarry near the Western Cleddau (locality I), yielded a fauna in which Pholidostrophia (Eopholidostrophia) matutinum (Lamont, 1935), a species previously recorded only from the Cautleyan of the Girvan area and of Cautley itself, occurs commonly (BM BB 69611-69614). A further exposure in the formation south of Little Clerkenhill, 9 km west of Haverfordwest (Grid Ref. SN 045 150) also yielded Eoehonetes (26%, n= 173) and Pleetothyrella (13%), but the most common brachiopod (at 39%) was an enteletacean probably related to Resserella. In no part of the Slade and Redhill Formation, however, do we consider a Hirnantia fauna to be present, although several of its constituents occur at different localities and horizons within the formation. Portfield Formation Lithostratigraphy. The name ‘Portfield Formation’, after the region of Haverford- west known as Portfield (see Portfield House on text-fig. 1), is proposed for the unit designated ‘Basement Beds’ by Strahan et al. (1914)— an unsatisfactory term because of its erroneous assumption about the position of the unit in relation to the Ordovician- Silurian boundary, as well as its lack of a local name. The Portfield Formation is divided into three members, two of shale with an intervening sandstone. The type section is in the railway cutting at Cethings (see text-fig. 2; Grid Ref. SM 966 161). At the north-east end of this cutting is exposed the unit which we propose to designate the Cethings Sandstone Member; here a thickness of about 8-5 m of well-sorted, fine-grained grey to buff sandstone dipping at 62° to the south. Below the sandstone, dark sooty shales of the Scotchwell Shale Member (named after Scotchwell, see text-fig. 2) are poorly exposed in a shallow ditch on the east side of the railway line. Their thickness was estimated by Strahan et al. (1914, p. 89) as at least 46 m. Shales of similar aspect form the Cuckoo Shale Member (named after Little Cuckoo, text-fig. 1), exposed to a thickness of about 9 m above the sand- stone and grading up over a distance of about 1 m in bioturbated beds into the greener mudstones of the overlying Haverford Mudstone Formation. From regional mapping the shales of the lowest member appear to be conformable with the underlying Slade and Redhill Mudstone Formation, but the junction is nowhere exposed. The sequence in the Cethings railway cutting applies over a region from about 7 km west of Haverfordwest to about 4 km to the east. Further to the east con- glomerates are locally and variably developed at or near the base of the formation, one of the most prominent forming the hill at Robeston Wathen (Grid Ref. SN 081 158); further details are given in Strahan et al. 1914, pp. 83-101. The Cethings Sandstone Member, although in places attenuated and locally containing some intercalated shale bands, is persistent in the sequence at least as far east as Narberth and Lampeter Velfrey and forms a valuable mapping horizon. Fauna. The Portfield Formation is largely barren of fossils. We have found none and the only known specimen (SM A32094) was collected by V. M. Turnbull from the 710 PALAEONTOLOGY, VOLUME 18 Scotchwell Shale Member in the Cethings railway cutting; it comprises the con- joined valves of an enteletacean brachiopod, perhaps referable to Onniella. The St. Martin’s Cemetery Horizon Litbostratigrapby. V. M. Turnbull made painstaking collections, now in the Sedg- wick Museum, from two fossiliferous localities (D and E on text-fig. 1) at the roadside west of St. Martin’s Cemetery. Because the fossils were described (Reed 1905, 1906, 1907) before the complete survey of the area (Strahan et al. 1914), a stratigraphical name, variously the St. Martin’s Mudstone or the St. Martin’s Cemetery Beds or Formation has been applied to the rocks from which Turnbull’s fossils came. The original localities, though no longer exposed, can be accurately located and lie at the junction of the Portfield Formation and the Haverford Mudstone Forma- tion; the fossiliferous horizon involved was almost certainly that also seen in the Cethings railway cutting. There a fossiliferous band about one metre in thickness occurs at the same junction (locality N on text-fig. 2), fossils from its lowest part having a dark shaley matrix and those from the upper part a light, more silty one. Most specimens from the St. Martin’s Cemetery localities have either a light siltstone or olive-green mudstone matrix which, as at Cethings, is often bioturbated. Elements of the same fauna, in a matrix similar to that from the St. Martin’s Cemetery localities, are known from Little Cuckoo (locality A, text-fig. 1), suggesting that there is a constant band from Little Cuckoo, through St. Martin’s Cemetery to Cethings railway cutting, a distance of approximately 4 km. This fossiliferous band, because of its thinness and because its dominant lithology is more similar to the rocks above rather than below it, we include within the basal part of the Haverford Mudstone Formation. We refer to the band informally as the St. Martin’s Cemetery horizon and recommend that the designation ‘St. Martin’s Cemetery’ should not again be used as a separate formal stratigraphical name for a formation or member. EXPLANATION OF PLATE 82 Figs. 1, 2. Lichas cf. laciniatus (Wahlenberg), x2. 1, SM A32014, internal mould of cranidium, dorsal view. 2, SM A4650, internal mould of pygidium, dorsal view. Figs. 3-8. Otarion cf. megalops (M’Coy). 3, SM A85575, internal mould of left free cheek, dorsal view, x 6. 4, SM A4648, internal mould of cranidium, dorsal view, x 8. 5, 6, SM A32068, internal mould of cranidium, right-lateral and dorsal views, x 8. 7, SM A85576a, internal mould of cranidium, dorsal view, X 8. 8, SM A4647b, internal mould of cranidium, dorsal view, x 8. Fig. 9. Brongniartella sp. GSM Pg 17, cast from external mould of incomplete pygidium, dorsal view, x 2. Figs. 10-13. Diacanthaspis stadensis (Reed), X 10. 10, SM A4646b, lectotype (selected Temple 1969, p. 203), cast from external mould of cranidium, dorsal view. 11, 12, SM A4644a, b, internal mould and cast from external mould of cranidium, dorsal views. 13, SM A32010, internal mould of small pygidium, dorsal view. Figs. 14, 15. cf. Leonaspis girvanensis (Reed), X 10. 14, SM A88536, internal mould of pygidium, dorsal view. 15, SM A32021, internal mould of partial pygidium, dorsal view. All specimens from St. Martin’s Cemetery horizon (basal Haverford Mudstone Formation); collected by V. M. Turnbull. Figs. 1, 2, 4, 6-15 from either of localities D and E on text-fig. 1. Fig. 3 from the Cethings railway cutting, locality N. Fig. 4 from Little Cuckoo, locality A. PLATE 82 COCKS and PRICE, Ordovician trilobites 712 PALAEONTOLOGY, VOLUME 18 Fauna. The fauna in Turnbull’s collections was listed by Reed (1906, p. 537). We have reidentified the trilobites and brachiopods in these collections in addition to those collected subsequently from all localities at this restricted horizon (an asterisk denotes species originally described from the horizon) : Trilobites. Brongniartella sp. (PI. 82, fig. 9), * Diacanthaspis sladensis (Reed, 1905) (PI. 82, figs. 10-13), cf. Leonaspis girvanensis (Reed, 1914) (PI. 82, figs. 14, 15), Lichasci. laciniatus (Wahlenberg, 1818) (PI. 82, figs. 1, 2), Mucronaspis mucronata (Brongniart, 1822) (PI. 83, figs. 1-4), Otarion cf. megalops (M’Coy, 1846) (PI. 82, figs. 3-8). Brachiopods. Lingula sp., Orbiculoidea concentrica (Wahlenberg, 1821) (PI. 83, fig. 5), Philhedra sp., Craniops sp., Skenidioides sp., *Giraldiella giraldi Bancroft, 1949, * Dalmanellal biconvexa 'WilWams, 1951, Dalmanella aff. testudinaria (Dalman, 1828) (PI. 83, fig. 1 1), Hirnantia sagittifera (M’Coy, 1851) (PI. 83, figs. 13, 14) of which *Orthis porcata sladensis Reed, 1905 is a junior synonym, Chonetoidea cf. papillosa (Reed, 1905), *Leptaena martinensis Cocks, 1968 (PI. 83, fig. 6), * Eostropheodonta whittingtoni Bancroft, 1949 (PI. 83, figs. 6, 8) of which * Eostropheodonta hirnantensis delicatula Bancroft, 1949 is a junior synonym, *Cliftonia lamellosa Williams, 1951 which may be a junior synonym of Cliftonia psittacina (Wahlenberg, 1821) (see Bergstrom, 1968, p. 11), Cryptothyrella crassa (J. de C. Sowerby, 1839) incipiens (Williams, 1951) (PI. 84, fig. 3). Diacanthaspis sladensis, together with forms very similar to Otarion cf. megalops and Lichas cf. laciniatus, is known from limestone bands immediately overlying the Keisley Limestone of Westmorland (Temple 1969), an horizon which Temple con- sidered to be lowest Silurian in age, but which Ingham and Wright (in Williams et al. 1972, p. 47) more recently considered to be Hirnantian. The type material of Leonaspis girvanensis is from the upper Drummuck Group of Girvan which is late Rawtheyan in age (Ingham 1966, p. 495). In addition, a pygidium (SM A43243) very similar to that figured here as Plate 82, fig. 14 is known from the 'Mucronatus Beds’ west of Trout beck in the Lake District, another late Rawtheyan horizon. In what can be seen of its ornamentation, the Welsh pygidium shows more affinity with these two forms than with the species from the basal Silurian of Watley Gill, Cautley, mentioned EXPLANATION OF PLATE 83 Figs. 1-4. Mucronaspis mucronata {Brongniart). 1,2, BM It 13246a, b, internal mould and cast from external mould of pygidium, dorsal views, x6. 3, BM It 13247, internal mould of cephalon, dorsal view, x4. 4, SM A32020, internal mould of cephalon, dorsal view, x4. Fig. 5. Orbiculoidea concentrica (Wahlenberg). SM A3 1850a, brachial valve, x2. Figs. 6, 8. Eostropheodonta whittingtoni Bancroft. 6, SM A30039a, pedicle valve with brachial valve of Leptaena martinensis Cocks, X 1-4. 8, SM A32035, pedicle valve, x 1-5. Figs. 7, 9, 12. Eochonetes a&. advena Reed. 7, BM BB 31678-31679, internal moulds of pedicle valves, note perforated hinge-lines, especially on top left-hand specimen, x 1-3. 9, BM BB 32230, brachial valve, X 1-5. 12, BM BB 31683, brachial valve, x3. Fig. 10. Anisopleurella gracilis (Jones). GSM 37555, internal mould of brachial valve, x5. Fig. 11. Dalmanella aff. testudinaria (Dalman). SM A3 1 899, internal mould of large brachial valve showing musculature, x 2. Figs. 13, 14. Hirnantia sagittifera (WPCoy). 13, SM A31908, pedicle valve, X 1-4. 14, SM A31912, brachial valve, X 2. Figs. 1-3 and 10 from lower Haverford Mudstones, locality K; 1-3 collected by L. R. M. C., 10 collected by O. T. Jones. Figs. 4-6, 8, 11, 13, and 14 from St. Martin’s Cemetery horizon (basal Haverford Mud- stones), 4-6, 1 1, 13, and 14 from either of localities D and E, 8 from locality N; all collected by V. M. Turnbull. Figs. 7, 9, and 12 from upper Slade and Redhill Mudstones, locality F; collected by L. R. M. C. PLATE 83 COCKS and PRICE, Ordovician trilobites and brachiopods 714 PALAEONTOLOGY, VOLUME 18 by Temple (1975, p. 158). Similarly, the Welsh material of Mucronaspis mucronata does not appear to belong to the subspecies M. m. brevispina which at Watley Gill also occurs in the basal Silurian (Temple 1952). Brongniartella is known in the fauna only from two pygidia, the better of which is figured here (PI. 81, fig. 1), and one poor, very small (?holaspid) cranidium (SM A85611). Although what features can be seen from this material are similar to the upper Ordovician B. platynota (Dalman, 1828), adequate comparison is not really possible. There are only two graptolite specimens known from the St. Martin’s Cemetery horizon, one collected by Turnbull from the Cemetery localities and one by Pringle from the Cethings cutting. Both were identified at Cambridge, the first by Miss Elies as Diplograptus cf. modestus Lapworth (Reed 1907, p. 537) and the second by her colleague Mrs. Shakespeare (Miss Wood) as Diplograptus modestusl Lapworth (Strahan et al. 1914, p. 101). Unfortunately the Turnbull specimen is now lost, but the Pringle specimen (GSM Pg. 54) has been kindly re-examined for us by Dr. R. B. Rickards who states that, while the specimen superficially resembles D. modestus, it is definitely not that form and represents an undescribed diplograptid species. It seems reasonable to assume that the lost Turnbull specimen was probably of the same form (particularly in view of its ‘cf.’ identification) so that these graptolites are at present of little use in any determination of the detailed age of the St. Martin’s Cemetery horizon. This fact is important since the original "D. modestus' determina- tion was one of the main palaeontological factors in the decision by Reed and the Survey Officers to assign the horizon to the Silurian. The shelly fauna from the St. Martin’s Cemetery horizon we interpret as a Hirnantia fauna of late Ashgill age; it is further discussed at the end of this paper. The Haverford Mudstone Formation Lithostratigraphy. Although in their vertical sections (e.g. Strahan et al. 1914, fig. 12) the Survey workers distinguished between their ‘Cartlett Beds’ and ‘Gasworks Mud- stones’, they made no attempt to map these as separate divisions. This is consistent with the experience of the present authors who have reached the conclusion that it is only the presence of distinctive shelly faunas at certain localities that enables them to be classed as developments of Gasworks Mudstones rather than Cartlett Beds; lithologically there is no clear distinction. Although there is a gradual increase in the number of thin sandstone beds upwards and also an increase in faunal content, there is no sharp change that could be used to separate two formations. We therefore group the Survey’s Cartlett Beds and Gasworks Mudstones together as a single formation for which we propose the name Haverford Mudstone Formation— taking the name used by the Survey workers for the lowest stage (what would today be termed a group) of their Silurian succession. There is no one section through which the entire formation may be followed. Many excellent localities, however, have become temporarily available for periods over the last ten years, including those due to the building of the Haverfordwest bypass, improvements along the A40 road to the east of the town, and the con- struction of a series of housing estates to the west of the town. The most important permanent sections in the formation are the Cethings railway cutting (text-fig. 2), where the contact with the underlying Portfield Formation is seen (locality N), the COCKS AND PRICE: ORDOVICIAN AND SILURIAN BIOSTRATIGRAPHY 715 TEXT-FIG. 2. Map of the solid geology of the Haverfordwest area. Lettered localities are those referred to in the text. The Carboniferous outcrop boundary is taken from the Geological Survey six-inch map (Pembrokeshire 27 NE.) and some of the fossil localities shown are Geological Survey localities. There are more strike-faults and minor local folds than are shown. 716 PALAEONTOLOGY, VOLUME 18 sections in the railway cuttings south-west of Haverfordwest Station (locality K), and the classic section running from New Road to opposite the entrance of Haver- fordwest gasworks (Strahan et al. 1914, pp. 89-91) (locality L), where the contact with the overlying Gasworks Sandstone Formation is exposed. The structure of the outcrop area (text-figs. 1 and 2) is complex and the exposures restricted; there are certainly more strike faults than we have shown on our maps, as well as many minor local folds. Fauna. The Haverford Mudstone Formation is estimated to be between 350 and 390 m in thickness and is divided faunally into three parts. The basal metre includes the St. Martin’s Cemetery horizon which carries a Hirnantia fauna, the next 210 to 250 m carries a sparse fauna discussed further below, and the uppermost 140 m con- tains a rich shelly fauna of typical lower Llandovery (Rhuddanian) aspect, best known through the classic exposures opposite the gasworks at Haverfordwest. The fauna of the St. Martin’s Cemetery horizon has been discussed above. The next division of the formation is largely barren of macrofauna but it has yielded fossils in four areas : (i) 9 m above the base of the formation in the Cethings railway cutting a single graptolite was collected by Strahan et al. (1914, p. 89) and identified by them as IDiplograptus modestus parvulus (H. Lapworth). Dr. R. B. Rickards reidentifies the specimen as IClimacograptus normalis Lapworth, although he reports a hint of apertural spines recalling the C. innotatus group. In either case the stratigraphical significance is doubtful. (ii) A series of exposures in the railway cutting south of Haverfordwest (locality K, Grid Ref. SM 955 146), where dark-green micaceous mudstones have yielded a shelly fauna dominated (80% in one collection, n= 103) by the small brachiopod Aniso- pleurella gracilis (Jones, 1925) (PI. 83, fig. 10; Cocks 1970, pi. 16, figs. 1-9), with subsidiary Mucronaspis mucronata{V\. 83, figs. 1-4), Leptaena, Eoplectodonta, Lingula, EXPLANATION OF PLATE 84 Figs. 1, 2, 5, 6. Hirnantia sagittifera (M’Coy). 1,2, BM BB 68722 and BM BB 68709, internal moulds of large brachial valves, x 2-5. 5, BM BB 38699, pedicle valve, x 2. 6, BM BB 68720, internal mould of small brachial valve, x 2. Fig. 3. CryptothyreUa crassa incipiens (Williams). SM A3 1930, internal mould of conjoined valves, posterior view, X 2. Figs. 4, 7. Eostropheodonta whittingtoni Bancroft. 4, SM A30041a, brachial valve, x 1-4. 7, SM A31884, pedicle valve, x 1-5. Figs. 8, 10. (M’Coy). 8, BM BB 38634, brachial valve, x 1-5. 10, BM BB 38660, pedicle valve together with Hirnantia sagittifera brachial valve, x 1 -7. Figs. 9, 13. Stricklandia lens lens (i . deC. Sowerby), brachial valves. 9, BM BB 69607, X 2. 13, BM BB 69608, X 1-5. Figs. 11,12. Katastrophomenaai{.scotica(^'dncroi\). 1 1, BM BB69610, pedicle valve, X 2. 12, BM BB 69609, brachial valve, x 1 -6. Figs. 1, 2, 5, 6, 8, and 10 from Flirnant Quarry, south-east of Bala, Merionethshire (Gwynedd), Grid Ref. SH 945 285; collected by L. R. M. C. Figs. 3, 4, 7 from St. Martin’s Cemetery horizon (basal Haverford Mudstones), localities D and E; collected by V. M. Turnbull. Figs. 9, 13 from upper Haverford Mud- stones, locality J; collected by L. R. M. C. Figs. 11,12 from upper Haverford Mudstones, locality H; collected by L. R. M. C. PLATE 84 COCKS and PRICE, Ordovician and Silurian brachiopods 718 PALAEONTOLOGY, VOLUME 18 Eospirigerina, and two undetermined species of enteletacean brachiopod. Un- fortunately the exact stratigraphical horizon of this locality within the formation is difficult to determine, since it lies on the southern limb of a syncline when com- pared with other localities (text-fig. 2). (iii) Several temporary exposures in the foundations of new houses in the area around Portfield House (text-fig. 1). At one locality (locality B, Grid Ref. SM 9375 1550) Anisopleurella gracilis occurred in some quantity, and 60 m north of this (SM 9374 1556, locality C) an indeterminate graptolite fragment. The former locality is an estimated 45 m from the base of the formation, the latter about 20 m. (iv) A series of exposures, mainly temporary, along the main A40 road just north of Bethany Farm (text-fig. 2). At locality P (Grid Ref. SM 9653 1590) A. gracilis occurred as many specimens on a single bedding plane and Orbiculoidea, Eospiri- gerina, Leptaena, Eoplectodonta, Skenidioides, and Resserella (BM BB 70622-70631) as scattered single specimens. This is near a locality (O on text-fig. 2) termed EA 23 by the Survey, which yielded to them, as well as A. gracilis, a graptolite (GSM TCC 1876/7) which Dr. Rickards identifies as Climacograptus cf. normalis Lapworth. From a stratigraphically slightly higher horizon (locality Q, Grid Ref. SM 9661 1589), no longer exposed, the Survey (their locality EA 24) recovered single specimens of Cryptothyrella, Leangella scissa (Davidson, 1871), Eospirigerina, IClorinda, Eostro- pheodonta, and "I Anisopleurella and three specimens of Resserella, a fauna which, although not fully diagnostic, suggests for the first time in the formation a positive Llandovery, rather than an Ashgill, age. Within 1 5 m above this (locality R, Survey loc. EA 28, Grid Ref. SM 9666 1591) a typical Llandovery fauna, including Stricklandia, occurs. Thus the age of this central division of the Haverford Mudstone Formation remains equivocal. Below it there is a definite Hirnantian horizon and above it a definite Rhuddanian horizon. Where within this division the boundary limit between these Stages, and hence between the Ordovician and Silurian, should be drawn is uncertain. There seems a good case for putting the highest 15 m of the division (locality Q and above) into the Rhuddanian, but the underlying 235 m with its sparse Anisopleurella fauna and Mucronaspis mucronata could just as well be Hirnantian; we do not regard the presence of Mucronaspis as being necessarily diagnostic in this respect. It is hoped that more graptolites may be recovered from these horizons in the future, although even graptolite faunas near the Ordovician-Silurian boundary still await a defini- tive study. The fauna of the uppermost 140 m of the formation is one of the richest in the Rhuddanian of Britain. Temple (1975) has reviewed the trilobites and redescribes Calymene crassa (Shirley, 1936), Calymene sp. A, Brongniartella sp., Hadromeros elongatus (Reed, 1931), Acernaspis sp., Dalmanites sp., Stenopareia sp., and an indeterminable odontopleurine. The faunas, however, are numerically dominated by brachiopods, of which only the strophomenides have yet been redescribed (Cocks 1968, 1970), although many of the forms described by Temple (1970) from Meifod also occur in the Haverfordwest area. The chief localities are; (i) The lane leading from New Road to the gasworks, Haverfordwest (locality L, Grid Ref. SM 9622 1500 to SM 9582 1537; Strahan et al. 1914, pp. 90-91). COCKS AND PRICE: ORDOVICIAN AND SILURIAN BIOSTRATIGRAPHY 719 (ii) Along the path known as Fortune’s Frolic (text-fig. 2) on the east bank of the Western Cleddau (Grid Ref. SM 9622 1500 to SM 9647 1461; Strahan et al. 1914, pp. 92-96), where the succession is repeated by local folding and faulting. (iii) The area around Priory Mill (Grid Ref. SM 959 149), including some large temporary exposures made during the construction of the southern bypass in 1974, from locality J (SM 9540 1478) eastwards. (iv) The area around Merlin’s Bridge (text-fig. 2) where there are several isolated exposures. Jones {in Strahan et al. 1914, pp. 96-99) was concerned that the faunal aspect of these ' Pentamerus undatus beds’, as he called them, was not the same as that of those opposite the gasworks entrance. We have examined the material collected by the Survey and made new collections from several localities, in par- ticular an old quarry west of Merlin’s Bridge (locality H, Grid Ref. SM 946 146), and there is no doubt that the exposures fall within the uppermost part of our Haver- ford Mudstone Formation. There are three different main brachiopod assemblages present in the upper division : (i) Faunas dominated by Clorinda undata (J. de C. Sowerby) and Eoplectodonta duplicata (J. de C. Sowerby), and typical of most of the exposures in the Merlin’s Bridge area. A collection from locality H yielded Clorinda undata (23%), Eoplecto- donta duplicata (18%), Resserella llandoveriana Williams (10%), Skenidioides wood- landiense (Davidson) (9%), nine other species of brachiopod, and eight species of other groups (n = 122). (ii) Faunas dominated by Stricklandia lens, very often in nearly monospecific assemblages covering single bedding planes, with some specimens even in position of growth (Ziegler et al. 1966). The subspecies present is chiefly S. lens lens (J. de C. Sowerby), but some populations and individuals are morphologically closer to S. 1. prima Williams, whose type horizon and locality (Williams 1951) is A2_3 Beds at Llandovery itself, and which is the earliest Silurian stricklandiid form. These Strick- /a«(i/a-dominated assemblages are widespread, extending well outside the area to such localities as that north of Woodford Cottage, south of Robeston Wathen (Grid Ref. SN 0848 1504). (iii) Diverse faunas without common pentamerids, the best examples coming from the exposures opposite the entrance to the gasworks at Haverfordwest (locality L). In a large collection from a band approximately 14 m below the top of the formation, brachiopods dominated the assemblage, with twenty different species, including Eoplectodonta duplicata (18%), Resserella llandoveriana Williams (9%), Leangella scissa (8%), Eopholidostrophia sefinensis ellisae Hurst (5%), Eostrophonella eothen Bancroft (3%), and Schizonema sowerbyiana Davidson (2%) (n = 658), but the collection also contained at least seventeen species of other phyla, including a thick stick bryozoan, possibly Hallopora (15%), Tentaculites (10%), the dasyclad alga Mastopora fava Salter (5%), a thin stick bryozoan (4%), and a compound bryozoan (3%), one species of orthoceratid, three species of gastropod, one of bivalve, two species of coral, much crinoid debris, and four different trilobites {Calymene crassa, an odontopleurine— probably Leonaspis, a phacopid, and an encrinurid). Another, much smaller, collection from the railway cutting 40 m NE. of the railway bridge 720 PALAEONTOLOGY, VOLUME 18 (Grid Ref. SM9579 1551) was from a single thin band and was very much less diverse, being dominated by Katastrophomena scotica (Bancroft) (59%), with the next most common taxa each at 7% (Resserella Uandoveriana and a bryozoan). A notable feature of this faunal group is the variety of assemblages encountered, with particular abundances of groups other than brachiopods, and an unusual absence of penta- merids. The interpretation of the first two of these upper division assemblages is that they can be identified with the Clorinda and Stricklandia Communities defined in the upper Llandovery of the Welsh Borderland (Ziegler et al. 1968). However, the interpretation of the third group, which is both varied and diverse, presents more of a problem. Perhaps the most likely solution is that assemblages are represented which ecologically parallel a typical Clorinda Community, but from an environment locally unsuited to Clorinda itself or other pentamerids; the abundance of bryozoa and Mastopora are also unusual. Whether or not the deposition was unusual is uncertain. Sanzen-Baker (1972, p. 1 52) suggests that the upper parts of the Haverford Formation were partly deposited from turbidity currents, and the jumbled nature of many of the third assemblage occurrences would be explained by this. On the other hand, the fact that many of the brachiopods are found with conjoined valves, and that the fragile calcareous algae are found at all, implies that the amount of pre-depositional disruption was not great. In any case a Rhuddanian age for the upper part of the Haverford Mudstone Formation is quite certain. Gasworks Sandstone and Millin Mudstone Formations Lithostratigraphy. Detailed discussion of these later formations is outside the scope of this paper. Sanzen-Baker (1972) has described the turbidites of the Gasworks Sandstone Formation, which succeed the Haverford Mudstone Formation apparently conformably. Above the Gasworks Sandstone there are thick mudstones which Strahan et al. (1914) divided into lower Uzmaston Beds and upper Canaston Beds. The Survey workers were not able to map these two divisions separately, and the present authors treat them as one formation, the Millin Mudstone Formation, whose name is taken from the Survey’s ‘Series’ name. Fauna. Fossils, chiefly brachiopods, occur sporadically within the Gasworks Sand- stone Formation, but their age is not diagnostic. The Millin Mudstone Formation is more fossiliferous, yielding late Llandovery faunas chiefly representing the Clorinda Community. These beds may be dated by stricklandiids and Eocoelia to a variety of ages within the Fronian and Telychian stages; a representative locality occurring on our map (locality M, Survey loc. FA 25, Grid Ref. SM 9620 1525) included Anthirhynchonella linguifera (J. de C. Sowerby), Eoplectodonta penkillensis (Reed), Clorinda undata (J. de C. Sowerby), Leptaena purpurea Cocks, Atrypa reticularis (Linnaeus), and Eocoelia curtisi Ziegler, indicating a Telychian age at approximately 90 m above the base of the Millin Mudstone Formation. THE HIRNANTIA FAUNA For many years a fauna has been known, typified by the association of the enteletacean Hirnantia sagittifera (M’Coy) and the strophomenide Eostropheodonta hirnantensis COCKS AND PRICE: ORDOVICIAN AND SILURIAN BIOSTRATIGRAPHY 721 (M’Coy), from near the Ordovician-Silurian boundary. The type area is at Aber Hirnant, south-east of Bala, North Wales, where the beds were often regarded as post-Ashgill (Elies 1922; Bancroft 1933, p. 4), although more recently these beds at Hirnant were revised to form the type Hirnantian, the highest stage within the Ashgill Series (Ingham and Wright 1970). It is perhaps unfortunate that the name of the fauna and the name of the stratigraphical time division should be so similar ; although this misfortune has since been compounded into error, for example by Lesperance (1974), who even explicitly equates the two terms, resulting in an erroneous hybrid ‘Hirnantian fauna’, which Lesperance identifies, as if by definition, with the Hirnantian time horizon (Stage). The beds around Aber Hirnant await modern redescription, but a collection from Hirnant Quarry yielded the following seven brachiopods: E. hirnantensis (30%, n=153), H. sagittifera (21%), Plectothyrella crassicosta (Dalman, 1828) (10%), Kinnella kielanae (Temple, 1965) (9%), Dalmanella sp. (9%), Bancroftinal bouceki (Havlicek, 1950) (8%), and Skenidioides sp. (1%). The only representatives of other phyla were a few crinoid ossicles, some compound bryozoa, and some borings, presumably of sponges, into the brachiopod shells. These data are comparable with the percentages (of brachiopods only) from the same locality recorded by Temple (1965, p. 419), and consist of the same species, with the addition only of the uncommon Skenidioides. The lithology of Hirnant Quarry is variable, but includes a pisolitic oolite not seen elsewhere. This Hirnantia fauna is very comparable in composition and diversity with others from near Llangollen, North Wales, and from Hoi Beck (Temple 1965, p. 418) and Cautley (Wright 1968, p. 361), both in northern England. These Hirnantia faunas, however, are less diverse than others which possess the same basic elements but with the addition of other taxa. One such is from the St. Martin’s Cemetery horizon, described above. Another, from Stawy, Poland, contains three inarticulate and seven articulate species of brachiopod as well as ‘trilobites, ostracods, bryozoans, worm tubes, a hyolithid and crinoid and graptolite fragments’ (Temple 1965, p. 380). A further fauna, from the Kildare Limestone, Ireland (Wright 1968) consisted of Cyptothyrella crassa incipiens (35%), Cliftonia oxoplecioides (28%), Plectothyrella platystrophoides (19%), dalmanellids (including Dalmanella) (12%), cf. Leptaenopoma (4%), H. sagittifera (3%), and Eostropheodonta sp. (less than 1%). Rare trilobites included Dalmanitina sp. and an odontopleurid. It is of great interest that Wright records that these Kildare Beds, which include the Hirnantia fauna elements, are actually interbedded with reef limestones with a rich and diverse fauna including Cliftonia, Streptis, Triplesia, Anisopleurella, Leptaena, and Christiania, as well as Sphaeroxochus, illanenids and other trilobites, ostracodes, byrozoans, and algae; and it is also interesting to note the records of fragmentary trinucleids from beds above those with the Hirnantia fauna. Bergstrom (1968) gives valuable data on the brachiopod fauna of the Dalmanitina Beds in Vastergotland, Sweden. Of the eighteen localities from which he records brachiopods, seven (his fig. 4 locality nos. 1, 3, 6-7, 8, 10, 14, and 28) are typical, fairly restricted, Hirnantia assemblages, four (his localities 18 and 22-24) are not Hirnantia assemblages, and the rest are diverse assemblages which include Hirnantia fauna elements to greater or lesser extents. His most prolific exposure (his locality 5) 722 PALAEONTOLOGY, VOLUME 18 yielded an interesting assemblage consisting of (percentages calculated from his fig. 4 of brachiopods only) ; Coolinia dalmani (43%) (n = 625), H. sagittifera (9%), K. kielanae (9%), E. hirnantensis (7%), P. crassicosta (6%), Cliftonia psittacina (5%^ Horderleyella fragilis (4%), Aphanomena schmalenseei (4%), Leptaenopoma trifidum (3%), Leptaena rugosa (3%), Orbiculoidea concentrica (2%), Drabovia westrogothica (1%), Giraldiella bella (1%), Dalmanella testudinaria (1%), Draborthis caelebs (1%), Titanomena grandis (1%), and rare Dalmanella pectinoides and Petrocrania aperta, a total of eighteen brachiopod species, which is quite diverse. Bergstrom also records (1968, p. 5) Hirnantia fauna elements from Jamtland, northern Sweden, occurring in the same beds as Dalmanitina mucronata, Brongniartella platynota, and also Tr etas pis. Marek and Havlicek (1967) described comparable assemblages from the Kosov Formation of Bohemia in which Hirnantia fauna elements— Kinnella, Dalmanella testudinaria, Cliftonia, E. hirnanentensis, Leptaena rugosa, Cryptothyrella, and Plectothyrella occur with other {oxm?,— Giraldiella subsilurica, Comatopoma sororia, Drabovia agnata, Draborthis caelebs, Onniella rava, Aegiromena ultima, Rafinesquina urbicola, R. ultrix, Leptaenopoma trifidum, Bracteoleptaena polonica, Eardenia comes, and Zygospira fallax. Although a few of these latter species have been recorded with Hirnantia fauna elements elsewhere (e.g. Bergstrom 1968), most of them are not found in the strict Hirnantia fauna at all. Havlicek (1971) also described a comparable fauna from the Deuxieme Bani of the Anti-Atlas, Morocco. Here, in addition to Hirnantia, Eostropheodonta, and Plecto- thyrella, he described another ten brachiopod species not so far recognized elsewhere. Hirnantia alf. sagittifera and endemic species of Plectothyrella have also been described from the Memouniat Formation of Libya (Havlicek and Massa 1973). Lesperance (1974, tables 1 and 2) reports a fauna from Perce, Canada, consisting of Brongniartella sp., M. mucronata, M. olini, Philipsinella parabola, two other endemic trilobites, Dalmanellal, E. hirnantensis, Hirnantia^}, Kinnella kielanae, and Plectothyrella, but he does not give relative abundances, or state whether the fauna was all collected from the same horizon. From the Portage River area, 17 km away, Lesperance records a fauna (without brachiopods) in which the trilobites M. mucro- nata, M. olini, Brongniartella, Portaginus, and Cryptolithus occur together with what he records as Climacograptus rectangularismedius, the latter suggesting an early Silurian age. However, Dr. Rickards (pers. comm.) believes that these graptolites probably represent an earlier climacograptid stock, perhaps evolved from C. normalis, and that their age, although uncertain, is more probably late Ordovician. The situation in Kazakhstan, U.S.S.R., requires further clarification: Nikitin (1971, p. 339) records M. mucronata and M. olini from the upper Tolen Beds in association with Glyptograptus persculptus, but a Hirnantia fauna as such does not seem to be present, the only brachiopod recorded being "Conchidium’’ munsteri. Thus the Hirnantia fauna assemblages are widely variable; sometimes restricted to a mere two genera, at other times consisting of the basic half-dozen Hirnantia fauna elements with up to twelve associated cosmopolitan or endemic brachiopods. Sometimes no trilobites are present; at other times one or more representatives of the ‘'Dalmanitina' fauna with or without other cosmopolitan or endemic forms. We believe that the Hirnantia fauna is best interpreted as representing an animal com- COCKS AND PRICE: ORDOVICIAN AND SILURIAN BIOSTRATIGRAPHY 723 munity comparable with those described by Ziegler et al. (1968), rather than as a single time assemblage zone, and that its occurrence is therefore a priori as likely to be diachronous as synchronous. As Wright (1968, p. 365) suggested, the Hirnantia Community, at least in its restricted form, suggests original deposition under relatively shallow water; but perhaps the more diverse Hirnantia assemblages could reflect deposition under slightly deeper water. Spectacular evidence for a late Ordovician-early Silurian glacial event has been accumulating from many parts of the world for some years, and this event is probably connected with the faunal changes seen across the Ordovician/Silurian boundary. Obviously near the then poles this glacial event would have been more prolonged than in equatorial regions, but to what extent the Hirnantia Community is a direct reflection of cold-water conditions is as yet uncertain. In the same way the degree to which this glaciation coincides with the extent of the Hirnantian Stage remains unknown. The age range of the Hirnantia Community also remains uncertain. Eostropheo- donta ranges from Cautleyan up to the Wenlock, Hirnantia itself is known from the early Ashgill to late Llandovery (Walmsley et al. 1969, p. 515), Cryptothyrella from the early Ashgill to the Wenlock, Dalmanella s.s. from the Caradoc to the Llandovery, and Plectothyrella from the Ashgill to the Llandovery. Of the typical Hirnantia Community forms only Kinnella appears to be confined to the late Ashgill, and that enteletacean has only been recognized comparatively recently (Bergstrom 1968) as a separate genus; its range is not definitively known. Sometimes the Hirnantia Com- munity occurs below tretaspid trilobites, at other times in the same beds, and at yet other times apparently later than the last local tretaspid fauna. In a similar fashion the ranges of the trilobites that make up the " Dalmanitina" fauna also vary and their occurrences should be assessed separately from those of the whole Hirnantia Com- munity. Very often the two occur together in a single assemblage, but at other times each is found separately. Thus to conclude that the Hirnantia Community occurrences are all of the same age appears to us to be a dangerous assumption. Acknowledgements. We are grateful to Dr. R. B. Rickards for identifying our graptolites and for re-examining old specimens, and to Dr. J. T. Temple for discussion and for access to unpublished material. We are also most grateful to Dr. A. W. A. Rushton for access to old Geological Survey collections and data. REFERENCES BANCROFT, B. B. 1933. Correlation tables of the stages Costonian-Onnian in England and Wales. 8 pp., privately published, Blakeney, Glos. BERGSTROM, J. 1968. Upper Ordovician Brachiopods from Vastergotland, Sweden. Geol. et Palaeontol. 2, 1-35, pis. 1-7. CANTRiLL, T. c. 1907. Stratigraphical Note. Geol. Mag. Dec. V, 4, 537-538. COCKS, L. R. M. 1968. Some strophomenacean brachiopods from the British Lower Silurian. Bull. Br. Mas. nat. Hist. (Geol.), 15, 283-324, pis. 1-14. 1970. Silurian brachiopods of the superfamily Plectambonitacea. Ibid. 19, 139-203, pis. 1-17. and TOGHiLL, p. 1973. The biostratigraphy of the Silurian rocks of the Girvan District, Scotland. Jl geol. Soc. bond. 129, 209-243, pis. 1-3. ELLES, G. L. 1922. The age of the Hirnant Beds. Geol. Mag. 59, 409-414. havliCek, V. 1971. Brachiopodes de TOrdovician du Maroc. Notes Mem. Serv. Geol. 230, 1-135, pis. 1-26. 724 PALAEONTOLOGY, VOLUME 18 HAVLiCEK, V. and MASSA, D. 1973. Brachiopodes de I’Ordovicien superieur de Libye occidentale : implications stratigraphiques regionales. Geobios, 6, 267-290, pis. 1-4. INGHAM, j. K. 1966. The Ordovician Rocks in the Cautley and Dent Districts of Westmorland and York- shire. Proc. Yorks. Geol. Soc. 35, 455-505, pis. 25-28. 1970. The Upper Ordovician trilobites from the Cautley and Dent Districts of Westmorland and Yorkshire. Palaeontogr. Soc. [Monogr.], 1-58, pis. 1-9. and WRIGHT, A. D. 1970. A revised classification of the Ashgill Series. Lethaia, 3, 233-242. JONES, o. T. 1925. The Geology of the Llandovery District: Part I— The Southern Area. Q. Jl geol. Soc. Lond. 81, 344-388, pi. 21. LAPWORTH, c. 1882. The Girvan Succession. Ibid. 38, 537-666. LESPERANCE, p. J. 1974. The Hirnantian Fauna of the Perce area (Quebec) and the Ordovician-Silurian boundary. Am. J. Sci. 274, 10-30. MAREK, L. and HAVLICEK, V. 1967. The articulate brachiopods of the Kosov Formation (Upper Ashgillian). Vest. Ustfed. ust. Geol. 42, 275-284, pis. 1 -4. MARR, J. E. and ROBERTS, T. 1885. The Lower Palaeozoic rocks of the Neighbourhood of Haverfordwest. Q. Jlgeol. Soc. Lond. 41, 476-491. NIKITIN, I. F. 1971. The Ordovician System in Kazakhstan. Mem. Bur. Rech. geol. minier. 73, 337-343. PRICE, D. 1973. The age and stratigraphy of the Sholeshook Limestone of Southwest Wales. Geol. J. 8, 225-246. REED, F. R. c. 1905. New Fossils from the Haverfordwest District. Geol. Mag. Dec. V, 2, 97-104, 444-454, 492-501, pis. 4, 23, 24. 1906. Sedgwick Museum Notes. New Fossils from the Haverfordwest District. Ibid. Dec. V, 3, 358- 368, pi. 20. 1907. Sedgwick Museum Notes. The Base of the Silurian near Haverfordwest. Ibid. Dec. V, 4, 535-537. SANZEN-BAKER, I. 1972. Stratigraphical Relationships and Sedimentary Environments of the Silurian- Early Old Red Sandstone of Pembrokeshire. Proc. Geol. 83, 139-164. STRAHAN, A., CANTRiLL, T. c., DIXON, E. E. L., THOMAS, H. H. and JONES, o. T. 1914. The geology of the South Wales Coalfield, Part XL The country around Haverfordwest. Mem. geol. Surv. U.K. 228, 1-262. TEMPLE, J. T. 1952. A revision of the trilobite Dalmanitina mucronata (Brongniart) and related species. Lunds. Univ. Arssk. N.s. (2), 48, 1-33, pis. 1-4. 1965. Upper Ordovician brachiopods from Poland and Britain. Acta palaeont. Pol. 10, 379-450, pis. 1-21. 1969. Lower Llandovery (Silurian) trilobites from Keisley, Westmorland. Bull. Br. Mus. nat. Hist. (Geol), 18, 199-230, pis. 1-6. 1970. The Lower Llandovery brachiopods and trilobites from Ffridd Mathrafal, near Meifod, Montgomeryshire. Palaeontogr. Soc. [Monogr.], 1-76, pis. 1-19. 1975. Early Llandovery trilobites from Wales with notes on British Llandovery calymenids. Palaeon- tology, 18, 137-159, pis. 15-21 . WALMSLEY, V. G., BOUCOT, A. J. and JOHNSON, J. G. 1969. Silurian and lower Devonian salopinid brachiopods. J. Paleont. 43, 492-516, pis. 71-80. WILLIAMS, A. 1951. Llandovery brachiopods from Wales with special reference to the Llandovery District. Q. Jl geol. Soc. Lond. 107, 85-136, pis. 3-8. STRACHAN, L, BASSETT, D. A., DEAN, W. T., INGHAM, J. K., WRIGHT, A. D. and WHITTINGTON, H. B. 1972. A correlation of Ordovician rocks in the British Isles. Spec. Kept. Geol. Soc. Lond. 3, 1 -74. WRIGHT, A. D. 1968. A westward extension of the Upper Ashgillian Hirnantia Eauna. Lethaia, 1, 352-367. ZIEGLER, A. M., BOUCOT, A. J. and SHELDON, R. p. 1966. Silurian pentameroid brachiopods preserved in position of growth. J. Paleont. 40, 1032-1036, pis. 121, 122. COCKS, L. R. M. and bambach, r. k. 1968. The composition and structure of Lower Silurian marine communities. Lethaia, 1, 1-27. Typescript received 21 January 1975 Revised typescript received 23 April 1975 L. R. M. COCKS Department of Palaeontology British Museum (Natural History) London, SW7 5BD D. PRICE Department of Geology Sedgwick Museum Downing Street Cambridge, CB2 3EQ COMPARATIVE ANALYSIS OF FOSSIL AND RECENT ECHINOID BIOEROSION by R. G. BROMLEY Abstract. One of the most abundant forms of bioerosion sculpture on Mesozoic and Cainozoic shells and other hard substrates has a pentaradiate symmetry based on a regular, stellate module consisting of five radiating grooves. Regular echinoids today, browsing on encrusting and boring organisms on hard substrates, produce identical sculp- ture to the trace fossil, and a common origin is suggested. The tooth scratches lose their pentaradiate orientation and become subparallel where the echinoid gnaws along edges of shells and flat pebbles; a corresponding sculpture is also encountered in the trace fossil. The pentaradiate trace fossil is designated as Gnathichnus pentax, ichnogen. et ichnosp. nov. A TYPE of hard substrate trace fossil that, despite its abundance, has received scant attention from geologists, is the sculpture produced by browsing and foraging animals. Such sculpture, commonly termed ‘bioerosion’ (Neumann 1966), occurs on substrate surfaces that have been exposed at the sea floor for a period of time. Indeed, in some post-Palaeozoic sediments of shallow marine origin it is difficult to find fossils unaffected by superficial bioerosion. One of the most common types of bioerosion sculpture has a basic pentaradiate symmetry and comparison with the traces produced by the teeth of living regular echinoids strongly suggests a common origin. DESCRIPTION OF FOSSIL MATERIAL The surface sculpture of bioeroded shells and other substrates may consist of random or grouped scratches of various depths and sizes. Examples have been described by Abel (1935), Boekschoten (1966, 1967), Riegraf (1973), Bishop (1975), and many others. Among these different types of scratches there is a single group that can be treated separately owing to its distinctive pentaradiate organization and regular morphology. The aspect presented by this type depends on (1) the spacing between the scratches, (2) the curvature of the substrate, and (3) the presence of borings in the substrate. More or less flat surfaces In its simplest form the trace fossil consists of a regular stellate arrangement of five radiating grooves making an angle of approximately 72° with each other. Such a ‘star’ is rarely seen in isolation but may be regarded as the ‘modular unit’ (Heinberg 1973) of the ultimate bioerosion sculpture. The ‘rays’ of this stellate module have a uniform length and depth. The diameter of the module rarely exceeds 5 mm and in most cases is less than 2 mm. Considerably more common than single stars are compound traces built up of a series of overlapping identical stars in which equivalent rays are repeated parallel [Palaeontology, Vol. 18, Part 4, 1975, pp. 725-739, pis. 85-89.] 726 PALAEONTOLOGY, VOLUME 18 to one another (PI. 85, fig. 1). In those cases where repeated rays lie closer together than they do to other rays of the same star, the closely spaced group of parallel grooves representing the repetition of a single ray may be erroneously interpreted as the module (as e.g. McKerrow et al. 1969, pi. 12, fig. 3) rather than the pentaradiate star itself. Compound stellate bioerosion sculptures may become increasingly complex by repetition of overlapping stars until the individual stars can no longer be distinguished and the substrate surface is completely covered with grooves of similar depth and length (PI. 86, figs. 4-5). Nevertheless, plotting of the orientation of the grooves over selected areas of the surface reveals the underlying stellate module. Indeed, the pentaradiate distribution of the grooves is so pronounced in most cases that it can be discerned with the naked eye, and accentuated by oblique illumination. Sharply curved and irregular surfaces The full development of the trace fossil as described above is seen only on flat substrates (e.g. smooth mollusc shells). Where the surface is irregular, the stellate module is commonly reduced to fewer rays, but the 72° angle between rays remains constant (PI. 85, fig. 3; PI. 89, fig. 1). In cases where the substrate describes a sudden and extensive convex curve, as at the edge of a flat pebble, the basic module changes so that the grooves become densely packed and more or less parallel (PI. 86, fig. 2). Where perforations occur in the substrate which exceed the diameter of the basic module, these are commonly surrounded by a series of closely packed grooves in this case aligned more or less perpendicular or normal to the edge of the hole. The dimensions of the individual grooves are precisely similar to those of the pentaradiate sculptures on related flat surfaces. Presence of sessile organisms within and upon the substrate Concentration of the grooves also occurs around borings and encrusting skeletons that are smaller than the diameter of the module. In contrast to the subparallel orientation of the grooves around large-scale perforations in the substrate, the grooves around smaller sites exhibit the characteristic regular pentaradiate arrange- ment. This relationship is particularly noticeable in the case of borings of organisms in the substrate, where the grooves are generally deep and associated with breakage of the rim of the boring. Well-developed stars are seen around acrothoracic barnacle EXPLANATION OF PLATE 85 Fig. 1. Gnathichnus pentax on a belemnite from Reutlingen, near Tubingen, West Germany. Upper Lias delta. Printed from a peel. x9. Fig. 2. Bite traces of a Recent echinoid on gastropod shell, Charonia tritonis. Locality unknown. MMH 13387, Mineralogisk Museum, Copenhagen. x7. Fig. 3. Gnathichnus pentax (holotype) on an oyster shell from lowermost Pleistocene at Kritika, Rhodes. MMH 13386. x8. Fig. 4. Bite traces of Sphaerechinus granularis on a flat, algal-coated limestone pebble. The traces were made in an aquarium at the Institut Rudjer Boskovic-Zagreb, Centre for Marine Research at Rovinj, Yugoslavia. The specimen is housed in the North Adriatic Collection of the Geologisch-Palaontolo- gisches Institut, Gottingen University. x9. PLATE 85 BROMLEY, echinoid bite traces 728 PALAEONTOLOGY, VOLUME 18 borings (PI. 88, figs. 1-3), borings of small worms (PI. 86, fig. 3; PI. 87, fig. 6), and the papillar orifices to clionid sponge borings. A particularly close association is found in the last case, and commonly a large proportion of the papillar orifices are surrounded by multiple stellate modules (PI. 87, figs. 1-5). Other comparable inhomogeneities of the substrate can also be surrounded by stellate groove patterns, such as the ambulacral pores of echinoids (PI. 88, figs. 4-5). GNAWING TRACES PRODUCED BY PRESENT-DAY MARINE ANIMALS Several groups of animals cause bioerosion through their eating activities. In many of these groups the process is chiefly one of ‘biting’ and ‘crushing’ and is caused by biramous tools, i.e. a pair of opposable jaws or claws, as in, for example, parrot fish and grapsid crabs. These animals work over hard substrates, breaking up the surface, especially around borings, in search of epilithic and endolithic organisms or eroding living substrate such as coral (Bakus 1964, 1966). The result of such foraging is generally a series of highly irregular scratches, pits, and broken protuberances that in no way resembles the uniform, pentaradiate traces discussed here (PI. 89, fig. 3) (Abel 1935, p. 325). In certain circumstances, however, fish can produce groups of subparallel scratches at breakage cavities (Kier and Grant 1965, p. 55). A more homogeneous form of bioerosion is produced by the methodical grazing of gastropods and polyplacophores. Boekschoten (1966, fig. 11) illustrated typical chiton rasping traces, while those of grazing gastropods have received more attention (see particularly Abel 1935, fig. 338 ; Ankel 1929, 1936, 1937). In these cases, extensive areas of substrate are eroded, but the rather even scratches have a subparallel distribu- tion within arcuate groups that reflect the swinging movement of the head as the gastropod progresses slowly over the substrate, and scratches of the individual teeth of the radula may be preserved (Ankel 1936, fig. 8, 1937, figs. 2 and 11). Predatory boring gastropods may scratch the shell surface of their prey with their radula before boring, but these scratches have random orientation and very local distribution (Carriker 1969, figs. 11-15). This radular erosion does not produce a sculpture of pentaradiate module. EXPLANATION OF PLATE 86 Fig. 1 . Gnawing traces of Sphaerechinus granularis on the rounded edge of an algal-coated limestone pebble. Details as for Plate 85, fig. 4. x 3. Fig. 2. Gnawing traces on the edge of a shell fragment (Inoceramus sp.) from Lower Maastrichtian white chalk, Dronningestolen, M^ns Klint, Denmark. MMH 13388. x6. Fig. 3. Gnalhichnus pentax along a worm boring, the roof of which has been largely broken away. Upper Campanian, Bluffport Marl Member, Demopolis chalk, north of Parker, Alabama, U.S.A. MMH 13389. X 6. See also Plate 87, fig. 6. Fig. 4. Surface of an oyster {Arctostrea dilmiana) entirely sculptured with Gnalhichnus pentax. Uppermost Lower Campanian calcarenite, Ivo Klack, Ivb, Scania, Sweden. MMH 13390. x6. Fig. 5. Enlargement of part of fig. 4. x 20. PLATE 86 BROMLEY, echinoid bite traces 730 PALAEONTOLOGY, VOLUME 18 Echinoid-gnawing traces The work of one particular group of organisms, however, is highly distinctive and provides an excellent model for the pentaradiate trace fossils, namely the browsing traces of regular echinoids. A considerable part of the body of these animals is taken up by the jaw apparatus, the so-called ‘Aristotle’s Lantern’, the five teeth of which can be brought to bear on the substrate with considerable power through the muscula- ture of the lantern and the concerted effort of the numerous tube feet. Regular echinoids are highly efficient bioeroders and cause considerable rock destruction in their quest for food. Umbgrove (1939) described intertidal notch erosion in coral rock chiefly by Echinometra mathaei in the East Indies (text-fig. 1) and Neumann (1966) attributed extensive notch erosion in limestone immediately below spring low tide in Bermuda chiefly to the work of Lytechinus variegatus. Neumann (1965) also emphasized the production of quantities of fine rock powder by the bioerosive TEXT-FIG. 1. A ‘toadstool island’ from the north coast of Batoe Daka, Togian Islands, Celebes, sketched after Umb- grove (1939, fig. 21). The intertidal notch is chiefly eroded by Echinometra mathaei. TEXT-FIG. 2. Echinus esculentus clears a browsing path about as wide as its own test by meandering over the substrate. Sketched from a photograph of an animal in the natural environment on the sea floor at Heligoland, West Germany. Inset photograph of gnawing traces of this species in an aquarium. Both from W. E. Krumbein, pers. comm. Meandering line from Krumbein and Van der Pers (1974, fig. 6a). BROMLEY: ECHINOID BIOEROSION 731 activities of Lytechinus variegatus. In many rocky shores echinoids use their teeth to bore deep protective cavities, commonly with narrow entrances, in granite, lime- stone, and artificial substrates (Market and Maier 1967 ; references in Bromley 1970). The prime function of the great jaw apparatus is for the exploitation of organisms encrusting and boring into hard substrates. A study of the feeding habits of regular echinoids reveals many features that render these animals likely candidates for the originators of the pentaradiate trace fossils. The mode of employment of the echinoid tooth involves a powerful scraping action, producing a single groove that has, on an even substrate, a characteristic and uniform width and depth. The simultaneous action of all five teeth produces a stellate pattern of grooves identical in form to the module of the trace fossil (PI. 85, fig. 2). This trace has been described by many workers. Krumbach (1914) stated that the scratch produced by Sphaerechinus granularis on limestone in the Adriatic Sea was up to 0-5 mm deep (PI. 85, fig. 4; see also Abel 1935, fig. 310). Krumbach observed that each bite in this species took 30-35 seconds at a temperature of 10°C— a little faster at higher temperatures— and comparable speeds have been recorded for other species (e.g. Milligan 1916). Between individual bites, i.e. during the time required to reopen the jaws, the echinoid will have travelled a certain distance over the substrate, so that at the next bite the five teeth cut fresh substrate adjacent to the first bite. In this way successive stars are scratched side by side. Krumbein and Van der Pers (1974) observed that as the browsing echinoid pro- gresses over the substrate it follows a regularly meandering course and covers a strip of substrate approximately the same width as the animal’s test (text-fig. 2). Owing to the non-cephalization of regular echinoids, the orientation of the body and its tooth apparatus remains more or less unaltered as the animal wanders, and the stellate grooves of the browsed area consequently show a corresponding constant alignment. This constancy of orientation is also characteristic of the trace fossil (PI. 85, figs. 3 and 4). There has been much speculation over the food preferences of regular echinoids and conflicting evidence has been recorded in the literature. Most species, however, appear to take advantage of a variety of types of organic matter. Shallow-water species feed predominantly on algal films on hard substrates, and some appear to be exclusively algal browsers. Encrusting animals, particularly bryozoans, are also scraped off shell and rock surfaces. Milligan (1916) recorded Psammechinus miliar is from British waters eating empty mollusc shell and serpulid tubes, and also the perio- stracum of the shells of living molluscs. Jensen (1969) regarded bryozoans as of vital importance as food for P. miliaris in Danish and Norwegian waters, whereas Krumbein and Van der Pers (1974) recorded a preference for the boring worm Polydora ciliata in this species and Echinus esculentus at Heligoland. Ormond and Campbell (1971) emphasized the browsing efficiency of Diadema setosum and Echinothrix diadema in the Red Sea off Sudan. These echinoids emerged from their borings and crevices at night to browse freely on the surrounding coral rock surfaces, which were kept largely clean from encrusting organisms. Only locally, where both echinoids were absent, were rich developments of encrusting algae to be found. The methodical exploitation of encrusting organisms for food invariably causes 732 PALAEONTOLOGY, VOLUME 18 scratching of the underlying substrate. The resulting stellate pattern of overlapping superimposed grooves (Krumbach 1914, fig. 1; Abel 1935, fig. 310; Neumann 1966, fig. 7 ; Krumbein and Van der Pers 1974, fig. 1 1 ; PI. 85, figs. 2 and 4) precisely dupli- cates the trace fossil. Furthermore, when an echinoid, browsing over a flat, algal-coated pebble, arrives at a sharply curved edge of the pebble, the mode of employment of the teeth changes to accommodate the different topography. The hitherto stellate orientation of the grooves is replaced around this edge by a subparallel orientation perpendicular to the boundary of the pebble (PI. 86, fig. 1), since on the curved surface only two or three teeth can operate at a time. The pattern again duplicates the trace fossil (PI. 86, fig. 2). The occurrence of the trace fossil finds a parallel in the feeding predelection of present-day regular echinoids for boring animals in general and clionid sponges in particular. Hancock (1957) reported that Psammechinus miliaris kept under experimental conditions attacked only those oyster shells (dead or alive) that were infested by the sponge Cliona celata or the polychaete worm Polydora ciliata, and that these boring organisms were the sole reason for the attack. The echinoid caused severe erosion of the shell in order to expose and eat the enclosed worms and sponges. In the natural environment of the North Sea, Krumbein and Van der Pers (1974) also recorded active erosion of limestone by Echinus esculentus feeding on Polydora ciliata. EXPLANATION OF PLATE 87 Fig. 1. Gnathichnus pentax around a pore of a sponge-boring (Entobia megastoma (Fischer)) in a belemnite (Belemnitella mucronata) from Upper Campanian white chalk, Keswick, Norfolk, England. 85.964(4), Norwich Castle Museum. x20. Fig. 2. Gnathichnus pentax around a pore of Entobia megastoma in Belemnitella mucronata from Upper Campanian white chalk, Norwich, England. 2127(1), Norwich Castle Museum. X 20. Fig. 3. Gnathichnus pentax around pores of Entobia cretacea Portlock (sponge-boring) in Inoceramus digitatusi. de C. Sowerby (non Schliiter). Probably Coniacian, white chalk, south-east England, locality unknown. Paratype. GSM 115027. x5. Fig. 4. Gnathichnus pentax around broken open boring of a sponge in Belemnitella aff. lanceolata. Degree of destruction of the substrate lies between those in figs. 2 and 8. Lower Maastrichtian white chalk, Kongsted, Denmark. MMH 13391. x6. Fig. 5. An unusually clearly pentaradiate Gnathichnus pentax around a clionid sponge papillar boring in Belemnitella sp. Lower Maastrichtian, Zeltberg/Liineburg, West Germany. Collection of Nieder- sachsischen Landesamtes fiir Bodenforschung, Hannover, catalogue kma 12. Photo E. Voigt. X 12. Fig. 6. As Plate 86, fig. 3. x4. Fig. 7. Typical location of Gnathichnus pentax, around the muscle attachment area of oysters. Loss of the aragonite myostracum leaves only that part of the trace that extended on to the surrounding calcite shell surface. Lower Campanian Burditt Marl Member, Austin chalk from Little Walnut Creek, east of Austin, Texas, U.S.A. MMH 13392. x3-5. Fig. 8. ‘Wreck’ of a Belemnitella sp. broken open by foraging animals eating the boring sponges that pro- duced the internal cavities. Scratches around the holes indicate the work of regular echinoids. Uppermost Campanian white chalk, 1 m below horizon 595, Saturn Quarry, Kronsmoor, West Germany. MMH 13393. x 3. PLATE 87 BROMLEY, echinoid bioerosion 734 PALAEONTOLOGY, VOLUME 18 DISCUSSION The close similarity of the fossil material with the work of many species of browsing and foraging regular echinoids renders it probable beyond reasonable doubt that the trace fossil is also the work of echinoids. The geological occurrence lends further support to this interpretation. The bioerosion sculpture has so far been found only in deposits that appear to have been laid down in fully marine conditions. The trace fossil is particularly abundant in sediments representing shallow-water well- oxygenated environments. So far the pentaradiate trace fossil, common in Jurassic and younger strata, has not been found in Triassic or Palaeozoic rocks. This may be correlated with evo- lutionary changes in the structural development of the jaw apparatus in regular echinoids. The first perignathic girdles appeared in the Permian and progressive evolutionary changes of both the girdle and the lantern occurred during the Mesozoic. Kier (1974, pp. 53-56 and 62) interpreted these changes in terms of promoting the biting power and mobility of the lantern. The appearance of the strengthened tooth with T-shaped cross-section in the stirodont lantern, and change over from apophyses to auricles in the girdle occurred in late Triassic to early Jurassic times. It is significant, therefore, that the earliest pentaradiate bite known is of early Jurassic age (PI. 85, fig. 1). The fully developed camarodont lantern appeared in the Maastrichtian, having extremely large muscles capable of moving the pyramids and their teeth with great force against the bottom (Kier 1974, p. 55). It may therefore also be significant that the earliest known occurrences of extensive areas browsed uniformly by five teeth date from only shortly before the Maastrichtian (PI. 86, figs. 4-5; PI. 88, fig. 7). From Upper Cretaceous rocks there is some evidence that the sculpture may prove a useful palaeoenvironmental indicator. Substrates from localities representing shallow-water environments have been extensively browsed (PI. 86, fig. 4) while in deeper-water deposits of comparable age the trace fossil is concentrated locally around borings (PI. 87, figs. 1-4). This difference may be a reflection of the presence and absence, respectively, of algal films in these environments. In most of the rocks in which these trace fossils have been found, one or more EXPLANATION OF PLATE 88 Figs. 1-3. Gnathichnus pentax around acrothoracic borings (Rogerella mathieui Saint-Seine) in Echimcorys sp., showing different stages in the destruction of the borings. x6. 1, Santonian or Coniacian, white chalk from Guston near Dover, England. Institute of Geological Sciences, London, CJW 806. 2, Cam- panian white chalk from West Harnham, SW. of Salisbury, England. I.G.S., London, Zn 1903. 3, Lower Maastrichtian white chalk of Gr§ryg, M0ns Klint, Denmark. MMH 13394. Fig. 4. Gnathichnus pentax around the aperture of a small boring in Echinocorys sp. Bed S, Lower Maas- trichtian white chalk at Sidestrand, England. X 10. Fig. 5. Gnathichnus pentax at site of attack of four tubefeet of Echinocorys sp. Santonian white chalk of the coast between Kingsgate and Foreness, Thanet, Kent, England. I.G.S., London, GSM 88258. x6. Fig. 6. Gnathichnus pentax around a broken open boring in Inoceramus digitatus. Same specimen as Plate 87, fig. 3. X 6. Fig. 7. Paratype of Gnathichnus pentax. Extensive but light bioerosion of the external surface of an Ino- ceramus sp. of "cuvierC group. Turonian? White chalk of SE. England, locality unknown. GSM 1 15029. X 1-5. PLATE 88 7 BROMLEY, Gnathicimus pentax 736 PALAEONTOLOGY, VOLUME 18 regular echinoids are preserved that may represent the trace maker(s) (e.g. Voigt 1972, p. 119). In the Lower Campanian chalk {Gonioteuthis quadrata Zone) of Hampshire, England, the trace fossil occurs with Stereocidaris sp., Salenia granulosa, and Phymosoma sp. In the Upper Campanian chalk of England they are accompanied by Stereocidaris 'serrifera', Salenia heberti, and Phymosoma regularis, while in the Maastrichtian chalk of England, Germany, and Denmark the sculpture is accom- panied by Salenia pygmaea, Stereocidaris spp., Phymosoma sp., and (Denmark only) Tylocidaris baltica (C. J. Wood, pers. comm. 1975). On the other hand, the extensive but otherwise rather similar grooves on shells in the Campanian littoral deposits of Sweden are again accompanied by species of Salenia, Tylocidaris, and Stereocidaris but the species are different from those of the correlative deeper-water chalk facies. In those cases where several regular echinoid species accompany the trace fossil it is doubtful whether the traces produced by the different species can be distinguished. The large Echinus esculentus and the small Psammechinus miliaris, feeding together in aquaria, each produce large or small traces according to local changes of feeding habits (W. Krumbein, pers. comm. 1974). Stars of a particular echinoid individual also tend to be smaller on hard substrates than on softer rocks (Krumbein and Van der Pers 1974, p. 12). Krumbach (1914), however, noted that Sphaerechinus granularis consistently produced more widely separated stars than Strongylocentrotus lividus in the same environment. The scratches of S. lividus were so close together that they overlapped so that the entire substrate surface was eroded clean of algae, but the grazing was restricted to limited territories. Arbacia pustulosa also fed in the same environment, but this species restricted its activities to narrow clefts in the substrate and to the underside of stones and overhangs, so that its feeding traces were readily separable from those of the other two species. NAMING THE TRACE FOSSIL For future reference it is necessary to name the distinctive groove pattern as a trace fossil. The name is applied to the basic stellate unit, multiplication of which produces the characteristic bioerosion sculpture. This is analogous to soft sediment trace fossils in which the isolated burrow bears the name, but its repetition produces a EXPLANATION OF PLATE 89 Fig. 1. Phosphatic pebble from Cenomanian greensand at Miilheim/Ruhr, near Essen, West Germany. Grooves scattered over the entire surface resemble the work of browsing regular echinoids. Private collection of H. Klaumann. x4. Fig. 2. External surface of a shell of Arctica islandica (L.) bioeroded by browsing organisms (Bromley and Tendal 1973, pi. Id). A remnant island of original shell surface at left, carrying a patch of black perio- stracum, shows the surface to have been lowered generally by about 1 mm. The double ridge is a ghost of an encrusting serpulid tube that originally protected the shell surface. Four orifices of a sponge-boring (papillae of Cliona celata are visible within) are surrounded by radiating grooves typical of the work of browsing echinoids (probably Psammechinus miliaris). The remainder of the surface bears fine striae from the radulae of gastropods. Dredged in southern Kattegat, Denmark. Housed in the Zoological Museum, Copenhagen, x 13. Fig. 3. Rodent gnawing traces on terrapin bone (plastron). Nacogdoches, Texas, U.S.A. x 3. PLATE 89 BROMLEY, echinoid bioerosion 738 PALAEONTOLOGY, VOLUME 18 bioturbation fabric. The definition of the name is based on morphological characters alone, with the understanding that the structures have a biogenic origin. The generic name is available for trace fossils of other types produced by rasping, biting, and gnawing animals. Ichnogenus gnathichnus nov. Type ichnospecies. Gnathichnus pentax nov. Diagnosis. Biogenic sculpture consisting of grooves, pits, and scratches on hard substrates. Ichnospecies Gnathichnus pentax nov. Plate 85, figs. 1-3; Plate 86, figs. 3-5; Plate 87, figs. 1-7; Plate 88, figs. 1-7. Type material. The variable aspects of the trace fossil cannot be represented by a single specimen. The holotype is an example showing particularly good preservation of the grooves. The paratypes illustrate two other typical modes of occurrence. Holotype. MMH 13386, housed in the Mineralogisk Museum, Copenhagen, Denmark (PI. 85, fig. 3). Paratypes. GSM 1 1 5029 (PI. 88, fig. 7) and GSM 1 1 5027 (PI. 87, fig. 3 ; PI. 88, fig. 6), housed in the Institute of Geological Sciences, London. Locus typicus. Kritika, Rhodes, Greece. Stratum typicum. Sgourou Formation, lowermost Pleistocene. Diagnosis. Gnathichnus consisting of a regular stellate grouping of five similar grooves radiating at c. 12°. Description. The trace fossil almost invariably occurs in multiples of several over- lapping stars and can cover considerable areas of substrate with grooves of similar dimensions intersecting at more or less 72° (and 144°). Commonly concentrated around skeletons of encrusting organisms and apertures to borings. Interpretation. Browsing and foraging traces attributed to dental erosion by regular echinoids. ' Range. Lower Jurassic to Recent. Acknowledgements. This paper has benefited considerably from the help and advice of C. J. Wood (London) and R. Goldring (Reading) who read earlier drafts; W. E. Krumbein (Oldenburg) provided photographs and facts (text-fig. 2); J. Schneider (Gottingen) lent recent material (PI. 85, fig. 4; PI. 86, fig. 1); W. Riegraf (Tubingen) supplied the peel for Plate 85, fig. 1 and E. Voigt (Hamburg) the photograph for Plate 87, fig. 5. The specimen in Plate 89, fig. 1 was lent by H. Klaumann (Mulheim/Ruhr) and W. Pockrandt (Hannover) also loaned comparative fossil material. REFERENCES ABEL, o. 1935. Vorzeitliche Lehensspuren. Fischer, Jena. 644 pp. ANKEL, w. E. 1929. Frassspuren einer Meeresschnecke. Natur Museum, 59, 95-99. 1936. Die Frassspuren von Helcion und Littorina und die Funktion der Radula. Zool. Anzeiger, 9 (Suppl.), 174-182. 1937. Wie frisst Littorinal Senckenhergiana, 19, 317-333. BROMLEY: ECHINOID BIOEROSION 739 BAKUS, G. J. 1964. The effects of fish-grazing on invertebrate evolution in shallow tropical waters. Occ. Pap. Allan Hancock Fdn, no. 27. 1966. Some relationships of fishes to benthic organisms on coral reefs. Nature, London, 210, 280. BISHOP, G. 1975. Fossil evidence of predation and paleopredation. In frey, r. w. (ed.). The study of trace fossils. Springer, New York. BOEKSCHOTEN, G. J. 1966. Shell borings of sessile epibiontic organisms as palaeoecological guides (with examples from the Dutch coast). Palaeogeogr., PalaeoclimatoL, Palaeoecol. 2, 333-379. 1967. Palaeoecology of some Mollusca from the Tielrode Sands (Pliocene, Belgium). Ibid. 3, 311-362. BROMLEY, R. G. 1970. Borings as trace fossils and Entobia cretacea Portlock, as an example. In crimes, t. p. and HARPER, J. c. (eds.). Trace fossils. Geol. J. special Issues, 3, 49-90. and TENDAL, o. s. 1973. Example of substrate competition and phobotropism between two clionid sponges. J. ZooL, Land. 169, 151-155. CARRiKER, M. R. 1969. Excavation of boreholes by the gastropod, Urosalpin.x: an analysis by light and scanning electron microscopy. Am. Zoologist, 9, 917-933. HANCOCK, D. A. 1957. The feeding behaviour of the sea urchin Psammechinus miliaris (Gmelin) in the laboratory. Proc. zool. Soc. Lond. 129, 255-262. HEiNBERG, c. 1973. The internal structure of the trace fossils Gyrochorte and Curvolithus. Letliaia, 6, 227-238. JENSEN, M. 1969. Breeding and growth of Psammechinus miliaris (Gmelin). Ophelia, 7, 65-78. KiER, p. M. 1974. Evolutionary trends and their functional significance in the post-Paleozoic echinoids. Paleont. Soc., Mem. 5, 95 pp. and GRANT, R. E. 1965. Echinoid distribution and habits, Key Largo Coral Reef Reserve, Florida. Smithsonian misc. Coll. 149, 68 pp. KRUMBACH, T. 1914. Mitteilungcn fiber die Nahrung felsenbewohnender Seeigel der nordlichen Adria. Notizen fiber die Fauna der Adria bei Rovigno. Zool. Anzeiger, 44, 440-451. KRUMBEiN, w. E. and VAN DER PERS, J. N. c. 1974. Diving investigations on biodeterioration by sea-urchins in the rocky sublittoral of Helgoland. Helgoldnder wiss. Meeresunters. 26, 1-17. MARKED, K. and MAiER, R. 1967. Beobachtungen an lochbewohnenden Seeigeln. Natur Museum, 97, 233-243. MCKERROW, w. s., JOHNSON, R. T. and JAKOBSON, M. E. 1969. Palaeoecological studies in the Great Oolite at Kirtlington, Oxfordshire. Palaeontology, 12, 56-83. MILLIGAN, H. N. 1916. Observations on the feeding habits of the purple-tipped sea-urchin. Zoologist (4), 20, 81 99. NEUMANN, A. c. 1965. Processes of recent carbonate sedimentation in Harrington Sound, Bermuda. Bull, mar. Sci. 15, 987-1035. 1966. Observations on coastal erosion in Bermuda and measurements of the boring rate of the sponge, Cliona lampa. Limnol. Oceanogr. 11, 92-108. ORMOND, R. F. G. and CAMPBELL, A. c. 1971. Observations on Acanthaster planci and other coral reef echino- derms in the Sudanese Red Sea. Symp. zool. Soc. Lond. no. 28, 433-454. RiEGRAF, w. 1973. Bissspuren auf jurassischen Belemnitenrostren. N. Jb. Geol. Paldont., Mh., 1973, 494- 500. UMBGROVE, J. H. F. 1939. De atollen en barriere-riffen der Togian-Eilanden. Leidsche geol. Mededeel. 11, VOIGT, E. 1972. liber Talpina ramosa v. Hagenow 1840, ein wahrscheinlich zu den Phoronidea gehoriger Bohrorganismus aus der Oberen Kreide, nebst Bemerkungen zu den fibrigen bisher beschreibenen kretazischen ‘Talpina’-Arten. Nachrichten Akad. ^Viss. Gottingen 2, math.-phys. Kl. 1972, 93-126. 132-187. Typescript received 10 March 1975 Revised typescript received 18 April 1975 R. G. BROMLEY Institute of Historical Geology and Palaeontology University of Copenhagen DK-1350 Copenhagen Denmark ENGLISH HYPSILOPHODONTID DINOSAURS (REPTILIA: ORNITHISCHI A) by PETER M. GALTON Abstract. A premaxillary tooth from the Stonesfield Basin (Bathonian) of Stonesfield may represent the oldest hypsilophodontid described to date. However, small bones from the Lias (Jurassic) of Charmouth are not hypsilopho- dontid and were correctly referred to the primitive ankylosaur Scelidosaurus harrisoni. A femur from the Oxford Clay (Callovian) of Peterborough is regarded as an iguanodontid (Camptosaunis (?) leedsi Lydekker). A dentary tooth from the Kimmeridge Clays of Weymouth represents the oldest undoubted hypsilophodontid described to date from England. In addition to the well-known Hypsilophodon fo.xii Huxley, a new Wealden species is tentatively referred to the genus Dryosaurus. Some Wealden specimens previously referred to Iguanodon are hypsilophodontid and represent individuals with a length of up to 4-2 m. The Hypsilophodontidae are a family of conservative bipedal ornithischian dinosaurs (ornithopods) with inset cheek teeth, and neither a rostral bone nor any marked thickening of the skull roof. They were herbivorous and fast-running or cursorial with an elongate hind limb with the tibia longer than the femur (Galton 1972, 1973, 1974fl, b). My concept of the family Hypsilophodontidae is more restricted than that ofThulborn(1970, 1971, 1972); I refer only the following to this family: Nanosaurus^l) rex, specimens referred to Laosaurus, Dryosaurus altus (all upper Jurassic, North America; Galton and Jensen 1973a, Gilmore 1925; Marsh 1896; Dysalotosaurus lettow-vorbecki (upper Jurassic, Tanzania; Janensch 1955); Hypsilophodon foxii (lower Cretaceous, England; see Galton 1974a); and 'Laosaurus' minimus, Parkso- saurus warreni (upper Cretaceous, North America; see Galton 1973; Gilmore 1924a; Parks 1926). Dryosaurus Marsh, 1894 and Dysalotosaurus Pompeckj, 1920 are extremely similar and, as will be detailed elsewhere, these two genera are probably synonymous. Consequently, the reported record of hypsilophodontids is very limited with the English records representing the whole of Eurasia. Previously described and new hypsilophodontid material from England is reviewed in stratigraphical sequence starting with the oldest record. The abbreviations used for measurements are explained in the caption to Table 1 and institution names have been abbreviated as follows; AM, American Museum of Natural History, New York; BM, British Museum (Natural History), London; CM, Carnegie Museum, Pittsburgh, Penn., U.S.A.; UCMP, University of California Museum of Paleontology, Berkeley, U.S.A.; US, United States National Museum, Washington D.C.; YPM, Peabody Museum, Yale University, New Haven, Conn., U.S.A. JURASSIC Sinemurian. Owen ( 1861 ) described several specimens of the ornithischian dinosaur Scelidosaurus harrisoni Owen from the Lower Lias of Charmouth, Dorset. Amongst this material are the bones which Owen (1861) regarded as representing a juvenile of Scelidosaurus harrisoni (dorsal centrum, phalanges, partial right hind limb, text-fig. 1a-d, casts as BM 5909, originals in Charmouth Museum; see Owen 1861, pi. 2, [Palaeontology, Vol. 18, Part 4, 1975, pp. 741-752.] 742 PALAEONTOLOGY, VOLUME 18 TABLE 1 . Measurements of femora in millimeters. FT, minimum distance from proximal end to distal edge of fourth trochanter; L, maximum length; LA, estimated total length of body, for hypsilophodontids calculated on a pro- portional basis from BM R196. Camptosaurus based on Gilmore (1909); Wd, greatest width of distal end; Wm, minimum width of shaft; Wp, greatest width of proximal end. LA L Wp Wd Wm FT FT/L m ft Hypsilophodon foxii BM R5830 101 27 25 11 43 0-43 0-91 3-0 BM R196 150 — — — 65 0-43 1-36 4-5 BM R5829 202 52 26 — 87 0-43 1-82 60 Dryosauriis (?) canaliculatus^ 140 3 33 14 58 0-41 1-27 4-2 Dryosaurus alius AM 834 222 59 55 22 96 0-43 2-03 6-7 YPM 1876 362 84 98 39 168^ 0-44 3-30 10-9 CM 1949 470 131 — — 212 0-45 4-27 141 Camptosaurus (?) leedsP 280 65 73 122^ 0-48 3-33 11-0 Camptosaurus ampins US 2210 258 72 71 137 0-53 3-03 100 YPM 1877 585 208 192 ■ 300 0-51 5-15 17-0 ' BM R185. ^ BM R1993. ^ Estimated. distal half of humerus figured as proximal part of tibia, metatarsal 3 figured as a partial fibula). Recently, Newman (1968) considered that these bones probably belong to the genus Hypsilophodon or some allied form. However, the femur (text-fig. 1a, b) differs from those of hypsilophodontids (text-figs. 2g-l, 3) in several respects; the shaft is straight rather than bowed antero-posteriorly, the apex of the lesser trochanter is well below that of the greater trochanter rather than at the same level, and the non-pendant fourth trochanter is at mid-length as against a pendant fourth trochanter more proximally placed. In these features the femur (text-fig. 1a, b) appears to agree with that of the complete skeleton of S. harrisoni (BM R1 1 1 1). The femur of the juvenile is almost identical to the femur (Charig 1972, pi. 6A) of the partial skeleton (BM R6704, see Rixon 1968, fig. 103) of a small individual that is referred to as Cf. 'Scelidosaurus harrisoni Owen’ by Charig ( 1 972, p. 138). The length of the femur (text-fig. 1 a) is about 1 33 mm and that of metatarsal 3 about 60 mm to give a femur to metatarsal 3 ratio of about 0-45. In Hypsilophodon foxii this ratio is 0-62 in BM R5830 (femoral length 101 mm) and 0-56 in BM R196 (femoral length 151 mm). On the basis of this ratio the bones from Charmouth should not be referred to the family Hypsilophodontidae which, as noted by Gabon (1972, 1974a, b), is restricted to genera which were cursorial. The value of 0-45 is about correct if the remains are regarded as a juvenile individual of S. harrisoni because the corresponding value for BM R1 1 1 1 is about 0-34 (from Owen 1863, pi. 10). Comparisons of BM R5909 and R6704 with the much larger BM Rllll (size ratio about 1:4) show that corresponding bones are almost identical, so all specimens are referable to Scelidosaurus harrisoni Owen rather than to two separate ornithopod families (BM R5909, R6704 to Fabrosauridae; BM Rllll to Scelidosauridae) as suggested by Thulborn (1974). The combined lengths of the femur, tibia, and meta- tarsal 3 of BM Rllll is short relative to the trunk (combined length of centre of dorsal vertebrae) so the hind limb to trunk ratio at 0-85 is comparable to that of fully quadrupedal ornithischians (stegosaurs, 0-86-0-90; Cretaceous ankylosaurs, 0-69; ceratopsians, 0-90-1 08; see Gabon 1970, table 2) but much less than that of the facultitively or fully bipedal ornithopods (hadrosaurs, 122-144, see Gabon, 1970, table 1 ; iguanodontids I-08-1-24; hypsilophodontids, 1-44 1-53; psittacosaurids 1-3; see Gabon, 19716, table 1). 1 disagree with the referral of Scelidosaurus, an obligatory quadruped while it walked or ran, to the Orni- thopoda, an order whose members were characterized by bipedality. Scelidosaurus is probably a very primi- tive ankylosaur but any discussion of its affinities must await the detailed anatomical study of Scelidosaurus being prepared by Dr. A. J. Charig. Balhonian. The tooth YPM 7367 (text-fig. 4a-c) was collected prior to 1870 by G. J. Chesler from the Stonesfield Slate (Oracilisphinctes progracilis Zone) of the Great Oolite Series at Stonesfield, Oxfordshire. The form of the tooth is similar to that of the premaxillary teeth of Hypsilophodon (Gabon 1974a) but it differs in the absence of small denticles on the anterior and posterior edges of the crown (text-fig. 4a, b) and the presence of a large concave wear surface (text-fig. 4b, c). However, isolated premaxillary teeth of the late Cretaceous iguanodontid Thescelosaurus (Gabon 19746, pi. 1, figs. 7-11) are almost identical to GALTON: H YPSILOPHODONTID DINOSAURS 743 A B C E F G TEXT-FIG. 1. A-D, SceMosaurus harrisoni, juvenile after Owen (1861), bones of right hind limb, xO-5; A, femur in anterior view; b, femur in posterior view; c, metatarsal 3 in anterior view; d, metatarsal 4 in anterior view; e-m, Camptosaurus nanus, left femur, xO-25, after Gilmore (1909); F, G, hypsilophodontid right tibia, BM 36506 in f, medial view, G, anterior view; h, hypsilophodontid left ischium, BM 2183, lateral view of proximal end, xO-33; i, hypsilophodontid left pubis, BM R720, lateral view with cross-section of postpubic rod, xO-25; J, k, hypsilophodontid right pubes in lateral view with cross-section of anterior process, xO-33; J, BM R169, k, BM 36538; l, m, hypsilophodontid left femoral shaft, BM R8669, xO-25 with L, proximal cross-section, m, medial view, a, acetabulum; ap, anterior or prepubic process; c, cnemial crest ; d, depression, area of insertion of M. caudi-femoralis longus ; il, surface for ilium ; 1, lesser trochanter ; o, obturator foramen; op, obturator process; p, posterior process or postpubic rod; pu, surface for pubis; 4, fourth trochanter. Scale line represents 10 cm. 744 PALAEONTOLOGY, VOLUME 18 E TEXT-FIG. 2. Upper Jurassic ornithopod femora, a-f, Camptosaurns{l) leedsi Lydekker, holotype left femur, BM R1993, xO-3; g-l, Dryosaurus altus (Marsh), left femur of holotype, YPM 1876, xO-23. Views: a, g, lateral; b, h, posterior; c, i, medial; d, j, anterior; E, k, proximal; F, L, distal. Fourth trochanter indices (minimum distance from proximal surface of head to distal edge of fourth trochanter) in a: a, 0-44; h, 0-46; c, 0-48; d, 0-50; for identification of structures see text-fig. 3. GALTON: H YPSILOPHODONTI D DINOSAURS 745 YPM 7367. Wear facets are also reported on the medial surface of teeth preserved in situ in a premaxilla of the Triassic ornithopod described as Lycorhimis by Thulborn 1970, fig. 2. The wear on these ornithopod premaxillary teeth was presumably caused by contact with the horny predentary sheath. YPM 7367 (text- fig. 4a-c) is tentatively identified as a left premaxillary tooth of an ornithopod dinosaur and it may represent the oldest hypsilophodontid yet described. Oxfordian. Lydekker (1889) described a left femur (BM R1993, text-fig. 2a-f) from the Oxford Clay near Peterborough, Northamptonshire, as a new species of Camptosaurus, C. leedsi. Gilmore (1909) pointed out that the fourth trochanter extends on to the distal half of the shaft in all described species of Campto- saurus and noted that, if C. leedsi is referable to an American genus, then its closest affinities are with Dryosaurus. ‘Camptosaurus' leedsi is shown as being closely related to the hypsilophodontids Dryosaiirus and Dysalotosaurus in the phyletic charts given by Galton (1972, 1973, 1974a, b). The lesser trochanter of all hypsilophodontids is relatively slender (text-figs. 2g, i, 3a, c, g, i) and it is not expanded antero-posteriorly as it is in Camptosaurus (text -fig. 1e) and BM R1993 (text-fig. 2a, c, e). On the basis of the figures given by Lydekker (1889, 1890), the fourth trochanter index of BM R1993 is about 0-45 (text-fig. 2a), a value comparable to that of hypsilophodontids (Table 1 ; Dysalotosaurus 0-45, Nanosaurus (?) rex 0-43, Galton and Jensen 19736). However, the distal surface of the fourth trochanter as given by Lydekker (1889, 1890) is based on a broken surface (text-fig. 2a, c). The exact value of the fourth trochanter index is not known but it was probably close to 0-48 (see text-fig. 2a). In Camptosaurus (text-fig. 1e) the fourth trochanter index is 0-51-0-53 (Table 1). In Camptosaurus (text-fig. 1e) and BM RI993 (text-fig. 2c) the depression for the M. caudi-femoralis longus (Galton 1969) is shallow and close to the fourth trochanter. In Dryosaurus (text-fig. 2i) and Dysalotosaurus (Janensch 1955, pi. 14, figs, lb, 2) it is deep and situated more anteriorly on the shaft but this position is unique for hypsilophodontids. The difference in depth is probably not significant because in Hypsilopliodon foxii this depression is shallow in some femora and deep in others (Galton 1969, 1974a). The distal ends of the femora of Camptosaurus (Gilmore 1909, YPM 1877) and Dryosaurus (text-fig. 2g-j, l) are very similar with a well-developed anterior intercondylar groove (text-fig. 2l) where as that of BM R1993 is quite shallow (text-fig. 2f). The femur BM R1993 differs from those of Camptosaurus in only a couple of respects; the fourth tro- chanter is more proximally placed (text-figs. 1e, 2a) and the anterior intercondylar groove is more shallow (text-fig. 2f). On the basis of the femur, BM R1993 from the Oxfordian is an ideal ancestor for the American species of Camptosaurus which are of Kimmeridgian or possibly Portlandian age. Unfortunately no other parts of the anatomy of the English form are known. I now consider that BM R1993 is best assigned to the family Iguanodontidae as Camptosaurus (?) leedsi Lydekker rather than as a hypsilophodontid related to Dryosaurus as suggested by Gilmore (1909) and Galton (1972, 1973, 1974a, b). Kimmeridgian. The history of the dentary tooth UCMP 4961 1 (text-fig. 4d-f) is unknown but it came from the Kimmeridge Clays of Weymouth, Dorset. It was collected along with three theropod teeth (UCMP 49612; two complete crowns, height 15 mm, one tip from a larger tooth) tentatively identified as Megalo- saurus sp. The more thickly enamelled surface of the crown (text-fig. 4d) has a strong central ridge, the size of which is not obvious because of the other longitudinal ridges on either side (text-fig. 4d, e). The longitudinal ridges on both sides of the crown (text-fig. 4d, f) are more numerous and more prominent than those on the teeth of Hypsilopliodon (Galton 1974a), Laosaurus (Marsh 1896, pi. 55, fig. 1), Dryosaurus (Marsh 1878 as Laosaurus, Galton and Jensen 1973a), and Dysalotosaurus (]ar\m&c\\ 1955). The longitudinal ridges are even more prominent on the teeth of Thescelosaurus with those of the thickly enamelled surface forming two converging cresentic patterns (Galton 19746; Sternberg 1940). Undescribed teeth (YPM, unnumbered) from the upper Jurassic of North America are very similar to UCMP 4961 1. UCMP 49611 undoubtedly represents a hypsilophodontid dinosaur but discussion of its affinities must await revision of the American Jurassic hypsilophodontids. CRETACEOUS Hypsilopliodon foxii. The holotype of H. foxii Huxley, 1869 is a skull and the centrum of a dorsal vertebra (BM R197, Huxley 1870) from the Wealden Beds (pre-Aptian and probably Barremian) exposed near F A B C D E TEXT-FIG. 3. Lower Cretaceous hypsilophodontid femora, a-f, Dryosaums (?) canaliculatus n. sp., left femur, BM R185 (with some details from right femur, BM R184), xO-45; G-l, Hypsilophodon foxii Huxley, left femur, BM R5830, x 0-75 with indication of lines of actions of muscles associated with trochanters, modified from Galton (1969). Views as in text-fig. 2. AG, anterior intercondylar groove; C-FB, M. caudi-femoralis brevis ; C-FL, M . caudi-femoralis longus ; FT, fourth trochanter ; GT, greater trochanter ; IC, inner condyle ; IF, M. ilio-femoralis; IT, M. ilio-trochantericus; LT, lesser trochanter; OC, outer condyle; PIFI, pubo- ischio-femoralis internus, dorsal part. GALTON. HYPSILOPHODONTID DINOSAURS 747 TEXT-FIG. 4. Jurassic hypsilophodontid teeth, x 3. a-c, left premaxillary tooth YPM 7367 in a, lateral (labial); b, posterior and c, medial (lingual) views; d-f, right dentary tooth UCMP 49611 in d, medial (lingual) ; e, posterior and f, lateral (labial) views. Cowleaze Chine on the south-western shore of the Isle of Wight. H.foxii (text-fig. 5) is the best-represented hypsilophodontid from England. Its diagnosis (Galton 1974a) is as follows: Five premaxillary teeth separated by step from maxillary row with 10 or 11 teeth, 13 or 14 on dentary; enamelled medial surface of a dentary tooth has a strong central ridge that is absent on the lateral surface of a maxillary tooth. Narial openings completely separated by anterior process of premaxillae; large antorbital recess or depression plus row of large foramina in maxilla; jugal does not contact quadrate; large fenestrated quadratojugal borders lower temporal opening. Five or six sacral ribs, the additional one borne on the anterior part of the first sacral vertebra. Scapula same length as humerus; obturator process on middle of ischium. Femur with following combination of characters: fourth trochanter on proximal half, lesser trochanter triangular in cross-section with a shallow cleft separating it from the greater tro- chanter, practically no anterior condylar groove and posteriorly outer condyle almost as large as inner. The holotype of Camptosaurus valdensis Lydekker, 1889, a large left femur (BM R167), represents a large individual (body length about 2-27 m or 7-5 ft) of H. foxii (see Galton 1974a, pp. 102-103, pi. 2, fig. 4). Hypsilophodon is usually considered to have been arboreal but, as discussed by Galton ( 1971a, 6, 1974a), Hypsdophodon was a ground-living and cursorial dinosaur. Dryosaurusl canaliculatus sp. nov. Derivation of name. From Latin caniculatus, a channel or conduit, with reference to the deep anterior intercondylar groove. Diagnosis. Femur with pendant fourth trochanter well on proximal half of shaft, rod-like lesser trochanter separated by deep cleft from greater trochanter, distally a deep anterior intercondylar groove. Lydekker (1888) listed under Hypsilophodon foxii the associated right and left femora (BM R184, R185) from the Wealden of the Isle of Wight. He noted that a small tibia (BM R186) was apparently associated with these femora but subse- quently (1891) he referred the tibia to the coelurosaur Calamosaurus. BM R185 (text- fig. 3a-f) resembles the femur of H.foxii (text-fig. 3g-l) in the proximal position of the fourth trochanter. In both femora the lesser trochanter is triangular in cross- section (text-fig. 3e, k) but the cleft separating it from the greater trochanter is deep 748 PALAEONTOLOGY, VOLUME 18 in BM R185 (text-fig. 3c, d) and shallow in Hypsilophodon (text-fig. 3i, j). At the distal end the anterior intercondylar groove is deep in BM R185 (text-fig. 3d, f) and practically non-existent in Hypsilophodon (text-fig. 3j, l). Posteriorly the outer con- dyle of BM R185 (text-fig. 3b, f) is sheet-like while that of Hypsilophodon (text-fig. 3h, l) is more massive so that it is almost as large as the inner condyle. The inner condyle of BM R185 (text-fig. 3c, f) is much squarer than that of Hypsilophodon (text-fig. 3i, l) and the rugose area of origin of the medial head of the M. gastrocnemius is much larger in R 185 (text-fig. 3c), extending on to the shaft and delimited anteriorly by a sharp edge. The form of the ends of BM R185 (text-fig. 3a-f) differs from those of Hypsilophodon (text-fig. 3g-l) in several other minor respects as can be seen by comparing equivalent views. These differences between BM R185 and Hypsilophodon are too great to make it likely that BM R185 belongs to that genus. (Even though there is individual variation in some features of Hypsilophodon foxii (Galton 1974a), this does not affect the femur.) Another possibility is that BM R185 might belong to another Wealden ornithopod. Two others are known: Vectisaurus?Lnd Yavelandia. Vectisaurus valdensis Hulke, 1879 is based on an ilium and a few vertebrae but, from an examination of the holotype (BM R2494) and of another specimen (BM R5849) that I refer to this genus, I conclude that Vectisaurus is an iguanodontid (Galton in press). It is very unlikely that BM R185 is referable to Vectisaurus because in iguanodontids the fourth trochanter is on the distal half of the femur. The primitive pachycephalosaurid Yaverlandia bitholus Galton (1971c) is based on a partial skull cap. The fourth tro- chanter is on the proximal half of the femur of the pachycephalosaurids Stegoceras (Gilmore 19246, pers. obs.), Homalocephale, and Prenocephale (Maryahska and Osmolska 1974) but the lesser trochanter is separated by a shallow cleft from the greater trochanter (Stegoceras, Prenocephale) and the anterior intercondylar groove is shallow (Stegoceras, Homalocephale). BM R185 might be a femur of Y. bitholus but this is considered very unlikely. The closest approach to the femur BM R185 (text-fig. 3a-f) are those of Dryo- saurus altus (text-fig. 2g-l) and Dysalotosaurus lettow-vorbecki (Janensch 1955, fig. 40; pi. 14, figs. 1, 2). BM R185 can be distinguished from femora of both taxa by the relative slenderness of the lesser trochanter (text-fig. 3a, c), the more proximal position of the fourth trochanter (text-fig. 3a), and distally by the greater depth of the anterior intercondylar groove (text-fig. 3d, f). The apparent slenderness of BM R185 in comparison with that of Dryosaurus (text-fig. 2g-j) is size related because smaller femora of Dryosaurus (AM 834) are comparably slender to BM R185. The femora of Nanosaurus(l) rex are similar to BM R185 except that distally there is practically no anterior intercondylar groove (Galton and Jensen 19736). The femora (BM R184, R185) may represent a new genus but, because of the limited nature of the available material, these specimens are made the holotype of a new species of hypsilophodontid tentatively referred to Dryosaurus Marsh. Dryosaurus (?) canaliculatus is shown on the phyletic charts in Galton (1972, 1973, 1974a, 6) as the Wealden hypsilophodontid. Additional material. BM 2459. Proximal parts of a large pair of femora ( Wm 46 mm, FT 1 52 mm, LA about 3 m or 9-84 ft), Wealden (Blue Clay), Heathfield, Sussex. BM 28697. Distal end left femur (Wd 45 mm). Isle of Wight. GALTON: H YPSILOPHODONTID DINOSAURS 749 750 PALAEONTOLOGY, VOLUME 18 BM 36509. Distal end of small right femur (Wd 27 mm) catalogued by Lydekker (1888) as Hypsilophodon foxii', Cuckfield, Sussex. The fossil record of H. foxii is now restricted to the Isle of Wight because this was the only specimen from elsewhere that was referred to H. foxii (Lydekker 1888; Swinton 1936). BM R8420, R8421. Distal ends of two femora (Wd 40 mm, 34 mm) previously catalogued by Lydekker (1888) under BM R 170 as Iguanodon, Isle of Wight. BM R8670. Distal end of right femur (Wd 50 mm), Bone Bed between high and low water, Clinton Chine, Isle of Wight. The partial left ischium (BM 2183, text-fig. 1h) from the Wealden of Cuckfield, Sussex is similar to those of Dryosaums and Dysalotosaurus (Janensch 1955). This ischium is probably also referable to Dryosaurus (?) canaliculatus rather than to Iguanodon as listed by Lydekker (1888, p. 235). Larger Wealden hypsilophodontid material. A search through the Wealden Iguano- don material resulted in the identification of several hypsilophodontid specimens representing larger individuals. The anterior or prepubic process of the pubis of hypsilophodontids is bar-shaped where as that of iguanodontids is a deep and laterally flattened plate. The following pubes are identified as hypsilophodontid : BM 36538. Fragmentary right pubis (text-fig. Ik), Cuckfield, Sussex; figured by Mantell (1827, pi. 16, fig. 3) as part of a scapula, listed by Lydekker (1888, p. 235) as Iguanodon pubis. The lips of the obturator process are separated by an obliquely inclined gap of 1 mm which in life was probably filled with cartilage. BM R169. Fragmentary right pubis (text-fig. It), Isle of Wight, listed by Lydekker (1888, p. 235) as Iguanodon. BM R720. Left pubis incomplete anteriorly (text-fig. Ill), Horsham, Sussex; listed by Lydekker (1888, p. 223) as I. mantelli. The range of variation of these pubes is comparable to that within Hypsilophodon foxii (Galton 1974a, figs. 46, 48, 49) and all may be referable to this taxon. The length of the postpubic rod of BM 720 at 340 mm is almost twice that of BM R 1 96 so BM 720 is from an animal with a total length of about 2-74 m or 9 ft. The section of femoral shaft (BM R8669, text-fig. 1l, m) from Compton Bay, Isle of Wight has a maximum width of 57 mm immediately below the fourth trochanter (originally pendant). On the basis of comparisons with the femora of Camptosaums and Dryosaurus the original length of this femur was about 470 mm so LA about 4-2 m or 14 ft. Three tibiae listed by Lydekker (1888, p. 237) as Iguanodon are much too slender to be iguanodontid and are regarded as hypsilophodontid. BM 36506. Right tibia (text-fig. If, g), Cuckfield, Sussex, L 332 mm, Wp 72 mm, Wd 65 mm, LA about 2-51 m or 8-3 ft. BM 36508. Left tibia. Isle of Wight, L 168 mm. BM R124. Right tibia. Isle of Wight, L 280 mm, Wp 67 mm, Wd 58 mm, LA about 212 m or 7 0 ft. It should be noted that the following specimens cited in the literature as H. foxii should be regarded as hypsilophodontid, generically and specifically indeterminate: BM Nos. R170, R183, R186, R199, R200, R202a, R752, R2481, R8422 (for details of specimens and citations see Galton 1974a, pp. 7-12) as are the following uncited specimens as H. foxii: BM Nos. R198, R201, R2479, R2480, R2482-2486, R2489-2493, R519LR6373. Acknowledgements. I thank the following for access to collections, A. J. Charig and C. A. Walker, British Museum (Natural History); J. H. Ostrom, Peabody Museum, Yale University; and S. P. Welles and R. Long of the University of California Museum of Paleontology at Berkeley. R. C. Fox kindly provided a cast of Stegoceros. P. Olsen drew the teeth and Miss P. Rubino typed the manuscript. 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Classification and evolution of ornithopod dinosaurs. Nature, Land. 239, 464-466. 1973. Redescription of the skull and mandible of Parksosaurus from the Late Cretaceous with comments on the family Hypsilophodontidae (Ornithischia). Contr. Life Sci. Div. R. Out. Mus. 89, 1-21. 1974a. The ornithischian dinosaur Hypsilophodon from the Wealden of the Isle of Wight. Bull. Br. Mus. (nat. Hist.) Geol. 25, 1-1 52c. 19746. Notes on Thescelosaurus, a conservative ornithopod from the Upper Cretaceous of North America, with comments on ornithopod classification. J. Paleont. 48, 1048-1067. (in press). The dinosaur Vectisaurus valdensis (Ornithischia: Iguanodontidae) from the Lower Cretaceous of England. Ibid. and JENSEN, J. A. 1973a. Small bones of the hypsilophodontid dinosaur Dryosaurus altus from the Upper Jurassic of Colorado. Gt Basin Nat. 33, 129-132. 19736. Skeleton of a hypsilophodontid dinosaur (Nannosaurus (?) rex) from the Upper Jurassic of Utah. Brigham Young Univ. Geol. Stud. 20, 135-157. GILMORE, c. w. 1909. Osteology of the Jurassic reptile Camptosaurus with a revision of the species of the genus, and descriptions of two new species. Proc. U.S. natn. Mus. 36, 197-332. 1924a. A new species of Laosaurus, an ornithischian dinosaur from the Cretaceous of Alberta. Trans. Roy. Soc. Can. (3) 18, 4, 1-6. 19246. On Troddon validus an orthopodous dinosaur from the Belly River Cretaceous of Alberta, Canada. Bull. Dept. Geol. Univ. Alberta, 1, 1-43. 1925. Osteology of ornithopodous dinosaurs from the Dinosaur National Monument, Utah. Mem. Carnegie Mus. 10, 385-410. HULKE, J. w. 1879. Vectisaurus valdensis, a new Wealden dinosaur. Q. Jl geol. Soc., Lond. 35, 421-424. HUXLEY, T. H. 1869. On Hypsilophodon, a new genus of Dinosauria. Abstr. Proc. geol. Soc. Lond. 204, 3-4. 1870. On Hypsilophodon foxii, a new dinosaurian from the Wealden of the Isle of Wight. Q. Jl geol. Soc. Lond. 26, 3-12. JANENSCH, w. 1955. Der Ornithopoda Dysalotosaurus der Tendaguru-Schichten. Palaeontographica, Suppl. 7, E.R. 3, 105-176. LYDEKKER, R. 1888. Catalogue of the fossil Reptilia and Amphibia in the British Museum {Natural History), Part 1 . London, 309 pp. 1889. On the remains and affinities of five genera of Mesozoic reptiles. Q. Jlgeol. Soc. Lond. 45, 41-59. 1890. Catalogue of the fossil Reptilia and Amphibia in the British Museum {Natural History). Part 4, London, 295 pp. 1891. On certain ornithosaurian and dinosaurian remains. Ibid. 47, 41-44. MANTELL, G. A. 1827. Illustrations of the geology of Sussex, with figures and descriptions of the fossils of Tilgate Forest. London, 92 pp. MARSH, o. c. 1878. Principal characters of American Jurassic dinosaurs. Am. J. Sci. 16, 411-416. 1894. The typical Ornithopoda of the American Jurassic. Ibid. 48, 86-90. 1896. The dinosaurs of North America. Rep. U.S. geol. Surv. 16, 133-244. MARYANSKA, T. and OSMOLSKA, H. 1974. Pachycephalosauria, a new suborder of ornithischian dinosaurs. Palaeont. pol. 30, 45-102. NEWMAN, B. H. 1968. The Jurassic dinosaur Scelidosaurus harrisoni, Owen. Palaeontology, 11, 40-43. OWEN, R. 1861. The fossil Reptilia of the Liassic Formations. Part 1. Palaeontogr. Soc. {Monogr.), 1-14. 1863. The fossil Reptilia of the Liassic Formations. Part 2. Ibid. 1-26. PARKS, w. A. 1926. Thescelosaurus warreni a new species of orthopodous dinosaur from the Edmonton Formation of Alberta. Univ. Toronto Stud. geol. Ser. 21, 1-42. POMPECKJ, J. F. 1920. Das angebliche Vorkommen and Wandern des Parietalforamens bei Dinosauriern. Sber. Ges. naturf. Freunde Berl. 1920, 109-129. RixoN, A. E. 1968. The development of the remains of a small Scelidosaurus from a Lias nodule. Museums J. 67, 315-327. 752 PALAEONTOLOGY, VOLUME 18 STERNBERG, c. M. 1940. Thescelosaurus edmontensis n. sp., and the classification of the Hypsilophodontidae. J. Paleont. 4, 481-494. swiNTON, w. E. 1936. The dinosaurs of the Isle of Wight. Proc. Geol. Ass. 47, 204-220. THULBORN, R. A. 1970. The systematic position of the Triassic ornithischian dinosaur Lycorhinus angustidens. Zool. J. Linn. Soc. 49, 235-245. 1971. Origins and evolution of ornithischian dinosaurs. Nature, Land. 234, 75-78. 1972. The post-cranial skeleton of the Triassic ornithischian dinosaur Fabrosaurus australis. Palaeon- tology, 15, 29-60. 1974. A new heterodontosaurid dinosaur (Reptilia; Ornithischia) from the Upper Triassic Red Beds of Lesotho. Zool. J. Linn. Soc. 55, 151-175. Original typescript received 18 October 1974 Revised typescript received 16 January 1975 P. M. GALTON Department of Biology University of Bridgeport Bridgeport, Conn. 06602 U.S.A. BIBLIOGRAPHY AND INDEX OF CATALOGUES OF TYPE, FIGURED, AND CITED FOSSILS IN MUSEUMS IN BRITAIN by MICHAEL G. BASSETT Abstract. Published (and some unpublished) information on the distribution of type, figured, and cited fossils in museums in Great Britain and Ireland is collated in a bibliography as an initial aid in tracing type collections and individual specimens. The catalogues are indexed taxonomically, stratigraphically, and by museums. A supplementary reference list draws attention to some further publications which may be useful in locating old collections. . . . Of what advantage was it to science that, when Dr Otto Jaekel was writing his admirable memoir on the Devonian crinoids of Germany, all the type specimens described by Schultze in his "Echinodermen des Eifler Kalkes’ were locked up in dusty boxes in a store room at Harvard? . . . F. A. BATHER. 1897. Science, New Ser. 5, 695. . . . The value of all types and figured specimens, and the necessity for their safe preservation are now duly recognised. The recognition has come none too soon. Specialists in particular have to regret the disappearance of many of the types figured by older authors. And the more doubtful the identification of a species, the more is the disappearance of the type to be regretted, and the greater would be its value if it could be recovered. . . . S. S. BUCKMAN. 1899. Proc. Cotteswold Nat. Eld Club, 13, 133. At the fifty-ninth annual meeting of the British Association for the Advancement of Science held at Newcastle upon Tyne in September 1889, a Committee was appointed ‘To consider the best methods for the registration of all Type Specimens of Fossils in the British Isles, and to report on the same’ {Rep. Br. Ass. Advmt Sci. 1 890, p. Ixxxiv). The following year the Committee gave details of a recording form which they recommended should be sent to the curators of all museums and owners of private collections, and at the meeting for 1891 they were able to report that ‘several valuable lists have already been received’. Progress in the gathering of this information was reported briefly and intermittently at subsequent meetings of the Association, up to that of 1903, after which the Committee appears to have become defunct, although there is no record of it being formally disbanded. Unfortunately the data accumulated as a result of this exercise were never collated, and a great deal of information on the whereabouts of many type specimens remained unpublished, notably those in private collections. However, in response to the stimulus generated by the British Association survey, and partly as a result of the direct influence of some members of the Committee, a number of museums did publish their own catalogues of type and figured specimens. In some cases the inventories have subsequently been revised and/or expanded from time to time, and other institutions have since also produced catalogues of all, or specialized parts of their collections. Together with a few earlier, nineteenth-century publications, which include information on type specimens, these catalogues form the main basis of this bibliography. In 1967 a similar compilation on a world-wide scale was attempted by the [Palaeontology, Vol. 18, Part 4, pp. 753-773.] 754 PALAEONTOLOGY, VOLUME 18 International Council of Museums (I.C.O.M.), to cover both zoological and palaeontological collections. This resulted in the publication in 1968 of A preliminary list of catalogues of type specimens in zoology and palaeontology (30 pp., compiled by A. W. F. Banfield, published by the State Committee of Culture and Art on the occasion of the 20th anniversary of the I.C.O.M., Bucharest, Romania, in French and English). This list contains only thirty-seven references to palaeontological collections for the whole of the world, with just eight from Britain, and has a limited index; it thus provides little guidance to the distribution of type-fossil specimens in British museums, a factor which partly prompted the present compilation. In modern systematic palaeontological literature it is standard practice to quote details of the repositories and registration numbers of type, figured, and individually cited specimens; indeed, most journals rightly insist that this information should be included as standard, in accordance with recommendations made by the International Commissions on Zoological and Botanical Nomenclature. Such practice ensures that specimens will be readily traceable in the future, but it is a relatively recent innovation and a vast bulk of past publications conspicuously lacks these basic data. It is frequently difficult or impossible, therefore, to determine from the primary literature the present whereabouts of old type or figured specimens which may be essential for revisionary studies of some fossil groups, or important for comparative purposes, especially where those specimens are not housed in major museums, and it is all too easy to regard old material as ‘lost’. Yet the published catalogues of type specimens contain a great deal of information on individual fossils and collections described in the past, which have fortunately found their way into museums ; a number refer to small institutions or are published in local journals which may be unfamiliar to many individuals. The time-consuming effort of tracking down old collections can often be solved simply by referring to these catalogues, and the primary aim of this bibliography is to draw the attention of palaeontologists to the published lists as an initial aid in such a search. Of course many old type and figured specimens are genuinely lost, but it seems certain too that many others exist unknowingly in public and private collections. The responsibility for tracing old type material in any systematic study rests very much with the individual, but there are limits to the extent that anyone can go in ensuring beyond all doubt that particular specimens no longer exist. These limits would be reduced significantly if all institutions were to accept their share of responsibility in checking collections for type material, and to ensure that details of such material are widely publicized ; this institutional responsibility is best summarized by Recom- mendation 72D of the International Code of Zoological Nomenclature, which states that : Every institution in which types are deposited should : ( 1 ) ensure that all are clearly marked so that they will be unmistakably recognized ; (2) take all necessary steps for their safe preservation; (3) make them accessible for study; (4) publish lists of type-material in its possession or custody; and (5) so far as possible, communicate information concerning types when requested by zoologists. BASSETT: TYPES OF FOSSILS 755 Unfortunately it is a sad fact that many institutions and individuals are unaware of, or neglect these recommendations with the result that some type material can still become mislaid or lost. Any such museum should carefully heed the following advice of D. E. Owen concerning the care of type specimens (1964, Mus. J. 63, 288-291). It is a prerequisite that such a museum must have a suitably qualified member of the staff always in charge of the types. For instance a museum with fossil types must have a geologist on the staff who will be replaced by another geologist if he leaves. This is even more important with perishable specimens which require regular technical treat- ment. The small museum that may be under the care of a geologist for a few years, an archaeologist next, and then an art expert, had much better place its types in more permanent hands. The University department with types but no permanent curator, had much better place these types in an institution whose staff are appointed primarily to care for the specimens. Owen also stresses that The publishing of a list of type and figured specimens in the collections must be the aim of every museum holding such specimens, and efforts should be made to keep this up to date. The specialist, studying a group, usually has great difficulty locating types, and such lists are invaluable. Strict attention to all these comments would ensure that essential specimens are both housed properly and brought to the attention of palaeontologists as a whole. One of the aims of the recently constituted Geological Curators Group is to trace type fossil specimens in museums in Britain, particularly those which have no permanent geological staff to uphold the responsibilities outlined above. Where necessary the Group will publish further catalogues of type material in its Newsletter, to add to those cited here. BIBLIOGRAPHY The format and content of the catalogues listed here varies considerably. Ideally they are published inventories of individual fossil specimens, with information on the repository, museum registration numbers, type data (where applicable), and details of page, plate, and figure numbers in a previous publication referring to those individual specimens; in the comparatively few cases where all these details are not included, the information that is given will generally allow an individual specimen to be identified. The bibliography specifically excludes many museum ‘Catalogues’ which are published as systematic monographs of particular fossil groups in the collections. The best known of these are the many monographic Catalogues published by the British Museum (Natural History), which will be familiar to specialists working on a particular fossil group. However, where such catalogues do give references to type or figured specimens in addition to those described systematically, they are listed here. Also excluded are the many Guides to displays of fossils in museum galleries, together with straightforward inventories of collections which contain no specific data on type, figured, or cited specimens. Unpublished, manuscript lists are included only where they have been widely distributed by their authors, or are available in the institutions to which they refer. Information in square brackets after some of the references draws attention to changes in the names or locations of some institutions, and to cases where specimens 756 PALAEONTOLOGY, VOLUME 18 are known to have been transferred to different institutions. In this supplementary information The Geological Museum of the Institute of Geological Sciences is referred to as IGS, London, the regional offices of the Institute are referred to as IGS, Leeds and Edinburgh, and the British Museum (Natural History) as BM(NH). ALLEN, H. A. 1900. Catalogue of types and figured specimens from the Eocene and Oligocene Series pre- served in the Museum of Practical Geology. Summ. Progr. geol. Surv. Land, for 1899, 195-208. [Speci- mens now in IGS, London.] 1901u. Catalogue of types and figured specimens from British Pliocene and Pleistocene strata pre- served in the Museum of Practical Geology, London. Ibid, for 1900, 182-195. [Specimens now in IGS, London.] 19016. Catalogue of types and figured specimens from British Devonian strata preserved in the Museum of Practical Geology, London. Ibid. 196-216. [Specimens now in IGS, London.] 1902a. Catalogue of types and figured specimens of British fossil Phyllocarida preserved in the Museum of Practical Geology, London. Ibid, for 1901, Appendix A, 200-203. [Most specimens now in IGS, London; Carboniferous specimens in IGS, Leeds.] 19026. Catalogue of types and figured specimens of British Palaeozoic Echinodermata preserved in the Museum of Practical Geology, London. Ibid. Appendix B, 204-211. [Most specimens now in IGS, London; Carboniferous specimens in IGS, Leeds.] 1903. Catalogue of types and figured specimens of British Gasteropoda and Scaphopoda from the Rhaetic beds. Lias and Inferior Oolite, preserved in the Museum of Practical Geology, London. Ibid, for 1902, 217-228. [Specimens now in IGS, London.] 1904. Catalogue of the types and figured specimens of British Gasteropoda and Scaphopoda from the Lower, Middle and Upper Oolites, preserved in the Museum of Practical Geology, London. Ibid, for 1903, 175-187. [Specimens now in IGS, London.] 1905. Catalogue of types and figured specimens of British Lamellibranchiata from the Rhaetic beds and Lias, preserved in the Museum of Practical Geology, London. Ibid, for 1904, 172-177. [Specimens now in IGS, London.] 1906. Catalogue of types and figured specimens of British Lamellibranchiata from the Lower, Middle and Upper Oolites, preserved in the Museum of Practical Geology. Ibid, for 1905, 175-195. [Specimens now in IGS, London.] 1915. Catalogue of types and figured specimens of British Cretaceous Lamellibranchiata preserved in the Museum of Practical Geology, London. Ibid, for 1914, 66-79. [Specimens now in IGS, London.] 1916. Catalogue of types and figured specimens of British Cretaceous Gasteropoda preserved in the Museum of Practical Geology, London. Ibid, for 1915, 47-51. [Specimens now in IGS, London.] ANDERSON, E. M. 1936. Catalogue of types and figured specimens of fossils in the Geological Survey collections now exhibited in The Royal Scottish Museum, Edinburgh. 1-77, H.M.S.O., London. [Specimens now in IGS, Edinburgh.] ANON. 1896. Museum Sub-Committee. Report for 1894-1895. In Rep. Brighton publ. Mus. for 1894-1895, 3-7. [Includes note on type specimens added to the collections.] 1957. Index to collection of sections and preparations of fossil plants. John Walton collection. [Typed MS., 25 pp. (numbered 1-12 only); specimens formerly in Department of Botany, University of Glasgow, now in Department of Geology, Hunterian Museum, from where copies of the catalogue are available; the manuscript is undated, but is here referred for convenience to 1957 since the latest paper quoted is 1956.] APPLEBY, R. M. 1958. A Catalogue of the Ophthalmosauridae in the collections of the Leicester and Peterborough Museums. 1-47, pis. 1-7, Leicester Museums and Art Gallery, Department of Geology. BASSETT, M. G. 1972. Catalogue of type, figured and cited fossils in the National Museum of Wales. 1-113, The National Museum of Wales, Cardiff. BATHER, F. A. 1899. The genera and species of Blastoidea, with a list of the specimens in the British Museum {Natural History), i-x, 1-70, British Museum (Natural History), London. BELL, A. 1917. A list of type and figured specimens in the Geological Gallery, Ipswich Museum. J. Ipswich Distr. nat. Hist. Soc. 5 [for 1916], 41-49. [Also reprinted verbatim (1917) by the Ipswich Museum, with emended pagination, 1-11.] BASSETT: TYPES OF FOSSILS 757 BLAKE, J. F. 1902. List of the types and figured specimens recognised by C. D. Sherborn, F.G.S., in the col- lection of the Geological Society of London. Verified and arranged, with additions, by J. F. Blake, M.A., F.G.S. {with an appendix). 1-100, i-xxxii. Geological Society, London. [British specimens now in IGS, London and Leeds, foreign specimens in BM(NH), to which institutions they were transferred in 1911.] BOLTON, H. 1892. A catalogue of types and figured specimens contained in the Geological Department of the Manchester Museum, Owens College. Rep. Proc. Mus. Ass. 96-129. 1894. Supplementary list of type and figured specimens in the Geological Department, Manchester Museum, Owens College. Ibid. 250-254. [BRIGHTON, A. G.j [1954]. List of ammonites in Sedgwick Museum, fig’d by S. Buckman 1886-1907. Mon. Pal. Soc. Amm. Inf. Oolite. [Typed MS., 7 pp., undated but approximately 1954 (fide H. S. Torrens).] BUCKMAN, s. s. 1899. List of types and figured specimens of Brachiopoda. Proc. Cotteswold Nat. Fid Club, 13 (2), 133-141. [1929]. [Catalogue of the S. S. Buckman collection.] [Handwritten MS. list compiled by Buckman between about 1 880 and 1 928, now in the BM(NH), bound in a single ledger ; undated, but for convenience referred here to 1929 since that was the date that part of the collection, together with the catalogue, was sold to the BM(NH). Collection now broken up and housed in a number of museums both in Britain and abroad, of which those in Britain are known to include at least the BM(NH), IGS, London, Sedgwick Museum, The Manchester Museum, Oxford University Museum; some specimens acquired by the City Museum, Bristol were destroyed in November 1940.] CALDER, M. G. 1959. Catalogue of the Kidston collection of sections of fossil plants in the Department of Botany of the University of Glasgow. [Typed MS., 1 14 pp., based on an unpublished catalogue compiled between 1933 and 1936; copies available from the Hunterian Museum, University of Glasgow, where all the specimens are now stored in the Department of Geology.] CANTRiLL, T. c., DIXON, E. E. L., THOMAS, H. H. and JONES, o. T. 1916. A list of types and figured specimens from Sheet 227 in the Survey and Museum Collections. Appendix III, P- 176, in The geology of the South Wales coal-field. Part 12, The country around Milford. Mem. geol. Surv. U.K. i-vii, 1-185, pis. 1-7. [Most specimens now in IGS, London; Carboniferous specimens in IGS, Leeds.] CARRECK, J. N. 1955. The Quaternary vertebrates of Dorset, fossil and subfossil. Proc. Dorset nat. Hist, archaeol. Soc. 75 [for 1953], 164-188. COLE, w. w. see Enniskillen, earl of. cox, L. R. and ARKELL, w. J. 1948-1950. A survey of the Mollusca of the British Great Oolite Series: primarily a nomenclatorial revision of the monographs by Morris & Lycett (1851-55), Lycett (1863) and Blake (1905-07). Palaeontogr. Soc. [Monogr.], i-xxiv, 1-105. [Text and revised plate explanations give data on previously figured specimens.] CRANE, E. 1892. Catalogue of types and figured specimens now in the Brighton Museum. In Rep. Brighton publ. Mus. for 1891-1892, Appendix B, 9-20. 1893. Museum Sub-committee. Report for 1892-3. In Ibid, for 1892-1893, 5-8. [Contains note on type specimens added to the collections.] CRICK, G. c. 1 898. List of the types and figured specimens of fossil Cephalopoda in the British Museum (Natural History). 1-103, British Museum (Natural History), London. 1922. Notes on specimens of Cephalopoda figured in Tate and Blake’s ‘Yorkshire Lias’, 1876. Naturalist, Aug.-Sept., 273-288. [Specimens in BM(NH).] CURRIE, E. D. and george, t. n. 1963. Catalogue of described and figured specimens in the Begg Collection in the Hunterian Museum of the University of Glasgow. Palaeontology, 6, 378-396. CURTIS, M. L. K. 1956. Type and figured specimens from the Tortworth Inlier, Gloucestershire. Proc. Bristol Nat. Soc. 29, 147-154. [1970]. [Bristol City Museum list of specimens figured in I909-1930''Type Ammonites' by S. S. Buckman.] [Handwritten MS., 3 pp., provided by M. L. K. Curtis for H. S. Torrens; undated but approximately 1970 (fide H. S. Torrens).] [CUTBILL, J. L.] 1973. Sedgwick Museum catalogue, H Section [Scn'ei] Devonian. [Computer printed catalogue dated 31 January 1973, comprising: H Series in numerical order (4 vols., 1-930), locality index (2 vols., 1-307), taxonomic index (2 vols., 1-182), stratigraphic index (1 vol., iv -1-1-145), personal names index (1 vol., 1-38), bibliographic index (1 vol., 1-36). Locality index subsequently revised slightly (pp. 1-306) and both vols. reissued on 27 July 1973, but in original covers.] 758 PALAEONTOLOGY, VOLUME 18 DAVIES, w. 1871a. Alphabetical catalogue of type specimens of fossil fishes in the British Museum. Geol. Mag. 8, 208-216. 18716. Supplementary list of type specimens of fossil fishes in the British Museum. Ibid. 334- 335. DELAIR, j. B. 1966a. Fossil footprints from Dumfriesshire, with descriptions of new forms from Annandale. Trans. J. Proc. Dumfries. Galloway, nat. Hist. Antiq. Soc. 43, 14-30. 19666. Catalogue of the fossil vertebrates in the Museum and Art Gallery, Paisley. [Typed MS., 23 pp., dated by author February 1966.] [delair, j. b.] 1966c. A catalogue of the vertebrate fossils in Kilmarnock Museum. [Typed MS., 22 pp., dated by author November 1966.] DONOVAN, d. t. 1954. Synoptic supplement to T. Wright’s ‘Monograph on the Lias ammonites of the British Islands’ ( 1 878-86). Palaeontogr. Soc. [Monogr.], 1-54. [Revised plate explanations give data on previously figured specimens.] DOUGHTY, p. 1974. Collections or information currently sought: 7. Captain R. B. Bennett. Newsletter of the Geological Curators Group, No. 2, 68-69. [Includes note on a figured Carboniferous bivalve in Ulster Museum.] EDMONDS, J. M. 1949. Types and figured specimens of Lower Palaeozoic Trilobites in the University Museum, Oxford. Geol. Mag. 86, 57-66. EGERTON, P. G. 1836. Catalogue of fossil fish, in the collections of Lord Cote and Sir Philip Grey Egerton, arranged alphabetically, with references to the localities, strata, and published description of the species. 13 pp., J. Seacombe, Chester. [Specimens now in BM(NH).] [egerton, p. m. g.] 1869. Alphabetical catalogue of type specimens of fossil fishes in the collection of Sir Philip de Malpas Grey Egerton, Bart., M.P., at Oulton Park. Geol. Mag. 6, 408-413. [Also published separately (1869) with emended pagination, 1-10. Specimens now in BM(NH).] ENNISKILLEN, EARL OE [w. w. COLE]. 1869. Alphabetical catalogue of the type specimens of fossil fishes in the collection of the Earl of Enniskillen, at Florence Court. Ibid. 556-561. [Also published separately (1869) with emended pagination, 1-9. Specimens now in BM(NH).] [GREGORY, J. w.] 1928. University of Glasgow, Hunterian Museum Geological Department, 1-12. [Pamphlet giving brief history of the collections, including some type and figured specimens.] HALLAM, A. D. 1937. Report on the geological collections in the Somerset County Museum. Proc. Somerset archaeol. nat. Hist. Soc. 82 [for 1936], 62-66. HENRICHSEN, I. G. c. 1970. A Catalogue of fossil vertebrates in the Royal Scottish Museum, Edinburgh. Part One. Actinopterygii. Royal Scottish Museum Information Series. Geology, 1, i-x, 1-102. 1971 . A catalogue of fossil vertebrates in the Royal Scottish Museum, Edinburgh. Part Two Agnatha. Ibid. 2, i-vi, 1-38. 1972. A catalogue of fossil vertebrates in the Royal Scottish Museum, Edinburgh. Part Three/ Actinistia and Dipnoi. Ibid. 3, i-vi, 1-26. HOPPING, c. A. 1957. Catalogue of fossil plants in the Hunterian Museum of the University of Glasgow [with a foreword by J. Walton]. [Typed MS., 390 pp., copies available from the Hunterian Museum.] HOWARTH, M. K. 1962. The Yorkshire type ammonites and nautiloids of Young and Bird, Phillips, and Martin Simpson. Palaeontology, 5, 93-136, pis. 13-19. HOWSE, R. 1888. Contributions towards a catalogue of the flora of the Carboniferous System of Northumber- land and Durham. Part 1.— Fossil Plants from the Hutton Collection. Catalogue of those specimens of the Hutton Collection of fossil plants that have been presented to the Natural History Society by the Council of the Mining Institute, and are now exhibited in the Geological Room of the Museum, at Barras Bridge, Newcastle-upon-Tyne. Nat. Hist. Trans. Northumb. 10, 19-151, pis. 1-6. [Also reprinted verbatim (1888) with emended pagination, 1-135. Specimens now in The Hancock Museum, Newcastle upon Tyne.] JACKSON, J. w. 1952. Catalogue of types and figured specimens in the geological department of the Man- chester Museum. Manchester Museum Publication, No. 6, i-vii, 1-170. JONES, T. R. 1882. Catalogue of the fossil Foraminifera in the collection of the British Museum {Natural History), Cromwell Road, S.W. i-xxiv, 1-100. British Museum (Natural History), London. JUKES-BROWN, A. J. and ELSE, w. J. 1907. A list of the type fossils and figured specimens in the Museum of the Torquay Natural History Society. Rep. Trans. Devon. Advmt Sci. 39, 399^09. BASSETT: TYPES OF FOSSILS 759 LANG, w. D. 1947. James Harrison of Charmouth, geologist (1819-1864). Proc. Dorset not. Hist, archaeol. Soc. 68 [for 1946], 103-118. [Includes list of specimens from Harrison’s collection purchased by BM(NH) in 1865.] LEBOUR, G. A. 1878. Catalogue of the Hutton Collection of fossil plants, including a synoptical list of the chief Carboniferous species not in the Collection. Drawn up by order of the Council of the North of England Institute of Mining and Mechanical Engineers, i-xii, 1-132, Newcastle upon Tyne. [Specimens now in The Hancock Museum, Newcastle upon Tyne.] LENEY, F. 1902. A list of the ‘Type’, figured and described fossils in the Norwich Castle Museum. Geol. Mag. Dec. 4, 9, 166-171,220-231. LYDEKKER, R. 1885-1887. Catalogue of the fossil Mammalia in the British Museum (Natural History), Cromwell Road, S.fV. 5 vols.; Part 1 (1885), i-xxx, 1-268; Part 2 (1885), i-xxii, 1-324; Part 3 (1886), i-xvi, 1-186; Part 4(1886), i-xxiv, 1-233; Part 5 (1887), i-xxxv, 1-345. British Museum (Natural History), London. 1888-1890. Catalogue of the fossil Reptilia and Amphibia in the British Museum (Natural History), Cromwell Road, S.W. 4 vols.; Part 1 (1888), i-xxviii, 1-309; Part 2 (1889), i-xxi, 1-307; Part 3 (1889), i-xviii, 1-239; Part 4 (1890), i-xxiii, 1-296. British Museum (Natural History), London. 1891. Catalogue of the fossil birds in the British Museum (Natural History), Cromwell Road, S.W. i-xxvii, 1-368. British Museum (Natural History), London. MCHENRY, A. and WATTS, w. w. 1898. Guide to the collections of rocks and fossils belonging to the Geological Survey of Ireland, arranged in the curved gallery of the Museum of Science and Art, Dublin. 1-155, H.M.S.O., Dublin. [Section 3, pp. 120-127, figured and type specimens of fossils.] MELMORE, s. 1945-1946. Catalogue of types and figured specimens in the Geological Department of the Yorkshire Museum. N-West Nat. [in three parts], 207-221 [1945], 72-91, 234-245 [1946]. [Also reissued, verbatim in one volume with original pagination, by The Yorkshire Museum.] MITCHELL, M. and WHITE, D. E. 1966. Catalogue of figured, described and cited Carboniferous corals in the collections of the Geological Survey and Museum, London. Bull. geol. Surv. Gt Br. 24, 19-56. [Specimens now in IGS, Leeds.] MORELLET, L. and MORELLET, J. 1939. Tertiary Siphoneous Algae in the W. K. Parker Collection with descrip- tions of some Eocene Siphoneae from England, i-xi, 1-55, Pis. 1-6, British Museum (Natural History), London. [morris, j. and owen, r.] 1856. Descriptive catalogue of the fossil organic remains of Invertebrata contained in the Museum of the Royal College of Surgeons of England, i-vi, 1-260, Taylor and Francis, London. NEA VERSON, E. 1950. The foundation of the University geological collection. Proc. Lpool geol. Soc. 20, 149-157. [Includes notes on specimens in Liverpool University, many of which have since been trans- ferred to BM(NH).] NEWTON, R. B. 1891. Systematic list of the Frederick E. Edwards collection of British Oligocene and Eocene Mollusca in the British Museum (Natural History), with references to the type-specimens from similar horizons contained in other collections belonging to the Geological Department of the Museum, i-xxviii, 1-365, British Museum (Natural History), London. 1902. List of Thomas Say’s types of Maryland (U.S.) Tertiary Mollusca in the British Museum. Geol. Mag. Dec. 4, 9, 303-305. NORTH, F. J. 1928. Type and figured fossils in the National Museum of Wales. Ibid. 65, 193-210. [Reprinted verbatim (1928) by the National Museum of Wales with emended pagination, 1-20.] OWEN, R. 1845. Descriptive and illustrated catalogue of the fossil organic remains of Mammalia and Aves contained in the Museum of the Royal College of Surgeons of England, i-vii, 1-391, pis. 110. Taylor and Francis, London. PATON, R. L. 1975. A catalogue of fossil vertebrates in the Royal Scottish Museum, Edinburgh. Part Four, Amphibia & Reptilia. Royal Scottish Museum Information Series. Geology. 5, i-ix, 1-38. PLATNAUER, H. M. 1891. List of figured specimens in York Museum. Rep. Yorks, phil. Soc. [for 1890], 56-89. 1894. Appendix to the list of figured specimens in the Museum of the Yorkshire Philosophical Society. Ibid, [for 1893], 45-56. PYRAH, B. J. In Press. Catalogue of type and figured material in the geological collections of the Yorkshire Museum. Part 1. Porifera, Coelenterata, Bryozoa, Annelida, ‘Unknown’, Brachiopoda, Crustacea, Insecta. Proc. Yorks, geol. Soc. 760 PALAEONTOLOGY, VOLUME 18 RILEY, T. H. 1974. Type specimens in the palaeontological collections of Sheffield City Museums, England. Newsletter of the Geological Curators Group, No. 2, 36-31. ROWE, F. w. E. 1974. Catalogue of the Sladen Collection in the Royal Albert Memorial Museum, Exeter, Devon. Biol. J. Linn. Soc. 6, 179-243, pis. 1-3. [Deals mainly with one of the most important collections of living and fossil echinoderms ever made, of which only the type and figured fossils are indexed here; there is also brief mention of the W. B. Carpenter Foraminifer Collection, which includes type fossil material.] SALTER, J. w. 1873. A catalogue of the collection of Cambrian and Silurian fossils contained in the geological museum of the University of Cambridge. With a preface by The Rev. Adam Sedgwick, Ll.D., F.R.S. Woodwardian Professor of Geology in the University of Cambridge, and a table of genera and index added by Professor Morris, F.G.S. i-xlviii, 1-204, University Press, Cambridge. [SAMUEL, E. M.] [1970]. Type specimens from the Jurassic [Dorset County Museum]. [Typed MS., 2 pp., undated but approximately 1970 {fide H. S. Torrens).] SANFORD, w. A. 1869. Catalogue of the feline fossils in the Taunton Museum. Proc. Somerset archaeol. nat. Hist. Soc. 14 [for 1867], 103-160. [Also published separately by the Society (? 1869) in large format, together with 26 plates.] SEELEY, H. G. 1869. Index to the fossil remains of Aves, Ornithosauria, and Reptilia, from the Secondary System of strata arranged in the Woodwardian Museum of the University of Cambridge. With a prefatory notice by the Rev. Adam Sedgwick, LL.D., F.R.S. Woodwardian Professor and Senior Fellow of Trinity College, i-xxiii, 1-143, Deighton, Bell and Co. Cambridge. [Now Sedgwick Museum.] SEWARD, A. c. 1894. Notes on the Bunbury Collection of fossil plants with a list of type specimens in the Cambridge Botanical Museum. Proc. Cambridge Phil. Soc. 3, 187-198. 1900. Notes on some Jurassic plants in the Manchester Museum. Mem. Proc. Manchr lit. phil. Soc. 44, 1-28, pis. 1-4. [Also issued separately as Notes from the Manchester Museum, No. 6; includes short list of type and figured specimens.] siME, I. F. 1972. A catalogue of Carboniferous corals in the Royal Scottish Museum, Edinburgh. Royal Scottish Museum Information Series. Geology, 4, i-x, 1-72. SIZER, c. A. 1962. A catalogue of the figured and cited specimens in the Department of Geology. 1-46, 1 pi., Leicester Museums and Art Gallery, Department of Geology. STRACHAN, I. 1971. A synoptic supplement to ‘A monograph of British graptolites by Miss G. L. Elies and Miss E. M. R. Wood’. Palaeontogr. Soc. [Monogr.], 130 pp. [Revised plate explanations give data on previously figured specimens.] STRAHAN, A., CANTRiLL, T. c., DIXON, E. E. L., THOMAS, H. H. and JONES, o. T. 1914. A list of type and figured specimens from Sheet 228 in the Survey and Museum collections. Appendix III, pp. 248-249. In The geology of the South Wales eoalfield. Part 11, The country around Haverfordwest. Mem. geol. Surv. U.K. i-viii, 1-249. [Specimens now in IGS, London.] STUBBLEFIELD, c. J. 1936. Notes on the types and figured specimens acquired from the late S. S. Buckman by the Geological Survey of Great Britain. Summ. Progr. geol. Surv. Lond. for 1934, Pt. 2. 52-59. [Specimens now in IGS, London.] 1938. The types and figured specimens in Phillips and Salter’s Palaeontological Appendix to John Phillips’ Memoir on ‘The Malvern Hills compared with the Palaeozoic districts of Abberley, etc.’ (Mem. Geol. Surv. Volume II, Part 1, June 1848.) Summ. Progr. geol. Surv. Lond. for 1936, Pt. 2, 27-51. [Speci- mens now in IGS, London.] THOMPSON, B. 1929. Obituary. Mr. Thomas Jesson, B.A., F.G.S. J. Northampt. nat. Hist. Soc. 25, 49-50. [Includes reference to publications based on Jurassic ammonites and fishes in Northampton Museum.] and GEORGE, T. J. A catalogue of the geological collection in the Northampton Museum. Part 1. The Silurian System. Ibid. 3, 39-46, 1 pi. [Includes note (p. 36) referring to one figured crinoid.] TORRENS, H. s. 1974. Collections and information: lost and found: A. Collections previously sought: 5. Wyville Thomson. Newsletter of the Geological Curators Group, No. 2, 67-68. [Figured Ordovician and Silurian trilobites in Oxford University Museum.] In press. Type, figured and cited fossils formerly in the Sherborne School Museum. BM(NH) = British Museum (Natural History) collection. Proc. Dorset nat. Hist, archaeol. Soc. 96. [Most specimens now in BM(NH), one ammonite in Oxford University Museum.] BASSETT: TYPES OF FOSSILS 761 TUTCHER, J. w. [1937], Lists of the types and figured specimens of British fossil organisms in the collection of J. W. Tutcher, Bristol. [Handwritten MS., 35 pp., original in BM(NH); undated, but for convenience referred here to 1937 since that was the date that the collection, together with the catalogue, was sold to the BM(NH).] WATERSTON, c. D. 1954. Catalogue of type and figured specimens of fossil fishes and amphibians in the Royal Scottish Museum, Edinburgh. Trans. Edinb. geol. Soc. 16, i-x, 1-91. [ ] 1968a. A list of specimens in the Forres Museum: Altyre and other collections. [Typed MS., 2 pp., dated 1968. All type and figured specimens since purchased by Royal Scottish Museum, Edinburgh.] [ ] 19686. Specimens of fossil fishes described and figured in Elgin Museum. [Typed MS., 2 pp., dated 1968.] 1968c. List of specimens in the Elgin Museum. [Typed MS., 2 pp., dated 1968 ] WILSON, E. 1890. Fossil types in the Bristol Museum. Geol. Mag. Dec. 3, 7, 363-372, 411-416. [wiNWOOD, H. H. and wilson, e.] 1892. Charles Moore, F.G.S. and his work; with a list of the fossil types and described specimens in the Bath Museum. Proc. Bath nat. Hist, antic/. Eld Club, 7, 232-292. WOODS, H. 1891. Catalogue of the type fossils in the Woodwardian Museum, Cambridge, i-xvi, 1-180, Uni- versity Press, Cambridge. [Now Sedgwick Museum.] 1893. Additions to the type fossils in the Woodwardian Museum. Geol. Mag. Dec. 3, 10, 111-118. [Now Sedgwick Museum.] WOODWARD, A. s. 1 889- 1901. Catalogue of the fossil fishes in the British Museum {Natural History), Cromwell Road, S.W. 4 vols.; Part 1 (1889), i-xlvii, 1-474, pis. 1-17; Part 2 (1891), i-xliv, 1-567, pis. 1-16; Part 3 (1895), i-xlii, 1-544, pis. 1-18; Part 4 (1901), i-xxxviii, 1-636, pis. 1-19. British Museum (Natural History), London. and SHERBORN, c. D. 1890. Catalogue of British fossil Vertebrata. i-xxxv, 1-396, Dulau & Co., London. WRIGHT, c. w. and wright, e. v. 1951. A survey of the fossil Cephalopoda of the Chalk of Great Britain: primarily a nomenclatorial revision of Daniel Sharpe’s 'Description of the fossil remains of Mollusca found in the Chalk of England. Part 1, Cephalopoda’ (1853-1857). Palaeontogr. Soc. [Monogr.], 40 pp. [Revised plate explanations give data on previously figured specimens.] WYATT, A. 1974. Geological collections at U.C.W. Aberystwyth. Newsletter of the Geological Curators Group, No. 2, 65. [University College of Wales, Aberystwyth.] INDEX The index is arranged in three sections ; 1 . A taxonomic index in which genera and species listed in individual catalogues are grouped together in major taxonomic divisions, each of which is then broken down stratigraphically and cross-referenced to authors. To save repetition and space the date of a publication is not given after authors’ names in cases where those authors have only one publication under their name, since those references can be located immediately in the bibliography; in all other cases both authors’ names and dates of publications are given. The major taxonomic groupings are generally those which are employed as headings in most of the catalogues and correspond with classificatory divisions which will be immediately familiar to palaeontologists. For the inverte- brates the groupings are initially at the Phylum level, with each Phylum being further subdivided, generally at the Class or Sub-Class level, wherever those lower categories are commonly studied as fossil groups. The vertebrates are listed under familiar Class groups, with the exception that agnathans and gnathostomes are loosely included together under the single heading Fishes. Plants are listed simply as Plantae or Algae. Where authors of catalogues have not themselves separated their specimens into the groupings adopted here, their genera and species are included as undifferentiated G 762 PALAEONTOLOGY, VOLUME 18 members of the highest appropriate division listed. The stratigraphical breakdown within the taxonomic index is as discussed below. 2. A stratigraphical index in which individual specimens listed in catalogues are grouped stratigraphically, with each stratigraphical division then broken down into major taxonomic groups corresponding with those outlined above. No reference is made here to authors since this information can be obtained simply by cross-reference back to the taxonomic index. In most cases the stratigraphical horizons given for specimens in the catalogues have been grouped together in the index within the geological Systems. Exceptions are made for specimens recorded as coming from undifferentiated Tertiary beds, which are listed here as such, and for specimens from the Tremadoc, Old Red Sand- stone, and Rhaetian which are listed separately in order to avoid any confusion which might arise from assigning the material to one or more Systems. 3. A museums index in which all the museums and institutions recorded in the catalogues as including type, figured, or cited fossil specimens are listed and cross- referenced to authors. As in the taxonomic index, dates of publications are given only in cases in which there is more than one reference by any one particular author. TAXONOMIC INDEX INVERTEBRATA Actinozoa: see Coelenterata. Ammonoidea ; see Mollusca. Annelida : CAMBRIAN, Anderson; Blake; Salter. ORDOVICIAN, Salter; Woods 1891. SILURIAN, Blake ; Curtis 1956 ; Salter ; Stubble- field 1938; Woods 1891. DEVONIAN, Blake. CARBONIFEROUS, Anderson; Lebour; Sizer. RHAETIAN, Sizer. JURASSIC, Anderson; Blake; Melmore; Pyrah; Sizer. CRETACEOUS, Blake; Melmore; Woods 1891. TERTIARY, Blake. PLEISTOCENE, Leney; Sizer. Anthozoa: see Coelenterata. Arachnida : see Arthropoda. Arthropoda (undifferentiated); CAMBRIAN, Anderson; Bolton 1892; North; Salter. ORDOVICIAN, Jackson. SILURIAN, Anderson; Jackson; McHenry and Watts. OLD RED SANDSTONE, Andcrson. DEVONIAN, [Cutbill]. CARBONIFEROUS, Anderson ; Jackson. JURASSIC, Jackson. Arachnida : DEVONIAN, [Cutbill]. CARBONIFEROUS, Bassett. Crustacea ; CAMBRIAN, Allen 1902a; Bassett; Bolton 1892; North; Salter; Woods 1891, 1893. TREMADOC, Bassett. ORDOVICIAN, Allen 1902a; Bassett; Blake; North; Woods 1891, 1893. SILURIAN, Allen 1902a; Bassett; Blake; Bolton 1892, 1894; North; Salter; Woods 1891, 1893. DEVONIAN, Allen 19026; [Cutbill]; Jukes- Browne and Else; Woods 1891. CARBONIFEROUS, Allen 1 902a ; Bassett ; Blake ; Bolton 1892; Sizer. PERMIAN, Blake. TRiASSic, Blake; Sizer. RHAETIAN, Blake; Sizer. JURASSIC, Blake; Lang, Melmore; Platnauer 1891; Pyrah; Sizer; [Winwood and Wilson]; Woods 1891. CRETACEOUS, Blake; Crane 1892; Melmore; Pyrah; Platnauer 1891. EOCENE, Blake. TERTIARY, Blake; Pyrah. PLEISTOCENE, Bell; Leney, Sizer. BASSETT: TYPES OF FOSSILS 763 Insecta : CARBONIFEROUS, Bassctt; North. RHAETIAN, Pyrah; Sizer. JURASSIC, Blake; Sizer. TERTIARY, Blake. Isopoda : CRETACEOUS, Woods 1891. Merostomata : SILURIAN, Bolton 1892; Woods 1891. CARBONIFEROUS, Bassett. Trilobita: CAMBRIAN, Bassett; Blake; Bolton 1892; Edmonds; North; Salter; Stubblefield 1938; Woods 1891, 1893. TREMADOC, Bassett; Curtis 1956; Salter. ORDOVICIAN, Anderson; Bassett; Blake; Currie and George; Edmonds; Gregory; Neaverson; Salter; Strachan el al.\ Stubblefield 1938; Torrens 1974; Woods 1891. SILURIAN, Bassett; Blake; Cantrill et al.; Currie and George; Curtis 1956; Edmonds; McHenry and Watts; Salter; Stubblefield 1938; Torrens 1974; Woods 1891. DEVONIAN, Blake; Bolton 1892; Jukes- Browne and Else; McHenry and Watts; Woods 1891. CARBONIFEROUS, Currie and George; Riley. Asteroidea: see Echinodermata. Belemnoidea : see Mollusca. Bivalvia: see Mollusca. Blastoidea : see Echinodermata. Brachiopoda : CAMBRIAN, Anderson; Salter; Woods 1891. TREMADOC, Curtis 1956. ORDOVICIAN, Bassett; Blake; Cantrill et al.-, Currie and George; Jackson; Strachan et al. -, Stubblefield 1938; Woods 1891. SILURIAN, Bassett; Blake; Bolton 1892; Cantrill et al. -, Currie and George; Curtis 1956; Jackson; McHenry and Watts; Salter; Stubblefield 1938; Woods 1891. OLD RED SANDSTONE, Blake. DEVONIAN, Allen 1901^; Blake; [Cutbill]; [Gregory]; Jukes-Browne and Else; Woods 1891. CARBONIFEROUS, Anderson ; Bassett; Blake; Currie and George; [Gregory]; Jackson; McHenry and Watts; Melmore; North; Platnauer 1891 ; Pyrah; Woods 1891. PERMIAN, Jackson; Woods 1891. TRiASSic, [Gregory] ; Sizer. JURASSIC, Anderson; Bassett; Blake; Buck- man 1899, [1929]; North; Pyrah; Sizer; Tutcher; [Winwood and Wilson]; Woods 1891, 1893. CRETACEOUS, Blake; Jackson; Melmore; Platnauer 1891; Pyrah; Woods 1891, 1893. TERTIARY, Blake; Pyrah. PLEISTOCENE, Leney; Melmore; Platnauer 1891. Bryozoa : CAMBRIAN, Salter. ORDOVICIAN, Bassett; North; Woods 1891. SILURIAN, Bassett; Blake; Woods 1891. DEVONIAN, Allen 19016; [Cutbill]; Jukes- Browne and Else. CARBONIFEROUS, Anderson ; Jackson ; Woods 1891. JURASSIC, Melmore; Platnauer 1891; Pyrah; [Winwood and Wilson]; Woods 1891. CRETACEOUS, Blake; Woods 1891. PLIOCENE, Allen 1901u. TERTIARY, Blake; Melmore. PLEISTOCENE, Leney; Pyrah. Cephalopoda : see Mollusca. Coelenterata (undifferentiated): CAMBRIAN, Jackson ; Salter. SILURIAN, Curtis 1956; Jackson; McHenry and Watts; Salter; Stubblefield 1938; Woods 1891. DEVONIAN, Allen 19016; [Cutbill]. CARBONIFEROUS, Jackson; McHenry and Watts; Melmore; Pyrah. PERMIAN, Jackson; Woods 1891. JURASSIC, Jackson; Sizer. CRETACEOUS, Melmore; Pyrah. OLIGOCENE, Allen 1900. TERTIARY, Pyrah. PLEISTOCENE, Melmore; Pyrah. Anthozoa : ORDOVICIAN, Woods 1891. SILURIAN, Blake; Cantrill et al.-. Woods 1891. DEVONIAN, Blake; [Cutbill]; Jukes-Browne and Else. CARBONIFEROUS, Anderson; Bassett; Blake; Mitchell and White; Neaverson; North; Platnauer 1891 ; Sime; Woods 1891. PERMIAN, Blake. JURASSIC, Blake; [Gregory]; Platnauer 1891 ; Woods 1891. CRETACEOUS, Blake; [Gregory]; Platnauer 1891. EOCENE, Blake; [Gregory]; Woods 1891. MIOCENE, Blake. TERTIARY, Blake. PLEISTOCENE, Bell. 764 PALAEONTOLOGY, VOLUME 18 Coelenterata (undifferentiated) (cont.) : Conulata : TREMADOC, Salter. ORDOVICIAN, Bassett; Currie and George. SILURIAN, Blake. DEVONIAN, Blake. CARBONIFEROUS, Bassett ; Mitchell and White. Hydrozoa : CAMBRIAN, Salter. DEVONIAN, Salter. CARBONIFEROUS, Anderson. PLIOCENE, Allen 1901a. Chitinozoa: ORDOVICIAN, Wyatt. Conodonts: see Miscellanea. Conulata: see Coelenterata. Crinoidea: see Echinodermata. Crustacea : see Arthropoda. Cystoidea : see Echinodermata. Decapoda : see Mollusca. Derived fossils: see Miscellanea. Echinodermata (undifferentiated): CAMBRIAN, Bolton 1892; Salter. ORDOVICIAN, Jackson. SILURIAN, Jackson; Melmore; Salter. DEVONIAN, Allen 1901Z); [Cutbill]: Jukes- Browne and Else. CARBONIFEROUS, Anderson; Jackson; Mel- more; Platnauer 1891. JURASSIC, Anderson; Blake; Bolton 1892; Jackson; Melmore; Platnauer 1891 ; Sizer. CRETACEOUS, Blake; Crane 1892; Jackson. EOCENE, Allen 1900. PLIOCENE, Allen 1901a; Platnauer 1891. PLEISTOCENE, Leney : Melmore ; Platnauer 1891. Asteroidea: ORDOVICIAN, Allen 19026; Woods 1891. SILURIAN, Allen 19026; Woods 1891. DEVONIAN, Allen 19026. JURASSIC, Woods 1891. Blastoidea: SILURIAN, Bather. DEVONIAN, Bather; [Cutbill]; Rowe. CARBONIFEROUS, Bather; Rowe. Crinoidea: ORDOVICIAN, Allen 19026; Bassett; Currie and George; Woods 1891. SILURIAN, Allen 19026; Neaverson; Thomp- son and George; Woods 1891, 1893. DEVONIAN, Allen 19026; Blake; [Cutbill]. CARBONIFEROUS, Allen 19026; Currie and George; McHenry and Watts; Sizer; Woods 1891. JURASSIC, Rowe; Woods 1891. CRETACEOUS, Woods 1891. Cystoidea : ORDOVICIAN, Allen 19026; Currie and George. SILURIAN, Allen 19026; Salter. Echinoidea : ORDOVICIAN, Currie and George; Strachan et al. SILURIAN, Stubblefield 1938. DEVONIAN, [Cutbill]. CARBONIFEROUS, McHenry and Watts; Woods 1891. RHAETIAN, Sizer. JURASSIC, [Gregory]; Tutcher; Woods 1891. CRETACEOUS, Bassett; Blake; [Gregory]; Woods 1891. MIOCENE, Blake. TERTIARY, Blake. PLEISTOCENE, Bell. Edrioasteroidea : ORDOVICIAN, Allen 19026. CARBONIFEROUS, Allen 19026; Rowe. Ophiuroidea : ORDOVICIAN, Woods 1891. DEVONIAN, Allen 19026. CARBONIFEROUS, Allen 19026. JURASSIC, Blake. CRETACEOUS, Blake. Stelleroidea : CARBONIFEROUS, McHenry and Watts. Echinoidea : see Echinodermata. Edrioasteroidea : see Echinodermata. Foraminifera : see Protozoa. Gastropoda : see Mollusca. Graptolithina: TREMADOC, Strachan. ORDOVICIAN, Anderson; Blake; Strachan; Strahan et al.; Woods 1891. SILURIAN, Anderson; Blake; Bassett; McHenry and Watts; Strachan; Wyatt. DEVONIAN, [Cutbill]. Hydrozoa: see Coelenterata. Hyolitha : see Miscellanea. Insecta: see Arthropoda. Isopoda: see Arthropoda. Lamellibranchia : see Bivalvia. Merostomata: see Arthropoda. Miscellanea: Conodonts: DEVONIAN, [Cutbill]. Derived fossils : in CARBONIFEROUS, Wyatt. in TRiASSic, Bassett. Hyolitha: ORDOVICIAN, Salter. BASSETT: TYPES OF FOSSILS 765 Problematica : PRECAMBRIAN, SizCf. SILURIAN, Blake. TRiASSic, Blake. JURASSIC, Pyrah. EOCENE, Blake. Tentaculitida : SILURIAN, Blake. Trace fossils: SILURIAN, Blake; McHenry and Watts. CARBONIFEROUS, Bassett; McHenry and Watts. TRIASSIC, Neaverson; Sizer. ‘Unknown’: see Problematica. Mollusca (undifferentiated): CAMBRIAN, Bolton 1892. SILURIAN, Bolton 1892. DEVONIAN, [Gregory]. CARBONIFEROUS, Bolton 1892; [Gregory]; Lebour. TRIASSIC, [Gregory]. JURASSIC, [Gregory]; Torrens, in press. CRETACEOUS, [Gregory]. TERTIARY, Newton 1902; Bell. Ammonoidea : DEVONIAN, [Cutbill]. CARBONIFEROUS, Blake ; McHenry and Watts. JURASSIC, Blake; [Brighton]; Buckman [1929]; Cox and Arkell; Crick 1922; Curtis [1970]; Donovan; Lang; Neaverson; Sizer; Stubblefield 1939; Thompson; Torrens, in press. CRETACEOUS, Blake; Wright and Wright. Belemnoidea : JURASSIC, Blake; Cox and Arkell; Crick 1922; Lang; Sizer. CRETACEOUS, Blake; Wright and Wright. TERTIARY, Blake. Bivalvia : CAMBRIAN, Salter. ORDOVICIAN, Blake; Currie and George; Jackson; Stubblefield 1938; Woods 1891. SILURIAN, Blake; Currie and George; McHenry and Watts; Salter; Stubble- field 1938; Wilson; Woods 1891. OLD RED SANDSTONE, Blake; McHenry and Watts. DEVONIAN, Allen 19016; Blake; [Cutbill]; Jukes-Browne and Else; Woods 1891, 1893. CARBONIFEROUS, Anderson; Bassett; Blake; Bolton 1894; Doughty; Jackson; McHenry and Watts; Melmore; North; Platnauer 1891; Sizer; Wilson; Woods 1891. PERMIAN, Platnauer 1891. TRIASSIC, Blake. RHAETIAN, Allen 1904; Sizer; Tutcher. JURASSIC, Allen 1904, 1906; Anderson; Blake; Cox and Arkell; Jackson; Mel- more; Platnauer 1891; Sizer; Torrens, in press; Tutcher; [Winwood and Wilson]; Woods 1891. CRETACEOUS, Allen 1915; Blake; Hallam; Jackson; Melmore; Platnauer 1891; Wil- son; [Winwood and Wilson]; Woods 1891 . EOCENE, Allen 1900; Jackson; Newton 1891. OLiGOCENE, Allen 1900; Newton 1891. MIOCENE, Blake. PLIOCENE, Allen 1910a; Jackson; Platnauer 1891; Woods 1891. TERTIARY, Blake; Jackson; Melmore. PLEISTOCENE, Bell; Leney; Platnauer 1891; Sizer. Cephalopoda (undifferentiated): CAMBRIAN, Anderson; Jackson. TREMADOC, Salter. ORDOVICIAN, Anderson; Blake; Crick 1898; Woods 1891. SILURIAN, Anderson; Bassett; Blake; Crick 1898; Curtis 1956; Jackson; Salter; Stubblefield 1938; Woods 1891. DEVONIAN, Allen 19016; Crick 1898; [Cut- bill] ; Jukes-Browne and Else ; Woods 1891. CARBONIFEROUS, Anderson; Bassett; Crick 1898; Jackson; McHenry and Watts; Melmore; Neaverson; North; Platnauer 1891 ; Sizer; Tutcher; Woods 1891. TRIASSIC, Crick 1898. JURASSIC, Anderson; Bassett; Crick 1898; Howarth ; Jackson ; Melmore ; Neaverson ; Platnauer 1898; Tutcher; Wilson; Woods 1891, 1893. CRETACEOUS, Blake; Crane 1892; Crick 1898; Howarth; Jackson; Melmore; Plat- nauer 1891; Tutcher; Wilson; Woods 1891. EOCENE, Crick 1898. Decapoda : CRETACEOUS, Woods 1891. Gastropoda : CAMBRIAN, Anderson; Salter; Woods 1891. TREMADOC, Curtis 1956; Salter. ORDOVICIAN, Anderson; Blake; Currie and George; Jackson; Stubblefield 1938; Woods 1891. SILURIAN, Anderson; Bassett; Blake; Curtis 1956; McHenry and Watts; Jackson; North; Salter; Stubblefield 1938; Wilson; Woods 1891. 766 PALAEONTOLOGY, VOLUME 18 Gastropoda (cont.)\ OLD RED SANDSTONE, Blake. DEVONIAN, Allen 1901ft; Blake; [Cutbill]; Jukes-Browne and Else; Woods 1891, 1893. CARBONIFEROUS, Anderson; Blake; Bolton 1894; Currie and George; Jackson; McHenry and Watts ; North ; Sizer ; Woods 1891. TRiASSic, [Winwood and Wilson]. RHAETiAN, Allen 1903. JURASSIC, Allen 1903, 1904; Anderson; Blake; Cox and Arkell: Jackson; Plat- nauer 1891; Sizer; Tutcher; [Winwood and Wilson]; Woods 1891, 1893. CRETACEOUS, Allen 1916; Blake; Crane 1892; Platnauer 1891; Wilson; Woods 1891. EOCENE, Allen 1900. OLiGOCENE, Allen 1900. MIOCENE, Blake; Jackson. PLIOCENE, Allen 1901a; Platnauer 1891. TERTIARY, Blake. PLEISTOCENE, Allen 1901a; Bell; Blake; Leney; Platnauer 1891 ; Sizer. Lamellibranchia : see Bivalvia. Nautiloidea: ORDOVICIAN, Blake. SILURIAN, Blake. OLD RED SANDSTONE, Blake. CARBONIFEROUS, Blake. JURASSIC, Blake; Cox and Arkell; Howarth; Neaverson; Sizer. CRETACEOUS, Blake; Wright and Wright. TERTIARY, Blake. Scaphopoda : DEVONIAN, [Cutbill]. CARBONIFEROUS, Anderson. PERMIAN, Riley. RHAETIAN, Allen 1903. JURASSIC, Allen 1903, 1904; Cox and Arkell; [Winwood and Wilson]. CRETACEOUS, Woods 1891. PLEISTOCENE, Melmore. Nautiloidea : see Mollusca. Ophiuroidea : see Echinodermata. Polyzoa: see Bryozoa. Porifera : CAMBRIAN, Salter; Woods 1891. ORDOVICIAN, Salter; Woods 1891 ; Wyatt. SILURIAN, Salter; Anderson; Woods 1891; Wyatt. DEVONIAN, [Cutbill]. JURASSIC, Blake; Platnauer 1891 ; Pyrah. CRETACEOUS, Melmore; Platnauer 1891; Pyrah; Woods 1891. PLEISTOCENE, Leney; Melmore. Problematica : see Miscellanea. Protozoa (undifferentiated) ; CARBONIFEROUS, Bolton 1892; Jackson. CRETACEOUS, Blake. EOCENE, Allen 1900. Foraminifera : SILURIAN, Cantrill et al. ; Jones. DEVONIAN, Jones. PERMIAN, Jones. JURASSIC, Blake; Jones; [Winwood and Wil- son]. CRETACEOUS, Jones. EOCENE, Jones. TERTIARY, Blake. Radiolaria : ORDOVICIAN, Anderson. Radiolaria: see Protozoa. Scaphopoda : see Mollusca. Stelleroidea : see Arthropoda. Stromatoporoidea : SILURIAN, Salter. DEVONIAN, [Gregory]. Tentaculitida: see Miscellanea. Trace fossils: see Miscellanea. Trilobita: see Arthropoda. ‘Unknown’: see Miscellanea. Vermes: see Annelida. VERTEBRATA Vertebrata (undifferentiated): OLD RED SANDSTONE, Anderson. EOCENE, Allen 1900. OLIGOCENE, Allen 1900. PLEISTOCENE, Bell. Amphibia: CARBONIFEROUS, Blake; Lydekker 1889; McHenry and Watts; Paton; Waterston 1954; Woods 1891 ; Woodward and Sher- born. PERMIAN, Lydekker 1889; Paton; Waterston 1954; Woodward and Sherborn. TRIASSIC, Blake; Lydekker 1889; Paton; Woodward and Sherborn. RHAETIAN, Sizer; Woodward and Sherborn. CRETACEOUS, Lydekker 1889. MIOCENE, Lydekker 1889. PLEISTOCENE, Lydekker 1889; Woodward and Sherborn. HOLOCENE, Carreck. BASSETT: TYPES OF FOSSILS 767 Aves: CRETACEOUS, Melmore ; Seeley ; Woods 1891; Woodward and Sherborn. EOCENE, Lydekker 1891 ; Woods 1891 ; Wood- ward and Sherborn. OLiGOCENE, Woods 1891; Woodward and Sherborn. PLIOCENE, Lydekker 1891. TERTIARY, Blake. PLEISTOCENE, Allen 1901a; Bell; Leney; Lydekker 1891; Melmore; Woodward and Sherborn. HOLOCENE, Carreck. Fishes: ORDOVICIAN, Henrichsen 1971. SILURIAN, Anderson; Bassett; Bolton 1892; Henrichsen 1971 ; Salter; Waterston 1954; Woodward and Sherborn. OLD RED SANDSTONE, Blake; Bolton 1892; McHenry and Watts; Waterston 1954, 1968a, 19686, 1968c; Woods 1891 ; Wood- ward 1891 ; Woodward and Sherborn. DEVONIAN, Blake; [Cutbill]; Davies 1871a; Egerton 1869; Enniskillen; Henrichsen 1970, 1971, 1972; Waterston 1954; Wood- ward and Sherborn. CARBONIFEROUS, Anderson; Bassett; Blake; Bolton 1892, 1894; Davies 1871a; [Delair] 1966c; Egerton 1836, 1869; Enniskillen; Henrichsen 1970, 1972; Lebour; McHenry and Watts; North; Platnauer 1891 ; Sizer; Waterston 1954; Wilson; Woods 1891, 1893; Woodward 1891; Woodward and Sherborn. PERMIAN, Davies 1871a; Egerton 1836, 1869; Enniskillen; Henrichsen 1970, 1972; Waterston 1954; Woodward 1891 ; Wood- ward and Sherborn. TRiASSic, Bassett; Blake; Egerton 1869; Henrichsen 1970, 1972; Sizer; Waterston 1954; Woodward and Sherborn. RHAETiAN, Blake; Bolton 1894; Egerton 1869; Wilson; Woodward and Sherborn. JURASSIC, Blake; Davies 1871a; Egerton 1836, 1869; Enniskillen; Hallam; Hen- richsen 1970, 1972; Lang; Platnauer 1891 ; Sizer; Thompson; Torrens, in press; Wil- son; Winwood and Wilson; Woods 1891 ; Woodward 1889, 1891; Woodward and Sherborn. CRETACEOUS, Anon 1896; Blake; Bolton 1894; Crane 1892, 1893; Davies 1871a; Egerton 1836, 1869; Enniskillen; Hen- richsen 1970, 1971 ; Platnauer 1891 ; Sizer; Waterston 1954; Woods 1891 ; Woodward 1889, 1891, 1895, 1901; Woodward and Sherborn. EOCENE, Bolton 1894; Davies 1871a; Egerton 1869; Enniskillen; Henrichsen 1970; Woodward 1889, 1891, 1901; Woodward and Sherborn. OLIGOCENE, Egerton 1 869 ; Enniskillen ; Hen- richsen 1970; Woodward 1901; Wood- ward and Sherborn. MIOCENE, Davies 1871a; Egerton 1869; Enniskillen; Woods 1891. PLIOCENE, Allen 1901a; Bell; Gregory; Hen- richsen 1970; Woodward 1891. TERTIARY, Egerton 1836, 1869; Enniskillen; [Gregory]; Henrichsen 1970; Leney; Plat- nauer 1891 ; Woodward and Sherborn. Mammalia ; TRIASSIC, Winwood and Wilson. RHAETIAN, Woodward and Sherborn. JURASSIC, Melmore; Woodward and Sher- born. CRETACEOUS, Woodward and Sherborn. EOCENE, Blake; Lydekker 1885, 1887; Mel- more; Platnauer 1891; Woods 1891; Woodward and Sherborn. OLIGOCENE, Blake; Lydekker 1889; Woods 1891 ; Woodward and Sherborn. MIOCENE, Blake; Lydekker 1885a, 18856, 1886a, 1887; Woods 1891. PLIOCENE, Allen 1901a; Lydekker 1885a, 18856, 18866, 1887. TERTIARY, Blake; Owen. PLEISTOCENE, Allen 1901a; Blake; Bolton 1892; Carreck; [Gregory]; Leney; Lydekker 1885a, 18856, 1886a, 18866, 1887; Melmore; Owen; Platnauer 1891; Sanford; Sizer; Woods 1891 ; Woodward and Sherborn. HOLOCENE, Carreck. Reptilia : CARBONIFEROUS, Blake; Baton. PERMIAN, Blake; Baton. TRIASSIC, Blake; Bassett; Lydekker 1889; North; Baton; Seeley; Sizer; Wilson; Woodward and Sherborn. RHAETIAN, Paton ; Sizer; Woodward and Sherborn. JURASSIC, Appleby; Blake; [Gregory]; Lang; Lydekker 1889; Melmore; Paton; Plat- nauer 1891; Seeley; Sizer; Torrens, in press; Woods 1891 ; Woodward and Sher- born. CRETACEOUS, Crane 1892; Lydekker 1889; Paton; Platnauer 1891; Seeley; Woods 1891 ; Woodward and Sherborn. 768 PALAEONTOLOGY, VOLUME 18 Reptilla (cont.): EOCENE, Lydekker 1889; Woodward and Sherborn. OLiGOCENE, Woodward and Sherborn. PLIOCENE, [Gregory]; Lydekker 1889. TERTIARY, Blake. PLEISTOCENE, Leney; Lydekker 1889; Wood- ward and Sherborn. Vertebrate footprints: PERMIAN, Delair 1966a, 19666; Paton. TRiASSic, Bassett; Neaverson; Paton. JURASSIC, Paton. PLANTAE Plantae (undifferentiated) : CAMBRIAN, Salter. ORDOVICIAN, Woods 1891. SILURIAN, Bassett; Blake; Jackson; Salter. OLD RED SANDSTONE, Andcrson; Jackson; McHenry and Watts. DEVONIAN, Bassett; Blake; Calder; Hopping. CARBONIFEROUS, Andcrson; Anon 1957; Bassett; Blake; Bolton 1892, 1894; Calder; Hopping; Jackson; Lebour; McHenry and Watts; Neaverson; Platnauer 1891; Riley; Seward 1894; Sizer; Winwood and Wilson; Woods 1891, 1893. PERMIAN, Calder; Hopping; Jackson; Sizer. TRIASSIC, Blake; Jackson; Lebour; Seward 1894; Sizer. RHAETIAN, Sizcr. JURASSIC, Anderson; Blake; Bolton 1892; Calder; Howse; Jackson; Lebour; Mel- more ; Seward 1 894, 1 900 ; Sizer. CRETACEOUS, Blake; Calder; Jackson; Plat- nauer 1891; Woods 1891. EOCENE, Allen 1900; McHenry and Watts; Woods 1891. OLIGOCENE, Allen 1900. PLIOCENE, Allen 1901a. TERTIARY, Calder; [Gregory]. PLEISTOCENE, Allen 1901a; Sizer. Algae (including stromatolites) : ORDOVICIAN, Salter. SILURIAN, Blake; Curtis 1956; Salter; Wyatt. DEVONIAN, [Cutbill]. EOCENE, Morellet and Morellet. STRATIGRAPHICAL INDEX PRECAMBRiAN : See Problematica. CAMBRIAN: see Annelida, Arthropoda (undiffer- entiated), Bivalvia, Brachiopoda, Bryozoa, Cephalopoda, Coelenterata (undifferentiated), Crustacea, Echinodermata (undifferentiated). Gastropoda, Hydrozoa, Mollusca (undiffer- entiated), Plantae (undifferentiated), Porifera. TREMADOC: see Brachiopoda, Crustacea, Gastro- poda, Graptolithina, Trilobita. ORDOVICIAN: see Actinozoa, Algae, Annelida, Asteroidea, Bivalvia, Brachiopoda, Bryozoa, Cephalopoda, Chitinozoa, Conulata, Crinoidea, Crustacea, Cystoidea, Echinodermata (undiffer- entiated), Echinoidea, Edrioasteroidea, Fishes, Gastropoda, Graptolithina, Lamellibranchia, Nautiloidea, Plantae (undifferentiated), Polyzoa, Porifera, Radiolaria, Trilobita. SILURIAN: see Algae, Annelida, Anthozoa, Arthro- poda (undifferentiated), Asteroidea, Bivalvia, Blastoidea, Brachiopoda, Bryozoa, Cephalopoda, Coelenterata (undifferentiated), Conulata, Crinoidea, Crustacea, Cystoidea, Echinodermata (undifferentiated), Echinoidea, Fishes, Foramini- fera. Gastropoda, Graptolithina, Hydrozoa, Lamellibranchia, Merostomata, Mollusca (un- differentiated), Nautiloidea, Plantae (undiffer- entiated), Polyzoa, Porifera, Problematica, Stro- matolites, Stromatoporoidea, Tentaculitida, Tri- lobita. OLD RED sandstone: See Arthropoda (undiffer- entiated), Bivalvia, Brachiopoda, Fishes, Nau- tiloidea, Plantae (undifferentiated), Vertebrata (undifferentiated). DEVONIAN : see Actinozoa, Algae, Annelida, Antho- zoa, Arachnida, Asteroidea, Bivalvia, Brachio- poda, Blastoidea, Bryozoa, Cephalopoda, Coelenterata (undifferentiated), Conodonts, Conulata, Crinoidea, Crustacea, Echinodermata (undifferentiated), Echinoidea, Fishes, Foramini- fera. Gastropoda, Graptolithina, Lamellibran- chia, Mollusca (undifferentiated), Ophiuroidea, Plantae (undifferentiated), Porifera, Protozoa, Scaphopoda, Trilobita. CARBONIFEROUS : See Actinozoa, Ammonoidea, Am- phibia, Annelida, Anthozoa, Arachnida, Arthro- poda (undifferentiated), Bivalvia, Blastoidea, Brachiopoda, Bryozoa, Cephalopoda, Coelen- terata (undifferentiated), Conulata, Crinoidea, Crustacea, Derived fossils, Echinodermata (undifferentiated), Edrioasteroidea, Fishes, Gastropoda, Hydrozoa, Insecta, Merostomata, Mollusca (undifferentiated), Nautiloidea, Ophiu- BASSETT: TYPES OF FOSSILS 769 roidea, Plantae (undifferentiated), Polyzoa, Protozoa (undifferentiated), Reptilia, Scapho- poda, Stelferoidea, Trace fossils, Trilobita, PERMIAN: see Amphibia, Anthozoa, Bivalvia, Brachiopoda, Crustacea, Fishes, Foraminifera, Plantae (undifferentiated), Reptilia, Scaphopoda, Vertebrate footprints. TRiASSic: see Amphibia, Bivalvia, Brachiopoda, Cephalopoda, Crustacea, Derived fossils. Fishes, Gastropoda, Mammalia, Mollusca (undiffer- entiated), Plantae (undifferentiated), Proble- matica, Reptilia, Trace fossils. Vertebrate foot- prints. rhaetian: see Amphibia, Annelida, Bivalvia, Brachiopoda, Crustacea, Echinoidea, Fishes, Gastropoda, Insecta, Lamellibranchia, Mam- malia, Plantae (undifferentiated), Reptilia, Scaphopoda. JURASSIC; see Actinozoa, Ammonoidea, Annelida, Anthozoa, Arthropoda (undifferentiated), Aste- roidea, Belemnoidea, Bivalvia, Brachiopoda, Bryozoa, Cephalopoda, Coelenterata (undiffer- entiated), Crinoidea, Crustacea, Echinodermata (undifferentiated), Echinoidea, Fishes, Foramini- fera, Gastropoda, Insecta, Lamellibranchia, Mammalia, Mollusca (undifferentiated), Nauti- loidea, Ophiuroidea, Plantae (undifferentiated), Polyzoa, Porifera, Problematica, Reptilia, Scaphopoda, Vertebrate footprints. cretaceous: see Ammonoidea, Amphibia, Antho- zoa, Annelida, Aves, Belemnoides, Bivalvia, Brachiopoda, Bryozoa, Cephalopoda, Coelen- terata (undifferentiated), Crinoidea, Crustacea, Decapoda, Echinodermata (undifferentiated), Echinoidea, Fishes, Foraminifera, Gastropoda, Isopoda, Lamellibranchia, Mollusca (undiffer- entiated), Nautiloidea, Ophiuroidea, Plantae (un- differentiated), Polyzoa, Porifera, Protozoa (un- differentiated), Reptilia, Scaphopoda. eocene: see Algae, Anthozoa, Aves, Bivalvia, Cephalopoda, Crustacea, Echinodermata (un- differentiated), Fishes, Foraminifera, Gastro- poda, Lamellibranchia, Mammalia, Plantae (undifferentiated), Problematica, Protozoa (un- differentiated), Reptilia, Vertebrata (undiffer- entiated). oligocene: see Aves, Bivalvia, Coelenterata (un- differentiated), Fishes, Gastropoda, Lamelli- branchia, Mammalia, Plantae (undifferentiated), Vertebrata (undifferentiated). MIOCENE: see Amphibia, Anthozoa, Bivalvia, Echi- noidea, Fishes, Gastropoda, Mammalia. PLIOCENE; see Aves, Bivalvia, Bryozoa, Echino- dermata (undifferentiated). Fishes, Gastropoda, Hydrozoa, Lamellibranchia, Mammalia, Plantae (undifferentiated), Reptilia. TERTIARY (UNDIFFERENTIATED): see Annelida, Anthozoa, Aves, Belemnoidea, Bivalvia, Brachio- poda, Bryozoa, Coelenterata, Crustacea, Echi- noidea, Foraminifera, Fishes, Gastropoda, Insecta, Lamellibranchia, Mammalia, Mollusca ( undifferentiated), Nautiloidea, Plantae ( undiffer- entiated), Polyzoa, Reptilia, Vertebrata (undiffer- entated). PLEISTOCENE : See Amphibia, Annelida, Aves, Bivalvia, Brachiopoda, Bryozoa, Coelenterata (undifferentiated), Crustacea, Echinodermata (undifferentiated). Fishes, Gastropoda, Lamelli- branchia, Mammalia, Plantae (undifferentiated), Polyzoa, Porifera, Reptilia, Scaphoda, Verte- brata (undifferentiated). QUATERNARY : see PLEISTOCENE. HOLOCENE: see Amphibia, Aves, Mammalia. MUSEUMS INDEX ABERYSTWYTH; See University College of Wales, Aberystwyth. AYLESBURY : See Buckinghamshire County Museum. BATH : see Victoria Art Gallery, Bath. BEDFORD museum: Woodward and Sherborn. BELFAST: see Ulster Museum. BIRMINGHAM: See University of Birmingham Geo- logical Department. BOTANY DEPARTMENT, UNIVERSITY OF GLASGOW ; See Hunterian Museum. BRADFORD: See City Art Gallery and Museum, Bradford. BRIGHTON: see Natural History Museum, Brighton. BRISTOL: see City Museum, Bristol, and University of Bristol. BRITISH MUSEUM (NATURAL HISTORY) : Bather ; Blake ; Buckman [1929]; Carreck; Cox and Arkell; Crick 1898, 1922; Curtis 1956; Davies 1871a, 18716; Delair 1966a; Donovan; Egerton 1836, 1869; Enniskillen; Howarth; Jones; Lang; Lydekker 1885-1887, 1891 ; Morellet and Morel- let; Newton 1891, 1902; Strachan; Torrens in press; Tutcher; Woodward 1889-1901; Wood- ward and Sherborn; Wright and Wright. BUCKINGHAMSHIRE COUNTY MUSEUM; Woodward and Sherborn. BURGH MUSEUM, DUMFRIES: Delair 1966a. CAMBRIDGE; see Sedgwick Museum, antf University of Cambridge, Botanical Museum. CARDIFF: see National Museum of Wales. 770 PALAEONTOLOGY, VOLUME 18 CASTLE MUSEUM, NORWICH: Lcncy; Woodward and Sherborn; Wright and Wright. CENTRAL LIBRARY, MUSEUM AND ART GALLERY, HULL : Woodward and Sherborn. CENTRAL MUSEUM AND ART GALLERY, NORTHAMPTON : Cox and Arkell; Thompson; Thompson and George; Woodward and Sherborn. CITY ART GALLERY AND MUSEUM, BRADFORD : Wood- ward and Sherborn. CITY MUSEUM, BRISTOL: Buckman [1929]; Curtis 1970; Wilson; Woodward and Sherborn. CITY MUSEUM, LEEDS: Woodward and Sherborn. CITY MUSEUM AND ART GALLERY, PETERBOROUGH: Appleby. CITY MUSEUM AND ART GALLERY, WORCESTER : Wood- ward and Sherborn. COUNTY MUSEUM, WARWICK : Woodward and Sher- born. DORCHESTER : see Dorset County Museum. DORSET COUNTY MUSEUM : Carreck ; [Samuel] ; Wood- ward and Sherborn. DUBLIN : see Geological Survey of Ireland, National Museum of Ireland, unJ Trinity College, Dublin. DUBLIN UNIVERSITY MUSEUM: See Trinity College, Dublin. DUMFRIES: see Burgh Museum, Dumfries. EDINBURGH: See Institute of Geological Sciences, Edinburgh, and Royal Scottish Museum. ELGIN museum: Watcrston 1968h, 1968c; Wood- ward and Sherborn. EXETER : see Royal Albert Memorial Museum, Exeter. FARNHAM : See Pitt Rivers Museum, Farnham. FORRES museum: Waterston 1968a; Woodward and Sherborn, see also Royal Scottish Museum, Edinburgh. GEOLOGICAL SURVEY OF IRELAND: McHcury and Watts; Woodward and Sherborn. GEOLOGICAL SURVEY MUSEUM: see Institute of Geological Sciences, Leeds, London, and Edin- burgh. GEOLOGY MUSEUM, UNIVERSITY OF BRISTOL: see University of Bristol. GLASGOW: see Hunterian Museum, University of Glasgow, and Royal College of Science and Technology, Glasgow. HALIFAX : see Museums and Art Galleries, Halifax. HANCOCK MUSEUM, NEWCASTLE UPON TYNE: HOWSC; Lebour; Woodward and Sherborn. hull: see Central Library, Museum and Art Gallery, Hull, and University of Hull Geology Department. HUNTERIAN MUSEUM, UNIVERSITY OF GLASGOW: Anon 1957; Calder; Currie and George; [Gregory]; Hopping; Woodward and Sherborn. INSTITUTE OF GEOLOGICAL SCIENCES, EDINBURGH: Anderson; Strachan; Woodward and Sherborn. INSTITUTE OF GEOLOGICAL SCIENCES, LEEDS: Allen 1902a, 19026; Blake; Cantrill et al. ; Mitchell and White; Strachan. INSTITUTE OF GEOLOGICAL SCIENCES, LONDON : Allen 1900, 1901a, 19016, 1902a, 19026, 1903, 1904. 1905, 1906, 1915, 1916; Blake; Buckman [1929]; Cantrill et al. ', Carreck; Cox and Arkell; Curtis 1956; Donovan; Howarth; Strachan; Strachan et al.', Stubblefield 1936, 1938; Woodward and Sherborn; Wright and Wright. IPSWICH museum: Bell; Woodward and Sherborn. KILMARNOCK: See Public Library, Museum and Art Gallery, Kilmarnock. LEEDS: see City Museum, Leeds, and Institute of Geological Sciences, Leeds. LEICESTERSHIRE MUSEUM, ART GALLERIES AND RECORDS service: Appleby; Sizer; Woodward and Sherborn. LUDLOW museum: Woodward and Sherborn. MALTON MUSEUM : Woodward and Sherborn. MANCHESTER MUSEUM: Bolton 1892, 1894; Buckman [1929]; Cox and Arkell; Seward 1900; Wood- ward and Sherborn. MUSEUM AND ART GALLERY, PAISLEY: Delair 19666. MUSEUM OF NATURAL HISTORY, SCARBOROUGH: Howarth; Woodward and Sherborn. MUSEUM OF PRACTICAL GEOLOGY, LONDON : See Institute of Geological Sciences, London. MUSEUM OF SCIENCE AND ART, DUBLIN: see National Museum of Ireland. MUSEUMS AND ART GALLERIES, HALIFAX: Woodward and Sherborn. NATIONAL MUSEUM OF IRELAND, DUBLIN : McHenry and Watts; Woodward and Sherborn. NATIONAL MUSEUM OF WALES, CARDIFF: BaSSett ; North; Strachan. NATURAL HISTORY AND ANTIQUARIAN MUSEUM, PENZANCE: Woodward and Sherborn. NATURAL HISTORY MUSEUM, BRIGHTON : Anon 1 896 ; Crane 1892, 1893; Woodward and Sherborn. NEWCASTLE UPON TYNE: See Hancock Museum, Newcastle upon Tyne. NORTHAMPTON: See Central Museum and Art Gallery, Northampton. NORWICH: see Castle Museum, Norwich. OWENS COLLEGE, MANCHESTER: See Manchester Museum. oxford: see University Museum, Oxford. paisley: see Museum and Art Gallery, Paisley. PENZANCE: see Natural History and Antiquarian Museum, Penzance. PETERBOROUGH: See City Museum and Art Gallery, Peterborough. BASSETT: TYPES OE EOSSILS 771 PITT RIVERS MUSEUM, FARNHAM : Carreck. PUBLIC LIBRARY, MUSEUM AND ART GALLERY, KIL- MARNOCK: Delair 1966c. PUBLIC MUSEUM AND ART GALLERY, SUNDERLAND: Woodward and Sherborn. ROYAL ALBERT MEMORIAL MUSEUM, EXETER : Rowe. ROYAL COLLEGE OF SCIENCE AND TECHNOLOGY, GLASGOW: Howarth. ROYAL COLLEGE OF SURGEONS, HUNTERIAN MUSEUM : [Morris and Owen]; Owen; Woodward and Sherborn. ROYAL SCOTTISH MUSEUM, EDINBURGH: Anderson ; Delair 1966a; Hennchsen 1970, 1971, 1972; Paton; Sime; Waterston 1954, 1968a; Wood- ward and Sherborn. ST. ANDREWS MUSEUM : Woodward and Sherborn. SALFORD : see Science Museum, Salford. SALISBURY AND SOUTH WILTSHIRE MUSEUM: Wood- ward and Sherborn. SCARBOROUGH: see Museum of Natural History, Scarborough. SCIENCE MUSEUM, SALFORD: Woodward and Sher- born. SEDGWICK MUSEUM, CAMBRIDGE UNIVERSITY: [Brighton]; Buckman [1929]; Cox and Arkell; Curtis 1956; [Cutbill]; Donovan; Howarth; Salter; Seeley; Strachan; Woods 1891, 1893; Woodward and Sherborn; Wright and Wright. SHEFFIELD CITY MUSEUMS : Riley. SHERBORNE SCHOOL MUSEUM: Torrens, in press. SHREWSBURY MUSEUM: Woodward and Sher- born. SOMERSET COUNTY MUSEUM, TAUNTON CASTLE : Carreck; Hallam; Sanford; Woodward and Sherborn. SUNDERLAND: See Public Museum and Art Gallery, Sunderland. TAUNTON : see Somerset County Museum, Taunton Castle. TORQUAY NATURAL HISTORY SOCIETY MUSEUM : JukeS- Browne and Else. TRINITY COLLEGE, DUBLIN: Strachan; Woodward and Sherborn. ULSTER museum: Donovan; Doughty. UNIVERSITY COLLEGE OF WALES, ABERYSTWYTH : Wyatt. UNIVERSITY MUSEUM, OXFORD: Buckman [1929]; Delair 1966a; Edmonds; Torrens 1974, in press; Woodward and Sherborn. UNIVERSITY OF BIRMINGHAM GEOLOGY DEPARTMENT : Strachan. UNIVERSITY OF BRISTOL, GEOLOGY MUSEUM: Curtis 1956. UNIVERSITY OF CAMBRIDGE, BOTANICAL MUSEUM: Seward 1894. UNIVERSITY OF HULL GEOLOGY DEPARTMENT : Strachan. VICTORIA ART GALLERY, BATH: [Winwood and Wilson]; Woodward and Sherborn. wales: see National Museum of Wales. WARWICK: see County Museum, Warwick. WHITBY museum: Howarth; Woodward and Sher- born. ' WOODWARDIAN MUSEUM, CAMBRIDGE : See Sedgwick Museum, Cambridge University. WORCESTER: see City Museum and Art Gallery, Worcester. YORKSHIRE MUSEUM, YORK: Cox and Arkell; Howarth; Melmore; Platnauer 1891, 1894; Pyrah; Woodward and Sherborn. SUPPLEMENTARY REFERENCES As noted earlier the whereabouts of a great many type, figured, and cited fossils may remain unknown if there is no published information on them, and there can be no guarantee that some museums are even aware that they house such material. Apart from catalogues of types, however, there are numerous other publications which contain information on old collections, and which may give some guidance in a search for a particular specimen. Most museums produce Annual Reports which list major accessions during any one particular year, and many also publish guides to the collections and galleries, often including notes on particular items of interest. Biographical and/or obituary notices of known collectors may include details of the whereabouts of their collections, with many journals of local natural history societies giving a great deal of information for a particular area. The new Newsletter of the Geological Curators Group plans to collate and publish these kinds of data and to provide general guidance on the location of collections of fossils in Britain. It is clearly not possible to cite the whole range of these publications here, but the following list is intended to draw attention to the variety of sources of information and to some 772 PALAEONTOLOGY, VOLUME 18 Standard references on museums, collections, and biographies of collectors; it makes no claim to be either complete or comprehensive in its coverage. Also included are a few useful references giving guidance to the maintenance and storage of type fossil collections. CHALMERS-HUNT, J. M. In prcss. Natural History auctions 1700-1972: a register of sales in the British Isles. Sotheby & Co., London. [Information on the disposal of collections at auctions.] COOPER, J. A. Geological collections and collectors of note; 2. Northampton Central Museum. Newsletter of the Geological Curators Group, No. 2, 40-45. [With an appendix (pp. 46-51) by H. S. Torrens on collectors represented at Northampton ; both the paper and appendix note important collections which have been discovered recently, and there is a note that a type catalogue is in preparation jointly by Cooper and Torrens.] cox, L. R. 1956. Fossil invertebrate collections from India and Pakistan in the British Museum (Natural History). J. Palaeont. Soc. India, 1, 94-98. [Valuable notes on collections and collectors, with the publica- tions in which the specimens are described.] CURTIS, M. L. K. 1962. [Note on location of type specimens of Silurian Bivalvia and Gastropoda.] Ludlow Research Group Bulletin, No. 10, p. 4. [City Museum, Bristol, and IGS, London.] DANCE, s. p. 1967. Report on the Linnaean shell collection. Proc. Linn. Soc. Lond. 178, 1-24, pis. 1-10. [Mainly conchological, but also with details of collectors who provided Linnaeus with fossils.] HUXLEY, T. H. and ETHERIDGE, R. 1865. A catalogue of the collections of fossils in the Museum of Practical Geology, with an explanatory introduction, lxxix + 381 pp., H.M.S.O., London. [Valuable information in footnotes referring to donors of collections in IGS.] LAMBRECHT, K., QUENSTEDT, w. and QUENSTEDT, A. 1938. FossUium catalogus I. Animalia. Pars 72: Palaeon- tologi. Catalogus bio-hibliographicus. xxii + 495 pp., W. Junk, Gravenhage. [A major, though often neglected, source of biographical details of palaeontologists; in German but with abundant data relevant to Britain.] LEBOUR, G. A. 1886. Materials for a palaeontology of Northumberland. Chapter 14, pp. 108-1 13. In Outlines of the geology of Northumberland and Durham. viii+ 156 pp., 5 pis., Lambert and Co., Newcastle upon Tyne. [An example of data on regional collections; many of those listed are now in the Hancock Museum.] LEEDS, E. T. Edited with notes and additions by w. e. swinton, 1956. The Leeds collection of fossil reptiles from the Oxford Clay of Peterborough. xii4 104 pp., 6 pis., B. H. Blackwell, Oxford. [History of the collection and disposal of one of the most important collections of British vertebrates.] MURRAY, D. 1904. Museums: their history and their use: with a bibliography and list of museums in the United Kingdom. Vol. 1, xvi-( 339 pp.; Vol. 2, 363 pp.; Vol. 3, 341 pp., James MacLehose and Sons, Glasgow. [Contains a great deal of information on early collectors and collections, and an extensive bibliography of museum publications, including fossil catalogues.] MURRAY, J. w. 1971. The W. B. Carpenter Collection. Micropalaeontology, 17, 105-106. [Notes on Car- penter’s collection of foraminifers in the P. F. Sladen Collection at the Royal Albert Memorial Museum, Exeter.] OWEN, D. E. 1964. Care of type specimens. Mus. J. 63, 288-291. PYRAH, B. J. 1974. Geological collections and collectors of note: 3. Yorkshire Museum. Newsletter of the Geological Curators Group, No. 2, 52-55. [With an appendix (pp. 56-58) by H. S. Torrens of notes on some Yorkshire Museum collectors.] SARJEANT, w. A. s. 1974. A history and bibliography of the study of fossil vertebrate footprints in the British Isles. Palaeogeography, Palaeoclimatology, Palaeoecology, 16 (Special issue), 165-378. [Contains a great deal of useful information on collectors and collections, including present repositories.] SHERBORN, c. D. 1940. Where is the Collection? An account of the various Natural History Collections which have come under the notice of the compiler Charles Davies Sherborn D.Sc. Oxon. between 1880 and 1939. 148 pp.. University Press, Cambridge. [The standard primary source of information on the location of natural history collections, with a bias towards geology; the information is being updated under the editorship of R. Cleevely of the BM(NH) to be incorporated in a 2nd edition of the book, which will be published by the BM(NH) and the Society for the Bibliography of Natural History.] lORRENS, H. s. I974u. Geological collections and collectors of note: 1. Lichheld Museums (pre 1850). Newsletter of the Geological Curators Group, No. 1, 5-10. BASSETT: TYPES OF FOSSILS 773 TORRENS, H. s. \91Ab. Geological collections and collectors of note: 1. Lichfield Museums (pre 1850) post- script. Ibid. No. 2, 38-39. 1974c. Locating and identifying collections of palaeontological material. Ibid. No. 1, 12-17. [Includes a useful list of published sources of biographies of geologists in addition to those listed here.] WOODWARD, A. s. 1904. The department of geology, pp. 197-340. In The history of the collections contained in the Natural History departments of the British Museum. Vol. 1, 442 pp., British Museum (Natural History), London. [Abundant data on important early collectors and collections, with information on publications in which specimens are described.] YOCHELSON, E. 1969. Fossils— the how and why of collecting and storing. In cohen, d. m. and cressey, r. f. (eds.). Symposium on Natural History collections, past, present, future. Proc. biol. Soc. Wash. 82, 585-601. Acknowledgements. I am particularly grateful to Dr. H. S. Torrens (University of Keele) for providing me with a great deal of information in the preparation of this bibliography. Dr. W. D. I. Rolfe (Hunterian Museum, Glasgow University), Dr. W. H. C. Ramsbottom (IGS, Leeds), and Dr. C. D. Waterston (Royal Scottish Museum) also gave me valuable information and together with Dr. Torrens and Dr. D. A. Bassett (National Museum of Wales) kindly read a first draft of the manuscript. Dr. R. L. Paton (Royal Scottish Museum) and Miss B. J. Pyrah (The Yorkshire Museum) allowed me to study their unpublished manu- script catalogues, and Dr. M. K. Howarth (British Museum, Natural History) gave me access to manuscripts in his care. I also thank the Library staffs at the National Museum of Wales, Geological Society of London, and Department of Palaeontology at the British Museum (Natural History) for their help in obtaining and checking numerous references. Miss G. Newton, Mrs. S. Thackray, and Mr. S. R. Howe helped to compile and check the index. MICHAEL G. BASSETT Department of Geology The National Museum of Wales Typescript received 14 February 1975 Cardiff, CFl 3NP ■■y -■V s ( £=sS, . i-'‘i r fifi 1 'W- r '-r w ' ■ - ; %■ ■ 1-A ■*' ':l® ''" ■v" : wi" '1^,^ ■ ' - -M" ’■' ci. ’ ■' ■■'.■ iVilAiifi' ’w\> , ■ ■*. ‘^V,V[ ■ , , ' ' '■ ^■?‘.* , ‘ " .' -'(y^ ' ' ' ^ ., ” ' ■ •’^ ' * ' ' '■ (t * „ V ,f Y •■ - ■- ' ' y? J' ^ ■ '" '"^'^•'f;^ •.,;.-,.3**/: > ■'■ V 'J- %_ £' ^Ml|fAjUiii|jjl^ :, ,j; ,„ '.. ,.. ' ’ ^^ ■?! ,• ’ , . ■+'‘''v ■■■ '._ ‘••A ry*-':.Vjf' ! ' ■'*1. ji> "... •.. w'^.; '' ■„ " ,jj^^ , ^ • '^'V tvVT' ' ;. ,■ ■1., ,. - « * .■y P«: > Q^r-' Jh. ' V* MID-CRETACEOUS ANGIOSPERM POLLEN FROM SOUTHERN ENGLAND AND NORTHERN FRANCE by J. F. LAING ABSTRACT. Angiosperm pollen grains are described from the Upper Albian to Middle Cenomanian strata of several localities in southern England and northern France. Twenty-two species are described, of which the following thirteen are new: Psilatricolpites rectilatibus, Retitricolpites amplifissus, R. crassitransennus, R. exiguiexemplum, R. meumendum, R. promiscuus, R. sarthensis, R. subtilimaculatus, Psilatricolporites complanatius, Retitricolporites ecommoyensis, R. insolitimorus, Triporopollenites curtisi, and T. worbarrowensis. A sequence of angiosperm pollen assemblages is suggested and an attempt is made to relate this to the ammonite zonation. The description of angiosperm pollen from the Albian and Cenomanian strata of southern Britain and northern France is important since this is an area which includes the stratotypes of both stages, and where the stratigraphy is understood in detail. Previous studies on early angiosperm pollen assemblages (e.g. Doyle 1969; Pacltova 1971) have generally been concerned with areas where the age of the strata is impre- cisely known. This is because correlation with the standard European sequence is impossible, owing to a lack of any suitable marine fossils. An exception to this is, perhaps, Dettmann’s (1973) recent study on the angiosperm pollen from the eastern Australian Albian to Turonian, but here the sequence appears to be rather different from that which occurs in contemporaneous European and North American strata. The present work represents an attempt to relate the sequence of angiosperm pollen assemblages to the ammonite zonation of the Albian and Cenomanian of north-west Europe, in the hope that it will help other workers to define better the stratigraphy in areas where the mid-Cretaceous sequence occurs in non-marine strata. LOCATION AND STRATIGRAPHY OF SAMPLES Samples have been examined from six localities: Lulworth Cove, Worbarrow Bay, Punfield Cove, and Compton Bay on the south coast of England; Saint-Jouin on the coast of Normandy; and Ecommoy near Le Mans. All the samples collected are of marine rocks, except those from Ecommoy which are of a non-marine or brackish facies. The position of each locality is shown on text-fig. 1, and details of each section are given in text-figs. 2-9. PREPARATION TECHNIQUE Samples were prepared as follows: crushing; removal of CaCOj with cold HCl; removal of silicates with cold 60% HE ; removal of excess fluorides with warm HCl; removal of remaining minerals by flotation in ZnBr2 solution (SG 2-5); short [Palaeontology, Vol. 18, Part 4, 1975, pp. 775-808, pis. 90-94.] 776 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 1. Map showing localities sampled. centrifuging; up to 30-minutes oxidation with cold concentrated HNO3; removal of oxidation products with cold 5% NH4OH for 5 minutes. Residues were mounted on eover slips using ‘Clearcol’, the cover slips then being mounted on slides using ‘DePeX’. Exeess residues were stored in glycerine (plus a few drops of phenol) in elosed plastic vials. SYSTEMATIC PALYNOLOGY A major problem with early angiosperm palynology is the small size of the pollen grains and of their ornamentation. This difficulty seems to have deterred many authors from producing descriptions of new species which are at all adequate for comparative purposes, with the result that it becomes necessary to create many new species. Angiosperm pollen is rare in the strata which I have studied, especially so in the marine roeks, and so it has not been possible to base my new species on as many specimens as I would have wished. A further problem is that many of the features of these grains are too small to be measured directly by light microscopy and for this reason I have often had to estimate sizes. Thus where fractions of a micron have been given these are only estimates. Where I have attributed my specimens to a previously published species, I have used the scheme of graded comparisons proposed by Hughes and Moody-Stuart (1967). When I have given the occurrences of the specimens that I have found, I have done so in terms of the zonal schemes of Spath (1923-1943) for the Albian, and of Kennedy (1969) for the Cenomanian, both summarized on Table 2. When I have referred to the occurrences of other specimens, and to the known ranges of species, the stratigraphic informa- tion is generally as stated by the original author; in areas lacking suitable zone fossils, this information may be only approximately correct. LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 111 TEXT-FIG. 2. Section at Punfield Cove, Dorset text-fig. 3. Section at north end of Swanage Bay, (SZ 045813). (Zonation after Hancock 1969; and Dorset (SZ 043812). Continuation of section at Drummond 1970.) Punfield Cove. (Zonation after Wright, in Arkell 1947.) TEXT-FIG. 4. Section c. 200 m SSW. of steps from text-fig. 5. Section c. 500 m NNE. of steps from Valleuse Boucherot, Saint-Jouin, Seine-Maritime. Valleuse Boucherot, Saint-Jouin, Seine-Maritime. (Zonation after Juignet 1972.) (Zonation after Juignet 1972.) H 778 PALAEONTOLOGY, VOLUME 18 tompling hptdon UPPER GREENSAND I I (■•How 9'sen, rhplo/nogenie MIDDLE Zona CENOMANIAN photphole nodulai Text-fig. 6. GlAUCONITtC MARL UPPER GREENSAI'Jd torcilonensit monleUi LOWER Horiton Zone CENOMANIAN phoipKaie nodulet Text-fig. 7. Fine, dork yellowish oronge sond with greyish clovey lentils ona bonds Medium light S.grey cloy and silt Qfiofr conglomeratic boulders rho tomogense MIDDLE ^ Zone CENOMANIAN f— 2 Om — l-5m — 1-Om “0 5m Text-fig. 9. TEXT-FIG. 6. Section at Lulworth Cove, Dorset (SY 825800). (Zonation after Hancock 1969.) TEXT-FIG. 7. Section at Compton Bay, Isle of Wight (SY 366853). (Zonation after Kennedy 1969.) TEXT-FIG. 8. Section at Worbarrow Bay, Dorset (SY 862804). (Zonation after Wright, in Arkell 1947; and Kennedy, pers. comm.) middle CENOMANIAN UPPER ALBIAN Text-fig. 8. TEXT-FIG. 9. Section at Carriere de Bezonnais, Ecommoy, Sarthe. (Zonation after Juignet and Medus 1972.) Palynological comparisons with the marine sequence suggest the Argiles noires to be of approximately lower Middle Cenomanian age (Laing 1973.) LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 779 The following abbreviations are used in the text ; D depth NT nexine thickness DC depth of colpus (colpi) OA oblique aspect E equatorial aspect P polar aspect ED equatorial diameter PD polar diameter ET exine thickness s standard deviation L length ST sexine thickness LC length of colpus (colpi) W width LD MW diameter of lumina of microreticulum width of muri of microreticulum WC width of colpus (colpi) The occurrence of each species in each horizon and locality is summarized on Table 1. All specimens are deposited in the Sedgwick Museum, Cambridge, where a catalogue of specimens may also be found on ‘Taxon Register’ forms (form 6109). Co-ordinates given are for Leitz Dialux microscope no. 469843, also in the Sedgwick Museum. Specimens shown in scanning electron micrographs are located according to the co-ordinate reference system described by Laing (1974). Anteturma pollenites Potonie, 1931 Turma plicates Naumova emend. Potonie, 1960 Subturma monocolpates Iversen and Troels-Smith, 1950 Genus asteropollis Hedlund and Norris, 1968 1968 Asteropollis Hedlund and Norris, p. 152. Type species. Asteropollis asteroides Hedlund and Norris, 1968, p. 153, pi. 6, figs. 18-20; pi. 7, figs. 1-5. Comments. Hedlund and Norris originally placed this genus in the subturma Polyp- tyches. However, I consider that it is better regarded as being a monosulcate form and I have accordingly transferred it to the subturma Monocolpates. CfB. Asteropollis asteroides Hedlund and Norris, 1968 Plate 94, figs. 12-14 1968 Asteropollis asteroides Hedlund and Norris, p. 153, pi. 6, figs. 18-20; pi. 7, figs. 1-5. Description of five specimens from samples EC03 and ECO 5. Sub-circular to circular in polar view, semi- circular in equatorial view. Tri-, tetra-, penta-, or hexachotomosulcate; sulcus margins poorly defined and rather ragged. Clear exine stratification into unstructured nexine and microreticulate sexine; sexine usually thicker than nexine (occasionally nexine thicker than sexine); sexine shows no tendency to detach from nexine. Microreticulum usually slightly imperfect (occasionally perfect) with some discrete clavae present ; lumina all of about the same size; sexine absent in patches over surface of sulcus. Dimensions. ED 21-26 /^tm (5), PD 13 ^^m (1), ET 1-2-1-5 jum (5), NT 0-5-0-8 (um (5), ST 0-5-10 /^m (5), ST/NT 0-6-2-0 (5), LD 0-2 ^.im (5), MW OT-0-2 pm (5), sulcus diameter 15-20 pm (5), sulcus diameter/ED 0-7-0-8 (5), L rays of sulcus/sulcus diameter 0-2-0-4 (5), W rays of sulcus/sulcus diameter 0-2-0-4 (5). Orientation. P 80 0%, E 20-0%. Occurrence. This study: inflatum Zone, Upper Albian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrences: Hedlund and Norris (1968), Middle Albian, Oklahoma; Dettmann (1973), Cenomanian and Turonian, eastern Australia. Known range: Middle Albian to Turonian. Comments. My attribution of these specimens to this species strictly requires an emendation of the genus, which should only include tetra- and pentachotomosulcate forms according to Hedlund and Norris’s diagnosis. However, I am reluctant to 780 PALAEONTOLOGY, VOLUME 18 make any formal emendation based on the few specimens which I have seen. The ! form described by Hedlund and Norris also differs in having the nexine slightly j thicker than the sexine. j \ Genus LiLiACiDiTES Couper, 1953 " 1953 Liliacidites Couper, p. 56. i, 1958 Clavatipollenites Couper, p. 159. 1961 Retimonocolpites Pierce, p. 47. Type species. Liliacidites kaitangataensis Couper, 1953, p. 56, pi. 7, fig. 97. Comments. Couper (1953) proposed the genus Liliacidites for monosulcate pollen grains with reticulate exines, adding that the genus be for the reception of pollen of liliaceous affinity which cannot be more accurately placed. The same author (1958) proposed the genus Clavatipollenites for monosulcate grains with a sexine of clavate projections which tend to expand and fuse at their tips to form a tectate exine. Couper made no suggestion as to how this genus was to be distinguished from Liliacidites. Kemp (1968) noted the morphological similarity of the two genera but implied that Liliacidites be used for grains of unquestionable angiospermous origin, whereas Clavatipollenites should be retained as a separate genus for forms of a more question- able affinity. In my opinion, such a distinction, based on the supposed affinity of a dispersed grain, has no place in palaeopalynology and any distinction should be made on morphological grounds. Dettmann (1973) attempted such a morphological distinction. She proposed that Liliacidites should include forms with a differentially thickened exine and a sulcus clearly formed in both the nexine and sexine. Clavatipollenites was proposed to include forms with an exine of uniform thickness in which the sulcus is invariably developed in the nexine but only occasionally in the sexine. I do not think that the question of the presence or absence of differential exine thickening is sufficiently important a character to justify the distinction of two genera. As for the question of the development of the sulcus in the sexine, the holotype of the type species of Clavatipollenites, C. liughesii, clearly has the sulcus developed in both the nexine and sexine. This is also the case with C. rotundas Kemp, which Dettmann seems pre- pared to leave in the genus Clavatipollenites. Thus, I do not think that the degree of development of the sulcus in the sexine is a valid feature for the distinguishing of these | two genera. I am thus of the opinion that no useful purpose is served by the retention j of Clavatipollenites as a genus separate from Liliacidites. CfA. Liliacidites peroreticulatus (Brenner) Singh, 1971 j Plate 93. figs. 2-5 1963 Peromonoliles peroreticulatus Brenner, p. 94, pi. 41, figs. 1-2. ^ ' 1971 Liliacidites peroreticulatus (Brenner) Singh, p. 188, pi. 28, figs. 6-1 1. De.scription of twenty-one speeimens from samples ECO 2, ECO 4, and ECO 5. Oval in polar view; semi- | circular to oval, sub-circular or circular in equatorial view. Monosulcate; sulcus parallel-sided or gaping with pointed ends; sexinal margins usually entire (occasionally slightly ragged); nexinal margins entire, often slightly infolded. Clear exine stratification into unstructured nexine and microreticulate sexine, which are often partially or completely separated from each other by a cavity ; where separation has not occurred, : LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 781 the sexine is attached to the nexine by bacula, the muri being swollen over the point of attachment. Micro- reticulum perfect, lumina of varying size and of irregularly polygonal shape. Dimensions. L (whole grain) 17 (20-4) 26 jum (15), L (nexinal inner body) 14 (17-4) 21 ,um (15), W (whole grain) 13 (18-8) 23 fxm (17), W (nexinal inner body) 10 (15-2) 21 ;um (17), D (whole grain) 12-19 jj.m (6), D (nexinal inner body) 10-20 ixm (6), L/W (whole gram) 10-1-6 (6), L/W (nexinal inner body) 10-1-9 (6), ET (where nexine and sexine are still in contact) 10 (1-6) 2 0 jj.m (21), NT 0-5 (0-7) 1 0 ;um (21), ST 0-5 (0-8) 10 ^^m (21), ST/NT 0-5 (1-2) 2-0 (21), LD (least) 0-2 (0-8) 1-5 fem to (greatest) 1-5 (2-5) 4 0 /xm (21), MW 0-2 (0-4) 10 /xm (21), sulcus L 12-18 /xm (8), sulcus L/L (whole grain) 0-7-0-9 (8), sulcus W 0-5 (2-8) 1 10 /ixm (19), sulcus W/W (whole grain) <01 (0-2) 0-5 (15), sulcus D 0-5 (21) 5-0 /xm (14), sulcus D/D (whole grain) < OT-0-3 (6). Orientation. P 381%, equatorial transverse aspect 28-6%, equatorial longitudinal aspect 0 0%, OA 33-3%. Occurrence. This study: inflatum Zone, Upper Albian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrences: Brenner (1963), Upper Barremian to Albian, Maryland; Norris (1967), Late Albian to ?Cenomanian, Alberta ; Brenner ( 1 968), Albian, Peru ; Agasie ( 1 969), Cenomanian, Arizona ; Singh (1971), Middle to Upper Albian, Alberta; Azema, Durand and Medus (1972), Middle Cenomanian, France. Known range: Upper Barremian to Cenomanian. TABLE 1. Presence ( + ) or absence ( — ) of individual species at each locality and horizon. A, inflatum Zone, Punfield Cove; B, inflatum Zone, Saint-Jouin; C, dispar Zone, Saint-Jouin; D, carcitanensis Horizon, Saint-Jouin; E, carcitanensis Horizon, Compton Bay; F, costatus Horizon, Punfield Cove; GJukes-brownei Horizon, Worbarrow Bay; HJukes-brownei Horizon, Lulworth Cove; I, Argiles noires of Ecommoy. Locality A B C D E F G H I A. asteroides — -b — — — + — — + L. peroreticulatus + + — + + + — — + L. rotundus + -b -b + + 4- — — -b P. erugatus — — — — -b — — — P. rectilatibus — — -f — — — + + + R. amplifissus — + + + + — + + + R. crassitransennus + + -b R. exiguiexemplum - + + — — + — — + R. georgensis — -b — + -f -b + + + R. meumendum — + + — — — — — + R. nemejci — — + — — — — — + R. promiscuus — -f + + — + + — + R. sarthensis — + — + — + -b — + R. subtilimaculatus — + — — + — — — + Retitricolpites sp 1 -I- + — — + + — — + S. sarstedtensis — + — — + — — + P. complanatius - - - - -b -b — — + R. ecommoyensis — + — — + + + — -b R. insolitimorus -b — + + ' + -b — + -b C. subtilis + — T. curtisi — — — — — — + — — T. worbarrowensis — — — — — — -b — — Comments. Distinction from L. rotundus (Kemp) is sometimes a little difficult. Generally, however, L. rotundus has a finer-meshed microreticulum with narrower muri, and has the muri composed of bacula or clavae rather than being supported by bacula. 782 PALAEONTOLOGY, VOLUME 18 Brenner (1963) described two similar species from the Potomac Group, Pero- monolites reticulatus and P. peroreticulatus, stating that they were distinguishable on the basis of grain size and lumen diameter. However, the specimens found in the present study overlap the ranges for these characters of both of Brenner’s species. I have examined some material from the Patapsco Formation of the Potomac Group and have found that these species differ as follows : P. peroreticulatus has more or less polygonal lumina and muri with a beaded surface, whereas P. reticulatus has more sinuous muri, such that the lumina are not so polygonal, the muri having smooth surfaces. CfB. Liliacidites rotundus (Kemp 1968) comb. nov. Plate 90, figs. 1 -6 1963 Liliacidites dividuus (Pierce) Brenner, p. 93, pi. 40, figs. 7-10. 1968 Clavatipollenites rotundus Kemp, p. 424, pi. 79, figs. 1-19; pi. 80, figs. 1-8; text-fig. 2. Description of seven specimens from samples JOU 3 and JOU 4. Oval to sub-circular in polar view, oval in equatorial longitudinal view, sub-circular or oval in equatorial transverse view. Monosulcate, sulcus slit- like or gaping, margins entire. Clear exine stratification into unstructured nexine and microreticulate sexine composed of clavae or bacula, sexine occasionally tending to detach from nexine. Microreticulum perfect, lumina generally of varying size (very rarely of more uniform size) and irregularly polygonal shape. Grain outlines generally finely indented (sometimes almost smooth). Dmensions. L 18-29 /urn (4), W 16-22 fxm (4), D 14-22 /uin (4), L/W M-L3 (2), D/W 0-7-1 -2 (2), L/D M ( 1 ), ET 1 -5-2-5 ;nm (7), NT 0-5- 1 -5 fxm (7), ST 0-9- 1 -0 pm (7), ST/NT 0-7-2-0 (7), LD (least) 0- 1 -0-3 /xm to (greatest) 0-3-1-5 pm (7), MW 0-2-0-3 pm (7), sulcus L 13-22 pm (4), sulcus L/L 0-7-0-8 (4), sulcus W 2-10 (um (4), sulcus W/W 01-0-5 (4), sulcus D 1-9 pm (4), sulcus D/D 01-0-6 (4). Orientation. P 28-6%, equatorial transverse aspect 28-6%, equatorial longitudinal aspect, 14-3%, OA 28-6%. Occurrence. This study: inflatum Zone, Upper Albian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrences: Brenner (1963), Albian, Maryland; Hedlund (1966), Cenomanian, Oklahoma; Brenner (1967), Cenomanian, New Jersey; Hedlund and Norris (1968), Middle Albian, Oklahoma; Kemp (1968, 1970), Lower Albian (Itardefurcata Zone) to Upper Albian, England; Habib (1969), Middle Cretaceous, sea bed near the Bahamas; Playford (1971), Albian, Saskatchewan and Mani- toba; Singh (1971), Albian to Cenomanian, Alberta; Azema, Durand and Medus (1972), Middle Ceno- manian, France. Known range: Itardefurcata Zone, Lower Albian to Cenomanian. EXPLANATION OF PLATE 90 All figures x 2000. Figs. 1-6. CfB. Liliacidites rotundus (Kemp). 1-2, oblique aspect; JOU 4, JL 169.1 ; 26.9, 106.9; 1, median focus; 2, low focus. 3-4, specimen with sexine partially detached from nexine; distal polar aspect; JOU 12, JL 177.1; 25.6, 104.6; 3, high focus; 4, median focus. 5-6, specimen with darkened sulcus borders; proximal polar aspect; ECO 6, JL 188.2; 24.1, 098.9; 5, median focus; 6, low focus. Figs. 7-8. CfC. PsHatricolpites erugatus {\\Qd\ux\d). Near equatorial aspect; ECO 5, JL 187.3; 34.1, 108.3; 7, high focus; 8, median focus. Figs. 9-12. Psilatricolpites rectilatihus sp. nov. 9- 10, holotype; polar aspect: ECO 5, JL 187.2; 59.0, 1 10.8; 9, high focus; 10, median focus. 1 1-12, oblique aspect; ECO 5, JL 209.3; 35.6, 101.2; 1 1, median focus; 12, high focus. Figs. 13-16. Retitricolpites amplifissus sp. nov. 13-14, holotype; oblique aspect; ECO 5, JL 209.2; 40.8, 096.6; 13, high focus to show ornament; 14, median focus. 15- 16, small specimen; polar aspect; ECO 5, JL 187.3; 41.4, 097.0; 15, high focus to show ornament; 16, median focus. PLATE 90 LAING, angiosperm pollen 784 PALAEONTOLOGY, VOLUME 18 Comments. See comments for L. peroreticulatus for distinction from this species. Kemp (1968) attempted to distinguish this species from Liliacidites (al. Clavati- pollenites) hughesii (Couper 1958, p. 159, pi. 31, figs. 19-22 emend. Kemp 1968, p. 426, pi. 80, figs. 9-19) comb. nov. on the basis of size-range and shape. However, I have found that the two species seem to show too great an overlap in the ranges of these characters to allow a reliable distinction to be made on this basis. Kemp further suggested that the nature of the sulcus could be used to differentiate the species, the sulcus having entire margins with darkened borders in L. rotundus, and being indistinct or with ragged margins and no darkened borders in L. hughesii. Although I have found a few specimens of L. rotundus with darkened sulcus borders (e.g. PI. 90, figs. 5-6), it is the exception in the specimens that I have observed ; further- more, the holotype of L. hughesii has a distinct sulcus with entire margins. Thus I do not consider that the nature of the sulcus should be used as a distinguishing character. In my opinion the most useful distinguishing character is (as Kemp also stated) the degree of development of the microreticulum, it being perfect in L. rotundus and imperfect in L. hughesii. Retimonocolpites dividuus Pierce, 1961, was poorly described and figured. Pierce did, however, state that the aperture (i.e. sulcus) almost encircles the grain, dividing it into two hemispheres; on the basis of this feature, Pierce’s species seems to be distinct. Brenner (1963) and later authors (Hedlund 1966; Hedlund and Norris 1968; Brenner 1967; Habib 1969; and Singh 1971) described or figured forms identified as Pierce’s species, which seem to more closely resemble L. rotundus. Subturma triptyches Naumova emend. Potonie 1960 Several genera have been used by various authors for early tricolpate pollen. I find the genera of van der Hammen (1956) the most convenient, at least for light micro- scope studies. For S.E.M. studies, different genera may be preferred based on the greater structural variation which can be observed, and for practical purposes it may become necessary to have separate taxonomies for each mode of observation (in which case the S.E.M. taxonomy will probably be the correct ‘formal’ one, and the light microscope taxonomy will be rather more informal). Genus psilatricolpites van der Hammen ex van der Hammen and Wymstra, 1964 1956 Psilatricolpites van der Hammen, p. 88. 1964 Psilatricolpites van der Hammen ex van der Hammen and Wymstra, p. 234. Type species. Psilatricolpites clarissimus (van der Hammen) emend, van der Hammen and Wymstra, 1964, p. 235, pi. 2, fig. 2. CfC. Psilatricolpites erugatus (Hedlund 1966) comb. nov. Plate 90, figs. 7-8 1966 Tricolpites erugatus Hedlund, p. 30, pi. 9, fig. 2a-b. 1967 Psilatricolpites parvulus (Groot and Penny) Norris, p. 107, pi. 17, figs. 5-6. Description of thirty-two specimens from samples ECO 1, ECO 3, ECO 4, ECO 5, and ECO 7. Perprolate to prolate (very occasionally prolate spheroidal); elliptical in equatorial view. Three distinct (occasionally LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 785 indistinct) slit-like (occasionally more gaping) colpi with entire (occasionally more ragged) margins. No clear exine stratification, Psilate. Dimensions: PD 10 (12-2) 17 fxm (27) s2-0 ;um, ED 5 (7-6) 1 1 /xm (32) sl-4 /Ltm, PD/ED 11 (1-6) 2-3 (27), ET 0-2 (0-7) M ^m (32), EC 7 (91) 13 /^m (27), LC/PD 0-5 (0-7) 0-9 (27). Orientation. P 0 0%, E 844%, OA 15-6%. Occurrence. This study: carcitanensis Horizon, mantelli Zone, Lower Cenomanian to rhotomagense Zone 0-costatus Horizon), Middle Cenomanian. Other occurrences: Hedlund (1966), Cenomanian, Oklahoma; Norris (1967), Late Albian, Alberta; Singh (1971), Upper Albian and Cenomanian, Alberta; Azema, Durand and Medus (1972), Middle Cenomanian, France. Known range: Upper Albian and Cenomanian. Comments. It is difficult to decide whether this form is more closely referable to Tricolpopollenites parvulus Groot and Penny, 1960 or Tricolpites erugatus Hedlund, 1966. Groot and Penny’s description of T. parvulus stated ‘grains about isodiametric, usually seen in polar view’, which seems to suggest that this species should have a spheroidal shape (although one of Groot and Penny’s figures, pi. 42, fig. 9, shows a clearly prolate form). Norris (1967) did not describe this species but, of the two specimens which he figured, one is prolate and the other more or less spheroidal. The forms described as Psilatricolpites parvulus by Singh (1971) are ‘sub-prolate to almost isodiametric’. I have placed the specimens that I have found in Hedlund’s species since this definitely includes prolate forms. However, Hedlund included both smooth and microgranulose specimens in this species, and the latter condition has not been observed in the specimens found in the present study. P. rectilatibus sp. nov. differs by generally having a greater equatorial diameter and a more spheroidal or oblate shape. It also seems to be more deeply trilobate. Psilatricolpites rectilatibus sp. nov. Plate 90, figs. 9-12 Description of fourteen specimens from samples ECO 5 and ECO 7. Spheroidal to oblate; deeply trilobate, more or less straight-sided triangular outline in polar view. Three distinct long slit-like or gaping colpi generally with entire margins, angul-aperturate. No clear exine stratification. Psilate. Holotype. Sample ECO 5, slide JL 187.2; 59.0, 110.8. Plate 90, figs. 9-12. Argiles noires, Ecommoy; rhotomagense Zone, Middle Cenomanian. Dimensions. ED 10 (12T) 15 /xm (14), ET 0-2 (0-7) 10 /xm (14), WC 0-2 (2-6) 5-0 ;ixm (4), WC/ED <01 (0-2) 0 4(4), DC 01 (l-6)3 0;ixm (4), DC/ED <01 (01) 0-2 (4). Orientation. P 28-6%, E 0-0%, OA 714%. Occurrence. This study: dispar Zone, Upper Albian to jukes-hrownei Horizon, rhotomagense Zone, Middle Cenomanian. Comments. Tricolpopollenites parvulus Groot and Penny, 1960 was not described adequately enough to allow a close comparison ; it does seem, however, to differ from this species in having short colpi. Tricolpites pachyexinus Couper, 1953 differs by being larger, by having a much thicker exine and by occasionally being tetracolpate. T. gillii Cookson, 1957 differs by being larger and by having a finely granular tectate exine. Tricolporopollenites triangulus Groot, Penny and Groot, 1961 differs by having pores. Psilatricolpites tetradus Brenner, 1968 differs by having a more circular amb, exine stratification, and by most commonly occurring in tetrads. See comments for P. erugatus for distinction from this species. 786 PALAEONTOLOGY, VOLUME 18 Genus retitricolpites van der Hammen ex van der Hammen and Wymstra, 1964 1956 Retitricolpites van der Hammen, p. 90. 1964 Retitricolpites van der Hammen ex van der Hammen and Wymstra, p. 234. Type species. Retitricolpites ovalis van der Hammen and Wymstra, 1964, p. 234, pi. 1, figs. 5-6. Retitricolpites amplifissm sp. nov. Plate 90, figs. 13-16; Plate 91, figs. 1-2 1968 Tricolpites sp. 2 Kemp, p. 432, pi. 81, figs. 23-24. Description of sixteen specimens from samples ECO 3, ECO 4, ECO 5, and ECO 7. Oblate, perhaps to spheroidal; circular to sub-triangular, deeply trilobate outline in polar view. Three distinct, quite short colpi which gape at the equator, margins entire to ragged. Clear exine stratification into unstructured nexine and microreticulate sexine; sexine of equal thickness to, or more commonly thicker than, nexine. Microreticulum most commonly perfect, but sometimes imperfect; lumina generally of varying size (but sometimes of fairly constant size) and irregularly polygonal in shape. Some specimens with a smooth inner central body (see PI. 91, figs. 1-2). Grain outlines finely indented. Holotype. Sample ECO 5, slide JL 209.2; 40.8, 096.6. Plate 90, figs. 13-14. Argiles noires, Ecommoy; rhotomagense Zone, Middle Cenomanian. Dimensions. Type material: ED 11 (19-9) 27 fim (16), ET 10 (T3) 2-0 /xm (16), NT 0-2 (0-5) 10 [xm (16), ST 0-5 (0-9) 10 fxm (16), ST/NT 0-9 (2-1) 5-0 (16), LD (least) 0-1 (0-2) 0-8 ,xm to (greatest) 01 (0-9) 1-5 /xm (16), MW 01 (0-2) 0-3 /xm (16), WC 2 0 (4-9) 8-0 /xm (8), WC/ED 01 (0-2) 0-3 (8), DC 2-0 (4-9) 9-0 /xm (8), DC/ED OT (0-2) 0-3 (8). Other material: Sample JOU 4, ED 15-23 /xm (6); Sample JOU 15, ED 16- 22 /xm (5). Orientation. Type material; P 50 0%, OA 50-0%. Occurrence. This study; inflatum Zone, Upper Albian to jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrences: Kemp (1968, 1970), Lower Albian (Itardefurcata Zone), England. Known range : Itardefurcata Zone, Lower Albian to jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. EXPLANATION OF PLATE 91 All figures x 2000. Figs. 1-2. Retitricolpites amplifissus sp. nov. Large specimen with inner central body; polar aspect; ECO 4, JL 1 84. 1 ; 3 1 . 1 , 111.6; 1 , low focus to show ornament ; 2, median focus to show inner central body. Figs. 3-8. Retitricolpites crassitransennus sp. nov. 3-4, holotype; polar aspect; ECO 5, JL 209.1; 40.1, 101.0; 3, high focus to show ornament; 4, median focus. 5-6, oblique aspect; ECO 5, JL 209.1; 41.3, 108.8; 5, median focus; 6, low focus. 7-8, equatorial aspect; ECO 5, JL 209.3; 32.8, 103.5; 7, high focus; 8, median focus. Figs. 9-10. Retitricolpites exiguiexemplum sp. nov. Holotype; oblique aspect; ECO 5, JL 209.1; 47.4, 099.1 ; 9, high focus; 10, median focus. Figs. 11-12. CfB. Retitricolpites georgensis Brenner. Equatorial aspect; ECO 7, JL 191.1; 29.5, 097.8; 11, median focus; 12, low focus to show ornament. Figs. 13-14. Retitricolpites meumendum sp. nov. Holotype; equatorial aspect; ECO 5, JL 209.3; 42.1, 108.8; 13, median focus; 14, low focus to show ornament. Figs. 15-16. CfC. Retitricolpites nemejci (Pacitova). Equatorial aspect; ECO 5, JL 209.1; 44.4, 100.6; 15, median focus; 16, low focus. Figs. 17-18. Retitricolpites promiscuus sp. nov. Holotype; specimen with lumina of varying size; equatorial aspect; ECO 5, JL 187.2; 26.4, 101.4; 17, median focus; 18, low focus to show ornament. r/ PLATE 91 LAING, angiosperm pollen 788 PALAEONTOLOGY, VOLUME 18 Comments. The size distribution of the type material suggests that two species could be present, one with an average equatorial diameter of about 17 /xm, the other of about 25 /xm, but insufficient specimens have been found to show this conclusively. Retitricolpites crassitransennus differs by having slightly longer colpi, a generally finer-meshed microreticulum, wider muri, and undulating grain outlines. R. pro- miscuus has a generally more prolate shape and longer, narrower, more slit-like colpi. R. vulgaris Pierce, 1961 and R. oblatoides Pierce, 1961 were both inadequately described; either could be conspecific with this species. Tricolpopollenites platyreti- culatus Groot, Penny and Groot, 1961 is a more coarsely reticulate form. Tricolpites sp. 2 of Agasie (1969) is, on average, a rather larger form, with a more straight- sided triangular outline and a microreticulum which becomes finer over the poles and at the colpus margins. Tricolpites heusseri Kimyai, 1966 seems to differ by having narrower colpi. T. sagax Norris, 1967 differs by sometimes being sub-prolate, by sometimes having a sub-granular exine, and by generally having narrower colpi. Tricolpites sp. A of Pacltova (1971) seems to differ in having a sexine of closely spaced (presumably discrete) pila rather than a microreticulum. R. maximus Singh, 1971 is larger and has thicker, more vermiculate muri and a more prolate shape. T. reticulata Cookson, 1947 is a generally rather larger form. T. cooksonae Dettmann, 1973 has a generally slightly coarser-meshed microreticulum with wider muri. Retitricolpites crassitransennus sp. nov. Plate 91, figs. 3-8 Description of sixteen specimens from samples ECO 1, ECO 5, and ECO 6. Oblate to prolate; circular to sub-triangular, quite deeply trilobate outline in polar view, elliptical to sub-circular in equatorial view. Three distinct colpi which gape at the equator, margins entire to slightly ragged. Clear exine stratification into unstructured nexine and microreticulate sexine; sexine of equal thickness to, or more commonly, thicker than nexine (very rarely sexine thinner than nexine). Microreticulum perfect; lumina usually of uniform size (rarely of varying size), irregularly shaped; muri sometimes of varying width, usually wider than lumina. Grain outlines undulating. Holotype. Sample ECO 5, slide JL 209.1 ; 40.1, 101.0. Plate 91, figs. 3-4. Argiles noires, Ecommoy; rhoto- magense Zone, Middle Cenomanian. Dimensions. PD 17-22 ;ixm (3), ED 13 (19-3) 27 ;xm(16), PD/ED 10-L4(3), ET 10 (1-5) 21 ^xm(16), NT 0-2 (0-6) M ^m (16), ST 0-5 (0-9) 1-2 p.m (16), ST/NT 0-5 (2-2) 6 0 (16), LD 0-2 (0-4) 10 pm (16), MW 0-2 (0-6) 10 /xm (16), LC 10-18 ^m (3), LC/PD 0-7-0-8 (3), WC 2 0-6 0 pm (4), WC/ED 01-0-3 (4), DC 2-0-5-0 ;um (4), DC/ED 01 -0-2 (4). Orientation. P 25-0%, E 18-8%, OA 56-3%. Occurrence. This study : rhotoniagense Zone, Icostatus Horizon to jukes-brownei Horizon, Middle Ceno- manian. Comments. See comments for Retitricolpites amplifissus and CfC. R. nemejci for distinction from these species. Tricolpopollenites virgeus Groot, Penny and Groot, 1961 has a coarser-meshed reticulum and is a little larger. R. fragosus Hedlund and Norris, 1968 is a little smaller and also differs in having the lumina reduced in size on the mesocolpia. Tricolpites harrandei Pacltova, 1971 is smaller and perhaps has a rather coarser-meshed microreticulum. Foveotricolpites concinnus Singh, 1971 differs by always being prolate, by having wider muri, and a coarser-meshed reticulum, and by being rather larger. LAING; MID-CRETACEOUS ANGIOSPERM POLLEN 789 Retitricolpites exiguiexemplum sp. nov. Plate 9 1 , figs. 9-10; text-figs. 10-11 Description of nine specimens from samples ECO 3, ECO 5, and ECO 7. Spheroidal. Three distinct long deep colpi, most commonly narrow and slit-like, less commonly wider and gaping at the equator, margins entire. Clear exine stratification into unstructured nexine and microreticulate sexine; nexine and sexine usually of equal thickness (occasionally sexine thicker than nexine). Microreticulum usually perfect (occasionally imperfect with some free bacula) ; lumina of approximately uniform size and equidimensional shape; some specimens psilate over the poles. Grain outlines smooth to slightly indented. Holotype. Sample ECO 5, slide JL 209.1; 47.4, 099.1. Plate 91, figs. 9-10. Argiles noires, Ecommoy; rhotomagense Zone, Middle Cenomanian. Dimensions. ED 7-12 fxm (9), ET 0-8-1 -8 /xm (9), NT 0-2-0-9 ;um (9), ST 0-4-0-9 /xm (9), ST/NT 1-0-4-0 (9), ED < 01-0-2 fxm (9), MW < 01-0-1 (9). Orientation. OA 100-0%. Occurrence. This study: inflatum Zone, Upper Albian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. jiiimininirm immmiin. TEXT-FIG. 10. Cross-sections of sexine of Retitricolpites subtilimaculatus sp. nov. (left) and R. exiguiexemplum sp. nov. (right). LOBE TEXT-FIG. 1 1 . Holotypes of Tricolpites albiensis Kemp (left) and Retitricolpites exiguiexemplum sp. nov. (right), x 1000. Comments. Retitricolpites meumendum is rather more prolate and has shallower colpi. Distinction from R. subtilimaculatus is sometimes difficult. The main difference seems to lie in the nature of the sexine ; in the case of R. subtilimaculatus the sculptural elements stand up separately from each other to give a more indented outline (see text-fig. 10), whereas in R. exiguiexemplum the sculptural elements appear more fused, so that the outline is less indented. Tricolpites albiensis Kemp, 1968 is a similar form. It differs from this species in having less rounded ‘lobes’ (i.e. the area between the colpi— see text-fig. 1 1 ). Also, in the case of T. albiensis the sexine shows a tendency to thicken as it passes over the centre of the lobe (this feature is well shown in Kemp’s (1968) pi. 81, fig. 7); such a tendency is less apparent in R. exiguiexemplum. Judging by Kemp’s description, a further difference is that T. albiensis has a coarser-meshed microreticulum (LD 0-3-0-4 pm) which is imperfect: however, the holotype appears to have a perfect microreticulum of LD 0-2 ,um. Further differences are that T. albi- ensis includes quite strongly prolate forms and is on average a little larger than R. exiguiexemplum. Tricolpopollenites micromunus Groot and Penny, 1960 was inadequately described; it might possibly be conspecific with this species. Tricolpites reticulominutus Jardine and Magloire, 1965 differs from this species by being some- what larger. 790 PALAEONTOLOGY, VOLUME 18 CfB. Retitricolpites georgensis BrtnnQV, 1963 Plate 91, figs. 1 1-12; text-fig. 12 1963 Retitricolpites georgensis Brenner, p. 91, pi. 38, figs. 6-7. 1973 Rousea georgensis (Brenner) Dettmann, p. 14, pi. 2, figs. 16-17. Description of eight specimens from samples ECO 1, ECO 3, ECO 5, and ECO 7. Sub-prolate to prolate; elliptical in equatorial view. Three distinct, narrow slit-like colpi, margins entire. Clear exine stratification into unstructured nexine and microreticulate sexine; sexine of equal thickness to, or thicker than, nexine (very rarely sexine thinner than nexine). Microreticulum perfect; lumina of varying size, usually becoming smaller towards the poles, irregularly shaped; muri sometimes of varying width, usually narrower than lumina. Grain outlines notched or coarsely indented at equator, becoming smoother towards the poles. Dimensions. PD 15-26 (5), ED 10-16 /um (8), PD/ED M-1-6 (5), ET 10- 1-8 /xm (8), NT 0-5- TO /xm (8), ST 0'5-lT /xm (8), ST/NT 0-5-2-8 (8), LD (least) 0-2-0-5 ju.m to (greatest) 10-2-5 pm (8), MW 0-2-0-8 /xm (8), LC 9 (13-3) 20 ^m (5), LC/PD 0-6 (0-7) 0-8 (5). Orientation. P 0 0%, E 62-5%, OA 37-5%. Occurrence. This study: inflatum Zone, Upper Albian to jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrences: Brenner (1963), Albian, Maryland; Norris (1967), Late Albian, Alberta; Habib (1969), Middle Cretaceous, sea bed near the Bahamas; Paden Phillips and Felix (1971), Cenomanian, Louisiana; Playford (1971), Middle and ?Late Albian, Saskatchewan and Manitoba; Singh (1971), Middle Albian to Cenomanian, Alberta; Azema, Durand and Medus (1972), Middle Cenomanian, France; Dettmann (1973), Late Albian and Cenomanian, eastern Australia. Known range: Albian and Cenomanian. Comments. The specimens described by Brenner (1963) are quite similar, but are, on average, larger (PD 18 (26) 36 ;ixm, ED 17 (22) 28 ju.m) and show a smaller range of variation in the lumina diameter (0-5- 1-5 /xm). See comments for Retitricolpites crassitransennus and Retitricolpites sp. 1 for distinction from these species. R. sar- thensis differs by having a finer-meshed microreticulum, a thinner exine either with unclear stratification or a thinner nexine relative to the sexine, and finely indented grain outlines. R. promiscuus has a rather finer-meshed microreticulum and more finely indented grain outlines. CfC. R. nemejci differs by having generally rather longer colpi, a finer-meshed more regular microreticulum, a generally thinner exine, a thinner nexine as compared to the sexine, and more finely indented grain outlines. Retitricolpites meumendum sp. nov. Plate 91, figs. 13-14 Description of twelve specimens from sample ECO 5. Prolate to sub-prolate (? perhaps to prolate spheroidal) ; elliptical or sub-circular in equatorial view. Three generally distinct narrow slit-like shallow colpi, margins entire (rarely ragged). Exine usually clearly stratified into unstructured nexine and a sexine which is usually psilate at the poles and microreticulate elsewhere, exine stratification unclear in some specimens; sexine usually thicker than nexine. Microreticulum perfect but not strongly developed; lumina of approximately uniform size and equidimensional shape. Grain outlines smooth at poles, elsewhere very finely indented. Holotype. Sample ECO 5, slide JL 209.3; 42.1, 108.8. Plate 91, figs. 11-12. Argiles noires, Ecommoy; rhotomagense Zone, Middle Cenomanian. Dimensions. PD 10-15 /xm (8), ED 7 (9-3) 14 /un (12), PD/ED T3-T9 (8), ET 0-4 (0-6) 11 ,-m (12), NT 0- 1 -0-2 /xm (8), ST 0-3-0-9 /xm (8), ST/NT 2 0-5 0 (8), LD < 0- 1 (0-2) 0-4 /xm ( 1 2), MW < 0- 1 (0- 1 ) 0-2 /xm (12), LC 8 (9-5) 13 /xm (8), LC/PD 0-6 (0-8) 0-9 (8). Orientation. P 0 0%, E 66-7%, OA 33-3%. LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 791 Occurrence. This study : inflatum Zone, Upper Albian to rhotomagense Zone (? costatus Horizon), Middle Cenomanian. Comments. See comments for Retitricolpites exiguiexemplum for distinction from this species. CfC. R. nemejci is generally rather larger, is less commonly psilate at the poles, and has a more distinct microreticulum with generally wider muri. R. sub- tilimaculatus has rather deeper colpi, the microreticulum developed all over the grain, and a thicker exine. CfC. Retitricolpites nemejci (Pacltova 1971) comb. nov. Plate 91, figs. 15-16 1971 Tricolpites nemejci Pacltova, p. 113, pi. 4, figs. 1-5; pi. 5, figs. 1-12; pi. 6, figs. 1-12. Description of five specimens from sample ECO 5. Sub-prolate to prolate; elliptical in equatorial view. Three distinct parallel-sided colpi, margins entire. Clear exine stratification into unstructured nexine and micro- reticulate sexine (sexine very occasionally psilate at the poles) ; sexine thicker than nexine. Microreticulum perfect; lumina either of approximately uniform or of slightly varying size, irregularly polygonal in shape; muri often of varying width. Grain outlines finely indented (very occasionally smooth at the poles). Dimensions. PD 16-24 /urn (5), ED 9-16 /nm (5), PD/ED 1-3- 1-8 (5), ET 0-6- 10 /iim (5), NT OT-0-2 jum (5), ST 0-5-0-8 fxm (5), ST/NT 4-0-7-0 (5), ED 01-0-4 ^.m (5), MW 0-2-L0 ,xm (5), EC 12 (17-1) 22 ixm (5), LC/PD 0-8 (0-8) 0-9 (5). Orientation. E 100 0%. Occurrence. This study: dispar Zone, Upper Albian to rhotomagense Zone (? costatus Horizon), Middle Cenomanian. Other occurrence: Pacltova (1971), Cenomanian, Bohemia. Known range: dispar Zone, Upper Albian and Cenomanian. Comments. Some of the specimens figured by Pacltova (1971) are similar to the forms described here. Pacltova described the shape as being oblate to sub-prolate although some of her figured specimens are clearly prolate. Pacltova’s specimens are, on average, rather larger (PD 23 (25) 28 p.m) and have slightly coarser microreticula than the specimens found in this study. See comments for CfB. Retitricolpites georgensis and R. meumendum for distinction from these species. R. crassitransennus differs by being more spheroidal and by having slightly shorter colpi, a generally slightly coarser-meshed microreticulum, a generally thicker exine, and undulating grain outlines. R. promiscuus has a coarser-meshed microreticulum, a generally thicker exine, nexine and sexine typically of about equal thickness, and possibly has narrower colpi. Foveotricolpites sphaeroides Pierce, 1961 and Querco'idites sp. of Azema and Ters (1971) seem to be similar forms but both were inadequately described for com- parative purposes. Retitricolpites sp. B of Hedlund and Norris (1968) also seems to be similar, but it was undescribed. Retitricolpites promiscuus sp. nov. Plate 91, figs. 17-18; Plate 92, figs. 1-2 Description of fifty-four specimens from samples ECO 1, ECO 2, ECO 5, and ECO 6. Spheroidal to prolate; sub-circular trilobate outline in polar view, elliptical in equatorial view. Three, usually distinct, slit-like (occasionally more gaping) colpi, margins entire or slightly ragged. Clear exine stratification into un- structured nexine and microreticula te sexine ; nexine and sexine usually of about equal thickness (occasionally 792 PALAEONTOLOGY, VOLUME 18 sexine a little thicker than nexine). Microreticulum perfect; lumina of varying size in about two-thirds of the specimens examined, and of more uniform size in about one-third of the specimens, irregularly polygonal in shape. Grain outlines finely indented. Holotype. Sample ECO 5, slide JL 187.2; 26.4, 101.4. Plate 91, figs. 17-18. Argiles noires, Ecommoy; rhotomagense Zone, Middle Cenomanian. Dimensions. Type material: PD 12 (17-4) 23 ;um (27) s3-4 /^m, ED 8 (13-7) 21 ;um (54) s3-5 ;um, PD/ED 10 (1-4) 1-8 (27), ET 10 (1-4) 2-0 ^m (54), NT 0-3 (0-6) l O^m (54), ST 0-5 (0-7) 10/xm(54), ST/NT 0-8 (1-3) 3-3 (54), LD (least) OT (0-2) 0-5 /xm to (greatest) OT (0-6) 2-0 fxm (54), MW OT (0-2) 0-3 jum (54), LC 8(11-6) 1 8 ,xm (26), LC/PD 0-5 (0-7) 0-9 (26), WC 0-5-2-0 /xm (2), WC/ED < 0- 1 -0- 1 (2), DC 1 -0- 1 -5 /xm (2), DC/ED 01 (2). Other material: Samples JOU 1, JOU 2, and JOU 4, PD 12 (14-6) 20 jum (13), ED 8 (101) 14 ;um (17); Samples JOU 8, JOU 16, and JOU 17, PD 13-20 (6), ED 10-17 f.nn (8). Orientation. Type material: P 3-7%, E 50 0%, OA 46-3%. Occurrence. This study: inflatum Zone, Upper Albian to jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Comments. See comments for Retitricolpites ampUfissus, CfB R. georgensis, and CfC. R. nemejci for distinction from these species. R. sarthensis differs by having a generally thinner exine, either with unclear exine stratification or with the nexine rather thinner than the sexine. Retitricolporites insolitimorus is superficially similar but it is sometimes tetrahedral in shape. Further, it does not always have three colpi, but has pores, and tends to have a thicker nexine than sexine, and shorter colpi. The specimens described as TricolpopoUenites retiformis Pflug and Thomson by Groot, Penny and Groot (1961) might be the same species, but they are inadequately described for a close comparison (Thomson and Pflug’s (1953) original description also is inadequate for comparative purposes). T. haraldii Manum, 1962 is a larger form with a thinner nexine relative to the sexine. Retitricolpites prosimilis Norris, 1967 differs by having a decrease in lumina diameter towards the poles and a generally thinner exine. Tricolpites variabilis Burger, 1970 differs in having a generally slightly EXPLANATION OF PLATE 92 All figures x 2000. Figs. 1-2. Retitricolpites promiscuus sp. nov. Specimen with lumina of approximately uniform size; equa- torial aspect; ECO 5, JL 209.1 ; 33.9, 097.7; 1, high focus to show ornament; 2, median focus. Figs. 3-6. Retitricolpites sarthensis sp. nov. 3-4, holotype; equatorial aspect; ECO 5, JL 187.3; 53.6, 105.9; 3, high focus; 4, median focus. 5-6, oblique aspects; PUN 1, JL 106.3; 40.4, 097.9; 5, median focus; 6, low focus. Figs. 7-10. Retitricolpites subtilimaculatus sp. nov. 7-8, holotype; equatorial aspect; ECO 5, JL 187.2; 32.1, 103.3; 7, high focus; 8, median focus. 9-10, oblique aspect; ECO 5, JL 209.2; 35.1, 105.7; 9, high focus; 10, median focus. Figs. II 14. Retitricolpites sp. 1. 11-12, equatorial aspect; ECO 5, JL 209.2; 52.5, 105.1; 11, median focus; 12, high focus to show ornament. 13-14, oblique aspect; ECO 5, JL 187.2; 54.5, 111.6; 13, high focus to show ornament; 14, median focus. Figs. 15-20. CfC. Striatopollis sarstedtensis Krutzsch. 15-16, oblique aspect; ECO 5, JL 187.2; 51.5, 099.8; 15, high focus; 16, median focus. 17-18, polar aspect; ECO 5, JL 187.2; 25.0, 100.5; 17, median focus; 18, high focus to show ornament, note the development of the polar microreticulum. 19-20, equatorial aspect; ECO 5, JL 209.2; 28.1, 1 1 1.8; 19, high focus to show ornament, note the cross pieces linking the muri; 20, median focus. PLATE 92 LAING, angiosperm pollen 794 PALAEONTOLOGY, VOLUME 18 thinner exine, the nexine thinner than the sexine, and by having narrow costae bordering the colpi. T. brnicensis Pacltova, 1971 differs by sometimes being oblate, by being generally larger, and by always having more or less uniform-sized lumina. Retitricolpites sarthensis sp. nov. Plate 92, figs. 3-6 1971 Tricolpites vulgaris (Pierce) Pacltova, p. 113, pi. 3, figs. 6-13. Description of forty-four specimens from samples ECO 2, ECO 5, ECO 6, and ECO 7. Prolate spheroidal to prolate; elliptical to circular in equatorial view. Three narrow slit-like (occasionally more gaping) colpi, margins entire (occasionally slightly ragged). Exine thin, microreticulate, stratification often unclear (specimens with thicker exines show stratification into unstructured nexine and thicker microreticulate sexine). Microreticulum perfect; lumina of varying size, irregularly polygonal in shape. Grain outlines finely indented. Holotype. Sample ECO 5, slide JL 187.3; 53.6, 105.9. Plate 92, figs. 3-4. Argiles noires, Ecommoy; rhoto- magense Zone, Middle Cenomanian. Dimensions. Type material: PD 13 (14-6) 18 /xm (26) sl-7 /xm, ED 7 (11-8) 19 /xm (44) s3-4 ;ixm, PD/ED IT (1-4) 1-9 (26), ET 0-4 (0-8) 1-2 /xm (44), NT (where determinable) OT (0-2) 0-2 /xm (21), ST (where determinable) 0-8 (0-9) 10 /xm (21), ST/NT (where determinable) 4-0 (5-8) 9 0 (21), LD (least) OT (0-3) 0-5 /xm to (greatest) 0-4 (TO) 2 0 /xm (44), MW OT (0-2) 0-5 /xm (44), LC 8 (11-2) 16 /xm (26), LC/PD 0-6 (0-8) 0-9 (26). Other material; Sample PUN 1, PD 16 (19-9) 24 /xm (11), ED 10 (14-7) 19 /xm (16); Sample WOR 1, PD 17-23 /xm (6), ED 9-16 /xm (6). Orientation. Type material: P 0-0%, E 61-4%, OA 38-6%. Occurrence. This study: inflatum Zone, Upper Albian to jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrence: Pacltova (1971), Cenomanian, Bohemia. Known range', inflatum Zone, Upper Albian to Cenomanian. Comments. See comments for CfB. Retitricolpites georgensis, R. promiscuus, and Retitricolpites sp. 1 for distinction from these species. The form described by Pacltova (1971) as Tricolpites vulgaris (Pierce) is very similar, but is a little larger (PD 20- 28 /um, ED 18-24 /u.m). R. vulgaris Pierce, 1961 was too briefly described for a close comparison, but it does seem to be a larger form, perhaps with a thicker exine and wider colpi. R. minutus Pierce, 1961 also seems to be a similar form. It also was inadequately described for a close comparison; however, it does seem to differ from this species by having wider colpi with slightly thickened margins. R. prosimilis Norris, 1967 differs by usually having a reduced ornament on the apocolpia. Norris noted, however, that some of his specimens lacked this feature and that these might represent a separate species; perhaps the latter belong to R. sarthensis. Tricol- popollenites microreticulatus Takahashi, 1961 is superficially similar; unfortunately, it was inadequately described for a close comparison. Retitricolpites subtilimaculatus sp. nov. Plate 92, figs. 7-10; text-fig. 10 Description of seven specimens from sample ECO 5. Spheroidal to prolate; elliptical to circular in equatorial view. Three colpi, narrow and slit-like or wide and gaping at the equator, quite deep, margins entire (occasionally slightly ragged), sometimes rather indistinct. Clear exine stratification into unstructured nexine and microreticulate sexine; sexine thicker than nexine. Microreticulum perfect; lumina of about uniform size and equidimensionally shaped. Grain outlines finely indented. LAING. MID-CRETACEOUS ANGIOSPERM POLLEN 795 Holotype. Sample ECO 5, slide JL 187.2; 32.1, 103.3. Plate 92, figs. 7-8. Argiles noires, Ecommoy; rhoto- magense Zone, Middle Cenomanian. Dimensions. PD 11-12 jiim (2), ED 8-12 fxm (7), PD/ED 10-1-4 (2), ET 10-1-7 nm (7), NT 0-2-0-8 (um (7), ST 0-7-0-9 (ixm (7), ST/NT M-4-0 (7), LD 0-1 -0-2 /urn (7), MW 0-1 ^^m (7), LC 7-10 /^m (2), LC/PD 0-6- 0-8(2). Orientation. P 0-0%, E 28-6%, OA 71-4%. Occurrence. This study: inflatum Zone, Upper Albian to rliotomagense Zone (? costatus Horizon), Middle Cenomanian. Comments. See comments for Retitricolpites exiguiexemplum and R. meumendum for distinction from these species. Tricolpopollenites mimitus Brenner, 1963 is a very similar form which perhaps differs in having a generally slightly thinner exine and possibly also in having smoother or less indented grain outlines. Tricolpites albiensis Kemp, 1968 differs by being somewhat larger and by having much more closely- spaced sexinal sculptural elements, such that the grain outlines are more or less smooth. Retitricolpites sp. 1 Plate 92, figs. 11-14; text-fig. 12 Description of seven specimens from sample ECO 5. Prolate spheroidal to prolate; sub-circular to elliptical in equatorial view. Three colpi, usually narrow and slit-like but occasionally wide and gaping at the equator, margins more commonly entire than ragged and sometimes a little thickened, sometimes indistinct. Clear exine stratification into unstructured nexine and a sexine composed of bacula which support a micro- reticulum; nexine usually thinner than sexine (very rarely nexine and sexine of about equal thickness). Microreticulum usually imperfect (often with some discrete bacula) but sometimes perfect; lumina of varying size, irregularly polygonal in shape. Grain outlines indented. Dimensions. Sample ECO 5: PD 15-17 ;um (3), ED 11-20 ^^m (7), PD/ED M-1-4 (3), ET 10-1-5 i^m (7), NT 0-2-0-5 /xm (7), ST 0-5-10 jum (7), ST/NT 1-0-4-5 (7), LD (least) 0-2-0-5 /xm to (greatest) T5-2-5 /xm (7), MW 01-0-2 ;txm (7), LC 7-13 ^xrn (3), LC/PD 0-5-0-8 (3). Samples JOU 1 and JOU 4; PD 16-23 ^tm (4), ED 12-17 nxm (6). Orientation. Sample ECO 5: P 0-0%, E 42-9%, OA 57-1%. Occurrence. This study: inflatum Zone, Upper Albian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. Comments. Since only a few specimens of this type have been found from any one locality, and of these some are not well preserved, I have not attempted to erect a new species to accommodate them. Retitricolpites sarthensis differs by having a constantly perfect, rather finer-meshed microreticulum. CfB. R. georgensis differs by having a microreticulum composed of solid muri which are in continuous contact with the nexine thus giving a different LO pattern (see text-fig. 12). The microreticulum of this species is also constantly perfect. Tricolpopollenites platyreticulatus Groot, Penny and Groot, 1961 seems to differ by having a constantly perfect microreticulum which (judging from the figures) continues down to the nexine rather than being supported on bacula. T. macroreticulatus Groot and Groot, 1962 seems to differ by being rather larger, by having the colpi bordered by a margo, and an apparently constantly perfect microreticulum which is in continuous contact with the nexine. T. virgeus Groot, Penny and Groot, 1961 seems to differ in having the microreticulum made up of. 796 PALAEONTOLOGY, VOLUME 18 LO PATTERN CROSS SECTION OF EQUATORIAL EXINE TEXT-FIG. 12. LO patterns and cross-sections of equatorial exine of Retitricolpites sp. 1 {left) and CfB. R. georgensis Brenner {right). rather than supported by, bacula. Tricolpites sp. 1 of Kemp (1968) differs by having a perfect microreticulum which tends to detach from the nexine. R. marginatus van Hoeken-Klinkenberg, 1966 differs by being larger, by having a rather coarser- meshed microreticulum which is reduced along the colpus margins, and by having a thicker exine. Genus striatopollis Krutzsch, 1959 1959 Striatopollis Krutzsch, p. 142. 1962 Striopollis Rouse, p. 212. Type species. Striatopollis sarstedtensis Krutzsch, 1959, p. 143, pi. 34, figs. 1-24; text-fig. 12. CfC. Striatopollis sarstedtensis K.r\xX.z^ch., 1959 Plate 92, figs. 15-20; Plate 93, fig. 1 1959 Striatopollis sarstedtensis Krutzsch, p. 143, pi. 34, figs. 1-24; text-fig. 12. EXPLANATION OF PLATE 93 Fig. 1. CfC. Striatopollis sarstedtensis Krutzsch. Scanning electron micrograph; near equatorial aspect; ECO 5, stub JL 8; 335714; x 5000. Figs. 2-5. CfA. Liliacidites peroreticulatus {Brenner). 2-3, distal polar aspect; ECO 4, JL 184. 1 ; 32.0, 1 10.6; 2, high focus to show ornament ; 3, median focus ; x 2000. 4-5, scanning electron micrographs ; oblique aspect; ECO 5, stub JL 8; 224803; 4, x2000; 5, x 5000. Figs. 6-7. Psilatricolporites complanatius sp. nov. 6, holotype; syncolpate specimen; polar aspect; ECO 5, JL 209.1 ; 30.2, 101.6; median focus; x2000. 7, specimen with small apocolpia; polar aspect; ECO 5, JL 209.2; 38.9, 103.1 ; median focus; x2000. Eigs. 8-13. Retitricolporites insolitimorus sp. nov. 8-9, holotype; ellipsoidal specimen with two colpi (one apparently with no pore) and two pores (one apparently not associated with a colpus); equatorial aspect; ECO 5, JL 209.2; 23.7, 105.0; 8, high focus to show ornament and pore; 9, median focus; x2000. 10-1 1, ellipsoidal specimen with three pores and three colpi; polar aspect; PUN 1,JL 106.3;39.3, 103.0; 10, high focus to show ornament; 11, median focus; x2000. 12-13, tetrahedral specimen with three colpi and three pores; ECO 1,JL 179.1; 35.2; 110.4; 12, median focus; 13, low focus; x2000. Figs. 14-15. Retitricolporites ecommoyensis sp. nov. Holotype; equatorial aspect; ECO 5, JL 209.2; 32.4, 106.9; 14, high focus; 15, median focus; x2000. PLATE 93 LAING, angiosperm pollen 798 PALAEONTOLOGY, VOLUME 18 Description of five specimens from sample ECO 5. Spheroidal to prolate; triangular trilobate outline in polar view, sub-circular to elliptical in equatorial view. Three slit-like colpi, margins entire, angul- aperturate, sometimes syncolpate. Clear exine stratification into unstructured nexine and striate or striato-microreticulate sexine; sexine thicker than nexine. Muri and striae tend to parallel the polar axis, sometimes anastomosing and occasionally (especially near the poles) linked by cross pieces to form a microreticulum; S.E.M. observation shows the muri to bear small cones. Dimensions. PD 15-24 ;^m (3), ED 10-23 nm (5), PD/ED 1-4-T6 (3), ET lT-1-6 /xm (5), NT 0-2-0-6 /xm (5), ST 0-7-1 0 /xm (5), ST/NT 1 -4-4-5 (5), LD 0-3 /xm (1), MW 0-2-0-5 /xm (5), W striae 0-2-0-5 /xm (5), number of muri between each pair of colpi 7-19 (4), LC 11-17 /xm (2), LC/PD 0-7-0-8 (2), WC 0-2 /xm (1), WC/ED<0-1 (1), DC l-0/xm(l), DC/ED<0-1 (1). Orientation. P 20-0%, E 60-0%, OA 20-0%. Occurrence. This study: inflatum Zone, Upper Albian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrences: Krutzsch (1959), Lower Paleocene, G.D.R.; Groot and Groot (1962), Cenomanian, Portugal. Known range', inflatum Zone, Upper Albian to Lower Paleocene. Comments. None of the specimens described by Krutzsch (1959) seems to show the development of a polar microreticulum. StriatopoUis cf. paraneus (Norris) in Dettmann (1973) differs by having ‘ropy’ muri (under S.E.M. observation). Subturma ptychotriporines Naumova emend. Potonie, 1960 As with the tricolpates, the genera of van der Hammen (1956) are used as they are the most convenient for light microscope studies. Genus psilatricolporites van der Hammen ex van der Hammen and Wymstra, 1964 1956 Psilatricolporites van der Hammen, p. 91. 1964 Psilatricolporites van der Hammen ex van der Hammen and Wymstra, p. 236. Type species. Psilatricolporites operculatus van der Hammen and Wymstra, 1964, p. 236, pi. 1, fig. 13. Psilatricolporites complanatius sp. nov. Plate 93, figs. 6-7 Description of nine specimens from samples ECO 5 and ECO 7. Strongly oblate; triangular or rounded triangular, usually quite shallowly trilobate outline in polar view. Three distinct long gaping (less commonly more slit-like) colpi, margins entire but usually faint, angul-aperturate, sometimes syncolpate; single equatorial pore in each colpus, often rather unclear. No clear exine stratification. Psilate. Holotype. Sample ECO 5, slide JL 209.1; 30.2, 101.6. Plate 93, fig. 6. Argiles noires, Ecommoy; rhoto- magense Zone, Middle Cenomanian. Dimensions. PD c. 1 - 5 /xm (1), ED 13-15 /xm (9), PD/ED c. 0-1 (1), ET 0-4-0-8 /xm (9), WC 1-5 (2-7) 6-0 /xm (9), WC/ED 0-1 (0-2) 0-4 (9), DC 0-0 (0-6) 1-5 /xm (9), DC/ED 0-0 (< 0-1) 0-1 (9), pore diameter 1-0 (2-4) 4-5 /xm (8). Orientation. P 100-0%. Occurrence. This study: carcitanensis Horizon, mantelli Zone, Lower Cenomanian to costatus Horizon, rhotomagense Zone, Middle Cenomanian. Comments. Tricolporopollenites orhiculatiisGroo\.,Ptnv\y dndGxooi, 1961 differs from this species by being slightly prolate. Tricolporopollenites sp. S. Cl. 215 of Jardine LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 799 and Magloire (1965) has a more sub-spherical shape. TricoIporopoUenites sp. S. Cl. 141 of Jardine and Magloire (1965) is larger, has pores with annuli and perhaps has shorter colpi. T. aliquantulus Hedlund, 1966 has a more prolate shape. TricoIporo- poUenites sp. B of Brenner (1968) has much shorter colpi. Nyssapollenites albertensis Singh, 1971 differs by having rim-like thickenings around the pores, and by having much shorter colpi. Genus retitricolporites van der Hammen ex van der Hammen and Wymstra, 1964 1956 Retitricolporites van der Hammen, p. 93. 1964 Retitricolporites van der Hammen ex van der Hammen and Wymstra, p. 235. Type species. Retitricolporites guianaensis van der Hammen and Wymstra, 1964, p. 235, pi. 3, figs. 1-2. Retitricolporites ecommoyensis sp. nov. Plate 93, figs. 14-15 Description of nine specimens from sample ECO 5. Prolate spheroidal to prolate; sub-circular to elliptical in equatorial view. Three distinct narrow slit-like colpi, margins entire and with nexinal thickening; single distinct equatorial pore in each colpus; many specimens have the colpi buckled out at the equator (i.e. they are tricolporoidate in the sense of Doyle 1969). Clear exine stratification into unstructured nexine and microreticulate sexine (sexine occasionally psilate at the poles); sexine generally thicker than nexine (except at colpus margins and sometimes at the poles), occasionally exine (particularly nexine) thickens at the poles. Microreticulum perfect; lumina of about uniform size and equidimensionally shaped. Grain outlines finely indented to smooth. Holotype. Sample ECO 5, slide JL 209.2; 32.4, 106.9. Plate 93, figs. 14-15. Argiles noires, Ecommoy; rliotomagense Zone, Middle Cenomanian. Dimensions. PD 10-16 /xm (8), ED 6-13 /um (9), PD/ED lT-1-7 (8), equatorial ET 0-5- 1-2 ;um (9), equatorial NT OT-0-4 nm (9), equatorial ST 0-4-0-8 /xm (9), equatorial ST/NT 1-5-4 0 (9), LD <0T-0-3 jum (9), MW <0T-0-2 ij.m (9), LC 7 (9-4) 13 ;um (8), LC/PD 0-6 (0-7) 0-8 (8), thickness of colpus margins 0-5- 10 jixm (9), pore diameter 0-2 (0-7) 1-2 jum (9). Orientation. P 0-0%, E 88-9%, OA 1 11%. Occurrence. This study: inflatum Zone, Upper Albian to jukes-brownei Horizon, rliotomagense Zone, Middle Cenomanian. Comments. TricoIporopoUenites inaequalis Groot, Penny and Groot, 1961 is a larger form which seems to have unthickened colpus margins. TricoIporopoUenites sp. S. Cl. 428 of Jardine and Magloire (1965) differs by its larger size and by the fact that it often occurs in tetrads. Tricolporoidites minimus Pacltova, 1971 has a rather thicker exine and a granulate nexine. T. subtilis Pacltova, 1971 differs in having a chagrenate exine. Retitricolporites insolitimorus sp. nov. Plate 93, figs. 8-13 Description of thirty-nine specimens from samples ECO 1, ECO 2, ECO 4, ECO 5, ECO 6, and ECO 7. Variable in shape, either ellipsoidal (oblate spheroidal to sub-prolate) or a more tetrahedral shape ; ellipsoidal grains with triangular quite deeply trilobate outline in polar view, elliptical in equatorial view; tetrahedral grains with a more triangular outline. Tricolporate development often aberrant with up to three colpi which may or may not have pores, or up to three pores, some of which may not be associated with colpi (the 800 PALAEONTOLOGY, VOLUME 18 apparent lack of a full complement of pores and/or colpi in some specimens may simply be caused by the aspect of these specimens). Ellipsoidal grains fossaperturate. Pores sometimes elongate parallel to the polar axis but more commonly approximately circular; colpi relatively short and deep. Clear exine stratification into unstructured nexine and microreticulate sexine; nexine most commonly thicker than sexine, less commonly nexine and sexine of about equal thickness, only rarely sexine thicker than nexine. Micro- reticulum perfect; lumina either of about uniform size and regularly polygonal shape, or of more varying size and irregularly polygonal shape. Grain outlines finely indented to almost smooth. Holotype. Sample ECO 5, slide JL 209.2; 23.7, 105.0. Plate 93, figs. 8-9. Argiles noires, Ecommoy; rhoto- magense Zone, Middle Cenomanian. Dimensions. Type material: PD 13 (17-8) 22 /im (15), ED 9 (15-7) 22 ;um (39) s3-7 fj.m, PD/ED 0-8 (IT) 1 -2 ( 1 5), ET 1 -0 ( 1 -5) 2-5 ^m (39), NT 04 (0-9) 1 -5 ^^m (39), ST 0 4 (0-6) 1 0 ,xm (39), ST/NT 0-3 (0-7) 2-3 (39), ED (when uniform) OT (0-2) 04 fxm (26), LD (when varying) (least) OT (0-2) 0-2 ^m to (greatest) 0-3 (0-9) 2-0 ^m (13), MW OT (0-2) 0-3 i^m (39), LC 3 (10-0) 15 ;um (15), LC/PD 0-2 (0-5) 0-8 (15), WC 2-0-5 0 fxm (2), WC/ED 01-0-3 (2), DC 1-5-3 0 /xm (2), DC/ED 01-0-2 (2), pore diameter (including W of elongate pores) 0-8 (2-3) 60 fxm (39), L of elongate pores 30-7-5 jum (6). Other material: Sample JOU 15, PD 15- 19 ^m (5), ED 12-17 ^m (5). Orientation. Type material: P 5-1%, E 410%, OA 53-8%. Occurrence. This study: inflatiim Zone, Upper Albian to jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Comments. See comments for Retitricolpites promiscuus for distinction from this species. Tricolporopollenites microreticulatus Thomson and Pflug, 1953 differs by being on average rather larger and in not showing an aberrant tricolporate development and tetrahedral condition. T. inaequalis Groot, Penny and Groot, 1961 differs by having the nexine thinner than the sexine and in not showing an aberrant tricolporate development and tetrahedral condition. T. subobscurus Groot and Penny, 1960, Retitricolporites crassicostatus van der Hammen and Wymstra, 1964,. and Tricol- poroidites bohemicus Pacltova, 1971 all differ in not showing an aberrant tricolporate development and tetrahedral condition. Turma poroses Naumova emend. Potonie, 1960 Subturma triporines Naumova emend. Potonie 1960 Genus complexiopollis Krutzsch emend. Goczan, Groot, Krutzsch and Pacltova, 1967 1959 Cowp/ex/opo//;5 Krutzsch, p. 134. 1967 Complexiopollis Krutzsch emend. Goczan et al., p. 453. Type species. Complexiopollis praeatumescens Krutzsch, 1959, p. 135, pi. 31, figs. 39-54; text-fig. 6. CfB. Complexiopollis subtilis (Krutzsch) Goczan, Groot, Krutzsch and Pacltova, 1967 Plate 94, figs. 1-3; text-fig. 13 1959 LatipoUis subtilis Krutzsch, p. 129, pi. 31, figs. 1-13; text-fig. 1. 1967 Complexiopollis subtilis (Krutzsch) Goczan et a!., p. 445. Description of three specimens from sample WOR 1. Sub-oblate; elliptical in equatorial view, strongly LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 801 TEXT-FIG. 13. Pore structure of CfB. text-fig. 14. Pore structure of Triporopollenites Complexiopollis subtilis (Krutzsch). curtisi sp. nov. three-rayed shape in polar view. Three pores, often unclear, seemingly with faint vestibula (see text-fig. 13), angul-aperturate. Exine stratified into unstructured nexine and a sexine with a rather rough surface; nexine and sexine of about equal thickness. Grain outlines rather irregular. Dimensions. PD 13-14 (2), ED 15-17 /xm (3), PD/ED 0-8-0-9 (2), ET 10- 1-2 fxm (3), NT 0-5-0-6 fivn (3), ST 0-5-0-6 /xm (3), ST/NT 10 (3), exopore diameter 0-5- 1-2 /xm (3), exopore diameter/ED 0 03-0 07 (3), endopore diameter 0-5- 1-2 /xm (3), endopore diameter/ED 0 03-0 07 (3), vestibulum diameter L5-3 0 /xm (3), vestibulum diameter/ED 0T0-0T7 (3), D of pores 2 0-2T /xm (3), D of pores/ED 0T17-0T33 (3). Orientation. P 0-0%, E 66-7%, OA 33-3%. Occurrence. This study : jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Other occurrence : Krutzsch ( 1959), ?Upper Cenomanian and Turonian, Central Europe. Known range: jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian to Turonian. Comments. Though the pore structure of the specimens described above is not clear, it does not appear to be as complicated as that described by Krutzsch (1959). Genus triporopollenites Thomson and Pflug, 1953 1953 Triporopollenites Thomson and Pflug, p. 82. Type species. Triporopollenites coryloides Thomson and Pflug, 1953, p. 84, pi. 9, figs. 20-24. Triporopollenites curtisi sp. nov. Plate 94, figs. 4-7; text-fig. 14 Description of six speeimens from sample WOR 1. Oblate: three-rayed or concave-sided triangular outline in polar view. Three, usually distinct, simple pores; exine sometimes a little thickened around the pores, and often a little constricted behind the endopore such that an arrow-head shaped or triangular cavity appears to be present behind the endopore (see text-fig. 14), angul-aperturate. Exine stratified into un- structured nexine and a sexine with a rather rough surface; nexine most commonly thinner than sexine, occasionally nexine and sexine of about equal thickness; exine stratification often rather unclear. Grain outlines rather irregular. Holotype. Sample WOR 1, slide JL 236.1; 41.8, 100.5. Plate 94, figs. 4-5. Glauconitic Marl, Worbarrow Bay; probable jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Dimensions. ED 14-20 /xm (6), ET 1 0- 1 -2 /xm (6), NT 0-2-0-6 /xm (6), ST 0-6-0-8 /xm (6), ST/NT 1 0- 1 -4 (6), exopore diameter 0-2 (0-7) IT /xm (6), exopore diameter/ED 0 01 (0 03) 0 07 (6), endopore diameter 0-2 (0-7) 10 /xm (6), endopore diameter/ED 0 01 (0-03) 0-07 (6), D of pore 10 (1-6) 2 0 /xm (6), D of pore/ED 0 052 (0 084) OTll (6). 802 PALAEONTOLOGY, VOLUME 18 Orientation. P 50 0%, OA 50 0%. Occurrence. This study: jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Comments. ComplexiopoUis praeatumescens Krutzsch, 1959 differs in having more complex pores, more exine layers, a finely punctate to reticulate sculpture, and by being larger. Latipollis vulgaris Groot and Groot, 1962 has a more circular cavity behind the endopore (see text-fig. 2 of Groot and Groot). TuronipoUis helmigii van Amerom, 1965 differs in having small atria and a granulate to reticulate sculpture. Conclavipollis densilatus Kimyai, 1 966 is a larger form with a thicker exine and perhaps wider pores. Triporopollenites pseudocanalis Paden Phillips and Felix, 1971 is a larger form which has annuli around the pores and a more convex- (or at least not so strongly concave-) sided shape with protruding apices. Triporopollenites worbarrowensis sp. nov. Plate 94, figs. 8-1 1 Description of twelve specimens from sample WOR 1. Oblate; straight or slightly convex-sided triangular outline in polar view, equatorial apices slightly protruding. Three, usually distinct, simple pores; when damaged the pores occasionally have the appearance of short slightly gaping colpi with a V-shaped cross- section, angul-aperturate. Exine stratified into unstructured nexine and a sexine with a smooth or slightly rough surface; sexine slightly thicker than, or of equal thickness to, nexine (occasionally nexine slightly thicker than sexine) ; exine stratification occasionally unclear. Grain outlines smooth or slightly irregular. Holotype. Sample WOR 1, slide JL 236.1 ; 26.0, 096.4. Plate 94, figs. 8-9. Glauconitic Marl, Worbarrow Bay; probable jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Dimensions. ED 16(18-4) 23 p.m (12), ET 0-7 (1-0) 1-3 ^m (12), NT 0-3 (0-4) 0-6 (12), ST 0-4 (0-6) 1-0 ^lm (12), ST/NT 0-7 (1-5) 3-3 (12), exopore diameter 0-5 (1-2) 2-2 ;um (11), exopore diameter/ED 0-02 (0-05) 0-10 (11), endopore diameter 0-5 (10) 2 0 /um (11), endopore diameter/ED 0 02 (0 04) 0 08 (11), D of pore 1 -0 ( 1 -3) 2 0 ^m ( 1 1 ), D of pore/ED 0-052 (0-068) 0-111 (11). Orientation. P 50-0%, OA 50 0%. Occurrence. This study: jukes-brownei Horizon, rhotomagense Zone, Middle Cenomanian. Comments. Triorites africanensis Jardine and Magloire, 1965 differs in being rather larger. EXPLANATION OF PLATE 94 All figures x 2000. Figs. 1-3. CfB. ComplexiopoUis subtilis (Krutzsch). 1-2, equatorial aspect; WOR 1, JL 236.1 ; 54.0, 095.9; 1, median focus; 2, low focus. 3, oblique aspect; WOR 1, JL 236.2; 33.1, 098.2; median focus. Figs. 4-7. Triporopollenites curtisi sp. nov. 4-5, holotype; polar aspect; WOR 1, JL 236.1; 41.8; 100.5; 4, high focus; 5, median focus. 6-7, oblique aspect; WOR 1, JL 236.2; 51.6, 106.5; 6, high focus; 7, median focus. Figs. 8-11. Triporopollenites worbarrowensis sp. nov. 8-9, holotype; polar aspect; WOR 1, JL 236.1 ; 26.0, 096.4; 8, high focus; 9, median focus. 10-1 1, oblique aspect; WOR 1, JL 238.1 ; 27.2, 1 1 1.2; 10, median focus; 1 1, low focus. Figs. 12-14. CfB. Asteropollis asteroides Hedlund and Norris. 12-13, proximal polar aspect; ECO 5, JL 209.3; 32.6, 103.1; 12, high focus to show ornament; 13, median focus to show sulcus. 14, equatorial aspect; ECO 5, JL 209.3; 32.6, 101.9; high focus to show ornament. PLATE 94 LAING, angiosperm pollen 804 PALAEONTOLOGY, VOLUME 18 SEQUENCE OF POLLEN ASSEMBLAGES Using the results of this study and the results of earlier workers (Couper 1958 ; Hughes 1958; Kemp 1968, 1970), it is possible to suggest a sequence of angiosperm pollen assemblages. Unfortunately, the data is as yet insufficient for the establishment of a zonal scheme, but I hope that this sequence will help others to make ‘rule-of-thumb’ stratigraphic assessments on material coming from this area. In another paper (Laing 1975), I have described a scheme which is, I hope, applicable over a wider area (perhaps over Europe and North America). The approximate level of the earliest occurrence of each assemblage has been referred to the ammonite zonations of Spath (1923-1943) for the Albian and of Kennedy (1969) for the Cenomanian. The sequence of pollen assemblages and their approximate correlation with the ammonite zones are outlined on Table 2. Liliacidites hughesii Assemblage. Base. Within the Upper Barremian. Diagnostic features. This assemblage is characterized by having reticulate and/or clavate monosulcate forms as the only angiospermous pollen present. In Britain and France there is only one angiospermous species at present known from this assemblage and that is Liliacidites (al. ClavatipoUenites) hughesii (Couper 1958 emend. Kemp 1968) comb. nov. The base of the occurrence of this assemblage is thus defined by the first appearance of this species which occurs in the Upper Bar- remian (Hughes 1958). Liliacidites rotundas- Retitricolpites amplifissus Assemblage Base. Within the Leymeriella tar defur cat a Zone (Lower Albian). Diagnostic features. This assemblage is characterized by the presence of monosulcate and tricolpate forms; tricolporate forms may also be present but triporate forms are absent. Although Retitricolpites sarthensis may be present it is never the dominant angiosperm species (neither, for that matter, is it present in any abundance). In this area, the base of the occurrence of this assemblage may be defined by the first appear- ance of Liliacidites rotundas and R. amplifissus, which according to Kemp (1968, 1970) is in her sample F270. This is probably from the tardefurcata Zone of the Lower Albian. At this level, the only angiospermous species present are these two species and L. hughesii. I have only studied the Upper Albian and Lower Cenomanian part of the time interval represented by this assemblage, and the evidence both from my work and that of Kemp (1968) is that L. rotundas, R. amplifissus, R. promiscuus, Retitricolpites sp. 1 and/or Tricolpites albiensisK.Qmp, 1968 are the dominant angiospermous species in the Upper Albian, and that Retitricolporites insolitimorus and/or Retitricolpites amplifissus may be the most abundant angiosperm species in the Lower Cenomanian. The time interval occupied by this assemblage is important in that it is the period during which reticulate, striate and psilate tricolpate, reticulate tri- to hexachotomo- sulcate (e.g. Asteropollis), and reticulate and psilate tricolporate forms first appear (for a fuller discussion of this see Laing 1975). LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 805 TABLE 2. Sequence of angiosperm pollen assemblages and their approximate correlation with the ammonite zonation of the mid-Cretaceous of southern Britain and northern France. (Ammonite zonation after Spath 1923-1943; and Kennedy 1969.) STAGE AMMONITE ZONE ASSEMBLAGE OR FAUNAL HORIZON POLLEN ASSEMBLAGE Acanthoceras jukes-brownei T riporopolleni tes worbarrowensis MIDDLE CENOMANIAN Acanthoceras rhotomagense Turrilites acutus 9 Retitricolpites sarthensis Turrilites costatus (uncharacterized) 9 LOWER CENOMANIAN Mantelliceras mantelli Mantelliceras gr. dixoni Mantelliceras saxbii Hypoturrilites carcitanensis UPPER Stoliczkaia dispar Liliacidites ALBIAN Mortoniceras inflatum rotundus- Retitricolpites amplifissus MIDDLE Euhoplites lautus ALBIAN Hoplites dentatus LOWER Douvilleiceras mammillatum ALBIAN Leymeriella tardefurcata 9 APTIAN Liliacidites hughesii BARREMIAN 9 806 PALAEONTOLOGY, VOLUME 18 Retitricolpites sarthensis Assemblage Base. Between the Hypoturrilites carcitanensis Assemblage horizon of the Man- telliceras mantelli Zone (Lower Cenomanian) and the Turrilites costatus Assemblage horizon of the Acanthoceras rhotomagense Zone (Middle Cenomanian). Diagnostic features. This assemblage is characterized by the presence of either Retitricolpites sarthensis or R. promiscuus as the most abundant angiosperm species. When R. promiscuus is the most abundant species, then R. sarthensis is the next most abundant. R. sarthensis is always more abundant than R. amplifissus. Triporate grains are absent. R. crassitransennus makes its first appearance during the time interval represented by this assemblage and, apart from the possibility of the presence of this species, and the relative abundance of R. sarthensis, this assemblage is quite like the later (i.e. Lower Cenomanian) part of the L. rotundus-R. amplifissus Assemblage. This assemblage occurs both in the base of the Glauconitic Marl at Punfield Cove and in the Argiles noires of Ecommoy. Triporopollenites worbarrowensis Assemblage Base. Between the Turrilites costatus and Acanthoceras jukes-brownei Assemblage horizons of the A. rhotomagense Zone (Middle Cenomanian). Diagnostic features. The base of the occurrence of this assemblage is defined by the first appearance of triporate pollen. Three triporate species occur in the material which I have examined, Triporopollenites worbarrowensis, T. curtisi, and Com- plexiopollis subtilis, the first mentioned being the most abundant angiosperm species present. This assemblage occurs in the base of the Glauconitic Marl at Worbarrow Bay. Although it would also be expected to occur in the base of the Glauconitic Marl at Lulworth Cove, I have found no triporate grains in this material. Indeed, this material is peculiar in being generally depleted in angiosperm pollen, such pollen being about six times as abundant (by comparison with the total spore/pollen content) in the material from Worbarrow Bay as it is in the material from Lulworth Cove. Acknowledgements. This research was carried out whilst I was in receipt of a N.E.R.C. training award. I wish to thank Mr. N. F. Hughes for his encouragement and advice, Messrs. D. Marriage and D. Bursill for their assistance with the photographic work, and Mr. R. S. Curtis for his assistance in the preparation of certain samples. REFERENCES AGASiE, J. M. 1969. Late Cretaceous palynomorphs from northeastern Arizona. Micropaleontology, 15, 15-30, pis. 1-4. AMEROM, H. w. j. VAN. 1965. Upper Cretaceous pollen and spores assemblages from the so-called ‘Wealden’ of the Province of Leon (Northern Spain). Pollen Spores, 1, 93-133. ARKELL, w. J. 1947. The geology of the country around Weymouth, Swanage, Corfe and Lulworth. Mem. geol. Surv. U.K. 386 pp. LAING: MID-CRETACEOUS ANGIOSPERM POLLEN 807 AZEMA,c., DURAND, s. and Mfeus, J. 1972. DesmiosporesduCenomanien moyen. Paleobiologie continentale, 3 (4), 54 pp., 27 pis. and TERS, M. 1971. Etude palynologique preliminaire du gisement cenomanien de la Bironniere, Vendee (France). Rev. Palaeobotan. Palynol. II, 267-282, pis. 1-3. BRENNER, G. J. 1963. The spores and pollen of the Potomac Group of Maryland. Bull. Md. Dep. Geol. 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Angiosperm and gymnosperm pollen from the Upper Albian to Middle Cenomanian of southern England and northern France. Unpublished Ph.D. thesis, Cambridge University. 1974. A specimen location technique for SEM strew mounts. Palaeontology, 17, 435-436. 1975. The stratigraphic setting of early angiosperm pollen. Linn. Soc. Symp. Ser. 1 (in press). MANUM, s. 1962. Studies in the Tertiary flora of Spitsbergen, with notes on Tertiary floras of Ellesmere Island, Greenland and Iceland. (A palynological investigation.) Skr. norsk Polarinst. 125, 133 pp., 21 pis. NORRIS, G. 1967. Spores and pollen from the Lower Colorado Group (Albian-?Cenomanian) of Central Alberta. Palaeontographica, B 120, 72-115, pis. 10-18. PACLTOVA, B. 1971. Palynological study of Angiospermae from the Peruc Formation (?Albian-Lower Cenomanian) of Bohemia. Sbornik geol. ved. P. 13, 105-141, pis. 1-16. PADEN PHILLIPS, p. and FELIX, c. J. 1971. A study of Lower and Middle Cretaceous spores and pollen from the southeastern United States. II. Pollen. Pollen Spores, 13, 447-473. PIERCE, R. L. 1961. Lower Upper Cretaceous plant microfossils from Minnesota. Bull. Minn. geol. Surv. 42, 86 pp., 3 pis. PLAYFORD, G. 1971. Palynology of Lower Cretaceous (Swan River) strata of Saskatchewan and Manitoba. Palaeontology, 14, 533-565, pis. 103-107. POTONiE, R. 1931 . Zur Mikroskopie der Braunkohlen Tertiare Sporen und Blutenstaubformen. Braunkohle, 27, 554-556. 1960. Synopsis der Gattungen der Sporae dispersae. 3en. Teil; Nachtrage Sporites, Forsetzung Pollenites. Mit Generalregister zu Teil 1-3. Beih. geol. Jb. 39, 189 pp., 9 pis. ROUSE, G. E. 1962. Plant microfossils from the Burrard Formation of western British Columbia. Micro- paleontology, 8, 187-218, pis. 1-5. SINGH, c. 1971. Lower Cretaceous microfloras of the Peace River area, northwestern Alberta. Bull. Res. Coun. Alberta, 28, 542 pp., 80 pis. SPATH, L. F. 1923-1943. A monograph of the Ammonoidea of the Gault. Palaeontogr. Soc. [Monogr.], 2 vols., 787 pp. TAKAHASHi, K. 1961. Pollen und Sporen des westjapanischen Altertertiars und Miozans; (Teil 2). Mem. Fac. Sci. Kyushu Univ., Ser. D (Geol.), 11, 279-345, pis. 13-27. THOMSON, p. w. and pflug, h. 1953. Pollen und Sporen des mitteleuropaischen Tertiars. Palaeontographica, B94, 1-138, pis. 1-15. Original typescript received 18 January 1975 Revised typescript received 28 April 1975 J. F. LAING Department of Geology Sedgwick Museum Downing Street Cambridge RADNORIA, A NEW SILURIAN PROETACEAN TRILOBITE, AND THE ORIGINS OF THE BRACHYMETOPIDAE by R. M. OWENS and a. t. thomas Abstract. The new trilobite genus Radnoria is proposed to include the type, R. syrphetodes sp. nov., and two other species, R. triquetra sp. nov. and R. humUlima (Barrande, 1852), from the Silurian of Britain and Czechoslovakia. Its morphology includes features typical of both the Brachymetopidae and Warburgellinae, suggesting a phyletic link between the two groups. The composition of the Brachymetopidae is discussed, and new family and subfamily diagnoses are given. Recent collecting from the Dolyhir Limestone (Silurian, Wenlock Series) in the Old Radnor district, Powys (Radnorshire), the Much Wenlock Limestone Formation of Wren’s Nest Hill, Dudley, West Midlands, and from a limestone of Wenlock age near Llandeilo, Dyfed (Carmarthenshire) has furnished large numbers of dissociated exoskeletal parts of two undescribed proetacean trilobite species, here placed in a new genus. Cyphaspis humillima Barrande, 1 852 from the late Wenlock of the Prague district, Czechoslovakia also belongs to the same genus. The significance of this new genus lies in its similarities both to members of the proetid subfamily Warburgellinae and to the family Brachymetopidae, and in the consequent implications for the origins of the latter. Terminology. Terms used in the descriptions are those dehned by Harrington et al. (in Moore 1959, pp. 0117-0126) and Owens (1973, pp. 3, 5; text-fig. 1a, p. 4). Repositories. The following abbreviations are used herein: GSM— The Geological Museum, Institute of Geological Sciences, London; NMW— National Museum of Wales, Cardiff; NMP— National Museum, Prague. SYSTEMATIC PALAEONTOLOGY Family brachymetopidae Prantl and Pfibyl, 1951 Diagnosis. The following diagnosis is based on that of Whittington (1960, p. 407), modified to include the Warburgellinae and other slight amendments. Cephalon with preglabellar field; tropidium or tropidial ridges may be present; glabella narrows forwards, commonly with well defined Ip lobe; 2p and 3p furrows may be present; palpebral lobe far back and close to glabella; anterior branches of facial sutures divergent; connective sutures diverge backwards; thorax of 8-10 segments; no preannulus; pygidium relatively large; axis with 76-14 rings, pleural ribs with flat- topped profile, or with posterior band elevated above anterior; pygidial margin entire or with short spines; external surface smooth, granular, tuberculate, rugulose, pitted, or spinose, or combination of these. [Palaeontology, Vol. 18. Part 4, 1975, pp. 809-822, pis. 95-96.] K 810 PALAEONTOLOGY, VOLUME 18 Stratigraphical range. Silurian (Llandovery) to uppermost Carboniferous, possibly to Permian. Subfamily warburgellinae Owens, 1973 [= V^arburgellinae Yolkin, 1974] Diagnosis. Ip furrow deep; tropidium or tropidial ridges may be present; occipital ring with lateral lobes; thorax of 8-10 segments; pygidium with narrow axis with ?6-14 rings; pleural areas with 15-1 pairs of ribs with flat-topped profile; pygidial border may be present ; sculpture granular or rugulose, or exoskeleton smooth. Genera and subgenera. Warburgella {Warburgella) Reed, 1931 ; W. (Tetinia) Chlupac, 1971 ; Prantlia Pfibyl, 1946; Tropidocare Chlupac, 1971 ; IKoneprusites Pfibyl, 1964. Stratigraphical range. Silurian (Llandovery) to Devonian (Gedinnian), possibly to Middle Devonian. Yolkin (1974, p. 64) included Warburgella, AstroproetusBegg, 1939, Tetinia, Cyphoproetus Kegel, 1927, and Paleodechenella Maximova, 1970 in the Warburgel- linae. Of these genera, Owens (1973, p. 8) placed Cyphoproetus in the Proetinae and Astroproetus in the Tropidocoryphinae (ibid., p. 40), and reasons for doing so are discussed therein. Without having seen original material of Paleodechenella, we cannot comment on its subfamilial affinities. Yolkin (1974, p. 64) referred the Warburgellinae to the Dechenellidae. Members of this family (which we consider to be a proetid subfamily) do show a broad resemblance to warburgellines, but possess a preannulus, and the pygidial pleural rib structure is like that of the Proetinae. On the basis of the thoracic and pygidial differences, and also because dechenellines are almost certainly phyletically linked with proetines (Owens 1973, p. 84), we consider that their general similarity to warburgellines is due to homoeomorphy. Subfamily brachymetopinae Prantl and Pfibyl, 1951 Diagnosis. Preglabellar field broad, concave or weakly convex in longitudinal section ; Ip lobe isolated except in Brachymetopus', 2p and 3p commonly absent or ill defined; anterior branches of facial sutures widely divergent (ankylosed in Brachymetopus) ', tropidium absent; occipital ring without lateral lobes; rostral plate large, may extend as far back as genal angle; thorax of nine segments; pygidial axis with 10-13 axial rings; pleural ribs commonly with posterior band elevated above anterior, but EXPLANATION OF PLATE 95 Figs. 1-6. Radnoria syrphetodes gen. et sp. nov. \a-e. Limestone of probable Wenlock age, old quarry opposite Ty-newydd Farm, 1-3 km at 127° from Llanarthney church, Dyfed (SN 5442 1951): GSM 103744, cranidium, anterolateral oblique, dorsal, posterolateral oblique, anterior, and left lateral views, X 8. 2-6, Wenlock Series, Dolyhir Limestone, disused quarry 475 m W. of Dolyhir Bridge, Old Radnor, Powys (SO 2409 5812): 2a-h, NMW 74.30G.12a, left free cheek, dorsal and left lateral views, x8. 3, NMW 74.30G.62b, right free cheek, ventral view, x8. 4, NMW 74.30G.15, left free cheek, oblique dorsal view, x 8. Note course of connective suture. 5, NMW 72.18G.177, holotype cranidium, dorsal view, x8. 6a~h, NMW 74.30G.23, pygidium and thoracic segment, left lateral and dorsal views, x8. PLATE 95 OWENS and THOMAS, Radnoria 812 PALAEONTOLOGY, VOLUME 18 rarely with flat-topped profile; pygidial margin entire or with short spines; external surface tuberculate, pitted, spinose, or smooth. Stratigraphical range. Silurian (Wenlock Series) to Carboniferous, possibly to Permian. Genera. Australosutura Campbell and Goldring, 1960; Brachymetopus M’Coy, 1847; Cordania Clarke, 1892; Mystrocephala Whittington, 1960; Proetides Walter, 1924; Radnoria gen. nov. ; Tscliernyshewiella Toll, 1899; ICheiropyge Diener, 1897. Discussion. Brachymetopus, Cordania, Mystrocephala and Australosutura are well known and there is no doubt as to their membership of the family. We agree with Hessler (1962, p. 812) that Proetides is a brachymetopid. No good illustrations are available for Tscliernyshewiella, but we accept Whittington’s (1960, p. 407) observa- tions on its close similarity to Cordania, and include it in the family. We consider that Piltonia Goldring, 1955 should be excluded; both Hahn (1964, p. 362) and Osmolska (1970, pp. 12, 13) considered it to be closely allied to ‘phillipsiid’ genera, in particular to Eocyphinium Reed, 1942, a view supported by Owens’s unpublished work. Cheiro- pyge, from the Permian of the Himalayas, was excluded from the family by Whitting- ton (1960, p. 408). His reasons for doing so were not discussed, except to state that the pygidium on which the genus is based did not, in his view, resemble those of other brachymetopids. Schmidt {in Moore 1959, p. 0408) questionably included Cheiropyge in the Brachymetopidae, and although existing illustrations (Diener 1897, pi. 1, fig. 2a-c; Moore 1959, fig. 310.4, p. 0407) are poor, they do show that the pygidium resembles spinose Brachymetopus pygidia. Until this genus can be revised, we follow Schmidt, and provisionally assign it to the Brachymetopidae. Namuropyge R. and E. Richter, 1939 was included with question in the Brachymetopidae by Schmidt {in Moore 1959, p. 0408), but we agree with Whittington (1960, p. 408) that it should be excluded; we also agree with Schmidt {in Moore 1959, p. 0408, footnote) and Whittington (1960, p. 408) that Panarchaeogonus Opik, 1937 is not a brachymetopid, and Owens (1974, p. 687) and Fortey and Owens (1975, p. 231) considered it to be an otarionid. Genus radnoria gen. nov. Derivation of name. From Old Radnor, Powys, from where most of the material of the type species originates. Type species. Radnoria syrphetodes sp. nov. Other species. R. triquetra sp. nov., R. humiltima (Barrande, 1852). Diagnosis. Preglabellar field concave or flat in longitudinal section; shallow depres- sion traverses its posterior part and inner part of fixed and free cheeks, running parallel to margin; anterior branch of facial suture diverges at 60-70° from an exsagittal line through y; pygidial axis with 10-13 rings, pleural areas with 6-7 pairs of ribs; latter with flat-topped profile or with posterior pleural band elevated above anterior; dorsal surface smooth or with fine pits and sporadic granules. OWENS AND THOMAS: RADNORIA 813 Radnor ia syrphetodes sp. nov. Plate 95, figs. 1-6; Plate 96, figs. 1,2; text-fig. 1 V. 1972 Warburgella cf. stokesii (Murchison); Bassett, p. 31. V. 1973 Warburgella (Warburgella) stokesii (Murchison); Owens, p. 67 pars, [reference only to single specimen from Ty-newydd Farm]. V. 1974 IPrantlia sp.; Bassett, p. 759. TEXT-FIG. 1. Reconstruction of Radnoria syrphetodes gen. et sp. nov. Topmost illustration represents the ventral aspect of the anterior part of the cephalon to show the inferred shape of the rostral plate (blank area). All x 1 1 approx. 814 PALAEONTOLOGY, VOLUME 18 Derivation of name. Greek syrphetodes, ]\imb\ed together; reference to the mosaic of characters of various genera seen in Radnoria. Holotype. Cranidium NMW 72.18G.177, from Wenlock Series, Dolyhir Limestone (lower Wenlock); disused quarry 475 m W. of Dolyhir Bridge, Old Radnor, Powys (SO 2409 5812) (Quarry ‘D’ of Garwood and Goodyear 1918, pi. 7). Paratvpes. Cranidia NMW 72.18G.178, 74.30G.4a-b, c, lOb-c, 13c-d, 18-19, 68, 73a, free cheeks NMW 74.30G.8-9, 10a, 11-13, 15-17, 62b, pygidia NMW 72.18G.179-180, 74.30G.3e-f, lOd, 14, 20-61, 62c-d, 67, 69-72, 73b, 74 from the type locality; pygidium NMW 74.30G.77 from shale band in Dolyhir Lime- stone, type locality; cranidia GSM 103744, NMW 74.30G.93a-b, pygidia GSM DEX2927, NMW 74. 30G. 94-98 from limestone of probable lower-middle Wenlock age, old quarry opposite Ty-newydd Farm, 1-3 km at 127° from Llanarthney church, Dyfed (SN 5442 1951). An ill-preserved cranidium, NMW 74.30G.99 from the Much Wenlock Limestone Formation (lundgreni Zone) of Wren’s Nest Hill, Dudley, may also belong to this species. Diagnosis. Glabella with weak forward taper; Ip furrows broad and shallow, Ip lobes reduced; pygidium with 10-13 axial rings and six pairs of pleural ribs with flat-topped profile. Description. Cranidium moderately vaulted, palpebral width about two-thirds sagittal length. Glabella about as wide as long, defined laterally by deep axial furrows; these shallow and narrow at Ip lobes, and at anterolateral corner of glabella run into shallower preglabellar furrow, which is shallowest at sagittal line. From its posterolateral corners, glabella tapers gently forwards to bluntly rounded frontal lobe. In lateral profile it is gently convex, with the posterior end elevated well above the occipital ring (PI. 95, fig. le). In transverse section it is strongly convex (PI. 95, fig. Id). Ip furrow runs into axial furrow opposite anterior part of palpebral lobe, and is directed inwards and backwards at about 25° to an exsagittal line, with steep adaxial slope and shallow abaxial slope. Ip furrow defines partially isolated, reduced, roughly triangular Ip lobe, which is fused with remainder of glabella at its inner end. 2p furrow a smooth area, not impressed, meeting axial furrow about two-thirds of way along glabella from its posterior end, directed backwards at about same angle as Ip. 3p small, not reaching axial furrow, placed a short distance in front of 2p, directed backwards at about 40°. Occipital furrow rather broad and shallow in its median section, deepening markedly behind Ip lobes, and arched forwards very weakly sagittally. Occipital ring about as wide (trans.) as base of glabella, its sagittal length about one-third that of preglabellar area. No lateral lobes; presence or absence of occipital node unknown. Preglabellar field about half sagittal length of glabella, weakly concave in longitudinal section, anteriorly merges almost imperceptibly into gently upturned, weakly convex anterior border, which is between one-third and one-half the sagittal length of preglabellar field. Preglabellar field traversed on its posterior portion by shallow depression running parallel with margin, and which continues on to EXPLANATION OF PLATE 96 Figs. 1-2. Radnoria syrphetodes gen. et sp. nov. Wenlock Series, Dolyhir Limestone, disused quarry 475 m W. of Dolyhir Bridge, Old Radnor, Powys (SO 2409 5812). la-c, NMW 74.30G.33a, pygidium, dorsal, posterior, and left lateral views, x8. 2, NMW 72.18G.179, pygidium, dorsal view, x8. Figs. 3-5. Radnoria triquetra gen. et sp. nov. Wenlock Series, Much Wenlock Limestone Formation, Nodular Beds, large bedding plane exposure on west side of Wren’s Nest Hill, Dudley, West Midlands (SO 9350 9210). 3a-c, NMW 71.6G.239, holotype, internal mould of cranidium, dorsal, left lateral, and anterior views, x 10. 4, NMW 71.6G.260, internal mould of cranidium, dorsal view, x8. 5a-d, NMW 71.6G.240, pygidium, dorsal, right lateral, oblique posterodorsal, and posterior views, x 12. Fig. 6. Radnoria humiUima (Barrande, 1852). Wenlock Series, Liten Formation, Lodenice, near Beroun, Czechoslovakia. NMP 215/68, latex cast of cranidium, oblique anterolateral, right lateral, and dorsal views, X 12. Original of Horny, Prantl and Vanek 1958, pi. 2, fig. 6. PLATE 96 OWENS and THOMAS, Radnoria 816 PALAEONTOLOGY, VOLUME 18 field of free cheek. This depression appears to correspond roughly with the inner edge of the cephalic doublure (PI. 95, figs. 2a, 3). Anterior branch of facial suture diverges at 60-70° from an exsagittal line through y. y a broad curve, a little way out from axial furrow. Palpebral lobe backwardly placed, subsemicircular and about one-third sagittal length of glabella, e and | a single angle, a short distance in front of posterior border furrow. Section e+^ to co short, nearly straight, defining minute, triangular posterior portion of fixed cheek. Visual surface unknown. Distinct eye socle, the lower margin of which is not incised and which diverges strongly from the upper margin at either end; median section directed almost exsagittally. Field of free cheek broad, lateral border more upturned and a little narrower than anterior. Posterior border furrow shallow, com- parable to lateral. Long genal spine with deep median groove, which dies out before reaching posterior end. Cephalic doublure broad (PI. 95, fig. 3); connective sutures of rostral plate backwardly divergent (PI. 95, fig. 4). Hypostome unknown. Thorax known only from one incomplete segment (PI. 95, fig. 6u-6). Pygidium rather weakly vaulted, about two-thirds as long as wide. Axis about one-quarter greatest transverse pygidial width, tapering gently backwards, not reaching posterior margin ; axial rings defined by shallow ring furrows which become progressively shallower posteriorly. No postaxial ridge. Pleural areas broad, weakly convex with six pairs of pleural ribs of flat-topped profile whose anterior and posterior pleural bands are of approximately equal width (exsag.). Pleural furrows rather shallow, of constant depth along their length, much deeper than ill-defined interpleural furrows, which become deeper at their abaxial ends. Both pleural and interpleural furrows reach close to pygidial margin. No border, but marginal area of pygidium flattened. Sculpture of fine pits (on preglabellar field, cheeks and Ip lobe) and granules (on glabella, anterior border, and palpebral lobe) seen on some cranidia (PI. 95, fig. 1), and some pygidia have very fine granulation (PI. 96, fig. 1) or pits (e.g. GSM DEX2927). The apparent absence of these sculptural elements on some specimens (PI. 95, figs. 5, 6) may be a product of preservation or of variation. The similarity of other features of all the material included in this species suggest that the presence or absence of fine sculptural details is not of taxonomic significance. Radnor ia triquetra sp. nov. Plate 96, figs. 3-5 Derivation of name. Latin triquetrus, triangular; with reference to the shape of the glabella. Holotype. Cranidium NMW 71.6G.239, from Wenlock Series, Much Wenlock Limestone Formation, Nodular Beds (lundgreni Zone), large bedding plane exposure on west side of Wren’s Nest Hill, 200 m SW. of ‘Caves’ public house, Dudley, West Midlands (SO 9350 9210). Paratypes. Cranidium NMW 71.6G.260 and pygidia NMW 71.6G.240, 72.18G.181; horizon and locality of holotype. Diagnosis. Glabella triangular with distinct Ip lobes; pygidium with thirteen axial rings, each with a posteriorly placed median node, and seven pairs of pleural ribs in which posterior pleural band is elevated above anterior. Description. Cranidium weakly vaulted, with palpebral width three-quarters of sagittal length. Glabella as wide posteriorly as long, defined by deep axial furrows which merge anteriorly with shallow preglabellar furrow. In lateral profile glabella gently convex, more strongly so in transverse section, with posterior end elevated above occipital ring. Ip furrow runs from axial furrow backwards and inwards at 60° from an exsagittal line, curved adaxially, into the occipital furrow, widening and shallowing at its posterior end. Ip lobe isolated, semi-oval, about one-third glabellar length. 2p and 3p furrows not seen on available material. Occipital furrow broad and shallow, arched very weakly forwards sagittally, deepening laterally behind Ip lobes. Occipital ring nearly one-third length (sag.) of preglabellar field, and marginally wider (trans.) than widest part of glabella. No lateral lobes. Preglabellar field approximately two-thirds sagittal length of glabella, nearly flat in longitudinal section, traversed on its posterior portion by a shallow depres- sion. Anterior border furrow weak, anterior border about half sagittal length of preglabellar field. Anterior branches of facial sutures strongly divergent, each branch diverging at about 70° from an exsagittal line through y, which is some distance out from axial furrow. Palpebral lobe crescentic, about half sagittal OWENS AND THOMAS: RADNORIA 817 length of glabella. Posterior section of facial suture unknown. Hypostome, rostral plate, free cheek, and thorax unknown. Pygidium about two-thirds as long (sag.) as wide (trans.). Axis anteriorly one-quarter greatest pygidial width, tapering gently backwards, not reaching posterior margin and with thirteen rings defined by moderately distinct ring furrows which become progressively shallower towards posterior. Median node on posterior edge of each ring. No postaxial ridge. Pleural areas broad, adaxial part horizontal in trans- verse section, abaxial part rather steeply declined. Seven pairs of pleural ribs, with the posterior pleural bands elevated above the anterior. Pleural furrows deeper and wider than the interpleural adaxially, but abaxial ends of latter are deeper than corresponding sections of pleural furrows. Interpleural furrows reach pygidial margin, pleural do not. Anterior and posterior pleural bands of approximately equal width (exsag.), abaxial ends of latter distinctly elevated and crest-like. No border. Section of pygidial doublure seen (PI. 96, fig. 5fl, c) shows that it has fine, parallel, terrace lines. Dorsal exoskeleton smooth. Radnoria hiimillima (Barrande, 1852) Plate 96, fig. 6a-c *1852 Cyphaspis hiimillima Barrande, p. 492, pi. 18, figs. 57-58. 1868 Cyphaspis humillimus Barrande; Bigsby, p. 47. 1951 Otarion (?) humillimum (Barrande); Prantl and Pfibyl, pi. 1, figs. 27, 28. V. 1958 Otarion! Immillinmm (Barrande); Horny, Prantl and Vanek, pi. 2, fig. 6. V. 1970 Otarion! humillimum (Barrande); Horny and Bastl, p. 169. Type specimens. Barrande (1852, p. 492) states that he had several specimens (all cranidia) at hand when he erected this species. Therefore the statement by Horny and Bastl (1970, p. 169) that specimen NMP IT309 is the holotype by monotypy is incorrect, and it is here designated lectotype. It is from high Liten Formation (late Wenlock), Listice, near Beroun, Czechoslovakia. Barrande’s other syntypes are also from this locality. Other material. One cranidium NMP 215/68, Liten Formation, Lodenice, near Beroun. Figured Horny, Prantl and Vanek 1958, pi. 2, fig. 6. We have only had the opportunity to examine the specimen figured by Horny, Prantl, and Vanek. This is poorly preserved and no preparation has been possible. A full description and comparison must await revision of Barrande’s material, but a latex cast is figured for comparison with the British species. Although R. humillimum shows certain similarities to R. syrphetodes, it is distinguished by the relatively longer, narrower, and more ovate glabella, while the anterior border is relatively narrower (sag. and exsag.). RELATIONSHIPS OF THE BR ACH YMETOPIDAE As previously conceived, the Brachymetopidae comprised a number of Upper Palaeozoic genera, the earliest being from the Lower Devonian. Different authors have classified these trilobites in different ways; Prantl and Pfibyl (1951, p. 439) pro- posed the Brachymetopinae as a subfamily of the Otarionidae; Hupe (1953, p. 220; 1955, p. 210) elevated them to family status, and believed that they were allied to proetids rather than to otarionids; Maximova (1957, pp. 60-61) and Whittington 0960, p. 407) considered their morphology to suggest relationship with the phillip- siids; Whittington and Campbell (1967, pp. 450-451) and Fortey and Owens (1975, p. 23 1 ) surmised that they could have evolved from otarionids ; the latter also suggested (1975, p. 231 ) a possible origin in the proetid subfamily Warburgellinae. So far, how- ever, no convincing evidence has been advanced in support of either a proetid or an otarionid ancestry. 818 PALAEONTOLOGY, VOLUME 18 In an attempt to trace brachymetopid relationships and ancestry, we have con- sidered the following morphological characters: rostral plate, cephalic doublure, lateral occipital lobes, preannulus, outline of pygidium, and structure of pygidial pleural ribs. We have selected these features since they show the greatest variation in the groups considered, and we believe that, taken together, they are of phylogenetic significance. Rostral plate. The Warburgellinae is the only proetid (sensu Owens 1973, p. 6) sub- family in which the connective sutures diverge backwards. The connective sutures also diverge backwards in Mystrocephala (Whittington 1960, pi. 54, fig. 3), Brachyme- topus (Hahn 1964, pi. 32, fig. 3), and Australosutura (Amos, Campbell and Goldring 1960, pi. 39, figs. 10, 11; pi. 40, figs. 1, 5, 6) (although in the last two genera the posterolateral corners of the greatly expanded rostral plate extend to the base of the genal spine). The only species of Cordania in which any part of the rostral plate is known is C.falcata Whittington (1960, p. 41 1, pi. 51, fig. 16), one specimen showing the anterior part of the left-hand connective suture. Whittington points out that the connective sutures converge backwards. He also figured free cheeks of C. macro- bins (Billings, 1869) and one ofthese (ibid., pi. 53, fig. 10) shows a very broad doublure. If the doublure of C. falcata is similar, only part of the connective suture is seen on the specimen mentioned above. It may therefore be that the connective sutures of C.falcata (and presumably other Cordania species) do diverge, after initially converg- ing. As all other known brachymetopids have backwardly diverging connective sutures it would be surprising if the same condition did not obtain in Cordania. R. syrphetodes has backwardly diverging connective sutures (PI. 95, fig. 4). In otarionids, and typical proetids, the rostral plate is small and triangular or i tr , y 7 TEXT-FIG. 2. Schematic sections through doublures of free cheeks of: 1, Cor- dania macrobius (Billings, 1869) (based on Whittington 1960, pi. 53, figs. 1, 10); 2, Australosutura gar dneriC&m^hcW and Goldring, 1960 (based on Amos, Campbell and Goldring 1960, pi. 39, figs. 1, 10); 3, Proetides msignis iyJmcite.W, 1863) (after Hessler 1962, fig. 1a, p. 812); 4, Radnoria syrphetodes sp. nov. (based on PI. 95, figs. 3, 4); 5, Proetus pluteus Whittington and Campbell, 1967 (based on Whittington and Campbell 1967, pi. 1, fig. 11; pi. 2, fig. 2); 6, Otarion plautum Whittington and Campbell, 1967 (based on Whittington and Campbell 1967, pi. 7, figs. 1, 6); 7, Warburgella rugulosa canadensis Ormiston, 1967 (based onOrmiston 1971, pi. 21, figs. 4, 5); 8, Prantliagrindrodi Owens, 1973 (based on Owens 1973, pi. 15, figs. 3, 5). Arrows indicate position of lateral border furrow, ‘tr’ the tropidium. OWENS AND THOMAS: RADNORIA 819 trapezoidal with backwardly converging connective sutures (see Whittington and Campbell 1967, pi. 6, figs. 2, 9; pi. 7, fig. 6; pi. 10, fig. 15). Cephalic doublure. In many Proetacea (see Owens 1973; Whittington and Campbell, 1967; Ormiston 1971) the cephalic border and doublure form a ‘tube’ (Fortey and Owens 1975, p. 236) (see text-fig. 2), where the inner margin of the doublure coincides with the border furrow, which in all these cases tends to be well defined. In some genera, as Hessler (1962, p. 811) has observed, the doublure extends well inside the border furrow (which in these cases tends to be ill-defined), and its inner section runs more or less parallel with the dorsal surface of the corresponding part of the cephalon (see text-fig. 2). In such cases a nearly flat ‘trough’ is commonly developed which crosses the cheeks and preglabellar field parallel to the cephalic margins. The inner edge of this ‘trough’ corresponds with the inner edge of the doublure, and is represented by an abrupt change in slope. This structure is found in R. syrphetodes {P\. 95, fig. 2a), Prantlia grindrodi Owens (1973, pi. 15, fig. 3), Proetides insignis (Winchell, 1863) and P. colemani Hessler, 1962 (see Hessler 1962, text-fig. 1, p. 812), Cordaniamacrobius (QWWngs, 1869) (see Whittington 1960, pi. 53, figs. 10-12), Mystrocephala pulchra (Cooper and Cloud, 1938) (see Whittington 1960, pi. 53, fig. 15), and Australosutura gardneri (Mitchell, 1922) (see Amos, Campbell and Goldring 1960, pi. 39, figs. 1, 6, 10, 11). Lateral occipital lobes. These are of common occurrence in the Proetacea, but are lacking in the Otarionidae, Brachymetopidae, and many Tropidocoryphinae. Lateral occipital lobes are well developed in Silurian Proetinae (but absent in later members of the subfamily), present in most Warburgellinae (but suppressed in some species of Warburgella), and have evidently been repeatedly acquired and lost at various times in different proetacean lineages. Preannulus. This feature is found in the Proetinae and their derivatives— e.g. Dechenel- linae and ‘phillipsiids’, but is lacking in Tropidocoryphinae, Warburgellinae, Brachy- metopinae, and Otarionidae. Structure and shape of the pygidium. Owens (1973, pp. 5-6; text-fig. 2, p. 5) has recognized three types of pygidial pleural rib structure in Lower Palaeozoic Proetidae, with different kinds characterizing the Tropidocoryphinae, Warburgellinae, and the Proetinae and their derivatives. R. syrphetodes has pleural ribs like those found in Warburgellinae. R. triquetra and other Brachymetopinae, however, have a different type, in which the posterior pleural bands are elevated above the anterior; this type of structure appears to be a modification of that typical of Warburgellinae. In Otarionidae the structure is similar to that found in Proetinae. Proetinae, Tropidocoryphinae, Warburgellinae, and Brachymetopinae normally have a pygidium of subparabolic outline with five (or commonly many more) axial rings. Within any one lineage there is commonly an increase in number of rings in successively younger genera; less commonly there is a decrease. Otarionidae differ from all the above groups in that the pygidium is short (sag.), with its width (trans.) commonly over twice its sagittal length, and the number of axial rings never exceeds seven, and is most commonly in the range three to four. 820 PALAEONTOLOGY, VOLUME 18 Inferred relationships. Brachymetopinae and Prantlia have in common the shape of the rostral plate, type of cephalic doublure, lack of preannulus, pygidial outline, and large number of pygidial axial rings. Other Warburgellinae share these characters, but have a different kind of cephalic doublure structure. Proetinae and Otarionidae have less in common with the above groups and, in particular, are distinguished by the type of rostral plate and pygidium, and the possession of the preannulus in the former. The Proetinae and their ‘phillipsiid’ derivatives, therefore, do not seem to be closely related to the Brachymetopinae. Otarionidae bear a close general re- semblance to certain Brachymetopinae, especially to Cordania species, in general cephalic morphology. There are marked contrasts, however, in the structure of the cephalic doublure, and probably also in the rostral plate. The similarity between otarionids and Cordania is therefore considered to be due to homoeomorphy. It would seem to be too great a coincidence for so many common features to be independently acquired in brachymetopines and warburgellines and we consider Radnoria and later brachymetopines to be derived from warburgellines along the paths outlined below. The earliest known warburgellines are Warburgella species from the mid-Llandovery (Owens 1973, p. 72). Warburgella has a backwardly widening rostral plate, a tropidium or tropidial ridges, lateral occipital lobes, and the pygidial pleural ribs are flat-topped in profile; the cephalic border and doublure together form a ‘tube’. The earliest known Prantlia species is P. grindrodi Owens, 1973 from the highest Llandovery and Wenlock. The stratigraphical occurrence and morphology of Prantlia suggest that it is derived from Warburgella through secondary loss of the tropidium and by modification and widening of the cephalic doublure. W. scutterdinensis Owens, 1973 from the early Wenlock is more similar to P. grindrodi than is any other Warburgella species. In particular, it has a flat-bottomed ‘trough’ running parallel to the margin, similar to that typical of P. grindrodi. The presence of this structure suggests that the doublure may be widened, but it is still unknown in this species. The pygidium of R. syrphetodes is similar to those of Prantlia species, particularly that of P. longula (Hawle and Corda, 1847) (see Chlupac 1971, pi. 20, fig. 10). The cephalon is also similar in its broad ‘trough’ and lack of tropidium but lateral occi- pital lobes are absent, the Ip lobes reduced, and the anterior branches of the facial sutures much more strongly divergent. R. triquetra is additionally distinguished by the structure of the pygidial pleural ribs. The range of characters of Radnoria species include some found in Prantlia (see above) and others— especially the strongly divergent anterior branches of the facial sutures, lack of lateral occipital lobes, and the pygidial pleural rib structure (of R. triquetra)^Io\xnd in Cordania. Radnoria thus has a mosaic of Prantlia and Cordania characters, implying a close relationship between the three genera. Systematic position of the Warburgellinae q/ Radnoria. Hitherto, warburgellines and brachymetopines have been classified in different families but, because of their inferred relationships, we consider such a division to be artificial. Because war- burgellines have more characters in common with brachymetopines than their presumed proetid ancestors, the tropidocoryphines, we classify them with the former. All three Radnoria species possess highly divergent anterior branches of the facial OWENS AND THOMAS: RADNORIA 821 sutures and lack occipital lobes— features typical of brachymetopines. The pygidial pleural rib structure of R. triquetra is also similar to members of this subfamily, although that of R. syrphetodes is more like that of warburgellines. We consider that brachymetopine characters outweigh warburgelline ones, and place Radnoria in the Brachymetopinae. Acknowledgements. We are indebted to H. B. Whittington, M. G. Bassett, and R. A. Fortey for valuable discussion and criticism of previous drafts. D. E. White (IGS) and V. Zazvorka and F. Bastl (NMP) kindly gave access to specimens in their care. We also thank Miss L. Cherns and P. D. Lane for assistance in the field. A. T. T. acknowledges a Research Studentship from the N.E.R.C.; R. M. O. thanks the National Museum of Wales for financial support for the fieldwork. REFERENCES AMOS, A. J., CAMPBELL, K. s. w. and GOLDRING, R. 1960. Australosutura gen. nov. (Trilobita) from the Carboniferous of Australia and Argentina. Palaeontology, 3, 227-236, pis. 39-40. BARRANDE, J. 1852. Systeme SUurien du Centre de la Boheme. lerepartie. Recherches paleontologiques, Vol. 1. Crustaces, Trilobites. xxx+935 pp., 51 pis. Prague and Paris. BASSETT, M. G. 1972. The articulate brachiopods from the Wenlock Series of the Welsh Borderland and South Wales. Palaeontogr. Soc. [Monogr.], (2), 27-78, pis. 4-17. 1974. Review of the stratigraphy of the Wenlock Series in the Welsh Borderland and South Wales. Palaeontology, 17, 745-777. BEGG, J. L. 1939. Some new species of Proetidae and Otarionidae from the Ashgillian of Girvan. Geol. Mag. 76, 372-382, pi. 6. BIGSBY, J. J. 1868. Thesaurus Siluricus, the flora and fauna of the Silurian Period, lii 4-214 pp. London. BILLINGS, E. 1869. Description of some new species of fossils with remarks on others already known, from the Silurian and Devonian rocks of Maine. Proc. Portland Soc. nat. Hist. 1, 104-126, figs. 1-28. CLARKE, J. M. 1892. On Cordania, a proposed new genus of trilobites. N.Y. St. Mus. 45th Ann. Rep. (for 1891), 440-443. chlupaC, I. 1971. Some trilobites from the Silurian/Devonian boundary beds of Czechoslovakia. Palaeon- tology, 14, 159-177, pis. 19-24. COOPER, G. A. and cloud, p. e. 1938. New Devonian fossils from Calhoun County, Illinois. J. Paleont. 12, 444-460, pis. 54-55. DiENER, c. 1897. The Permocarboniferous fauna of Chitichun No. 1. Mem. geol. Surv. India Palaeont. indica, Ser. 15, Himalayan Fossils, 1, 1-105, pis. 1-13. FORTEY, R. A. and OWENS, R. M. 1975. Proetida— a new order of trilobites. In bruton, d. l. (ed.). Evolution of the Trilobita, Trilobitoidea and Merostomata, Fossils and Strata, No. 4, pp. 227-239. GARWOOD, E. J. and Goodyear, e. 1918. On the geology of the Old Radnor district, with special reference to an algal development in the Woolhope Limestone. Q. Jl geol. Soc. Loud. 74, 1-30, pis. 1-7. GOLDRING, R. 1955. The Upper Devonian and Lower Carboniferous trilobites of the Pilton Beds of N. Devon. Senckenberg. leth. 36, 27-48, 2 pis. HAHN, G. 1964. Trilobiten der unteren PericyclusSiuIs (Unterkarbon) aus dem Kohlenkalk Belgiens. Teil 2: Morphologie, Variabilitat und postlarvale Ontogenie von Brachymetopus maccoyi spinosus Hahn 1964 und von Piltonia kuehnei n. sp. Ibid. 45, 347-379, pis. 32-33. HAWLE, I. and CORDA, A. J. c. 1847. Prodrom einer Monographic der bbhmischen Trilobiten. 176 pp., 7 pis. Prague. HESSLER, R. R. 1962. The Lower Mississippian genus Proetides (Tril.). J. Paleont. 36, 81 1-816, pi. 119. HORNY, R. and BASTL, F. 1970. Type specimens of fossils in the National Museum, Prague. Vol. 1. Trilobita. 354 pp., 20 pis. National Museum, Prague. PRANTL, F. and VANEK, J. 1958. On the limit between the Wenlock and the Ludlow in the Barrandian. Sbor. ust. Ust. geol.. Odd. Palaeont. 24 (for 1957), 217-278, pis. 29-37. [In Czech, with English summary.] HUPE, p. 1953. Classe de trilobites. In piveteau, j. (ed.). Trade de paleontlogie, 3, 44-246, 140 text-figs. Paris. 1955. Classification des trilobites. Annls Paleont. 39, 1-110. 822 PALAEONTOLOGY, VOLUME 18 KEGEL, w. 1927. Uber obersilurische Trilobiten aus dem Harz und dem Rheinischen Schiefergebirge. Jb. preuss. geol. Landesanst. 48, 616-647, pis. 31-32. MAXIMOVA, z. A. 1957. On the morphology of the genus Brachymetopus M’Coy. Ann. All-Union Pal. Soc. 16, 58-63, 1 pi. [In Russian.] 1970. Silurian trilobites of Vajgac Island. /« Silurian stratigraphy and fauna of Vajgac Island. Nauchno- issled. Inst. Geol. Arktiki, 195-209, pis. 1-2. [In Russian.) m’coy, f. 1847. On the fossil botany and zoology of the rock associated with the coal of Australia. Ann. Mag. nat. Hist. 20, 145-157, 226-236, 298-312. MITCHELL, J. 1922. Description of two new trilobites, and note on Griffithides convexicaudatus Mitchell. Proc. Linn. Soc. N.S.W. 47, 535-540, pi. 54. MOORE, R. c. (ed.). 1959. Treatise on Invertebrate Paleontology, Part O, Arthropoda 1 . xix-|- 560 pp., 415 figs. Geol. Soc. Amer. and Univ. Kansas Press (Lawrence). OPiK, A. A. 1937. Trilobiten aus Estland. Acta Comment. Univ. Tartu, (A), 32 (3), 1-163, pis. 1-26. (Publ. Geol. Inst. Univ. Tartu, no. 52.) ORMiSTON, A. R. 1967. Lower and Middle Devonian trilobites of the Canadian Arctic islands. Bull. Geol. Surv. Can. 153, 1-148, pis. 1-17. 1971. Silicified specimens of the Gedinnian trilobite Warburgella rugulosa canadensis Ormiston, from the Northwest Territories, Canada. Palaont. Z. 45, 173-180, pis. 19-21. OSMOLSKA, H. 1970. Revision of non-cyrtosymbolinid trilobites from the Tournaisian-Namurian of Eurasia. Palaeont. pol. 23, 1-165, 22 pis. OWENS, R. M. 1973. British Ordovician and Silurian Proetidae (Trilobita). Palaeontogr. Soc. [Monogr.], 1-98, 15 pis. 1 974. The affinities of the trilobite genus Scharvia, with a description of two new species. Palaeontology, 17, 685-697, pis. 98-99. PRANTL, F. and PRiBYL, A. 1951. A revision of the Bohemian representatives of the Family Otarionidae R. and E. Richter (Trilobitae). Stdt. geol. Ust. Cesk. Rep. 17 (for 1950), 353-512, 5 pis. [Czech and English text, Russian summary.) PRIBYL, A. 1946. O nekolika novych trilobitovych rodech z ceskeho siluru a devonu. Pfiroda, Brno, 38 (5-6), 7 pp., 1 1 text-figs. 1964. Neue Trilobiten (Proetidae) aus dem bohmischen Devon. Spis bulg. geol. Druzli. 25, 23-51, pis. 1-3. REED, F. R. c. 1931. The Lower Palaeozoic trilobites of Girvan. Supplement No. 2. Palaeontogr. Soc. [Monogr.], 30 pp. 1942. Some new Carboniferous trilobites. Ann. Mag. nat. Hist. (1 1), 9, 649-672, pis. 8-11. RICHTER, R. and RICHTER, E. 1939. Ueber Namuropyge n.g. und die basisolution der Trilobiten-Glatze. Bull. Mus. r. Hist. nat. Belg. 15, no. 3, 1-29, 2 pis. TOLL, E. VON. 1899. Geologische Forschungen im Gebiete Kurlandischen Aa. Mit einem Anhangen, Gunnar Andersson’s Verzeichniss der Glacialpflanzen von Tittelmund enthalfend. Protok. Obshch. Estest. Yurev. 12, 1-33. WALTER, o. T. 1924. Trilobites of Iowa and some related Paleozoic forms. Iowa Geol. Surv. 31, 167-400, 27 pis. WHITTINGTON, H. B. 1960. Cordania and other trilobites from the Lower and Middle Devonian. J. Paleont. 34, 405-420, pis. 51-54. and CAMPBELL, K. s. w. 1967. Silicified Silurian trilobites from Maine. Bull. Mus. comp. Zool. Harv. 135, 447-482, pis. 1-19. wiNCHELL, A. 1863. Description of fossils from the yellow sandstones lying beneath the ‘Burlington Lime- stone’ at Burlington, Iowa. Proc. Acad. nat. Sci. Philad. 2-25. YOLKIN, E. A. in YOLKIN, E. A. and ZHELTONOGOVA, V. A. 1974. The most ancient dechenellinds (trilobites) and Silurian stratigraphy of the Altai Mountains. Akad. Nauk. SSSR, Sib. Otdel., Trudy Inst. geol. geophyz. Issue 130, 1111, 13 pis. [In Russian.) R. M. OWENS A. T. THOMAS Department of Geology National Museum of Wales Cardiff CFl 3NP Original manuscript received 31 December 1974 Revised manuscript received 16 February 1975 Department of Geology Sedgwick Museum Downing Street Cambridge CB2 3EQ A NEW CRAB, COSTACOPLUMA CONCAVA FROM THE UPPER CRETACEOUS OF NIGERIA by j. s. H. COLLINS and s. f. morris Abstract. A new genus and species of retroplumid crab is described from the upper Cretaceous of Nigeria and comparisons are made with Retropluma and the closely allied genus, Archaeopus. Archaeopus senegalensis Remy is transferred to the new genus. Included in a collection of fossils from the upper Cretaceous of Nigeria, deposited in the Department of Palaeontology, British Museum (Natural History) by Professor R. A. Reyment (formerly of the Nigerian Geological Survey), are two crabs from the Coniacian of Abakaliki Province of East Central Region, three from the ?Maastrich- tian of Shendam, Plateau Province of Benue-Plateau Region, and ten from the upper Campanian of Enugu Province, East Central Region. The transverse ridges on the dorsal surface of the carapace, the narrow front, together with the structure of the orbital and antennular cavities clearly place these crabs in the Retroplumidae as defined by Glaessner (1969, R531). The new material, however, possesses features sufficiently distinct from Retropluma to allow a new genus, Costacopluma, to be described. SYSTEMATICS Section brachyrhyncha Borradaile, 1907 Superfamily ocypodoidea Rafinesque, 1815 Family retroplumidae Gill, 1894 (= Ptenoplacidae Alcock, 1900) Genus costacopluma gen. nov. Type species. Costacopluma concava sp. nov. Derivation of name. Referring to the strong transverse ridges and the familial root. Diagnosis. Carapace transversely suboval with three transverse arched ridges, the foremost extending across the protogastric lobes to unite with the mesogastric lobe; the areas between the ridges are concave ; the lateral edges are thinly raised from the front to the posterior ridge and the urocardiac depression is distinct. The 5th coxae are subdorsal. Costacopluma concava sp. nov. Plate 97, figs. 1 -9 Derivation of name. The trivial name refers to the concave areas between the transverse ridges on the carapace. Diagnosis. Costacopluma with anterolateral notch, anterior transverse ridge reaches [Palaeontology, Vol. 18, Vol. 4, 1975, pp. 823-829, pi. 97.] 824 PALAEONTOLOGY, VOLUME 18 the lateral margin, areas between ridges deeply concave. Flat triangular rostrum not strongly produced. Material. Fifteen more or less complete carapaces from three horizons in South-east Nigeria : Holotype, In. 44642 (PI. 97, figs. 1-3) and paratypes, In. 44643-In. 44648, In. 44650-In. 44652, upper Campanian, Zone of B. polyplocum, horizon of Libycoceras afikpoense, Anofia, on River Cross c. 8 miles (c. 12 km) south of Afikpo Government Station, Enugu Province, East Central Region. Additional paratypes are In. 46496-In. 46498, from ?Maastrichtian, Shendam, Plateau Province and In. 46499-In. 46500, Coniacian, Awgu Limestone, Awgu, Abakaliki Province, East Central Region. Description. The carapace is suboval in outline, the length being about two-thirds the greatest width; it is gently arched longitudinally and transversely nearly flat. The lateral margins are inclined almost at right angles to the dorsal surface and the lateral edges from the front to the ridge on the metabranchial lobe, are drawn up slightly into a thin rounded ridge. The anterolateral margin is short and the broadly rounded lateral angle is about two-thirds distant from the front. The posterolateral angles are sharp and lead by shallow incisions for the 5th coxae into the posterior margin which is nearly straight, bounded by a low ridge and as wide as the orbitofrontal margin. The orbitofrontal margin is nearly straight and occupies about three-quarters of the greatest width of the carapace. The sharply triangular rostrum is steeply downturned and thinly grooved round the apex of fused frontal lobes reaching nearly to its tip; the frontal lobes become more elongate and less prominent as growth advances. The orbits are subovate and directed forwards. The upper orbital margin, divided by a blunt spine into two nearly equal parts, is thickened to form a low granulated ridge and terminates externally in a rounded spine barely projecting beyond the front. The short, similarly thickened, and granulated lower orbital margin terminates at the buccal margin in a tuberant spine projecting somewhat beyond the upper orbital margin. A thin septum separates the basal antennular segments which occupy about a third of the antennular-orbital cavity; the segments are not well preserved, but appear to be triangular with the angles much rounded. The orbital peduncle is long, slightly contracted medially, and almost circular in transverse section. The corneal surface is oblique and, where it is laying in position on the type, directed downwards. From a shallow marginal notch, the cervical groove curves inconspicuously to a pit level with the narrow part of the mesogastric lobe, then commencing with another pit the cervical groove deepens considerably and passes across the mid-line of the carapace some two-thirds distant from the front. The dorsal surface is divided trans- versely by three ridges; the foremost curves broadly forward from the lateral margin across the protogastric lobes to unite with the tip of the mesogastric lobe; the crest of the second ridge crosses the fused epi- and mesobranchial lobes and extends EXPLANATION OF PLATE 97 Costacopluma concava gen. et sp. nov. Figs. 1-5, 7-9 from the upper Campanian of Enugu Province, Nigeria. 1-4, holotype BM. In. 44642. 1, dorsal view. 2, right lateral view. 3, anterior view showing orbital peduncle. 4, ventral view. 5, 9, para- type BM. In. 44644. 5, dorsal view. 9, anterior view. 7, 8, paratype BM. In. 44647. 7, dorsal view. 8, ventral view. All x2. Fig. 6, from the ?Maastrichtian of Plateau Province, Nigeria. Paratype BM. In. 46497. Dorsal view, x 3. PLATE 97 COLLINS and MORRIS, Costacopluma 826 PALAEONTOLOGY, VOLUME 18 downwards from the lateral margin towards the base of the mesogastric lobe. The third ridge, on the metabranchial lobe, occurs about midway from the second ridge to the posterior margin ; it is directed upwards in a broadly sinuous curve and although interrupted by deep epimeral muscle scars, it continues across the carapace by a row of four tubercles on the anterior of the cardiac region. The cardiac region is sub- pentagonal in outline and has another small tubercle at its base. The mesogastric lobe forms an elongated oval ; at its base are three forwardly directed pits set in an inverted triangle, the lateral ones being the most prominent. On each metabranchial lobe is an elongated tubercle close to the posterior margin. There is a tendency for the ridges to become sharper as growth advances. While the subsurface shell layer of the ridge tops exposed on the holotype is seen to be pitted, they are normally smooth or lined with granules. The areas between the ridges are markedly concave and finely pitted ; several larger pits are scattered along the outer course of the cervical groove in addition to those already mentioned. The triangular pterygostomian process is inflected almost at right-angles to the carapace margin; a faint groove extending from the cervical groove curves towards the buccal margin, and the sternal border is bounded by a strong granulated ridge (In. 44647, PI. 97, fig. 7). The buccal cavity is about as broad as long and the margins are straight. The ischiognath of the 3rd maxilliped is about twice as long as wide and a shallow longitudinal depression reaches a little over one-half the width from the convex inner margin; the outer margin is nearly straight. The merognath is subovate in outline and almost as long as the ischiognath, a low ridge extends to the articulating facet and the outer margin is thickened ; the three segments of the palp are of equal length. The exognath tapers distally and reaches to about the middle of the merognath, its width is a third of its length and there is a depression along the outer margin. The abdominal sternites are very wide; the lst-3rd are separated by transverse grooves and are divided by a median cleft widening posteriorly ; the groove separating the 3rd from the 4th sternites runs back a short way from the margin before turning sharply inwards. The 5th-7th sternites are drawn up into strong oblique ridges, while the 8th is much reduced and subdorsal. Male abdomina only are preserved and none is complete. The 4th-6th somites are of about equal length and rapidly decrease in width so that the width of the posterior margin of the 6th is one-half that of the anterior margin of the 4th; they are divided from each other by sutures and each has a median transverse ridge. The telson is about twice as long as broad, it widens slightly coincident with the 4th/5th sternal groove before tapering to a broadly rounded apex. The abdominal trough is deep and extends almost the entire length of the 4th sternite. The specimens range in size from 6-9 mm to 26 mm across the carapace ; those from the Coniacian and ?Maastrichtian localities are smaller than those from the Cam- panian, but this may represent only a collecting bias, since fewer specimens were collected from the first two localities. Discussion. Hitherto, the earliest known member of the Retroplumidae has been Retropluma eocenica Via. It differs from Costacopluma concava in having much straighter anterior and posterior transverse ridges and in the posterior one (across the metabranchial and cardiac lobes) being more entire; the anterolateral margin in COLLINS AND MORRIS: CRETACEOUS CRAB FROM NIGERIA 827 C. concava is continuous with the general marginal curvature towards the front, but in R. eocenica it is slightly hollowed. The family Retroplumidae was erected by Gill (1894) to contain Retropluma Gill, 1894 ( = Archaeoplax Alcock and Anderson, 1894 non Stimpson, 1863) which is represented in the Lutetian of Spain by R. eocenica Via, in the Pliocene of Italy by R. craverii (Crema), and by four Recent species inhabiting the Indo-Pacific region. Archaeopus senegalensis Remy (19606, p. 316) from the Palaeocene of Senegal is very close to C. concava and must be included in Costacopluma. It differs from C. concava by the absence of an anterolateral notch and the anterior ridge does not reach the lateral margin ; the mesogastric lobe of C. concava is smaller and the transverse ridges are narrower with steeper slopes and the areas between the ridges are more concave. The median transverse ridge of C. senegalensis is more continuous, i.e. with shorter gaps between the segments of the ridge. The triangular rostrum of C. senegalensis is more strongly produced, with its median depressed and the margins elevated, also the orbits are wider. C. senegalensis would appear to be a direct descendant of C. concava. TEXT-FIG. 1. Costacopluma senegalensis (Remy). Holotype, X 2. Reproduced from Bull. Soc. geol. Fr. (7) 1, pi, 19a, fig. 1, with the kind permission of the Societe geologique de France. Beurlen (1930, p. 352) included the Cretaceous Archaeopus Rathbun, 1908 from North America in the Retroplumidae, and whilst Glaessner (1969, R532) tentatively placed it in the Palicidae, Via (1969, p. 339) again drew attention to the affinities of this genus to Retropluma', also it appears to be closely related to Costacopluma. Archaeopus is known by two species, A. antennatus Rathbun and A. vancouverensis (Woodward) both from the upper Cretaceous (probably Campanian) of western North America. Both species have well-developed ridges across the carapace, but the gastric one (less well defined in A. antennatus) is more or less straight, not arched as in Costacopluma, in which the branchial ridge also differs by curving down towards the posterolateral angles. The cervical groove follows much the same course in both 828 PALAEONTOLOGY, VOLUME 18 genera, but does not weaken laterally in Archaeopus. The lateral margin of Costaco- pluma is entire whereas the margin of Archaeopus is dentate. Via (1957, p. 554; 1969, p. 339 et seq.) postulated that the origin of the Retroplumidae (in which he includes Archaeopus, Re tr op luma, as well as Ophthalmoplax) lay in the Americas during the Cretaceous. He suggested that a primitive, more robust, stock stayed in America— Arehaeopus in North America and Ophthalmoplax in the region of the Gulf of Mexico and northern South America— and another migrated eastward, adapting as it did so, to deeper waters. It is difficult to accept entirely Via’s suggestion as to the origin of the family since the Coniacian specimens from Nigeria are older than all the American species, except for Ophthalmoplax comancheensis Rathbun (1935, p. 54) which was based only on fingers from the Comanche Series (Albian) of Texas. It would appear that Costacopluma started to adapt to deeper water within the North African area. There is no evidence for any deep-water deposits in the Cretaceous of Nigeria but by Palaeocene times Tessier (1952, p. 414) thought that the total Palaeo- cene fauna of Senegal indicated a well-aerated, moderately deep sea of a maximum of 50 m depth. Via (1969, p. 325) summarizes the details of catches of Recent Retro- pluma spp. The shallowest species he records is R. denticulata Rathbun which is caught off the coasts of Japan in the depth range 80-125 m. The presence of the ocypodid Goniocypoda tessieri Remy in the Maastrichtian of Senegal suggests that it is possible that Africa might have been the centre of ocypodid evolution. An east- ward trend from Africa, possibly through southern Europe towards south-east Asia had certainly been established by Miocene times for both the Retroplumidae and Macrophthalminae. Previous knowledge of fossil crabs from Nigeria has been limited to descriptions by Withers (1924) of the xanthid, Holcocarcinus suleatus and a xanthid cheliped, both from the middle Eocene (Lutetian) of Ameki, southern Nigeria. From nearby Senegal and Ivory Coast, Tessier (1952) and Remy (1954; 1960a, b) have recorded: from the Maastrichtian — Zanthopsis africana (Remy), Goniocypoda tessieri Remy; from the Palaeocene — Necroearcinus simplex Remy, Raninella ornata Remy, Laeviranina sp., Pleolohites erinaceus Remy, Menippe frescoensis Remy, Zanthopsis multispinosa Remy, Zanthopsis sp., Branchioplax ballingi Remy, Glyphithyreus wetherelli (Bell); from the Ypresian— Glyphithyreus wetherelli', and from the Guitinm—Colneptunus hungaricus lutetianus Remy, Colneptunus sp., Palaeocarpilius straeleni Remy, Micro- maia simplex Remy, Atelecyclus gorodiskii Remy, Zanthopsis africana, and Branchio- plax bcdlingi. Joleaud and Hsu (1935) described Necroearcinus multituberculatus (Joleaud and Hsu) and a new genus of the family Potamidae from the upper Cretaceous of the Niger Territory. REFERENCES ALCOCK, A. 1900. Materials for a Carcinological Fauna of India. No. 6. The Brachyura Catometopa, or Grapsoidea. J. Asiat. Soc. Beng. 69, 279-456. and ANDERSON, A. R. 1894. Natural History Notes from H.M. Indian Survey Steamer Investigator, Commander C. F. Oldham, R.N. Commanding. Series II, No. 14. An Account of Recent Collections of Deep Sea Crustacea from the Bay of Bengal and Laccadive Sea. Ibid. 63 (3), 141-185, 9 pis. BEURLEN, K. 1930. Vcrgleichende Stammesgeschichte Grundlagen, Methoden, Probleme unter besonderer Beriicksichtigung der hoheren Krebse. Fortschr. Geol. Palaeont. 8, 317-586. COLLINS AND MORRIS: CRETACEOUS CRAB FROM NIGERIA 829 BORRADAiLE, L. A. 1907. On the classification of the Decapoda. Atm. Mag. not. Hist. (7) 19, 457-486. CREMA, c. 1895. Sopra alcuni decapod! terziarii del Piemonte. Atti Accad. Sci. Torino, 30, 664-681. GILL, T. 1894. A New Bassalian Type of Crabs. Am. Nat. 28, 1043-1045. GLAESSNER, M. F. 1969. Decapoda: R399-533, 626-628. In moore, r. c. (ed.). Treatise on Invertebrate Paleontology, Part R, Arthropoda 4 (2), Geol. Soc. America and Univ. Kansas Press. JOLEAUD, L. and hsu, t.-y. 1935. Crustaces decapodes du Cretace de Tanout (Damergou Niger frangais). Archs Mus. natn. Hist. nat. Paris, (6) 13, 99-1 10, 11 figs. RAFINESQUE-SCHMALTZ, c. s. (rafinesque). 1815. Analyse de la nature, ou tableau de Tunivers et des corps organises. 224 pp. Palermo. RATHBUN, M. j. 1908. Descriptions of fossil Crabs from California. Proc. U.S. natn. Mus. 35, 341-349, pis. 45-49. 1926. The fossil stalk-eyed Crustacea of the Pacific slope of North America. Bull. U.S. natn. Mus. 138, 156 pp., 39 pis., 6 text -figs. 1935. Fossil Crustacea of the Atlantic and Gulf Coastal Plain. Spec. Pap. geol. Soc. Am. 2, 160 pp., 26 pis., 2 text-figs. REMY, J.-M. 1954. In REMY, J.-M. and TESSiER, F. Decapodes nouveaux de la partie ouest du Senegal. Bull. Soc. geol. Fr. (6)4, 185-191, pi. 11. 1960a. Etudes paleontologiques et geologiques sur les falaises de Fresco (Cote d’Ivoire). 2 Crustaces. Annls Fac. Sci. Dakar, 5, 55-64, 1 pi. 19606. In GORODiSKi, a. and remy, j.-m. Sur les Decapodes eocenes du Senegal occidental. Bidl. Soc. geol. Fr. (7) 1, 315-319, pi. 19a, fig. 1. REYMENT, R. A. 1956. On the stratigraphy and palaeontology of the Cretaceous of Nigeria and the Cameroons, British West Africa. Geol. For. Stockh. Fork. 78, 17-96. TESSIER, F. 1952. Contribution a la stratigraphic et a la paleontologie de la partie ouest du Senegal (Cretace et Tertiaire). Bull. Dir. Mines Geol. Afr. Occid.fr. 14, 1-465. VIA, L. 1957. Contribution a I’etude paleontologique du Ocypodoida, Beurlen. C.r. hebd. Seanc. Acad. Sci. Paris, 245, 553-554. 1969. Crustaceos Decapodos del Eoceno espanol. Pirineos, 91-94, 479 pp., 39 pis., 41 figs. WITHERS, T. H. 1924. Eoccnc Brachyurous Decapod Crustaceans from Nigeria. Ann. Mag. nat. Hist. (9) 13, 94-97, pi. 5. WOODWARD, H. 1896. On some Podophthalmatous Crustacea from the Cretaceous Formation of Vancouver and Queen Charlotte Islands. Q. Jl geol. Soc. Land. 52, 221-228. J. S. H. COLLINS 63 Oakhurst Grove London, S.E.22 Typescript received 14 November 1974 Revised typescript received 10 April 1975 S. F. MORRIS Department of Palaeontology British Museum (Natural History) London, SW7 5BD ■•^'■Mir>5 ^ ^ , t . ^ ^ /.'^J..:'^ "'- '"*■> ■ ■■; ' !'(i,v',i '* i.u '■*tSiJ ^ " W V , ' v:''l ^ ,<’.'V" ■■■'f V ' itj: ifl" '.' y,V.. .,'..^v.' A' . V. .* • ' -unejaft ■ ■* ^.'' t-Y tj ■i' , A ^ ■I ., «v «-. *1 A ’if -jJ- •;, 5^' ''• I A .1 r» ■ . f A ' - ,M ,•* r:V'' ..s«4 'V|»'. i< ! V * :' t 'i-'f , .. ■0. < '■' >v,‘ A LOWER PERMIAN TEMNOSPOND YLOUS AMPHIBIAN FROM THE ENGLISH MIDLANDS by ROBERTA L. PATON Abstract. The holotype skull of Dasyceps bucklandi (Lloyd, 1850) from the Lower Permian (Autunian) Kenilworth Breccia is redescribed and its relationships with other members of the family Zatrachydidae are discussed. The two species of the American genus Zatrachys, the type species Z. serratus Cope, 1878 and Z. microphthalmus Cope, 1896 are considered. Z. microphthalmus is transferred to the genus Dasyceps as a new species D. microphthalmus, leaving Z. serratus as the only species of the genus Zatrachys. It is shown that Acanthostomatops Kuhn, 1961 is not the larval form of Dasyceps, but may instead be the larva of Z. serratus. It is suggested that Dasyceps was a terrestrial labyrinthodont, and a possible function for its enormous median nasal vacuity is put forward. The unique skull (Warwick County Museum, no. Gz 42) is the holotype of the species Labyrinthodon bucklandi Lloyd, 1850. It was more fully described by Huxley (1859) who recognized it as a form distinct from other known labyrinthodonts and separated it as a new genus Dasyceps. Von Huene (1910) studied it further, giving the most complete description to date. Case (1911) was the first to note its close relationship to the aberrant family of labyrinthodonts, the Zatrachydidae. The other generally recognized members of this family are Stegops Moodie, 1909, a primitive form from the Westphalian D of Linton, Ohio (Romer 1930); Acanthostomatops Kuhn, 1961 (previously known as Acanthostoma Credner, 1883, but Kuhn pointed out that this name was preoccupied by a polychaete), a small form found in the lower Permian Niederhasslich deposits of Saxony (Steen 1937); and Zatrachys Cope, 1878 from the lower Permian of Texas and New Mexico. The poorly known genus Platyhystrix Williston, 1911, from the lower Permian of New Mexico, was thought to belong in this family at one time, but this was because Williston (1911, 1916) figured what is almost certainly a Z. microphthalmus skull (Langston, 1953) in artificial association with long-spined Platyhystrix vertebrae, believing the two to belong to one genus. This has given rise to the erroneous belief that some zatrachydids possessed ‘sails’ of pelycosaurian type on their backs. The affinities of Platyhystrix, which did have a ‘sail’, are uncertain, and are irrelevant to the present topic; for a good discussion of them see Langston (1953). The Zatrachydidae have always been considered as rhachitomous labyrinthodonts, and Romer (1947, 1966) placed them in the superfamily Eryopoidea. The dilferences used by Case (1911) to distinguish Dasyceps from Zatrachys will be discussed later. Dasyceps has been brieffy discussed by Romer (1930, 1939, 1945), but a detailed study of it has not been attempted since von Huene (1910) examined it. Some authors (e.g. Romer 1947, p. 172) have suggested that Acanthostomatops, which appears to be a juvenile form, is in fact the larva of Dasyceps. At the same time Romer suggested that Dasyceps and Zatrachys be synonymous, a view also held by Broom (1913). These points will be discussed later. The specimen, an almost complete skull, is in two pieces, part and counterpart. [Palaeontology, Vol. 18. Part 4, 1975, pp. 831-845, pis. 98-99.] 832 PALAEONTOLOGY, VOLUME 18 Much of the skull roof has adhered to one portion, so exposing the ventral surface of the bones with some impressions of their dorsal surfaces. The other portion shows some of the skull roof, but anteriorly a considerable part of the dorsal surface of the palate is exposed. The occiput has at some time been destroyed. Further preparation of the specimen would appear to be impossible owing to its extremely fragile nature, but the thick coat of dark shellac which covered both parts of the specimen, obscuring all detail, has been removed. The skull has been crushed dorso-ventrally but it must in life have been shallow anteriorly and of a moderate depth posteriorly. The skull was found in a quarry close to Kenilworth itself (grid ref. SP 290720) ; the quarry has long been disused and its exact location cannot now be determined. The matrix is a coarse, red, loosely cemented sandstone containing pellets of red clay. The horizon of the specimen is probably Autunian (Paton \91Ab). DESCRIPTION Von Huene (1910) described and figured the specimen fairly accurately, although his plates show that it was then covered by the above-mentioned shellac. The skull is much larger than those of other known zatrachydids, being twice as large as the largest known specimen of Zatrachys; its maximum length is 298 mm and the maxi- mum width is 230 mm. Its general shape, and the arrangement of the bones, is typical of a rhachitomous temnospondyl, as can be seen from text-figs. 1-4 and Plates 98 and 99. Several features of interest are apparent. TEXT-FIG. I. Specimen Gz 42, Dasyceps huckkmdi (Lloyd), showing the ventral surface of the skull roof. Stippled areas indicate where bone is missing. (For abbreviations see p. 837.) TEXT-FIG. 2. Reconstruction of skull roof of Dasyceps bucklancii (Lloyd). (For abbreviations see p. 837.) PATON: PERMIAN AMPHIBIAN FROM ENGLAND 833 The triangular skull is constricted slightly at the level of the maxillary /quadratojugal suture, so that it appears to be swollen across the maxillae. Posterior to this con- striction, the quadratojugals flare outwards in a lateral flange which shows signs of having carried a bony frill at the edge. The quadratojugals also have posterior extensions, which extend further back than the tabular horns. The latter rise to a level somewhat above the rest of the skull surface. The postparietals are unusual in having small posterior extensions; they are not, however, as prominent as was shown in previous reconstructions. This feature has also been seen in ^ Platyhystrix' (Williston 1916), Zatrachys (Broom 1913), and, to a much lesser extent, in Stegops (Romer 1930). The orbits are very small and are situated in the posterior third of the skull. They are elevated above the general skull surface and lie at the apices of two quite sharply defined bony prominences, connected by a transverse ridge 16 mm in front of the pineal foramen. Four other ridges radiate out from each prominence (these are best seen as depressions on the ventral surface of the skull roof). The largest of these extends forward antero-medial to the orbit to the level of the posterior edge of the median nasal vacuity. The other three are of approximately equal size, one extending laterally from the orbit to about the centre of the jugal, another extending posteriorly from the orbit, and the third postero-medially to the middle of the parietal. The height of these prominences and ridges is exaggerated antero-lateral and postero- lateral to the orbit by two depressions: a particularly deep one on the jugal and lachrymal, and a shallower one on the squamosal and jugal, the two being separated by the bony ridges on the jugal. Case (1911) noted similarly situated preorbital depressions in Zatrachys, although they were not at that time known to be present in Dasyceps. Identically positioned ridges and depressions can be seen on the skulls of the terrestrial labyrinthodonts Eryops (Cope 1877) and Peltobatrachus (Panchen 1959). Sawin (1941) has suggested that they were occupied by the trabecular cartilages in life. The nares are small, oval, with their long axes transverse, and lie far back, at the junction of the premaxillae, maxillae, and nasals. Their posterior position is caused by the very great enlargement of the premaxillae, which occupy approximately one- third of the total skull length. The main zones of intensive growth (Bystrow 1935), which determine the adult skull shape, are confined to (i) the premaxillae and maxillae ; (ii) the jugal and quadratojugal; (iii) the tabular horns. There is a lesser zone across the nasals and maxillae just posterior to the nares. There are no signs of these zones posterior to the orbits. The pineal foramen, which is small, is thus situated very close behind the level of the posterior edges of the orbits. Probably the most dominant feature of the skull is the very large median vacuity situated between the premaxillae and the nasals. It is drop-shaped, with the blunt end facing anteriorly, and is 86 mm long and 38 mm wide. The edge of this median nasal vacuity, where preserved, is smooth. The anterior part of the broken palate shows the posterior edge of the median anterior palatal vacuity, which corresponds in position to the dorsal vacuity, although the palatal vacuity is considerably smaller. Only a small part of the dorsal surface of the palate is visible (text-fig. 3), but it shows that the longitudinal elongation of the premaxillae also affected the palate. In addition, the vomers are very large, extending into the posterior half of the skull. This means that the interpterygoid vacuities, although not visible, must be relatively 834 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 3. Specimen Gz 42, Dasyceps bucklandi text-fig. 4. Reconstruction of palate of Dasyceps (Lloyd), showing parts of the palate and skull roof. bucklandi (Lloyd). (For abbreviations see p. 837.) Stippled areas indicate where bone is missing; rest of cranial surface damaged except where ornament is shown. (For abbreviations see p. 837.) very small. Portions of the palatine and ectopterygoid bones can be seen, as well as the posterior palatal extension of the maxilla, which extends back to about the level of the squamosal/quadratojugal suture. The bases of three vomerine tusks can be seen, one on the left side, and two on the right side ; one palatine tusk on each side can be seen just posterior to each choana. The choanae are, in contrast to the external nares, very large— they are oval in shape with the long axis antero-posterior and 38 mm in length, and the transverse axis 24 mm long. Because of the elongation of the anterior part of the snout, they are situated about half-way along the skull. Only a few marginal teeth are preserved, on the left premaxilla and maxilla. The exact number is very difficult to determine because of the fragmentary nature of the specimen in this region, but remains of eighteen teeth and seven sockets are thought to be present in a maxillary length of 149 mm. Most of the teeth are broken off close to the jaw, but two are almost complete. They are situated at the level of the choanae and are 5 mm long, curving slightly inwards while being directed slightly outwards. For their position and the over-all skull size, the teeth are small. The palatal tusks are also relatively small. The dorsal surface of the cranial bones is very poorly preserved, and only a small EXPLANATION OF PLATE 98 Dasyceps bucklandi (Lloyd). Kenilworth. Ventral surface of skull roof, x^. Warwick County Museum, Gz 42. PLATE 98 PATON, Permian amphibian 836 PALAEONTOLOGY, VOLUME 18 part of the ornamentation is intact. It apparently consisted of very small, fairly shallow pits separated by wide ridges which form blunt, upwardly directed points at junctions of two or more ridges, thus giving the bone surface a pustular appearance. A similar slightly pustular type of ornament can be seen in Stegops, "Platyhystrix', and Zatrachys. No trace of any lateral-line system can be seen, and it seems likely that von Huene (1910) was incorrect in figuring parts of it in his reconstruction. The only other member of the family in which this system has been figured is Stegops, and even here there is some doubt about its presence. No other material of Dasyceps bucklandi is known, although part of a rib in the Institute of Geological Sciences, GSM 90490, from the lower Permian of Kenilworth, is labelled as ‘? Dasyceps'. It appears to be a labyrinthodont rib, but is so poorly preserved that further identification is impossible. DISCUSSION Case (191 1) noted the similarities between Dasyceps and Zatrachys, but distinguished between them because of the apparent lack of the deep preorbital pits in Dasyceps, and the apparent absence of the median nasal vacuity in Zatrachys. These features were in fact later found in both genera, and Broom (1913) concluded that the two were congeneric. This conclusion does not appear to have been widely accepted and Romer (1966) still recognized both genera. Langston (1953) has discussed the genus Zatrachys in considerable detail, based upon a study of a large number of specimens of Z. serratus. A cast of one of the best specimens used by Langston was available to the author. Case (1911) suggested that Z. serratus and Z. microphthalmus were conspecific. Langston (1953), however, gives fairly conclusive evidence that they are in fact distinct species. He cites many dif- ferences in the skulls of the two species of Zatrachys, and goes on to list various skull characters in these, and in Dasyceps bucklandi, Acanthostoniatops, and Stegops. A modified version of this table, omitting Stegops and bringing the information on Dasyceps up to date, is given here (Table 1). Some of the points Langston included are left out, as they are considered irrelevant to the discussion on Dasyceps', these are the basal articulation, ossifications in palatal roof, occiput, sclerotic plates, and scutes. This table again emphasizes the differences between Z. serratus and Z. micro- phthalmus. Of the 17 characters listed here, they differ in 9 and agree in 5, while 3 are unknown in one or the other. When Z. microphthalmus is compared with D. bucklandi, there are only 2 differences, 4 unknown characters (the cultriform process in Dasyceps is hypothetical and therefore considered here as an unknown character), and 1 1 similarities. Some of the characters are dependent upon the over-all size of the speci- men, e.g. orbital size, depth of orbital pit, quadratojugal spikes, otic notch depth, size of interpterygoid vacuities. The two features in which D. bucklandi differs from Z. microphthalmus (the narrower otic notch and narrower internasal vacuity) are here considered to be growth factors probably affected by the much larger size of D. bucklandi. That Z. microphthalmus resembles D. bucklandi much more than it PATON: PERMIAN AMPHIBIAN FROM ENGLAND 837 TABLE 1. Comparative osteology of the Zatrachydidae. Modified after Langston (1953). Dasyceps bucklandi Zatrachys microphthalmus Zatrachys serratus A can thostomatops vorax Dorsal outline Acute U-shape, slight Acute U-shape, max. Broad U-shape, no Broad U-shape, no max. exp. exp. max. exp. max. exp. Jaw articln. Post, to occiput Post, to occiput In line with occiput In line with occiput Dermal bone Pits + ridges, low Similar to D. buck- Pits-bridges, pro- Similar to Z. serratus. ornament bosses on ridges landi minent spikes + bosses but less complex Preorb. pit Deep Deeper Deep Shallower L.l.g. Not known Not known Not known Not known Cornua Broad T and PP cornua Broad T and PP cornua Slender T and PP cornua Weak T cornua only QJ spikes Lateral QJ flange and Like D. bucklandi but Many long spikes on 3 spikes on QJ, small postartic. proc. less pronounced QJ and postartic. proc. postartic. proc. Orbits Small, rims elevated Small, rims elevated Slightly larger, rims less elevated Large, rims slightly elevated Nares Small, far posterior Small, posterior Large, posterior Large, more anterior Otic notch Narrow, deep Broad, deep Broad, deep Broad, shallow Median nasal Long, fairly narrow. Shorter, wider, partly Very large, separates Small, hardly separates vacuity partly separates Ns. separates Ns. Ns., partly divides Fs. Same size as nares, post, to nares Ns. Choanae Larger than nares, post, to nares Not known Same size as nares, posterior to nares Interpt. vacuities Widely triangular, very short (?) Widely triangular Widely triangular Widely triangular, relatively large Cultr, proc. ? short, broad Broad, ? longer Short, broad Short, narrow Ant. pal. vac. Large Not known Not known Large Mandible Not known Not known ANG. bSA. ridged, low bosses on ANG. 5 long spines on ANG. Dentition Marginal teeth small. Marginal teeth small. Marginal teeth small. Marginal teeth small. 3 tusk pairs tusk pairs not known 3 tusk pairs 3 tusk pairs Abbreviations used in text-figures and in Table 1 ANG angular PO postorbital ant. pal. vac. anterior palatal vacuity postartic. proc. postarticular process ch choana PP postparietal cultr. proc. cultriform process preorb. pit preorbital pit ECT ectopterygoid PRF prefrontal F frontal PSP parasphenoid interpt. vac. interpterygoid vacuity PT pterygoid J jugal p.t. palatal tusk L lachrymal Q quadrate l.l.g. lateral line groove QJ quadratojugal max. exp. maxillary expansion r.o. ridges around orbit MX maxilla SA surangular N nasal SM septomaxilla P parietal SQ squamosal p.a.p.v. position of anterior palatal vacuity ST supratemporal PF postfrontal T tabular PL palatine V vomer PMX premaxilla 838 PALAEONTOLOGY, VOLUME 18 Zatrachys serratus Cope, after Langston (1953). /, ‘Platyhystrix' (probably Dasyceps microphthalmus), after Williston (1911). g, ^Zatrachys' microphthalmus Cope, after Broom (1913). h, Dasyceps bucklandi (Lloyd). resembles Z. serratus can also be seen quite clearly from text-fig. 5. The positions of the various sutures in Z. microphthalmus and D. bucklandi are very similar (although Broom’s 1913 figure of the former shows a large lachrymal and small jugal, the suture between these bones is dotted in, so presumably there is some doubt about its position). The tabular meets the squamosal, excluding the supratemporal from the otic notch, only in Z. microphthalmus and D. bucklandi. Since the differences between Z. serratus and Z. microphthalmus are of a much greater order than those between Z. microphthalmus and D. bucklandi, it is felt that this confirms Broom’s (1913) decision that the latter two species belong to the same genus. The name of Dasyceps Huxley, 1859 antedates that of Zatrachys Cope, 1878 and Z. microphthalmus must therefore become a species of Dasyceps, D. micro- phthalmus. It was thought advisable to retain this as a distinct species, separate from D. bucklandi, because of the poor illustrations of D. microphthalmus, the imper- fections of the specimen of D. bucklandi, and the difference in size between the specimens. Langston (1953) considered that it would serve no useful purpose to synonymize Zatrachys and Dasyceps. This is not the case, if only from a stratigraphical point of view. The presence of two very closely related, possibly even conspecific, forms, one in North America and the other in England, provides yet more evidence for the lower Permian age of the Kenilworth Breccia and for the proximity of the two countries at this time. EXPLANATION OF PLATE 99 Dasyceps bucklandi (Lloyd). Kenilworth. Part of dorsal surface of skull roof and palate, xf. Warwick County Museum, Gz 42. PLATE 99 PATON, Permian amphibian 840 PALAEONTOLOGY, VOLUME 18 Z. serratus shows so many differences from the two species of Dasyceps that it is considered necessary to retain it in a separate genus. The other point put forward by previous authors is the possibility of Acantho- stomatops being the juvenile form of Dasyceps. Probably the most complete growth series known in fossil Amphibia is that shown by the skull of Benthosuchus sushkini (Bystrow and Efremov 1940; Westoll 1950) in which most stages between skull lengths of 30 mm and 600 mm are known. The development of the fairly elongated skull can be seen easily when specimens of different sizes are reduced to a standard width (Westoll 1950, fig. 26). A similar diagram has been produced for some growth stages of Acanthostomatops, and for the skulls of D. bucklandi, D. microphthalmus, and Z. serratus (text-fig. 5). From this diagram it can be seen that 'Platyhystrix' (almost certainly a badly preserved skull of D. microphthalmus) and D. micro- phthalmus are only slightly larger than the largest known specimen of Acantho- stomatops and that there are substantial differences between the two forms in the skull shape and in the positions of bones. Other dilferences are apparent from Table 1 . The skulls of D. microphthalmus and D. bucklandi, however, although very different in size, are very similar in shape and bone arrangement. Thus it seems most unlikely that Acanthostomatops can be the larva of either species of Dasyceps. However, a different picture emerges when Acanthostomatops and Z. serratus are compared. Even the largest specimens of Acanthostomatops are believed to be juvenile, and no true adult of this genus is known (Romer 1947; Langston 1953). The converse is true of Z. serratus; many specimens are known, all are of similar size and all are undoubtedly adults. Langston (1953, p. 396) states that ‘this suggests that near adulthood was attained elsewhere, but nothing is known of the habitat’. The skull width of the largest known Acanthostomatops specimen is 92 mm measured across the quadratojugals, while that of the smallest Z. serratus is approximately 117 mm. It can be seen from Table 1 that, in a comparison between these two forms, there are 1 1 similarities, 5 differences, and 1 unknown character. The only significant difference between them is the apparent absence of the anterior palatal vacuity in Z. serratus. Other differences (i.e. no postparietal cornua, small internasal vacuity, short premaxillae and therefore more anteriorly placed nares, shallower otic notch) are features which are likely to be associated with growth. Since juveniles of Z. serratus are unknown, it is obvious that its larval stages grew and metamorphosed elsewhere— perhaps this was a mechanism to prevent possible cannibalism by the adults. Equally, no adults of Acanthostomatops are known, therefore metamorphosis occurred else- where and the adult form inhabited a different environment. Because of this and the many similarities between Acanthostomatops and Z. serratus, it is suggested that the former is the juvenile form of Z. serratus. It would appear that, just before meta- morphosis occurred, the juvenile migrated and only moved to the adult habitat after it had reached a definite size. A possible reason for the large and relatively rapid increase in size of the median nasal vacuity at metamorphosis is given later (p. 844). It is not suggested that the juvenile Z. serratus migrated the considerable distance which would separate Niederhasslich and New Mexico even when the effects of continental drift are taken into account and the two placed on a single Laurasian continent. It is merely thought to indicate that Z. .serratus was fairly widespread over the whole of Laurasia (see later, p. 843), but that larva and adult, inhabiting different PATON: PERMIAN AMPHIBIAN FROM ENGLAND 841 environments, would have been preserved under differing conditions, and therefore would not have been preserved together. Z. serratus Cope, 1878 has priority over A. vorax (Credner, 1883) so the species remains Z. serratus. The apparent absence of the anterior palatal vacuity in the adults of Z. serratus is most surprising in view of its large development in other members of the family. Langston (1953) has indicated that a very small vacuity might perhaps be present in the adult Z. serratus. He states, however, that the vomer is not usually preserved and is in no case intact, so there is possibly some doubt about this point. The author (1974a) has suggested that minor differences in the normal labyrintho- dont ornamentation pattern of pits and ridges may be of taxonomic value, and it is therefore interesting to note that the patterns found in the four groups discussed above fall into two distinct types. That in Dasyceps bucklandi and D. microphthalmus consists of very small, shallow pits separated by wide ridges which have low bosses on them at their junctions. Langston (1953) describes that of the adult Z. serratus as having prominent spikes and bosses superimposed on the ridges, which also appear to be wide, separating small, shallow pits. He states that the ornament of ‘‘Acantho- stomatops' is very similar to that of Z. serratus but is less complex. This is what would be expected, as Bystrow and Efremov (1940) have shown that the juvenile pattern of dermal bone ornamentation is less complex than that in the adult. This division of the ornament into distinct groups confirms the conclusions reached above that D. buek- landi and D. microphthalmus are closely related, as are Z. serratus and 'Acantho- stomatops\ the two groups being separate. Normal rhachitomous vertebrae are found in all the genera of Zatrachydidae (the vertebral structure of D. bucklandi is unknown, but there can be little doubt that it too was rhachitomous). Stegops is the earliest zatrachydid known but is considered to be too aberrant to be ancestral to other members of the family, and Milner (pers. comm.) suggests that it constitutes a separate family of specialized early dissorophoids. The ancestry of the Zatrachydidae is unknown, but it seems probable that it was derived from an early edopoid. It was included by Romer (1966) in the superfamily Eryopoidea and it is not proposed to remove it from this superfamily, which contains many widely divergent families and which is probably a polyphyletic assemblage of advanced rhachitomes. SYSTEMATIC PALAEONTOLOGY OF THE ZATRACHYDIDAE Order temnospondyli Superfamily eryopoidea Family zatrachydidae for family diagnosis see Langston (1953) Genus dasyceps Huxley, 1859 Zatrachydids with acutely U-shaped skulls showing slight expansion across maxillae; large median nasal vacuity; premaxillae much expanded antero-posteriorly; nares far posterior; orbits small, in posterior third of skull, with rims much elevated; pro- nounced lateral and posterior flanges on quadratojugal ; tabulars broad; small M 842 PALAEONTOLOGY, VOLUME 18 postparietal process; supratemporal excluded from otic notch; ornament of pits and ridges but with low bosses on the ridges; jaw articulation posterior to occiput. Dasyceps bucklandi (Lloyd) 1850 Labyrinthodon bucklandi lAoyd, p. 56. Very large zatrachydid with drop-shaped median nasal vacuity; orbits and nares relatively very small ; laehrymal excluded from both orbit and naris. Dasyceps microphthalmus (Cope) 1896 Zatrachys microphthalmus Cope, p. 436. Small zatrachydid with oval median nasal vacuity; lachrymal excluded from naris but not from orbit; quadratojugal flanges less pronounced than in D. bucklandi. Genus zatrachys Cope, 1878 1878 Zatrachys serratus Cope, p. 523. Zatrachys serratus Cope Small zatrachydids with broad U-shaped skulls; no maxillary expansion; very large median nasal vacuity in adult ; premaxillae with moderate antero-posterior expansion ; nares slightly posterior and large; orbits small, in posterior half of skull, with slightly elevated rims; lachrymal forms part of orbital border; quadratojugal flanges orna- mented with long spikes; tabulars narrow; small postparietal process present in adult; supratemporal forms part of edge of otic notch; ornament of pits and ridges with prominent spikes and bosses on ridges; jaw articulation in line with occiput. MODE OF LIFE Dasyeeps and Zatrachys have always been considered as aquatic forms. The reason for this is not clear and it seems possible that at least one species of Dasyceps was terrestrial. Lateral-line grooves seem to be unknown in Dasyceps and Zatrachys, and the skull appears to have been protected by an outstanding bony frill on the postero- lateral edges; this was probably present in all members of the family but is not often preserved complete. Such a bony frill would seem to be a distinct disadvantage to a purely aquatic animal, as it would impede its progress through the water. In addition, the skull shape, shallow anteriorly but moderately deep posteriorly and with ridges radiating outwards from the orbits, is very similar to that found in known terrestrial labyrinthodonts such as Eryops and Peltobatrachus. Advanced procolophonids and the pareiasaurs, particularly Elginia, which were certainly terrestrial, also had spiny edges on the posterior margins of the skull. Similar spines are found in present-day lizards, e.g. Moloch horridus and Phrynosoma, where their function may be camouflage as they break up the skull outline (Walker, pers. comm. ; Langston 1953). Thus from an anatomical point of view it seems likely that Dasyceps and Zatrachys were terrestrial forms. This view is confirmed by the nature of the sediments in which D. bucklandi PATON: PERMIAN AMPHIBIAN FROM ENGLAND 843 occurs. The Kenilworth Sandstone or Breccia is a coarse, red, terrestrial deposit of lower Permian (Autunian) age (Hains and Horton 1969; Paton 1974^). These deposits are almost barren, the only other fossils known being three genera of pelycosaurs (Paton 1974^?), a species of the conifer Lebachia (Walchia) (Hains and Horton 1969), and some reptilian and amphibian footprints (Haubold 1970, 1971, 1972). Thus D. bucklandi occurs in deposits of terrestrial origin and in association with a com- pletely terrestrial fauna and flora. It therefore seems most unlikely that the species was aquatic. Anatomical similarities in the skulls of D. bucklandi, D. microphthalmus, and the adults of Z. serratus indicate that all three were probably terrestrial. Milner and Panchen (1973) suggest that terrestrial animals were able to move freely over the single continent of Laurasia during the lower Permian while a partial barrier seems to have separated the aquatic tetrapods of the eastern and western parts of the super- continent. If, as suggested here, D. bucklandi and D. microphthalmus, and Z. serratus and ' Acanthostomatops' form two genera, the fact that the members of these two genera are found widely apart on what was the Laurasian continent is added evidence for their being considered terrestrial. This leads to a consideration of the function of the relatively enormous median nasal vacuity found in all zatrachydids except Stegops. The occurrence of a very small interpremaxillary foramen is widespread among labyrinthodonts, and it is generally accepted that this foramen was connected to a mucus-producing gland which had another opening into the mouth in the anterior palatal vacuity. The mucus pre- sumably lubricated the edges and inside of the mouth, and it has also been suggested that it may have functioned either to attract prey or to repel predators (see Langston 1953). In all cases the interpremaxillary foramen is situated wholly between the pre- maxillae and is in the vertical overhang of these bones above the mouth— a position whence gravity would aid the mucus to run downwards to the mouth. This is not the case in Dasyceps. The vacuity is situated between the premaxillae and nasals, is very large, and lies horizontally on the dorsal surface of the snout. The anterior palatal vacuity is positioned directly below it but is considerably smaller, its position relative to the median nasal vacuity is shown in text-fig. 2. The appearance of the two vacuities suggests that they were in fact confluent in life. Confluent fora- mina between snout and palate are known, for example in Mastodonsaurus where they accommodate the relatively enormous symphysial tusks of the lower jaws. This is obviously not their function in Dasyceps. While it is possible that a small part of the vacuity may still be glandular in function, it seems most unlikely that such an enormous area could be given over entirely to mucus production. Assuming that Dasyceps was terrestrial, sueh vast quantities of mucus spilling on to the skull surface would cause considerable evaporation and consequent heat loss, and thus might be disadvantageous. D. bueklandi probably inhabited a fairly hostile environment. Its teeth are not large and suggest a diet of small, fairly inactive animals. But it in turn may have been hunted by predators including the large carnivorous pelycosaur Sphenacodon britannicus which occurs at the same locality near Kenilworth. In common with other large terrestrial labyrinthodonts, it was probably a ponderous animal which would have to rely upon forms of protection other than a speedy retreat. No postcranial material is associated with D. bucklandi but evidence (admittedly poor) from the 844 PALAEONTOLOGY, VOLUME 18 Other species of zatrachydids suggests that little armour was present on the body. The skull, however, possesses a prominent bony frill around the posterior edge which may have helped to camouflage the animal but which, in view of its size, also suggests that the head could be used as a means of defending the whole animal. For this reason it is very tentatively suggested that the large median nasal vacuity which is thought to connect directly with the mouth may have been the site of an expandable sac which could be inflated as an aggressive defence mechanism. The anterior palatal vacuity, situated directly below and approximately in the centre of the median nasal vacuity, but being much smaller, may have been the site of a valve which could cut off the inflated sac from the mouth, thus enabling it to remain inflated independent of respiration. This suggestion may appear unlikely at first sight, but such forms of defence mechanisms occur in modern amphibians and reptiles and are known to deter relatively large predators very effectively (see references in Cott 1940). It is also possible that the throat could be inflated as in some modern frogs and the resultant apparent increase in size combined with the visual effect of the bony frill round the skull would probably be quite effective as a psychological deterrent. The bony frill and internasal vacuity are relatively undeveloped in the juvenile Zatrachys serratus although their development can be traced in the larger specimens. If the functions for these structures suggested above are correct, they would of course be unnecessary in the aquatic larval form, although the median nasal vacuity would probably be glandular at this time. Acknowledgements. I wish to thank Dr. A. D. Walker most sincerely for his continued help throughout this work, and for his constructive criticisms of the manuscript. I am also grateful to Dr. S. M. Andrews for reading the manuscript and for helpful suggestions, and Dr. A. R. Milner for useful discussions. I wish to thank Miss J. Morris, Dr. W. Allen, and the Trustees of Warwick County Museum for their help and permission to borrow and study Dasyceps bucklandi, and Mr. D. E. Butler of the Institute of Geological Sciences, London, for the loan of specimens. REFERENCES BROOM, R. 1913. Studies on the Permian temnospondylous stegocephalians of North America. Bull. Am. Mus. not. Hist. 32, 563-596. BYSTROW, A. p. 1935. Morphologische Untersuchungen der Deckknochen des Schadels der Wirbeltiere. I Mitteilung. Schadel der Stegocephalen. Acta zool. Stockh. 16, 65-141. and EFREMOV, j. A. 1940. Benthosuchus sushkini Efr., a labyrinthodont from the Eotriassic of the Sharzhenga River. Trudy Paleozool. Inst. 10, 1-152. [Russian, English summary.] CASE, E. c. 1911. Revision of the Amphibia and Pisces of the Permian of North America. Pubis. Carnegie Instn, 207, 1-176. COPE, E. D. 1877. Descriptions of extinct Vertebrata from the Permian and Triassic formations of the United States. Proc. Am. phil. Soc. 17, 182-193. 1878. Descriptions of extinct Batrachia and Reptilia from the Permian formation of Texas. Ibid. 505-530. 1896. The reptilian order Cotylosauria. Ibid. 34, 436-456. COTT, H. B. 1940. Adaptive Colouration in Animals. 508 pp., 48 plates. London. CREDNER, H. 1883. Die Stegocephalen aus dem Rothliegenden des Plauen’schen Grundes bei Dresden. IV Theil. Z. dt. geol. Ges. 35, 275-300. HAiNS, A. and HORTON, A. 1969. British Regional Geology— Central England. H.M.S.O. London. HAUBOLD, H. 1970. Versuch einer Revision der Amphibien-Fiihrten des Karbon und Perm. Freiberger ForschHft. 260, 83-117. PATON: PERMIAN AMPHIBIAN FROM ENGLAND 845 HAUBOLD, H. 1971. Die Tetrapodenfahrten aus dem Permosiles (Stefan und Rothliegendes) des Thiiringer Waldes. Abh. Ber. Mus. Nat. Gotha, 15-41. 1972. Panzerabdriicke von Tetrapoden aus dem Rothliegenden (Unterperm) des Thiiringer Waldes Sonderdruck aus Geologie. Akad.- Verb Berlin, 21, 110-115. HUENE, E. VON. 1910. Neubeschreibung des Permischen Stegocephalen Dasyceps bucklandi (Lloyd) aus Kenilworth. Geol. paldont. Abh. 8, 325-338. HUXLEY, T. H. 1859. On Dasyceps bucklandi {Labyrinthodon bucklandi Lloyd). Mem. Geol. Surv. U.K. 1859, 52-56. KUHN, o. 1961. Die Familien der rezenten und fossilen Amphibien und Reptilien. Bamberg. LANGSTON-, w. 1953. Permian amphibians from New Mexico. Univ. Calif. Publ. geol. Sci. 29, 349-416. LLOYD, G. 1850. On a new species of Labyrinthodon from the New Red Sandstone of Warwickshire. Kept. Br. Assoc. Adv. Sci. 19, 56-57. MILNER, A. R. and PANCHEN, A. L. 1973. Geographical variation in the tetrapod faunas of the Upper Car- boniferous and Lower Permian. In tarling, d. h. and runcorn, s. k. (eds.). Implications of Continental Drift to the Earth Sciences, vol. 1. London, Academic Press, pp. 353-368. MOODiE, R. L. 1909. Carboniferous air-breathing vertebrates of the U.S. National Museum. Proc. U.S. nat. Mus. 31, 11-28. PANCHEN, A. L. 1959. A ncw armoured amphibian from the Upper Permian of East Africa. Phil. Trans. R. Soc. B 242, 207-281. PATON, R. L. 1974u. Capitosauroid labyrinthodonts from the Trias of England. Palaeontology, 17, 253-290. 19746. Lower Permian pelycosaurs from the English Midlands. Ibid. 541-552. ROMER, A. s. 1930. The Pennsylvanian tetrapods of Linton, Ohio. Bull. Am. Mus. nat. Hist. 59, 77-147. 1939. Notes on branchiosaurs. Am. J. Sci. 237, 748-761. 1945. The late Carboniferous vertebrate fauna of Kounova (Bohemia) compared with that of the Texas Red Beds. Ibid. 243, 417-442. 1947. Review of the Labyrinthodontia. Bull. Mus. comp. Zool. Harv. 99, 1-352. 1966. Vertebrate Paleontology. (3rd edition) Chicago, University Press. 468 pp. SAWIN, H. J. 1941 . The cranial anatomy of Eryops megacephalus. Bull. Mus. comp. Zool. Harv. 86, 407-463. STEEN, M. c. 1937. On Acanthostoma vorax Credner. Proc. zool. Soc. Lond. B 107, 491-500. WESTOLL, T. s. 1950. In ‘A discussion on the measurement of growth and form.’ Proc. R. Soc. Lond. B 137, 490-509. WILLISTON, s. w. 1911. American Permian Vertebrates. Chicago, University Press. 145 pp. 1916. Synopsis of the American Permo-Carboniferous Tetrapoda. Contr. Walker Mus. 1, 193-236. ROBERTA L. PATON Department of Geology Royal Scottish Museum Chambers Street Edinburgh, EH 1 IJE Original typescript received 22 November 1974 Revised manuscript received 17 February 1975 A ' , 0 . VI ' ^ 'V* ■'■' ^ j^<- # i = . ■ ', ' <:• i ■-. . T '■) '■■ = '•■'''■‘’4V>V -■ -r' ! ^.'.f t-' . '-0' ■ -* ■- •■'V^’4'ife^>''v‘'*k'«i!;l<^ •’■'■ '■ • ,: Vf’i" ■iVI‘f-iy>v5?'.'i. “•.#)! ■ ' ,v* ’.’ .y„ ^ ^^5^. <■' . "; -At. ^ :. ■ : ' ' Sf es- . ')6.4iyrtv*. I I ,.., , .' If-- .«>.>. • ■' : -’ >V;t. 1 '»■!/' I ' ' ‘I >1 ■■ - ’ m ►vv '■'5 ■‘■^' r^it ' l!t '%■ *'-im 'w '' A REVISION OF THE TRIASSIC TO LOWEST JURASSIC DINOFLAGELLATE RHAETOGONYA ULAX by R. HARLAND, S. J. MORBEY and W. A. S. SARJEANT Abstract. A re-evaluation of the dinoflagellate cyst genus Rhaetogonyaulax shows it to have a complex tabulation of 4'-?6', 5a-?6a, lav, 7", 7c, 7'", Ip, Ipv, 3s, 3'"'. The archaeopyle is shown to be developed by loss of the epitract anterior to the precingular plate areas. In consequence of recognition of the high degree of intraspecific variability, all specimens examined are attributed to the single species R. rhaetica', the former species R. chaloneri is recognized as an extreme in the morphological range and reduced to varietal status. One of the authors (S. J. M.), in his research on the Rhaetic Formation (Morbey and Neves 1974, p. 161) of a borehole at Bunny Hill, Nottinghamshire, and the Rhaetian Stage of the Kendelbachgraben, Austria, encountered dinoflagellate cysts attributable to the genus Rhaetogonyaulax Sarjeant, 1966. Since the holotypes of the two species of this genus (including the type species) were lodged with H.M. Geological Survey, now the Institute of Geological Sciences, a request was made to I.G.S. for permission to study the type material, which was located, remounted, and re-examined. In addition, it was decided to supplement the types by processing topotype material from a sub-sample of the original rock specimen. Normal palyno- logical processing techniques were used and a total of thirty-eight single grain mounts were made, together with several strew mounts. The type material and topotype material, together with other specimens from other localities under investigation by S. J. M., are used here in a reconsideration of the genus. The two described species of Rhaetogonyaulax have a particular significance in dinoflagellate studies, since they are among the oldest undoubted dinoflagellate cysts known. They have in consequence figured in many discussions of dinoflagellate evolution (see Wall and Dale (1968, p. 288), Sarjeant in Erdtman (1969, p. 179), Evitt in Tschudy and Scott (1969, p. 462), and Evitt (1970, p. 31)). HISTORICAL BACKGROUND In 1963 W. A. S. S. described two new species of dinoflagellates that had been dis- covered, initially by Professor W. G. Chaloner, during a palynological study of H.M. Geological Survey Stowell Park Borehole. The specimens were encountered at a depth of 2059 ft 2 in (627-63 m) in Rhaetic (Upper Triassic) strata. Their tabulation, which is poorly developed, was interpreted as being of a relatively simple character, according with that of the living motile genus Gonyaulax\ in consequence, though they were from the outset recognized to be cysts, they were named G. rhaetica and G. chaloneri. The holotypes were deposited by W. A. S. S. in the collections of H.M. Geological Survey. Archaeopyle formation was said to have taken place ‘by breakage immediately anterior to, and not along, the transverse furrow’ (Sarjeant 1963, p. 353). [Palaeontology, Vol. 18, Part 4, 1975, pp. 847-864, pis. 100-104.] PALAEONTOLOGY, VOLUME 18 Sarjeant, in Davey et al. (1966), reviewing cysts with a Gonyaulax-iy^Q tabulation, erected the new genus Rhaetogonyaulax to accommodate the species R. rhaetica and R. chaloneri, arguing that, although they possessed a gonyaulacacean tabulation, they were spindle-shaped and had an epitractal archaeopyle. This is in marked con- trast to Gonyaulacysta (Deflandre) Sarjeant, the genus to which most fossil species formerly attributed to Gonyaulax had by then been referred; this latter genus had been diagnosed as being spheroidal, ovoidal, or polyhedral with a single-plate precingular archaeopyle. Unfortunately, the transference of the two species to the genus Rhaetogonyaulax did not conform to Article 33 of the International Code of Botanical Nomenclature (Lanjouw et al. 1966), since their basionyms were not clearly indicated; Loeblich and Loeblich (1968) rectified the position for Gonyaulax rhaetica and subsequently Sarjeant, in Davey etal. (1969), did likewise for G. chaloneri. The original studies of these cysts were made with a monocular petrological micro- scope, with a maximum attainable magnification of X 800 and relatively low intensity of illumination. The new studies here reported have taken full advantage of the improvements in microscope technology since 1963. The work was done using a Vickers microscope, Gillet and Sibert and Leitz photomicroscopes equipped for phase-contrast work, and a Zeiss photomicroscope equipped for both phase-contrast and Nomarski-interference contrast work. In addition, specimens were mounted for scanning-electron photomicrography. The morphology of this genus is one of especial complexity. It was early recognized that the original interpretation of the tabulation was greatly oversimplified and that archaeopyle formation was by schism between plates, not across plates as had originally been believed. Moreover, difficulty was encountered in assigning speci- mens to the two species originally proposed by Sarjeant. The results of our restudy of the genus are presented below. GENERIC RECONSIDERATION Introduction It has become increasingly apparent in dinoflagellate taxonomy that one of the principal criteria in any systematic scheme is the form and method of archaeopyle formation (Wall and Dale 1969, p. 287). Evitt (1967) has suggested, for instance, that EXPLANATION OF PLATE 100 All figures at a magnification of x750 and in plain light unless otherwise stated. Figs. 1-6. Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend. 1, dorsal view of specimen MPK 805. On the epitract plates 4", 5", and 4a are most readily seen; on the hypotract, plate 5"'. Cingular plate 4c is also well shown ; all other reflected plates are not in clear focus. Nomarski interference contrast xc. 1200. 2, ventral view of MPK 805. Only the hypotract is in focus showing plates 6"', T", 2'”', and 3"", together with 7c and the median sulcal plate. Nomarski interference contrast X c. 1 200. 3-6, holotype, specimen 1, PF 1983. 3, dorsal view. 4, ventral view. 5, dorsal view showing the antapical horn, the initial separation of one of the intercalary plates (?5a). Phase contrast. 6, ventral view showing some of the intercalary plates and the suture between those and the apical plates. Nomarski interference contrast. Figs. 7-8. Holotype of Rhaetogonyaulax rhaetica (Sarjeant) var. chaloneri stat. nov, specimen 2, PF 1983. 7, oblique dorsal view showing the reticulate ornamentation and sutures between precingular and inter- calary plates. 8, oblique ventral view showing antapical horn and some precingular plates. PLATE 100 HARLAND et a!., Rhaetogonyaulax 850 PALAEONTOLOGY, VOLUME 18 archaeopyle type or form should be used in circumscribing taxa at the generic level, though it should be noted that Wall, Dale and Harada (1973) have demonstrated some variation in archaeopyle form in Lingulodinium, a Cainozoic genus. Wall and Dale (1968, table 2) included Rhaetogonyaulax with genera possessing an apical archaeopyle, whereas Evitt (1967) regarded the genus as having an AP combination archaeopyle, i.e. one in which all plates of the apical and precingular series were lost. Archaeopyle formation and reflected tabulation Detailed examination of cysts with archaeopyles shows that the margins left, after the operculum has been shed, are regular in form and show a consistent ‘scalloping’ (PI. 101, figs. 5, 6 and PI. 102, figs. 2, 3). This does not accord with the cross-plate schism originally visualized by Sarjeant (1963), which is in any case without parallels in other genera; instead, it indicates that separation has taken place along the boundary between two reflected-plate series. There is a distinct sulcal notch which enables ready orientation of such specimens, and seven precingular plates, of very meagre dimension, are shown to be present between cingulum and archaeopyle margin. Some specimens appear to show only six precingular plates together with a doubtful area around the sulcus (PI. 101, figs. 5, 6). We believe that the stereoscan photomicrographs demonstrate the presence of seven precingular plates, the sulcal area lying immediately to the right of reflected plate \ " (see especially PL 102, fig. 3). A particular feature of this plate series is the prominent \" plate. Text-fig. 1a, b TEXT-FIG. 1 . A, B, a semidiagrammatic sketch of Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend, showing complete archaeopyle development, particularly the prominent 1" reflected plate and the scalloped suture on the dorsal surface. A~ventral surface, b— dorsal surface, c, an interpretative semi- diagrammatic drawing of the ventral surface of the holotype of Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend, showing the tabulation where discernible. The dorsal surface of the specimen is not shown, as no clear tabulation could be seen on that surface. (For abbreviations, see legend to text- fig. 2.) HARLAND ET AL.: DINOFL AGELL ATE RH AETOGONYAU LAX 851 gives a diagrammatic representation of a fully ruptured cyst of Rhaetogonyaulax showing the precingular plate series. In certain of the specimens studied (e.g. PI. 103, figs. 1-3), some plates anterior to the precingular series are still attached to the abandoned cyst. This might result from chance damage only; but we consider it much more probable that this is evidence that the archaeopyle is developed by successive loss of opercular pieces, not by the complete apical third of the cyst being simultaneously thrown off. The recovery of complete apices with four definite (possibly six) apical plates still present, quite separate from the anterior intercalary plates (PI. 103, fig. 4, and PI. 104, fig. 9), supports this concept. The plates posterior to the apical series and anterior to the precingular series, five or six in number, appear to form a complete ring surrounding the epitract. However, we do not consider them truly analogous to the anterior circle plates of Egmonto- dinium (see Gitmez and Sarjeant 1972), since their position is rather on the flanks of the cyst than on its anterior surface. One of the authors (Morbey 1975) has pro- posed the term ‘postapical plates’ for a similarly positioned plate series in another genus. For the moment, however, we have preferred to follow Wiggins (1973) by designating these plates as ‘intercalary plates’. We believe that the archaeopyle begins to develop by initial splitting along the margins of some of the reflected intercalary plates (PI. 103, fig. 13; PI. 104, figs. 1-3). One or more intercalary plate-areas separate from each other and from the cyst, leaving the cyst otherwise intact. Further splitting results in the progressive loss of the remaining intercalary plate-areas, the apex as a unit, the anterior ventral and anterior sulcal plates ; the order of these events has not yet been definitely determined, but it seems likely that the apex and sulcal plates are the last to detach. The holotype of R. rhaetica shows initial separation of one of the intercalary plates (PI. 100, fig. 5; text-fig. Ic), and other specimens have been observed in which the only discernible rupture is between the apical and intercalary plates. Although several detached apices have been found (see above), none show any surviving attachment to the anterior ventral and anterior sulcal plates; the latter, if they separate (as seems probable), would be so small as to be difficult to identify as such. The reflected tabulation of Rhaetogonyaulax is extremely difficult to observe on complete specimens, including the holotypes, whose orientation is consequently often indeterminate. Indeed, the original photographs of the holotypes of R. rhaetica and R. chaloneri are inverted, as are the specimens illustrated by Orbell (1973) and Fisher (1972^). Some suture lines are occasionally evident, and in some cases the plate boundaries are defined by partially or incompletely developed rows of ‘orna- ment’. Plate areas are most readily to be observed after complete or partial rupture, especially on the epitract. The hypotractal tabulation is especially difficult to decipher clearly, as evidenced in the stereoscan photomicrographs. The interpretation here presented was arrived at only after some weeks of study by one of us in particular (W. A. S. S.), of specimens by Nomarski-interference contrast, in which it proved possible laboriously to trace the plate boundaries (PI. 100, figs. 1, 2; PI. 101, figs. 1, 2). Even after this study, some doubt concerning the tabulation exists. In particular, a rupture line has been observed on some specimens, perhaps separating off a poly- gonal platelet at the apical end of plate \" (see text-fig. 1a). It is also possible that 852 PALAEONTOLOGY, VOLUME 18 additional posterior intercalary plates may be developed (see text-fig. 2d). Some degree of variation in plate shape is also apparent, as seen especially in the most prominent and easily recognizable plate, I" (see text-figs. 1 and 2; PI. 101, figs. 6, 12; PI. 102, fig. 2; and PI. 103, figs. 7, 9). The tabulation inferred is of great complexity, according neither with the gonyaula- cacean lineages nor the peridiniacean lineages of Wall and Dale (1968). There is, however, close accord with the tabulation of the Upper Triassic dinoflagellate SImblikodinium Wiggins, 1973, which likewise has 4-6 apical plates lost together with a complete series of ‘intercalary’ plates in archaeopyle formation, and has a hypotract with three antapical plates. The two genera, though differing in symmetry and in other tabulation details, are quite evidently closely related and may represent an ancestral stock from which the two named lineages diverged. In fact, any residual differences in tabulation are probably a result of two subjective interpretations. The long-ranging genus Pareodinia Deflandre, whose tabulation has not yet been fully determined but is known to be complex, may be a persistent representative of this ancestral stock. Variability It is apparent that there is a great deal of variability in many aspects of the mor- phology of Rhaetogonyaulax. The cysts are typically spindle-shaped but vary in outline from slender and elongate to broad and squat (see Pis. 103 and 104); speci- mens have been seen which appear to show the presence of an incipient second antapical horn (see PI. 104, figs. 2, 5). Although this may be of some significance, the authors wish to reserve further comment at this time. In addition, specimens have been observed, typically from the Swabian Facies and the Limestone Li tliodendron (Group VI), Kendelbachgraben, Austria, which show only rudimentary antapical horn development (PI. 103, figs. 1, 2). The nature of the cyst ‘ornamentation’ is such that specimens may carry variously EXPLANATION OF PLATE 101 All figures at a magnification of x 750 and by Nomarski interference contrast unless otherwise stated. Figs. 1-2, 5-12. Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend. 1, dorsal view of MPK 806 showing a prominent cingulum, plates 2", 3", and 4" on the epitract and plates 2'" and 3"' and the edge of plates \"' and Ip and the antapical plates 2"" and 3""; compare with text-fig. 3a. xc. 1200. 2, ventral view of MPK 807, showing plates ?5a, ?6a, lav, la, and 2a on the epitract and plates L", Ip, and Ipv on the hypotract, compare with text-fig. 3c. Plain light xc. 1200. 5, specimen MPK 804, in dorsal view showing the ‘scalloping' and precingular plates 4", 5", and 6". 6, specimen MPK 804, in ventral view showing the sulcus and prominent 1". 7, specimen MPK 803, ventral view showing some intercalary and postcingular plates together with a broad sulcus and plate bounding granular ornamentation on hypotractal plate 2"'. 8, specimen MPK 802, oblique ventral view showing apical and intercalary plates. Plain light. 9, specimen MPK 802, oblique ventral view. 10, specimen MPK 802. oblique dorsal view showing the antapical horn. 1 1, specimen MPK 809, dorsal view showing broad cingulum. Plain light. 12, specimen MPK 809, ventral view showing prominent 1 ", as and 7" plates. Compare with fig. 6 for variation in plate shapes. Plain light. Figs. 3-4. Rhaetogonyaulax rhaetica (Sarjeant) var. ehaloneri stat. nov. 3, holotype in oblique ventral view showing the ornamentation. Phase contrast. 4, holotype in oblique dorsal view showing lack of orna- mentation on the cingulum. PLATE 101 HARLAND et ai, Rhaetogonyaulax 12 854 PALAEONTOLOGY, VOLUME 18 developed elements, i.e. spinelets, granules, and/or bacules. The elements of the ‘ornamentation’ (i.e. granules-spinelets) possess tapered or expanded stems and truncate, furcate, or rounded terminations; a reticulation and a microgranulation may also be developed. Any one specimen may carry several types of such abbreviate ‘processes’, in addition to being rough- or smooth- walled. (The holotype of R. chaloneri (PI. 100, figs. 7, 8, and PI. 101, figs. 3, 4) carries both a reticulation and granules and spinelets.) Occasionally, forms may occur which are more or less completely smooth- walled and virtually devoid of ‘ornament’ (PI. 103, fig. 12). The ‘ornamentation’ is so disposed that the cingulum may, for instance, be devoid of ‘ornament’ (PI. 102, fig. 2) or may not differ in ornamentation from that on the epitract or hypotract (PI. 102, fig. 1). The ‘ornamentation’ occurs in the form of random or orientated intratabular or plate-bounding processes on the epitract and hypotract, being distinctly plate-bounding between the cingulum and precingular and postcingular plates, and between the sulcus and adjacent hypotractal plates. The continuation of the sulcus on the epitract is defined either by plate-bounding processes or by an apparent difference in texture between the wall structure of the sulcus and the adjacent plate areas (PI. 103, fig. 2). Variation in reflected plate morphology has also been noted and is commented upon in the section on archaeopyle formation and reflected tabulation. A biometrical study was undertaken on the topotype material. Sixty-five complete specimens were used to construct the scatter diagram and the histograms seen in text-figs. 3-5. The parameters used were the length (distance between the apex and antapex), width, and the maximum cingulum width of the cysts and it was hoped to learn something of the variation within the topotype population of Rhaetogonyaulax. The resulting scatter diagram of cyst length/cyst width v. cyst length/width of cingu- lum (text-fig. 3) produced a distribution of points indicating a relationship between EXPLANATION OF PLATE 102 All figures at a magnification of xc. 1500 unless otherwise stated. Figs. 1-9. Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend. Scanning electron photo- micrographs of specimens showing archaeopyle formation and the variability of the cyst surface ‘orna- mentation’. 1, a reticulate form in oblique ventral view that carries granules and bacules; the ornamenta- tion is also present on the cingulum and sulcus. Plates ps, pv, Ip, T", and 2"' are possibly discernible. MPK 820. 2, a form in lateral view showing complete archaeopyle formation, the seven precingular reflected plate areas, and the over-all smooth cyst surface with some intratabular ‘ornamentation’ elements and a cluster of intratabular elements in the centre of a postcingular plate area. MPK 815. 3, a specimen in lateral view showing complete archaeopyle formation and a slightly rougher ‘ornament’ than fig. 2. MPK 813. 4, as form in oblique ventral view showing a rough cyst surface with plate-bounding and intratabular granules and bacules. Compare with text-fig. 2b. M PK 819. 5, a specimen in dorsal view show- ing complete archaeopyle formation, rough ‘ornamentation’ and two antapical plates 1"" and 2"", also Ipv, ps, and the inbulge of ms, a single intercalary plate, at least three precingular plates, three postcingular plates, and two antapical plates. MPK 814. 6, form with well-developed granules and bacules in oblique ventral view, plates ps, pv may also be seen. MPK 824. 7, detail of MPK 8 1 3 showing the shape of the precingular plates 4" and 5" and a cingular plate boundary and their ornament, x c. 3000. 8, detail of MPK 8 1 4 showing the plates and ornament of the antapex, x c. 3000. 9, detail of MPK 820 to show the nature of the reticulate ornamentation in the sulcus, x c. 4500. PLATE 102 HARLAND et al., Rhaetogonyaulax 856 PALAEONTOLOGY, VOLUME 18 the parameters, that the more slender the cyst the wider the cingulum width in relation to the length. The data gives a correlation coefficient of 0-3706. It would appear that only one population is involved here, with respect to the parameters measured, as there is no suggestion of clumping or separation into two or more groups, and the histograms of the frequency of cyst length/cyst width (text-fig. 4) and of cyst length/ cingulum width (text-fig. 5), are unimodal and are skewed to the right. The bio- metrical study does not and cannot, however, in itself prove or disprove the existence of one, two, or many species; but it is additional evidence for treating the topotype specimens as belonging to a single population. In the light of the present study, the authors feel that an emendation, not only of the genus Rhaetogonyaulax but also of the species R. rhaetica, is necessary. Sarjeant’s (1963) division into two species, rhaetica and chaloneri, based largely upon ornamenta- tion, is no longer felt to be justified. In particular, we believe that Rhaetogonyaulax EXPLANATION OF PLATE 103 All figures are phase contrast photomicrographs and at a magnification of x750 unless otherwise stated. Slide co-ordinates given here and subsequently refer to microscope No. 158226 housed in the Depart- ment of Geology, University of Sheffield. Figs. 1-14. Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend. 1-9, cysts in various stages of rupture, archaeopyle formation, and preservation. 1, specimen slide ref 23//lq/l/458/1254; Lime- stone (Group VI), Kendelbachgraben, Austria; Rhaetian (sensu lato). Antapical horn rudimentary in development and partial archaeopyle formation. 2, specimen slide ref 22>l /lq/1/347/1214; as above, following incomplete rupture, a single intercalary, seven precingular reflected plates clearly visible. Antapical horn rudimentary in development. Ornamentation well developed. Processes clearly intratabular on anterior intercalary and precingular reflected plates. 3, specimen slide ref 5/ /2j/2/300/ 1254; Swabian Facies (Lower), Kendelbachgraben, Austria; Rhaetian (.?. /.). Antapical horn showing greater development and also showing precingular plates, one intercalary, and some apical plates. Specimens not possessing clear antapical horns are morphologically very similar to some specimens of Shublikodinium and possibly bridge the gap between the two genera. 4, specimen slide ref 26d/246/1305; Westbury Member, Rhaetic Formation, Bunny Flill Borehole, Notts., England; Rhaetian. Detached apical horn comprising at least four reflected apical plates. 5, specimen slide ref 52c/420/1254; Gotham Member, Rhaetic Formation, Bunny Hill Borehole, Notts., England; Hettangian Stage, apical com- pression of completely ruptured cyst. 6, specimen slide ref 44/ /x 13/beta/400/1276; x875. Equatorial compression of completely ruptured cyst. Archaeopyle clearly evident. Precingular reflected plates splitting apart. 7, specimen slide ref 44//x 13/beta/363/1291 ; x875. 6 and 7, in Salzburg Facies, Kendelbachgraben, Austria; cyst illustrating archaeopyle formation. 8, specimen slide ref 14//lz/5/ 252/1284; x 875; cyst illustrating archaeopyle formation and also the boundary between 2'"' and 3"". 9, specimen slide ref. 14//lz/4/332/1285; x 875. 8 and 9, in Swabian Facies, Kendelbachgraben, Austria; cysts illustrating archaeopyle formation. 10-14, cysts illustrating various outline shapes and degrees of development of body ornamentation. 10, specimen slide ref 52c/420/1254; Gotham Member, Rhaetic Formation, Bunny Hill Borehole, Notts., England; Hettangian Stage; randomly ornamented with processes. Orientation indeterminate. Gyst complete. 11, specimen slide ref. 29//lj/2/586/1276; Gar- pathian Facies, Kendelbachgraben, Austria; Rhaetian (5. /.); x 875; sulcus well developed, ornamenta- tion randomly developed. Sulcus tending to be broader in hypotract. 12, specimen slide ref 16//lx/l/ 375/1294; Swabian Facies (Upper), Kendelbachgraben, Austria; Rhaetian {s. /.); x875; cyst un- ornamented, wall smooth. Orientation indeterminate. 13, specimen slide ref 16//lx/3/269/1289; x875; Swabian Facies (Upper), Kendelbachgraben, Austria. Orientation indeterminate. 14, specimen slide ref 33b/418/1219; Westbury Member, Rhaetic Formation, Bunny Hill Borehole, Notts., England; Rhaetian. Gyst inequifusiform in outline, wall reticulation superimposed by ‘ornament’. PLATE 103 HARLAND et al., Rhaetogonyaulax 858 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 2. An interpretative reconstruction of the tabulation of Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend. A-B, specimen MPK 806. a, in left lateral view, slightly oblique; B, in right lateral view, slightly oblique, c, specimen MPK 807 in ventral view, d-e, specimen MPK 805. d, in left lateral view; E, in right lateral view. Abbreviations: l'-6', apical plates; lav, anterior ventral plate; la-6a, anterior intercalary plates; as, anterior sulcal plate; ms, median sulcal plate; l"-7", precingular plates; lc-7c, cingular plates; l'"-7"', postcingular plates; Ipv, posterior ventral plate; Ip, posterior intercalary plate; antapical plates. is a genus that has a demonstrably large variation of surface ornamentation, such that there is no justification in treating a reticulate form as a separate species. The fact that the topotype material, based upon certain measurable parameters, acts as a unified population, is additional evidence for our view. HARLAND ET AL.\ DINOFLAGELLATE RH AETOGONY AU LAX 859 30- 1-0- -1 1 ^ r- 7 0 9 0 no 130 TEXT-FIG. 3. Scatter diagram of the topotype material based upon sixty-five complete speci- mens. h'— holotype of Rhaetogonyaulax rhaetica; h”— holotype of R. chaloneri', m— mean. The diagram has a correlation coefficient of 0-3706. h TEXT-FIG. 4. Histogram showing the frequency of text-fig. 5. Histogram showing the frequency of the L/W parameter in the topotype material h', h", the L/Wc parameter in the topotype material h', h", and m as in text-fig. 3. F calculated as percentages of and m as in text-fig. 3. F calculated as percentages of the total. Standard deviation of L/W is 0-36. the total. Standard deviation of L/Wc is 1 -72. 860 PALAEONTOLOGY, VOLUME 18 SYSTEMATIC PALAEONTOLOGY Division pyrrhophyta Pascher Class DiNOPHYCEAE Pascher Order peridiniales Lindemann Genus Rhaetogonyaulax Sarjeant, 1966, emend. 1966 Rhaetogonyaulax 152. 1967 [Rhaetogonyaulax Sarjeant]; Evitt, p. 46. 1968 Rhaetogonyaulax Sarjeant; Loeblich Jun. and Loeblich III, p. 212. 1968 Rhaetogonyaulax Sarjeant; Wall and Dale, table 2. 1973 Rhaetogonyaulax Sarjeant; Lentin and Williams, p. 119. Type species. Rhaetogonyaulax rhaetica (Sarjeant 1963) Loeblich Jun. and Loeblich III, 1968 O.D. emend. Upper Triassic (Rhaetic), England. Emended diagnosis. Cyst proximate, elongate-biconical to spindle-shaped, with rudimentary or pronounced apical and antapical horns. Wall apparently single-layered, smooth, rough; punctate, granulate, or reticu- late. Cingulum helicoid, laevorotatory, moderately indented; cingulum and sulcus generally defined by ridges. Tabulation 4'-?6', 5-?6a, lav, 1", 7c, 1"', Ip, Ipv, 3s, 3""; boundaries of plate-areas marked by raised lines, lines of short processes, or rupture. Processes, where developed, may be sutural or intratabular, simple or furcate. Archaeopyle development by progressive loss of all plates anterior to the precingular series. Remarks. Wiggins (1973, p. 4) commented that ‘it is remarkable that Shublikodinium superficially resembles Rhaetogonyaulax ... in both cyst and archaeopyle outline, when their sutural tabulation series is so different’. Our restudy emphasizes the close comparability of the two genera ; residual differences are in over-all shape, Shubliko- dinium being ovoidal with two antapical horns, one of which may be reduced, whereas EXPLANATION OF PLATE 104 All figures are phase contrast photomicrographs and at a magnification of x 875. Figs. 1-12. Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich emend. 1-5, cyst specimens illustrating partial rupture of some anterior intercalary plates, variation in over-all outline with development of antapical horn, and broad sulcus on hypotract. 1, specimen slide ref. 44/ /x 13/beta/ 400/1276; Swabian Facies, Kendelbachgraben, Austria; Rhaetian (5. /.). Cyst equifusiform in outline, broad sulcus on hypotract. 2, specimen slide ref. 33a/274/1248; Westbury Member, Rhaetic Formation, Bunny Hill Borehole, Notts., England; Rhaetian. On epitract, apical, anterior intercalary, and pre- cingular reflected plates clearly defined, broad sulcus on hypotract, rudimentary secondary (?) horn developing (? process) in addition to prominent antapical horn. 3, specimen slide ref. 44/ / x 13/gamma/ 397/1310, Salzburg Facies, Kendelbachgraben, Austria; Rhaetian {s. /.). 4, specimen slide ref. 54/ /x4/ 5/589/1290; Pre-planorbis Beds, Kendelbachgraben, Austria; Rhaetian (.9. /.). 5, specimen slide ref 5//2j/beta/380/1295; Swabian Facies (Lower), Kendelbachgraben, Austria; Rhaetian. Rudimentary antapical horn (? process), coarsely ornamented. 6-8, 10-12, cyst specimens showing variation in over-all outline, preservation, and development of ornamentation. 6, specimen slide ref 55// x 3/gamma/612/1200; Pre-planorbisBeds, Kendelbachgraben, Austria; Rhaetian. 7, specimen slide ref 45/ / x 12/beta/305/1283; 1 Salzburg Facies, Kendelbachgraben, Austria; Rhaetian. 8, specimen slide ref 44/ /x 13/beta/400/1276; j Salzburg Facies, Kendelbachgraben, Austria; Rhaetian (s. /.). 9, specimen slide ref 56/ / x 3/1/691/1230; j Pre-planorbis Beds, Rhaetian. Kendelbachgraben, Austria; apical horn comprising at least four pro- 1 minent reflected apical plates. 10, specimen slide ref 44//x 13/gamma/588/1303, Salzburg Facies, 1 Kendelbachgraben, Austria; Rhaetian (s. /.). 11, specimen slide ref 29//lj/2/586/1276; Carpathian 1 Facies, Kendelbachgraben, Austria; Rhaetian. Coarse body ornament. Antapical horn developed 1 (preservation ?). 12, specimen slide ref 41d/352/1228; Cotham Member, Bunny Hill Borehole, Notts., ! England, Rhaetic Formation; Hettangian. Oblique ventral view, with plates I"', 2'" visible also Ip and much of 7'", 1'"', and 3"". PLATE 104 HARLAND et at., Rhaetogonyaulax 862 PALAEONTOLOGY, VOLUME 18 Rhaetogonyaulax is basically spindle-shaped, rarely ovoidal, and rarely exhibiting two antapical horns. Rhaetogonyaulax is also much more sharply attenuated than Shublikodinium. The two genera also differ in tabulation details, especially on the hypotract, as Rhaetogonyaulax possesses postcingular, posterior intercalary, sulcal and antapical plates as opposed to the postcingular and antapical plates of Shubliko- dinium. Since the plate designated V by Wiggins (1973, text-fig. 2) does not in fact form a part of the apex, we have preferred to refer to it as an anterior ventral plate (lav) in reference to its position. The plate which Wiggins (1973) referred to as the ‘apical closing plate’ is here designated V . Rhaetogonyaulax rhaetica (Sarjeant 1963) Loeblich and Loeblich 1968 emend. Plates 100-104; text-figs. 1-2 V* 1963 Gonyaulax rhaetica Sarjeant, p. 353, figs. 1, 2 left. 1963 Gonyaulax chaloneri Sarjeant, p. 354, figs. 2 right, 3. 1964 Gonyaulax rhaetica Sarjeant; Downie and Sarjeant, p. 115. 1966 Gonyaulax chaloneri Sarjeant; Downie and Sarjeant, p. 114. 1966 Rhaetogonyaulax rhaetica Sarjeant nom. nud.\ Sarjeant, p. 153. 1966 Rhaetogonyaulax chaloneri Sarjeant nom. nud.; Sarjeant, p. 153. 1968 Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich, p. 212. 1969 c/ta/o/ten (Sarjeant); Sarjeant, p. 15. \912b Rhaetogonyaulax sp.; Fisher, p. 105, pi. 2, fig. 15. 1973 Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich; Orbell, pi. 2, fig. 1. 1973 Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich; Lentin and Williams, p. 120. 1973 Rhaetogonyaulax chaloneri (Sarjeant) Sarjeant; Lentin and Williams, p. 1 19. 1974 Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich; Morbey and Neves, p. 168, pi. Ill, figs. 3, 4. 1975 Rhaetogonyaulax rhaetica (Sarjeant) Davey, Downie, Sarjeant and Williams; Felix, pi. II, fig. 2. 1975 Rhaetogonyaulax rhaetica (Sarjeant) Loeblich and Loeblich; Morbey, pi. 14, fig. 17, pi. 15, figs. 1-4. Emended diagnosis. Cyst proximate, typically spindle-shaped, unornamented or ornamented. Antapical horn may be rudimentary or well developed. Wall apparently single-layered, thin, smooth, rough, punctate, reticulate or granulate. Processes small, variable in development and distribution; random or orientated, intratabular or plate-bounding, simple and furcate. Cingulum helicoid laevorotatory, unornamented or ornamented, forming a moderately indented furrow; displacement may be as much as twice the cingulum width. Seven cingular plates are developed. Sulcus ornamented or unornamented, generally expanded on the hypotract. Cingulum and hypotractal sulcus clearly defined by plate-bounding processes or ridges; the epitractal sulcus defined by plate-bounding processes or by textural differences between the epitractal plate wall and the sulcal wall. Plate sutures most readily evident where partial or complete detachment of opercular plates has occurred; hypotractal tabulation especially difficult to define. Reflected tabulation 4'-?6', lav, 5a- ?6a, 7”, 7c, 1"', 1 p, 1 pv, 3a, 3"" ; an additional plate-area may be present in the anterior extension of plate la as here delineated. Archaeopyle formed initially by detachment of one or more intercalary plates, there- after by loss of the remaining intercalary plates, the apex as a unit, and the anterior ventral and anterior sulcal plates; cysts with archaeopyles thus show a ‘scalloped’ edge formed by the anterior margins of the pre- cingular plates and a deep sulcal notch resulting from the loss of the anterior sulcal plate. The median sulcal plate is often deeply indented and probably corresponds to the position of origin of the two flagella. Typification. Holotype specimen 1, slide PF 1983 (not specimen 98, slide PS 1983, as quoted by Sarjeant (1963)). Type locality. Rock specimen Bj 6011, Stowell Park Borehole (N.G.R. SP 0835 1 173), Northleach, Glou- cestershire. Depth 2059 ft 2 in, i.e. 627-63 m. Repository. The holotype and all figured specimens from the topotype material are held in the Palynological HARLAND ET AL.: DINOFLAGELLATE RH AETOGON Y AU LAX 863 Collections of the Institute of Geological Sciences, Leeds, England, and are registered in the PF and MPK collections. Comparative material from the Bunny Hill Borehole, Nottinghamshire, and the Kendel- bachgraben, Austria, is held in the collections of the Department of Geology, University of Sheffield, Dimensions. Holotype: cyst length 63-75 /urn, width 37-5 jum, cingulum width 8-75 /nm. Topotype material; length 47-5 (64-72) ll-S fj.m, width 17-5 (35-72) 48-75 jum; cingulum width 5-0 (7-73) 1 1 -25 /Lim, based upon sixty-five complete specimens. Bunny Hill Borehole and Kendelbachgraben material: cyst length 50-0 (69-0) 92-0 /um; width 34-0 (43-0) 54-0 /rm ; cingulum width 7-0- 13-0 /^rm, based upon thirty-one complete specimens. (The data given are the minimum, mean, and maximum measurements.) Rhaetogonyaulax rhaetica (Sarjeant) var. chaloneri, stat. nov. Plate 100, figs. 7, 8; Plate 101, figs. 3, 4 v*1963 Gonyaulax chaloneri Sarjeant, p. 354, figs. 2 right, 3. 1964 Gonyaulax chaloneri Sarjeant; Downie and Sarjeant, p. 1 14. 1966 Rhaetogonyaulax chaloneri (Sarjeant), nom. nud. ; Sarjeant, p. 153. 1969 Rhaetogonyaulax chaloneri (Sarjeant) ; Sarjeant, p. 15. 1973 Rhaetogonyaulax chaloneri (Sarjeant); Lentin and Williams, p. 1 19. Typification. Holotype specimen 2, slide PF 1983. Remarks. Rhaetogonyaulax chaloneri is here redesignated as a variety of R. rhaetica as no justification can be found in maintaining this form as a distinct species in an obviously variable morphological group. Geological and geographical range o/ Rhaetogonyaulax rhaetica Cotham Beds [Rhaetic], Stowell Park Borehole, Gloucestershire, England (Sarjeant 1963); Cotham Beds [Rhaetic] and Pre-planorbis Beds [Lias], Barnstone Railway Cutting, Nottinghamshire, England (Fisher 1972a); lower ‘Cotham Beds’ [lower Rhaetian and basal upper Rhaetian], Bristol Channel region, England (Fisher 19726); Grey Marls, Westbury Beds, Cotham Beds, White Lias, lowermost Watchet Beds [Rhaetic], Lavernock Point, Glamorgan, Wales. Westbury Beds, Cotham Beds [Rhaetic], Owthorpe, Nottingham- shire, England. Westbury Beds, Cotham Beds [Rhaetic], Upton Borehole, Oxfordshire, England (Orbell 1973); Tea-green Marl Member, Parva Formation and Westbury Member, Cotham Member, Rhaetic Formation [Rhaetian sensu lato and Hettangian], Bunny Hill Borehole, Nottinghamshire, England. Swabian Facies, Limestone ±Lithodendron (Group VI), Carpathian Facies, Kossen Facies, Salzburg Facies, Lre-planorbis Beds [Rhaetian sensu lato and Hettangian], Kendelbachgraben, Austria (Morbey and Neves 1974); Highest Grey Marls [Keuper Marl], Westbury Beds, lower Cotham Beds [Rhaetic], Watchet, Somerset, England (Warrington 1974); Westbury Beds, Cotham Beds [Rhaetic], Larne Borehole, Antrim, Northern Ireland (Warrington and Harland in press). Westbury Beds, Cotham Beds [Rhaetic], Steeple Aston and other boreholes near Chipping Norton, Oxfordshire, England. Westbury Beds, Cotham Beds [Rhaetic], borehole near Chipping Sodbury, Gloucestershire, England (G. Warrington, pers. comm.). Flatsalen Formation [?Rhaetian], Hopen, Svalbard, Norway (D. Smith, pers. comm.) and recorded as cf. B R. rhaetica (Smith, Harland and Hughes 1975). Acknowledgements. The authors would like to thank Dr. G. Warrington for his assistance in reprocessing the topotype material, for his discussions, and for taking certain of the scanning electron photomicrographs. Mrs. Brenda Coleman has also assisted with the scanning electron microscope work; her help is gratefully acknowledged. S. J. Morbey is most grateful to the Natural Environment Research Council for financial assistance toward his research and to Professor Moore, Dr. R. Neves, and the Department of Geology, University of Sheffield, for the facilities provided. One of us (R. H.) publishes with the permission of the Director, Institute of Geological Sciences, London. The work of W. A. S. Sarjeant was supported by Research Grant A-8393 of the National Research Council of Canada. Helpful discussions in correspondence with Dr. David Wall (Woods Hole Oceanographic Institution) and the provision of specimens by Mr. Michael J. Fisher (Robertson Research, Calgary, Alberta) are also gratefully acknowledged. 864 PALAEONTOLOGY, VOLUME 18 REFERENCES DOWNiE, c. and sarjeant, w. a. s. 1964. Bibliography and index of fossil dinoflagellates and acritarchs. Mem. Geol. Soc. Amer. 94, 1-180. EviTT, w. R. 1967. Dinoflagellate studies IE The archeopyle. Stanford Univ. Publ. Geol. Sci. 10, No. 3, 1-82. 1969. Dinoflagellates and other organisms in palynological preparations. In tchudy, r. h. and SCOTT, r. a. (eds.). Aspects of Palynology. Wiley-Interscience, New York, 439-479. 1970. Dinoflagellates— a selective review. Geoscience and Man, 1, 29-45. FELIX, c. J. 1975. Palynological evidence for Triassic sediments in Ellet Ringnes Island, Arctic Canada. Rev. Palaeobot. Palynol. 20, 109-117. FISHER, M. J. 1972fl. Rhaeto-Liassic palynomorphs from the Barnstone railway cutting, Nottinghamshire. Mercian Geologist, 4, 101-106. 19726. The Triassic palynofloral succession in England. Geoscience and Man, 4, 101-109. GITMEZ, G. u. and sarjeant, w. a. s. 1972. Dinoflagellate cysts and acritarchs from Kimmeridgian (Upper Jurassic) of England, Scotland and France. Bull. Br. Mas. nat. Hist. (Geol.), 21, 171-257. LANJOUW, J. et al. 1966. International Code of Botanical Nomenclature. International Bureau for Plant Taxonomy and Nomenclature, Utrecht, 1-402. LENTIN, J. K. and Vv^iLLiAMS, G. L. 1973. Fossil dinoflagellates; index to genera and species. Geol. Surv. Canada, Paper 73-42, 1-176. LOEBLiCH, A. R., Jun. and loeblich, a. r. III. 1968. Index to the genera, subgenera, and sections of the Pyrrhophyta, II. J. Paleont. 42, 210-213. morbey, s. j. 1975. The palynostratigraphy of the Rhaetian Stage, Upper Triassic in the Kendelbach- graben, Austria. Palaeontographica, B, 152, 1-75. and NEVES, R. 1974. A scheme of palynologically defined Concurrent-range Zones and Subzones for the Triassic Rhaetian Stage (sensu lato). Rev. Palaeobot. Palynol. 17, 161-173. ORBELL, G. 1973. Palynology of the British Rhaeto-Liassic. Bull. Geol. Surv. G.B. 44, 1-44. SARJEANT, w. A. s. 1963. Fossil dinoflagellates from Upper Triassic sediments. Nature, Land. 199, 353-354. 1966. Dinoflagellate cysts with Gonyaulax-iype, tabulation. In davey, r. j. et al. Studies on Mesozoic and Cainozoic dinoflagellate cysts. Bull. Br. Mus. nat. Hist. (Geol.), Suppl. 3, 107-156. 1969. Taxonomic changes proposed by W. A. S. Sarjeant. In davey, r. j. et al. Appendix to 'Studies on Mesozoic and Cainozoic dinoflagellate cysts’. Ibid. Appendix to Suppl. 3, 7-15. 1969. Microfossils other than pollen and spores in palynological preparations. In erdtman, g. Hand- book of Palynology. Hafner Publishing Co., New York, 165-208. SMITH, D. G., HARLAND, w. B. and HUGHES, N. F. 1975. Geology of Hopen, Svalbard. Geol. Mag. 112, 1-23. WALL, D. and DALE, B. 1 968. Modern dinoflagellate cysts and evolution of the Peridiniales. Micropaleontology, 14, 265-304. and HARADA, K. 1973. Descriptions of new fossil dinoflagellates from the late Quaternary of the Black Sea. Ibid. 19, 18-31. WARRINGTON, G. 1974. Studies in the palynological biostratigraphy of the British Trias. I. Reference sections in west Lancashire and north Somerset. Rev. Palaeobot. Palynol. 17, 133-147. and HARLAND, R. (in press). Palynology of the Trias and Lower Lias of the Larne Borehole. In MANNING, p. I. and WILSON, H. E. The stratigraphy of the Larne Borehole, Co. Antrim. Bull. Geol. Surv. WIGGINS, V. D. 1973. Upper Triassic dinoflagellates from arctic Alaska. Micropaleontology, 19, 1-17. G.B. 50. REX HARLAND Institute of Geological Sciences Ring Road, Halton Leeds, LSI 5 8TQ S. JACK MORBEY Robertson Research International Ltd. ‘Ty’n-y-Coed’ Llanrhos Llandudno, North Wales Original typescript received 14 October 1974 Revised typescript received 16 December 1974 WILLIAM A. S. SARJEANT Department of Geological Sciences University of Saskatchewan Saskatoon, Saskatchewan, Canada THE PRODUCTION OF FAUNAL LISTS BY AUTOMATIC METHODS by IAN E. PENN Abstract. Computer programs have been developed in the Institute of Geological Sciences which, after eliminating any unwanted data from original determinations, generate correctly type-set and punctuated faunal lists. These are suitable for direct publication or for easy incorporation into accounts dealing with wider geological topics. Lists of species found are a simple and most fundamental means of recording faunal (or floral) distribution and, since the days of William Smith and his recognition of strata distinguished by means of fossil content, they have occupied a place of special importance in geology. After the palaeontologist has recorded his observations, he may still spend a considerable amount of time in non-palaeontological work when he communicates his discoveries, even by a means apparently as simple as a faunal list. Thus the fossil names must be written, typed, and checked (often in several copies). This process may be repeated more than once when, in a large organization, the palaeontologist’s report is incorporated in a larger work such as a geological account or memoir written by a colleague, which itself must be typed and checked (often in several copies). Finally, the lists must again be checked at least once on return from the printers, prior to eventual publication. When for any reason some part of the data has to be published additionally or even separately, the whole process may need to be repeated. Within the Institute of Geological Sciences, analogous problems had been encountered in the production of the relatively more sophisticated stratigraphical range-diagram, and a package of computer programs was written to eliminate non- palaeontological activity as far as possible (Penn 1974; Farmer and Johnson 1975, in press). It was then decided to generate fossil lists suitable for direct publication in the same manner as the range-diagrams and to incorporate a program which would simultaneously eliminate unwanted data. The main features of these programs are here outlined (text-fig. 1), while full program listings may be obtained on request. The programs are housed on the Institute’s IBM 1130 computer configuration and also on the Edinburgh Regional Computing Centre’s PDP- 11/45 configuration. They may be installed and used to produce ‘crude’ line-printer output by anyone having access to such machines. Production of type-set lists requires access, however, to a more specialized instrument such as the Institute’s Addressograph-Multigraph AM -747. The species dictionaries contain the names used by individual palaeon- tologists within the Institute, and it is intended that these will be subsequently integrated, as will the data generated by them. It is envisaged that users outside I.G.S. could construct similar dictionaries and data files which may subsequently be brought together. The Institute’s facilities are, however, available at the discretion of the Director. [Palaeontology, Vol. 18, Part 4, 1975, pp. 865-869.] 866 PALAEONTOLOGY, VOLUME 18 PROGRAM INPUT, CONTENTS AND OUTPUT The fossil data (F DATA in text-fig. 1) are presented on punch cards in stratigraphical order such that a preliminary card lists the number of batches in the stratigraphic section being described. Then the first card in each batch states the number of species found as well as the measured stratal range (e.g. depth range in a borehole of the sampled horizon), while each subsequent card records the species code number (corresponding to the full fossil name stored in a companion dictionary) and a code denoting species abundance at that horizon (see Penn 1974). At the present embryonic stage of this data bank, each such stratigraphical section is identified manually. Program CUF 10 reads these data and stores them on magnetic discs ready for accession by remaining programs. But program RCVET is firstly presented with a list of the code numbers of those species which it is desired to eliminate (or retain, as the case may be) from the main body of the data. Only these selected species, with their abundance codes, are read and stored by program RCVET. Indication is given if such selection results in the elimination of all species from the data. Thus in the example shown (text-fig. 2), the Bivalves have first been selected from the total data and listed, followed by listing of the remaining species. Preliminary inspection of the data may be made by printing a list of the encoded TEXT-FIG. 1. Flow chart of the various programs. F DATA represents the input of fossil data. The various identifiers within rectangles represent the various program decks. PREPT produces paper-tape and line-printer output. PENN: AUTOMATIC FAUNAL LISTS 867 data, and a list of all the species found in the total data, by using programs CUF 1 1 and CUZ 88 respectively (Penn 1974). Program PREPT, however, translates the encoded data and, after consulting the species dictionary, punches out a paper-tape of the full fossil name preceded by an indication of abundance for every determination made. This tape, which contains type-setting instructions obtained from the species dictionary, is fed into a phototypesetter to produce a correctly type-set and punctuated list (text-fig. 2) for each sampling horizon. Provision has been made for an addition and multiplication factor to be incorporated into the depth-range values, so as to SPECIMEN DATA. ALL MACROFOSSILS SPECIMEN DATA. BIVALVES SPECIMEN DATA. NON BIVALVES SAMPLING HORIZON I 35,55 to 36,23 p wood [frag.] fc RhynchoneUoidella smiihi (Davidson) p Anisocardia bathemis Cox fc bivalve [indet.] p Caiinula cf. ampulla (d’Archiac) p Eniolium sp. p Grammatodon bathonicus Cox & Arkell p burrow [horizontal and straight] SAMPLING HORIZON 2 36.23 to 37.19 p bivalve [indet ] p Modiolus sp. p belemnite [indet.] SAMPLING HORIZON 3 37.37to 38.12 p serpulid [indet.] Ic rhynchonellacean [indet ] fc RhynchoneUoidella smithi (Davidson) p RhynchoneUoidella waitonensis Muir-Wood fc RhynchoneUoidella sp. fc arcacean [indet ] c bivalve [indet ] fc Caiinula cf. ampulla (d’Archiac) p Chlamys ( Radulopecten ) sp. p Gervillella sp. p pectinoid [mdet ] SAMPLING HORIZON 4 38.12 to 38 39 p RhynchoneUoidella sp. p bivalve [indet ] fc Eniolium sp. p Gervillella sp. SAMPLING HORIZON 5 38,39 to 38.60 SAMPLING HORIZON 1 35.55 to 36.23 p Anisocardia baihensis Cox fc bivalve [indet.] p Cannula d. ampulla {6' fiixchizc) p Eniolium sp. p Grammatodon bathonicus Cox & Arkell SAMPLING HORIZON 2 36.23to 37 19 p bivalve [indet.] p Modiolus sp. SAMPLING HORIZON 3 37.37 to 38.12 fc arcacean [indet.] c bivalve [indet.] fc Caiinula cf. ampulla (d’Archiac) p Chlamys (Radulopecten) sp. p Gervillella sp. p pectinoid [indet ] SAMPLING HORIZON 4 38.l2to 38.39 p bivalve [indet ] fc Eniolium sp. p Gervillella sp. SAMPLING HORIZON 5 38.39 to 38.60 fc bivalve [indet ] ? Campionectes sp. fc Eniolium sp. p Inoperna plicata (J . Sowerby) p Liostrea sp. fc Modiolus anatinus Wm. Smith p Modiolus sp. p Vaugonia sp. SAMPLING HORIZON 1 35.55 to 36.23 p wood [frag ] fc RhynchoneUoidella smithi ( Davidson) p burrow [horizontal and straight] SAMPLING HORIZON 2 36,23 to 37 19 p belemnite [indet ] SAMPLING HORIZON 3 37.37 to 38 12 p serpulid [indet ] fc rhynchonellacean [indet ] fc RhynchoneUoidella smithi (Davidson) p RhynchoneUoidella waitonensis Muir-Wood fc RhynchoneUoidella sp. SAMPLING HORIZON 4 38.l2to 38,39 p RhynchoneUoidella sp. SAMPLING HORIZON 5 38,39 to 38.60 p Sarcinella socialis (Goldfuss) fc serpulid [indet ] fc RhynchoneUoidella sp. p Ornithella balhonica (RoWier) p Proceriihium sp. p Sarcinella socialis (Goldfuss) fc serpulid [indet.] fc RhynchoneUoidella sp. p Ornithella (Rollier) p Proceriihium sp. fc bivalve [indet ] ? Campionectes sp. fc Eniolium sp. p Inoperna plicata (J . Sowerby) p Liostrea sp. fc Modiolus anatinus Smith p Modiolus sp. p Vaugonia sp. TEXT-FIG. 2. Specimen output from a Middle Jurassic borehole near Bath. ? = possibly occurring; p = present; fc = fairly common; c = common. The total data on the left of the diagram has been split into the Bivalve and non-Bivalve sections shown on the right-hand side. 868 PALAEONTOLOGY, VOLUME 18 eliminate the punching of unnecessary digits where, for example, closely spaced samples have been taken from considerable depth in a borehole. Such factors may also be used as a security ‘link’ on the depth range of the sample in the case of con- fidential material. PROGRAM PERFORMANCE The size limits for the data are at present 100 (species) x 100 (horizons) and the number of species at any one horizon must be limited to 50 as in the range-chart program (Penn 1974). Data preparation (including the noting of the preliminary raw observations) and checking for the computer takes about the same time as preparing a first draft of a clean-copy manuscript for typing. Typing the first copy, however, takes about as long as drafting the manuscript, and checking the first and each subsequent typescript is conservatively estimated at 50% of the time taken to prepare the first manuscript. Typing of subsequent copies is slightly quicker (perhaps by about 25%). Thus, after the first draft of the manuscript, the time spent by the palaeontologist in non-palaeontological work increases by 50% of his original time, and similarly that of the typist by 75% for each successive ‘round’ of typing. The final ‘round’ is that done by the printer and is estimated to be 120% of the time taken by an ordinary typist. Thus a manuscript taking 1 hr for the preparation of the first draft of a clean-copy manuscript would take (assuming two further drafts) 2 hr 45 min to submission and 1 hr 20 min work by the printer as against 1 hr for punching and checking and 4 min computer time. Program RCVET, which selects data during the loading process, performs basically the same functions as the normal loading pro- gram and, indeed by setting it so that no selection is made, may be used as a substitute for program CUF 10. The operational time taken by program PREPT is dominated by the number of species determinations in the data. Since most of the activity is in punching paper-tape, the time taken to produce the output is almost entirely depen- dent on the size of machine, the speed, and the arrangement of output devices. Thus the IBM 1 130 configuration, on which the program was established, does not con- veniently allow separate operation of the central processor and paper-tape punch. The speed of the operation was therefore determined by the speed of the punch which, at 14-8 characters per sec, is very slow. Operation on a larger computer (a PDP- 11/45) with a faster paper-tape improved the run times, in a conservative estimate, by a factor of five times. In practice this means a job of around 250 deter- minations is run in around 5 min. In fact, in a multi-user environment, output devices would be operated simultaneously with entirely different operations, meaning that the time spent producing the fossil list would be almost negligible. The advantage is even more marked if the palaeontologist needs an accompanying range-chart, since the same data input is used, and producing the fossil list simply involves a small amount of extra computer time. It is thus possible to free the palaeontologist from a very considerable proportion of non-palaeontological work once he has initially recorded and checked his data. In addition, his data can be stored in computer-processable form ready for the per- formance of other analytical techniques and, in the long term, ready for incorporation into a computerized data bank. PENN. AUTOMATIC FAUNAL LISTS 869 Acknowledgements. The programs were written by Dr. D. G. Farmer (Computer Unit, I.G.S.) and Dr. T. J. Dhonau (Editorial and Publication Section, I.G.S.) advised on the use of the phototypesetter. The paper is published by permission of the Director of the Institute of Geological Sciences. REFERENCES FARMER, D. G. and JOHNSON, L. 1975. Rep. Inst. geol. Sci. (In press.) PENN, I. E. 1974. The production of stratigraphical range-diagrams by automatic methods. Palaeontology, 17, 553-563. Typescript received 23 December 1974 Revised typescript received 24 Eebruary 1975 IAN E. PENN Department of Palaeontology Institute of Geological Sciences Exhibition Road London, SW7 2DE THE LECTOTYPE OF THE AMMONITE CADOMITES PSILACANTHUS (WERMBTER) by G. E. G. WESTERMANN and M. RIOULT Abstract. The inflated "Am. humphriesianus’’ d’Orbigny (1845, pi. 134, figs. 1-4), non J. Sowerby (1825), has sub- sequently been named three times; the oldest objective synonym is Stephanoceras psilacanthus Wermbter (1891). The lectotype has been found in the British Museum (Natural History) and is redescribed. It probably came from the boundary Humphriesianum-Subfurcatum Zones at Sully, near Bayeux, Normandy. Specimens from the Parkinsoni Zone described under Cadomites arkelli Sturani (1964), the youngest objective synonym, are C. psilacanthus sturanii subsp. nov. The type specimen of 'Ammonites Humphriesianus, Sow.’ figured by d’Orbigny (1845) on plate 134, figs. 1-2 {non Am. humphriesianus Sowerby, 1825) has now been found in the Tesson Collection of the British Museum (Natural History). Tesson, mentioned by d’Orbigny (1845, p. 400) as one of the collectors of the ‘species’, was a teacher at the Lycee of Caen, a naturalist and friend of Professor J. A. Eudes- Deslongchamps. After his death, his fossil collections from all regions of Normandy were purchased by the British Museum (1857). Separate examinations by us in 1972-1973 of specimen No. 37309 labelled 'Ammonites (Stephanoeeras) Brodioei, J. Sow., Inferior oolite, Bajocian, Bayeux. Figd. as Amm. Humphriesianus, by A. d’Orbigny, Pal. Fr. Terr, jurass. Vol. I, p. 398 (1846), pi. 134, figs. 1-2’ confirmed beyond doubt the identity with d’Orbigny’s illustration as labelled. Both of us had searched independently for this type specimen in the Museum National d’Histoire Naturelle, Paris, where A. d’Orbigny apparently stored most of his collections. Following the conviction of most authorities that in d’Orbigny’s figures, characters of several specimens were united into one, the inability to match specimens with illustrations seemed to confirm the artistic licence of the engraver, rather than their absence from the collections. However, several specimens from the Tesson Collection have been shown beyond reasonable doubt to be the originals to A. d’Orbigny’s illustrations (e.g. B.M. 37325, lectotype of Wagnericeras wagneri (Oppel) = Ammonites planula d’Orbigny, pi. 144, non Hehl in Zieten 1830, illustrated by Arkell 1958, text-fig. 65), and we hope that this new find of a complete specimen closely matching d’Orbigny’s figures will lead to a thorough search for other type specimens. Moreover, this is also an example of the nomenclatural confusion arising from the designation of old illustrations in old monographs as the holotype or even syntypes of new species, rather than specimens ; particularly if this is done repeatedly for the same illustrations. [Palaeontology, Vol. 18, Part 4, 1975, pp. 871-877, pi. 105.] 872 PALAEONTOLOGY, VOLUME 18 Family stephanoceratidae Neumayr, 1875 Subfamily cadomitinae Westermann, 1956 Genus cadomites Munier-Chalmas, 1892 Cadomites psilacanthus (Wermbter, 1891) Plate 105 vl845 Ammonites Humphriesianus, Sowerby; d’Orbigny, pp. 398-400, pi. 134, figs. 1-2 [lectotype], ?3-4 [nucleus or juv.]. 1852, d’Orbigny, 11(2), p. 489, fig. 430 [reproduction of d’Orbigny 1845, pi. 134, xO-5]. *1891 Stephanoceras psilacanthus Behr. ms. (= Humphriesianum d’Orb., p.p., pi. 134, non 133); Wermbter, pp. 270-271 [citation of types only, not his specimens]. 1895 Coeloceras cosmopoliticum = Coeloceras Humphriesianum d’Orb. (non Sow.); Moricke, pp. 20, 21 [for d’Orbigny, pi. 134, figs. 1-2]. 71923, Cadomites cosmopoliticum Moericke; Fallot and Blanchet, p. 151, pi. XI, fig. 10. Non 1937, Gillet, p. 82, pi. 5, fig. 8 [fide Sturani 1966]. 71939, Roche, pp. 200-201. 1964 Cadomites n. sp. (=' Ammonites humphriesianus' (non Sow.) d’Orbigny 1842-1849, t. 134, ff. 1-2; = Cadomites cosmopoliticus (non Moricke) Fallot and Blanchet 1923, t. 11, f. 10); Sturani (1964u), p. 37, pi. 6, fig. 6 [ = C. p. sturanii subsp. nov.]. 1964 Cadomites arkelli n. sp. ; Sturani (1964(t), p. 20 [text-fig. 20, pi. 2, fig. 5 = C. p. sturanii subsp. nov., holotype]. 1966 Cadomites psilacanthus (Wermbter); Sturani, p. 27 [correction for Sturani 19647); text- fig. 2 = 1C. p. sturanii subsp. nov.]. 71974 Cadomites (Cadomites) psilacanthus (Wermbter, 1891); Kopik, p. 13, pi. 1, fig. la, b. History A. d’Orbigny (1845, pp. 398-400, pis. 133-135) described and illustrated several specimens under Ammonites Humphriesianus Sow. none of which belongs to the true species of J. de C. Sowerby (1825, pi. 500, fig. 1 centre; S. S. Buckman 1908, pi. VII, fig. \a, b). In the text, d’Orbigny mixed characters now attributed to several genera and/or subgenera; according to text and plates {excl. pathological specimen, pi. 135, fig. 2), he distinguished (1) a serpenticone variety with subcircular whorl section (pi. 133) which became the holotype of Stephanoceras (Skirroceras) bayleanum (Oppel 1856-1858, p. 377), and (2) an involute inflated variety with depressed whorl section (pi. 134) which Oppel (1856-1858, p. 376) regarded as the true Am. hum- phriesianus [= Stephanoceras s.s.], but Wermbter (1891) separated as S. psilacanthus. No details on d’Orbigny’s locality are available and Wermbter did not explain why he distinguished his species; in fact, Wermbter’s faunal lists and field experience in the Weser Mountains, Lower Saxony, of one of us (G. E. G. W.), permit the con- clusion that the German specimens were Stephanoceras s.s. or S. (Stemmatoceras) EXPLANATION OF PLATE 105 Cadomites psilacanthus (Wermbter), lectotype; type specimen to 'Ammonites Humphriesianus, Sowerby’ of d’Orbigny (1845, plate 134, figs. 1-2). Boundary of Humphriesianum and Subfurcatum Zones, near Bayeux, Normandy. Tesson Collection No. 37309, British Museum (Natural History). 1, left side with complete peristome and damaged shell wall; 2, apertural view; 3, right side with damaged peristome, complete shell wall, and relatively retarded uncoiling of the body chamber; 4, ventral view. All figs, at xO-9. PLATE 105 WESTERMANN and RIOULT, Cadomites psilacanthus 874 PALAEONTOLOGY, VOLUME 18 from the Humphriesianum and possibly also from the Sauzei Zone, i.e. generically distinct from the type specimens. However, the designated plate 134 of d’Orbigny illustrates two specimens, one (figs. 1-2) large and complete, the other (figs. 3-4) very small and septate; they are thus syntypes, although all authors quite obviously had the large complete specimen in mind which was finally designated as the lectotype by Sturani (1966). Apparently without knowledge of Wermbter’s work, W. Moricke (1895) desig- nated the same large specimen of d’Orbigny’s plate 134 as the type of Coeloceras cosmopoliticum (in heading p. 20 and text p. 21), this time in conjunction with Chilean stephanoceratids ; even if the specimen figured by Steinmann (1881) referred to in the synonymy is taxonomically different— he did not himself describe any specimens —the case is similar to that of C. psilacanthus, so that Moricke’s name is a junior objective synonym (cf. Sturani 1966). Because of the nomenclatural procedure, Sturani (1964u, b) considered Moricke’s name a nomen nudum and, not knowing of Wermbter’s previous naming, introduced the new (third) name, Cadomites arkelli, for the same figure in d’Orbigny. In correcting his error, Sturani (1966) formally designated the complete large specimen of d’Orbigny’s figs. 1-2 as the lectotype. His own material, mainly from the Parkinson! Zone of the Venetian Alps, however, differs from the designated holotype and is here distinguished at the subspecific level. The lectotype Specimen No. 37309 of the Tesson Collection, British Museum (Natural History), is a complete macroconch with 1 10 mm diameter and most of the test and aperture preserved, from the ‘Inferior oolite, Bajocian, of Bayeux’ (according to label). The outer phragmocone whorls terminating at 75 mm diameter, are moderately involute and depressed subovate in section with steep umbilical wall, convex flanks (no lateral/umbilical shoulder), and a more gently convex venter. The ornament consists of sharp fiexuous ribbing, with moderately spaced primaries and dense secondaries, and mid-lateral pointed to slightly elongate tubercles; the subradiate primaries are adaperturally concave and very prominent ; the much finer secondaries are almost four times as numerous and cross the venter with slight convexity. The umbilical seam runs along the line of tubercles. The test is complete on the phragmo- cone so that the septal suture is not exposed (d’Orbigny’s plate 135, fig. 1 is not of this specimen). The body chamber, three-fifths whorls (225°) in length, becomes rapidly more evolute with the overlap decreasing from about two-fifths to one-third, resulting in moderate ‘elliptical’ coiling, and slightly contracted towards the end; there is marked negative allometry for both whorl height and breadth (see measurements). The ornament becomes increasingly prominent, particularly on the venter. The con- cave primaries lengthen at the end of the phragmocone and at the beginning of the body chamber, so that the tubercles move from mid-lateral outward to approximately three-fifths whorl height ; but at the end of the body chamber, tuberculation is again mid-lateral. Parallel growth lines appear between the distant primaries. Slight asymmetry is present at the beginning of the body chamber with the egression of the umbilical seam being relatively retarded on the right side. Noteworthy is the strong reduction of relief on the internal mould of the left flank of the body chamber where the sharp ribbing of the shell becomes blunt. WESTERMANN AND RIOULT: CADOMITES PSILACANTHUS 875 The peristome begins with a prominent slightly prorsiradiate collar parallel to the ribs and growth lines, and continues with a smooth sinuous margin covered by growth lines which indicate a broad umbo-lateral sinus and a straight ventral lip. Measurements in mm on ribs/tubercles Whorl Diameter height Peristome 110-3 40 End body chamber 105-5 35-5 (0-33) Beginning body 81-5 33 (0-40) chamber Locality and age The sediment in the body chamber is a grey micritic limestone with small shiny ferruginous ooids. This lithofacies is well exposed in the ancient quarry of Sully, a few kilometres north of Bayeux, at the base of the ‘Oolithe ferrugineuse de Bayeux’ ; i.e. the boundary of the condensed Humphriesianum and Subfurcatum Zones (lower or middle/upper Bajocian) (Rioult 1964, layers 3a-3b). The lectotype originated either here or in any of several other quarries of the immediate vicinity which have long been filled in. D'Orbigny's illustration Figs. 1 and 2 on plate 134 of d’Orbigny (1845) show good likeness to the actual specimen and are thus not synthesograms. It appears, however, that the lithographer, J. Delarue, engraved the more complete right side (marked by relatively retarded egression of the umbilical seam) and reversed the sides in the printing process; while the aperture is from the left side. D’Orbigny’s figures differ from the original also as follows: (1) 10% reduction; (2) narrower and less depressed whorl section, parti- cularly at the beginning of the body chamber (B/H = 1-34 v. 1-48) which thus appears to grow isometrically rather than negatively allometric; (3) section of aperture too narrowly curved laterally; (4) less flexuous ribbing particularly at the base of the secondaries; (5) more distant primaries on the inner whorls; and (6) most tubercles pointed rather than somewhat elongate. The paralectotypes The original to figs. 3 and 4 of d’Orbigny’s plate 134 is neither in the Tesson nor in the d’Orbigny Collections. The illustrations, said to be natural size, show a small septate specimen of 22 mm diameter which closely resembles the nucleus of the lecto- type (for which the primaries were illustrated too widely spaced) and appears to be a juvenile, nucleus, or microconchiate phragmocone of the same or closely allied species. The septum is shown to have two (paired) subequal saddle axes indicating two saddles of the internal suture, typical for Cadomites (see Westermann 1956). The third original collection referred to by d’Orbigny (1845, p. 400) was made by Deslong- champs and kept at the University of Caen; it was destroyed by fire and bombing in 1944. Umbilical Primaries/ Secondaries/ Breadth diameter whorl whorl 56 44 33 127 50-6 (0-47) 41 (0-38) 32 48-7 (0-59) 28 (0-34) 876 PALAEONTOLOGY, VOLUME 18 Taxonomic remarks and comparison In spite of appreciable efforts, no topotypes of C. psilacanthus have been discovered. It appears that in general the genus Cadomites becomes more abundant only in the uppermost Bajocian, Parkinsoni Zone. C. psilacanthus is morphologically transitional between Stephanoceras and Cado- mites combining the relatively short primaries of the former with the body chamber coiling and sharpness and density of ribbing of the latter; the primaries, however, are still widely spaced as in Stephanoceras and the body chamber does not contract significantly as in Cadomites. However, the septum of the paralectotype (above) and the stratigraphic range to the top of the Bajocian indicate strong affinity to Cadomites. The specimens, mainly from the Parkinsoni Zone of the Alps described under C. psilacanthus or ‘C. arkelli by Sturani (1964«, b, 1966) are here distinguished as a new subspecies of C. psilacanthus. The Andean 'Coeloceras cosmopoliticum" Moricke (1895) from northern Chile has been illustrated only in a single specimen by Steinmann (1881, p. 268, pi. XII, fig. 7). It has the curved primaries and round tubercles of C. psilacanthus but differs in the circular whorl section and the more distant primaries on the inner whorls. Current reinvestigation by one of us (G. E. G. W.) of the Caracoles fauna suggests closer affiliation to Stephanoceras s.s. than to Cadomites. There is close resemblance to C. deslongchampsi (Defrance in d’Orbigny, nom. eorr.) from the Parkinsoni and Zigzag Zones and the closely allied C. homalogaster Buckman (1925, pi. 543) from the ‘Leptosphinctes hemera’ (= Subfurcatum Zone), except for the shorter primaries and the absence of a lateral shoulder in C. psilaeanthus. The somewhat similar probable Cadomites described by Roche (1939, pis. 2 and 3) from the Humphriesi- anum-Subfurcatum Zones of eastern France (C. humphriesiformis, C. perplicatus, C. ? lissajousi) are all much more compressed than C. psilacanthus. Cadomites psilaeanthus sturanii subsp. nov. (Synonymy see under C. psilacanthus.) Diagnosis. More rounded (narrower) whorls and less flexed ribs than in C. psila- eanthus s.s. Holotype. Cadomites arkelli Sturani, \%Ah, p. 20, text-fig. 20, pi. 2, fig. 5, from the Parkinsoni Zone of Cava Magnavacca, Venetian Alps (for nomenclature of C. arkelli see above). Age. This subspecies occurs at a higher level in the upper Bajocian (Parkinsoni Zone) than C. psilacanthus s.s. Acknowledgements. We thank Dr. M. K. Howarth and Mr. D. Philips of the British Museum (Natural History) for their kind co-operation during our visits and for furnishing some of the photographs. REFERENCES ARKELL, w. j. 1951-1958. Monograph of English Bathonian ammonites, parts 1-8. Palaeonlogr. Soc. [Monogr.]. 1-264, 33 pis. BUCKMAN, s. s. 1908. Illustrations of type specimens of the Inferior Oolite ammonites in the Sowerby collection. Ibid. pis. I-VII with explanations. 1909-1930. (Yorkshire) Type ammonites, parts 1-7. London, text and 790 pis. FALLOT, p. and BLANCHET, F. 1923. Observations sur la faune des terrains jurassiques dans la region de Cardo et de Tortosa (Province de Tarragone). Treh. Inst. Catal. Hist. nat. 1921-1922, 71-260, 13 pis. WESTERMANN AND RIOULT: CADOMITES PSILACANTHUS 877 GILLET, s. 1937. Les ammonites du Bajocien d’Alsace et de Lorraine. Serv. Carte geol. Alsace-Lorraine, Mem. 5, 130 pp., 5 pis. KOPiK, J. 1974. Genus Cadomites Munier-Chalmas, 1892 (Ammonitina) in the Upper Bajocian and Bathonian of the Cracow-Wielun Jurassic Range and the Gory Swietokrzyskie Mountains (southern Poland). Inst. Geol., Bull. 276, 7-53, pis. I-XI. MORiCKE, w. 1895. Beitrage zur Geologic und Palaeontologie von Stidamerika. II, Die Versteinerungen des Lias und Unteroolith von Chile. Neues Jb. Miner. Geol. Paldont. Beil.-Bd. 9, 1-100, pis. I-VI. MUNIER-CHALMAS, E. c. p. A. 1892. Sur la possibilitc d’admettre un dimorphism sexuel chez les Ammoni- tides. C.r. Soc. geol. Fr. ser. 3, 20, 170-174. NEUMAYR, M. 1875. Die Ammoniten der Kreide und die Systematik der Ammonitiden. Z. dt. geol. Ges. 27, 854-892. OPPEL, A. 1856-1858. Die Juraformation Englands, Frankreichs und des sudwestlichen Deutschlands. Jh. Ver. vaterl. Naturk. Wiirtt. XII, 221-556; XIII, 141-396; XIV, 129-291. ORBiGNY, A. d’. 1842-1849. Paleontologie Frangaise, Terrains jurassiques, Cepbalopodes. Paris (Masson), text 1-642, Atlas pis. 1-234. 1850-1852. Cours elementaire de paleontologie et de geologie stratigraphique. V. Masson ed., Paris, 1-847, 628 figs. RIOULT, M. 1964. Le stratotype du Bajocien. In CoU. Jurass. Luxembourg 1962, Compt. Rend. Mem. Inst. grand-ducal, sect. sci. nat. phys. math. Luxembourg, 239-263. ROCHE, p. 1939. Aalenien et Bajocien du Maconnais et de quelques regions voisines. Trav. Lab. Geol. Univ. Lyon, 35, Mem. 29, 1-355, pis. I-XIII. SOWERBY, J. DE c. 1822-1846. Mineral Conchology. Pis. 338-648. STEiNMANN, G. 1881. Zur Kenntniss der Jura- und Kreideformation von Caracoles (Bolivia). Neues Jh. Miner. Geol. Paldont. Beil.-Bd. 1, 239-301, pis. I-XVII. STURANi, c. 1964fl. La successione delle faune ad ammoniti nelle formazioni mediogiurassiche delle Prealpi Veneto occidentale (region! tra il Lago di Garda e la valle del Brenta). 1st. Geol. Miner. Univ. Padova, Mem. 24, 1-64, pis. I-VI. 19646. Ammoniti mediogiurassiche del Veneto, faune del Baiociano terminale (Zone a Garantiana e a Parkinsoni). Ibid. 1-43, pis. I-IV. 1966. Ammonites and stratigraphy of the Bathonian in the Digne-Barreme area. Boll. Soc. paleont. ital. 5, 3-57, pis. 1-24. WERMBTER, H. 1891. Der Gebirgsbau des Leinethales zwischen Greene und Banteln. Neues Jh. Miner. Geol. Paldont. Beil.-Bd. 7, 246-294, pis. IV-V. WESTERMANN, G. E. G. 1956. Phylogenie der Stephanocerataceae und Perisphinctaceae des Dogger. Neues. Jb. Geol. Paldont. Abh. 103, 233-279. ziETEN, c. H. V. 1830-1834. Die Versteinerungen Wiirttemhergs, parts 1-12, 102 pp., 72 pis. Stuttgart. G. E. G. WESTERMANN Department of Geology McMaster University Hamilton, Ontario L8S 4M1 Canada M. RIOULT Departement de Geologie Universite de Caen Esplanade de la Paix 14000-Caen, France Typescript received 4 September 1974 Revised typescript received 6 February 1975 SHORT COMMUNICATIONS TEREBRATULIDE AFFINITY OFTHE BRACHIOPOD SPIRIFERA MINIMA MOORE by P. G. BAKER and c. J. t. copp Abstract. Investigation of seventy-three recently rediscovered specimens of Spiriferinal minima (Moore) enables resolution of the problem of possible synonymy with Nannirhynchia longirostra Baker, 1971. Comparison of the cardinal areas and delthyria of the two species enables the distinction between S. ? minima and N. longirostra to be clearly demonstrated. Further, the characters of the shell show that 5.? minima (Moore) is a juvenile terebratulidine assignable to Terehratula and that N. longirostra Baker is validly designated. The micromorphic Spiriferinal minima has periodically attracted the attention of palaeontologists (Davidson 1876; Buckman 1918; Ager 1967; Baker 1971) since the first record (Moore 1861) of its occurrence in the Inferior Oolite of Dundry Hill near Bristol. Unfortunately, the precise location from which Moore obtained his material is not known. All investigation of the species has been hampered by the absence of the holotype and the apparent lack of any syntypes or topotypes. It is particularly gratifying, therefore, that a part of the Charles Moore Collection, recently rediscovered in the Somerset County Museum, Taunton Castle, should include a box containing seventy-three specimens labelled, ‘4462. Spirifera minima, Dundry’. No precise horizon is given but the adherent matrix is identical with that of the accompanying thecidellinids of undisputed Bajocian age. The material was presented to the museum in 1905 by the Revd. H. H. Winwood, who had been in charge of the Moore Collec- tion at Bath following Moore’s death in 1881. The part of the collection presented to the Taunton Museum apparently consisted of specimens which were kept at Moore’s house and, therefore, not sold with the main collection housed in the Bath Literary and Scientific Institution. It is probable that Moore’s widow kept them and later gave them to Winwood. This would account for the absence of S.l minima from the Bath Museum when earlier workers wished to refer to it. Davidson (1876, p. 103) tentatively proposed the name Spiriferinal for Spirifera Moore, 1861, but did not formally designate the genus, observing ‘I know so little of this minute fossil I cannot venture to express any opinion with respect to the genus to which it belongs’. As S.l minima is certainly a juvenile terebratulidine and as there is, at present, no way of assigning the species to an adult genus, the authors would prefer formal designation to remain in abeyance. However, in view of the con- siderable time which has elapsed since Moore’s description, and in view of the recurring interest in S.l minima, it is considered that Moore’s original diagnosis merits repro- duction and emendation. [Palaeontology, Vol. 18, Part 4, 1975, pp. 879-882.] 880 PALAEONTOLOGY, VOLUME 18 "Terehratula' minima (Moore) Text-fig. Ia-d; text-fig. 2 1861 Spirifera minima Moore, p. 190, pi. ii, figs. 19, 20. 1876 Spiriferinal minima (Moore) Davidson, p. 103, pi. XI, fig. 17. 1918 Nannirhynchial (Spiriferinal) minima (Moore) Buckman, p. 68. 1967 Nannirhynchial minima (y[ooxQ), Kgtr,p. 137. Original diagnosis. Shell microscopic, often one sided or asymmetrical, slightly rugose; valves moderately convex; deltidium triangular; area broad and flattened; hinge line broad ; front of shell rounded. In some specimens the shell presents a uni- formly flattened surface, whilst in the majority the outer surface of the smaller valve possesses mesial folds and in the larger valve a central sinus (Moore). Emended diagnosis. Minute, asymmetric " Ter ebr alula' \ planoconvex to ventribi- convex, slightly longer than wide, characterized by low, poorly defined mesial folds which fail to deflect the commissure. Apex of the delthyrium closed by a rudimentary pedicle collar. Shell endopunctate. Lectotype. There is very little evidence of a type specimen or specimens having been used by Moore in his original description of the species in 1861. It is likely that, adopting the procedure of many palaeontologists of the time, he established the species on knowledge obtained from several examples which he considered to be typical or characteristic forms. This belief is borne out by the comments ‘In some specimens’ and ‘whilst in the majority’ in Moore’s original diagnosis. In addition, figs. 19 and 20 (Moore 1861, pi. ii) are quite clearly prepared from different specimens. His locality and stratigraphical details were vague. Since the only known specimens are those in the Somerset County Museum, No. 4462, the specimen figured in this paper (text-fig. 1a-d) is here proposed as a lectotype. TEXT-FIG. 1. A-D. Stereoscaii photomicrographs of the lectotype (No. 4462A) of 'Terehratula' minima (Moore), showing the general morphology. Specimen coated with evaporated aluminium before photo- graphy. A, brachial view showing the characteristic lateral deflection of the beak, x 35. b, lateral view, x 35. c, anterior view, x 50. Specimen tilted forwards slightly, to show the poorly defined mesial folds, d, enlarged view of the umbonal region, showing the rudimentary pedicle collar closing the apex of the delthyrium, X 85. BAKER AND COPP: 'TEREBRATULA' MINIMA (MOORE) 881 Dimensions of lectotype. Length 1-2 mm, width 10 mm, thickness 0-4 mm. Distribution. Uncertain. Moore (1861, p. 190) states that the species is not uncommon in the Inferior Oolite of Dundry. The Somerset County Museum specimens are simply labelled Dundry and it is presumed that they are topotypes. They are associated with moorellinids of Murchisonae Zone age. Description. External characters. A juvenile terebratulidine up to about T8 mm long, 1-6 mm wide, and 0-4 mm thick, often symmetrical but more commonly with a marked lateral deflection of the beak. Typically planoconvex or ventribiconvex but biconvex forms are seen. A characteristic feature is the flattening of the cardinal area to form an interarea sensu lato, bounded by very sharp beak ridges. Small disjunct deltidial plates are present, with their inner edges elevated above the plane of the cardinal area. Specimens, in which the structure is not obscured by matrix, show a rudimentary pedicle collar closing the apex of the delthyrium, undoubtedly repre- senting the triagular ‘deltidium’ noted by both Moore (1861) and Davidson (1876). Internal characters. Apart from immature hinge teeth and sockets, no other internal characters have been noted. Discussion. As noted earlier, attempts to study the species have been hampered by the unavailability of a holotype. An important feature overlooked by Moore but presumably noted by Davidson (hence Spiriferinal) is the endopunctate shell. Although even Davidson (1876, p. 103) had to rely on drawing ‘one of Moore’s specimens’. It appears that by 1918 even the topotypes had been mislaid or Buckman (1918, p. 68) would surely have been able to differentiate between 'Terehratula minima and Nannirhynchia subpygmaea Buckman (ex Walker MS.) particularly as weathered specimens of ‘T.’ minima are so obviously endopunctate. In the absence of actual specimens for study, subsequent workers (Ager 1967; Baker 1971) have also been misled by the superficial resemblance between ‘T.’ minima and Nanni- rhynchia Buckman. Of particular interest was the possibility of synonymy of ‘T.’ minima with N. longirostra Baker, 1971. The recently discovered specimens show that ‘T.’ minima is much more dorso-ventrally compressed than N. longirostra. Diagnostic differences are seen in the cardinal areas and delthyria of the two species and in the observation that ‘T.’ minima is endopunctate whereas N. longirostra is impunctate. The flat cardinal area and sharp beak ridges (text-fig. 2a, b) of ‘T.’ minima are in sharp contrast with the rounded beak ridges and well-defined palintropes (text-fig. 2c) of N. longirostra. A pedicle collar is characteristic of both species but in N. longirostra this is an almost sessile structure (Baker 1971, pi. 135, fig. 10; pi. 136, fig. 1) not usually visible externally. A further minor difference is that in the brachial valve of ‘T.’ minima, a shallow sulcus develops on either side of the umbonal region but in N. longirostra the brachial valve is regularly convex in this region. Demonstration of the distinction between ‘T.’ minima and N. longirostra still leaves the affinity of ‘T.’ minima for consideration. ‘T.’ minima displays all the characters which are typical of juvenile cancellothyridids. If the cardinal area and delthyrial characters are compared with an early juvenile cancellothyridid aflf. Plectothyris (text-fig. 2d) from a different locality (Baker 1 97 1 , p. 696) they are found to correspond in almost every detail, even to the rudimentary pedicle collar. The closeness of the 882 PALAEONTOLOGY, VOLUME 18 TEXT-FIG. 2. Detail of the morphology of the posterior portion of the shells of four specimens investigated. All x25 magnification, a, b, small, A, and larger, b, specimens oVTerebratula' minima (Moore), c, Nanni- rhynchia longirostra, holotype (Brit. Mus. BB.45820). D, early juvenile terebratulidine afif. Plectothyris. resemblance must be genetic rather than coincidental and the conclusion drawn from the study of the newly available material must be, therefore, that S.l minima (Moore) is a juvenile of an undetermined terebratulidine brachiopod assignable to 'Tere- bratula\ Acknowledgements. The authors wish to thank Dr. H. Torrens, Department of Geology, University of Keele, for information leading to the rediscovery of the material and Dr. J. D. Hudson, Department of Geology, University of Leicester, for comments on a previous version of the manuscript. REFERENCES AGER, D. v. 1967. The British Liassic Rhynchonellidae, Part IV. Palaeontogr. Soc. (Monogr.), London, 121, 137-172. BAKER, p. G. 1971. A new micromorphic rhynchonellide brachiopod from the Middle Jurassic of England. Palaeontology, 14, 696-703. BUCKMAN, s. s. i 9 1 7 ( 1 9 1 8). The Brachiopoda of the Namyau Beds, Northern Shan States, Burma. Palaeont. Indica, new ser. 3, 299 pp. DAVIDSON, T. 1876. Supplement to the British Jurassic and Triassic Brachiopoda, British Fossil Brachio- poda, pt. 4, 103, Suppl. PI. 11. Palaeontogr. Soc. (Monogr.), London. MOORE, c. 1861. On new Brachiopoda and the development of the loop in Terebratella. Geologist, 4, 190-194. P. G. BAKER Division of Geology Derby College of Art and Technology Kedleston Road Derby, DE3 1GB C. J. T. COPP Department of Geology University of Keele Keele, STS 5BG Typescript received 12 March 1975 Revised typescript received 18 April 1975 NEW DATA ON TREMADOC GRAPTOLITES FROM YUKON, CANADA by D. E. JACKSON Abstract. The Tremadocian subzones of Staurograptus tenuis, Anisograptus richardsoni, Clonograptus aureus, and Adelograptus antiquus are given full zonal status in northern Richardson Mountains. Bryograptus ramosus Br0gger and a species of Dictyonema are described from the upper Tremadoc. The occurrence of B. ramosus in the C. aureus Zone supports a correlation with shales of 3ajS age in Norway. In 1974 Jackson presented findings on the sequence of graptolites found in Trema- docian shales on Peel River, Yukon Territory. In addition to simplifying zonal terminology the paper proposed that the Adelograptus Zone and the Staurograptus Zone each be divided into two subzones. This short paper offers important new data from two river sections in the Richardson Mountains. The Rock River section which lies 100 km north of Peel River demonstrates the usefulness of the Peel River zonal scheme, and the Canyon Creek section 40 km north-west of the Upper Canyon on Peel River provides supplementary data on the faunal content of the upper Tremadoc. TEXT-FIG. la, b, d, Bryograptus ramosus Br0gger; a, d, GSC hypotypes 27000 and 27001 respectively, x 3; ft, GSC hypotype 27002, x 5; c, Dictyonema sp. GSC hypotype 27003 (not described); e, Dictyonema cf. percancellatum Ruedemann GSC hypotype 27004, x3',f, 1 Dendrograptus sp. GSC hypotype 27005 (not described), x 3. All figures are camera lucida drawings. [Palaeontology, Vol. 18, Part 4, 1975, pp. 883-887.] 884 PALAEONTOLOGY, VOLUME 18 TABLE 1. Rock River Section (66° 48' N.; 136° 07' W.) measured by geologists of Chevron Standard Ltd., in 1968; field designation ZB- 19. “d o o ^ o n 4^ X n "s cd b n "s P (T O C) Oq oq II D T3 S 5 C) O5 Oq t3 -T3 P 2 :::: ^ cd I si §■ s ts| ^ ^ III S s 5 S-T3 ? f“ -S' ® 2. ^ ~. • ^ K a ^ S P == H H S' • • C/5 ^ c/3 g X K P CO II 5 2 a a a 2 a. a a a- 05 T3 2 2 S 2 H on X p ZONES 8490 8310 8250 8240 8145 8125 8025 7945 7855 7805 X X 9 X ? X X X X X T. approximatus ■ A. antiquus 7765 7760 7750 7690 7685 C. aureus A. richardsoni S. tenuis TABLE 2. Canyon Creek Section (66° 10' N.; 136° 05' W.) measured by Dr. B. S. Norford, Geological Survey, Canada, 1963. O o o S o’ cr .05 0? o' ■< fc g JS 3 3 0“ < a n, n p D P CL O O P cr o < rp cr p S ^ 5^ a I 11- 2 ■§ 5 c« a Ti b n S' S' '§ a a 3? a a 2 i » a . O 55 ^ a .'o t/5 ■a Xi NJ "J /a O S ^ CD OQ OQ P O ?*r c/3 £ o c bIQQ -=—33 .2 2 a a 35 c^ 05 •S a .2 ^ “a as a a a a 5' Qd a. ; . 53034 53032 53031 1054-7 862 503-504 X X XXX XXX JACKSON: TREMADOC GRAPTOLITES 885 Remarks. The four graptolite subzones proposed by Jackson (1974) are recognized at the following levels in the Rock River section: Adelograptus antiquus 7805-8310 ft; Clonograptus aureus 7760-7765 ft; Anisograptus richardsoni 7690-7750(7) ft; and Staurograptus tenuis 7685 ft. In the Canyon Creek section, a limestone breccia at 948-967 ft is correlative with a conglomerate marker horizon in the Upper Canyon on Peel River (Jackson 1974, p. 57). The assemblage from GSC loc. 53031 is probably from the C. aureus Zone because adelograptids and Anisograptus are absent. The two younger collections probably represent the Adelograptus antiquus Zone on the basis of the clonograptid composition. In conclusion, the occurrence of Jackson’s (1974) proposed subzones on Rock River, 100 km north of Peel River, demonstrates that these biostratigraphic units are widely distributed along the Richardson Trough and for this reason are raised to zonal status. The discovery of Bryograptus ramosus in the basal upper Tremadoc tends to support the correlation of the Clonograptus aureus Zone with shales of 3a/3 age in Norway. SYSTEMATIC DESCRIPTIONS Class GRAPTOLiTHiNA Bronn, 1849 Order dendroidea Nicholson, 1872 Family dendrograptidae Roemer in Freeh, 1897 Genus dictyonema Hall, 1851 Dictyonema cf. percancellatum Ruedemann Text-fig. \e cf. Dictyonema percancellatum n. sp. Ruedemann 1947, p. 172, pi. 4, figs. 13, 14. Material. One compressed and fragmented rhabdosome GSC (Geological Survey of Canada) hypotype 27004 from GSC loc. 53032, Canyon Creek, collected by B. S. Norford, 1963. Description. Rhabdosome fragmented 11 mm long and 10 mm wide. Stipes are 0-3-0-4 mm wide dorsally and number fourteen per cm. Details of thecae not seen. Dissepiments are less robust, 0-4 mm long, number eighteen per cm, and tend to have a common alignment across the entire rhabdosome. The frequency of dissepimental spacing suggests that dissepiments are produced at the level of every autotheca (or bitheca) or at alternate autothecae and bithecae. Intra rhabdosomal spaces tend to be square. Remarks. The close spacing of stipes and dissepiments makes this a distinctive dendroid. The nearest comparison that I have been able to make is with D. per- cancellatum from St. Pauls Inlet, Newfoundland. Ruedemann’s original description merely dated the species as Ordovician. However, published accounts by Kindle and Whittington (1958, p. 327) show that Tremadocian rocks do exist in the area. 886 PALAEONTOLOGY, VOLUME 18 Family anisograptidae Bulman, 1950 Genus bryograptus Lapworth, 1880 Bryograptus ramosus Br0gger, 1882 Text-fig. la, b, d 1882 Bryograptus ramosus Br^gger, p. 37, pi. XII, fig. 21. non 1894 Bryograptus ramosus Br^gger; Marr, p. 125, figs. 1-5. 1925 Bryograptus ramosus Br0gger; Monsen, p. 160, pi. 1, fig. 9; text-fig. 3. 1954 Bryograptus cf. ramosus Br0gger; Bulman, p. 34, pi. 4, fig. 9. 1963 Bryograptus ramosus Br0gger; Spjeldnaes, p. 122, pi. XVII, figs. 7-9; text-fig. 1. 1965 Bryograptus ramosus Br0gger; Erdtmann, p. 105, pi. 2, fig. 5. 1966 Bryograptus ramosus (Br0gger); Szymanski, pp. 50, 59, pi. vi, fig. 9. 1971 Bryograptus ramosus Br0gger; Bulman, pp. 365-366, figs. le,f, 2c. Material. Five compressed specimens GSC hypotypes 27000, 27001, and 27002 from GSC loc. 53031, Canyon Creek, collected by B. S. Norford, 1963. Description. Rhabdosome 21 mm long and 20 mm across distally. Fourteen terminal stipes are produced by dichotomous and ? lateral branching from three primary stipes. Two zones of branching occurs at 3 0-3-6 mm and 6-6-9 0 mm from sicula. Sicula 1-3 mm long furnished with a fine nema. Two primary stipes have three thecae and the third stipe has one theca, these stipes diverge from sicula at about 60-80° then curve rapidly inwards to become sub-parallel. Stipes have a maximum dorso-ventral width of 0-6-0-7 mm across thecal aperture and 04-0-5 mm just above the aperture; free ventral wall of thecae are concave and inclined at 30-40° near aperture. Auto- thecae number 16-20 per cm, bithecae not seen. Remarks. Bryograptus ramosus differs from B. kjerulfi in having more widely spaced zones of dichotomy and closer spacing of autothecae. It is distinct from B. broeggeri Monsen which has more widely dispersed zones of branching and a characteristically long and slender sicula. In Scandinavia, this species is characteristic of the lower part of 3a^ (Monsen 1925) and according to Erdtmann (1965) ranges upwards into 3ay beds. Similarly, Szymanski (1966) recorded it from upper Tremadoc of Bialowieza, Poland. The assemblage from GSC loc. 53032 possibly should be assigned to the C. aureus Zone on account of its position relative to the conglomerate marker and because of the lack of adelograptids. REFERENCES BROGGER, w. c. 1882. Die silurischen Etagen 2 und 3 im Kristianiagebiet und auf Eker. Krisfiania (Oslo). 376 pp. BRONN, H. G. 1849. Index Palaeontologicus B. Enumerator. Stuttgart. 980 pp. BULMAN, o. M. B. 1950. Graptolites from the Dictyonema Shales of Quebec. Q. Jlgeol. Soc. Land. 106, 63-99. 1954. The graptolite fauna of the Dictyonema Shales of the Oslo region. Norsk geol. Tidsskr. 33, 1-40. 1971. Some species of Bryograptus and Pseudohryograptus from Northwest Europe. Geol. Mag. 108,361-371. ERDTMANN, B.-D. 1965. Fine spat-Tremadocische Graptolithen fauna in Oslo. Norsk geol. Tidsskr. 45, 97-112. FRECH, F. 1897. Letliaea Geognostica, 1, Th. Leth. pal. 1. 11, Graptolithen. Stuttgart. HALL, J. 1851. New genera of fossil corals etc. Am. J. Sci. (2), 11, 398-401. JACKSON: TREMADOC GRAPTOLITES 887 JACKSON, D. E. 1974. Tremadoc Graptolites from Yukon Territory Canada. In rickards, r. b., jackson, D. E. and HUGHES, c. p. (eds.). Graptolite Studies in Honour of O. M. B. Bulman. Spec. Pap. Palaeont. 13, 35-58. KINDLE, c. H. and WHITTINGTON, H. B. 1958. Stratigraphy of the Cow Head Region, Western Newfoundland. Geol. Soc. Am. Bull. 69, 315-342. LAPWORTH, c. 1880. On New British Graptolites. Ann. Mag. nat. Hist. (5), 5, 149-177. MARR, J. E. 1894. Notes on the Skiddaw Slates. Geol. Mag. 31, 122-130. MONSEN, A. 1925. liber eine neue Ordovicishe Graptolithen fauna. Norsk geol. Tidsskr. 8, 147-187. NICHOLSON, H. A. 1872. Monograph of British Graptolites. Edinburgh and London. NORFORD, B. s. 1964. Reconnaissance of the Ordovician and Silurian rocks of Northern Yukon Territory. Geol. Surv. Canada Paper 63-39, 1 39 pp. RUEDEMANN, R. 1947. Graptolites of North America. Mem. Geol. Soc. Am. 19, x-|-652 pp., 92 pis. SPJELDNAES, N. 1963. Some Upper Tremadocian graptolites from Norway. Palaeontology, 6, 121-131. SZYMANSKI, B. 1966. Dictyonema Shales of the Krzyze Beds Region of Bialowieza. Kwart. geol. 10, 44-62. Typescript received 16 October 1974 Revised typescript received 11 December 1974 D. E. JACKSON Department of Earth Sciences The Open University Milton Keynes, MK7 6AA THE PALAEONTOLOGICAL ASSOCIATION Annual Report of the Council for 1974 Membership and Subscriptions. Membership of the Association totalled 1,431 on 31 December 1974 (840 Ordinary, 198 Student, and 393 Institutional Members). 122 individual and 103 Institutional Members subscribed to Special Papers in Palaeontology for the year. In addition, 380 institutions subscribed to Palaeontology and 144 to Special Papers in Palaeontology, through Blackwell’s agency. Total membership showed an increase of 65 since 31 December 1973, and subscriptions by members to Special Papers an increase of eight. A slight decrease (10) in the number of institutions subscribing to Palaeontology as members reflected a trend among overseas institutions to subscribe through agents, and therefore to the Association through Blackwell’s. Subscriptions through Blackwell’s to Palaeontology and Special Papers rose by 56 and 24 respectively over the year. Both membership and subscription totals therefore set new high records. Finance. During 1974 the Association published Volume 17 of Palaeontology at an estimated cost of £17,863 and Special Papers 13 and 14 which are expected to cost £8,003. This expenditure of £25,866 is by far the greatest on publication in the Association’s history. Part of the increase comes from even faster rises in printing charges, but is also the result of our decision to publish more in one year than ever before. Total expenditure was £28,055, nearly £10,000 more than last year, and £7,147 more than the previous high in 1 97 1 . Administration cost only £209 more in 1 974 than in 1 973 ; this is a reminder that the Association is fortunate in having unpaid officers and no buildings to maintain. Total income in 1974 was £23,665 which is a fall of £5,817 on last year, although part of this is because the Association has not yet received from Blackwell’s the money for regular sales of part 4 of Volume 17 of Palaeontology and Special Paper 14. During this period of rapidly rising costs, the Association is the more indebted to all the individuals and organizations who have given money to help publication. Such donations in 1974 were the highest for eight years at £1,185, and we warmly thank the Universite Laval, Sidney Sussex College (Cambridge), and the Government of New South Wales for their support of Special Paper 13, the Burmah Oil Company (Australia) Ltd. for their support of Special Paper 14, and the University of Connecticut and the Carnegie Trust for Scotland for their subsidies for papers in Palaeontology. The Association’s reserves now stand at £18,918 which is no longer sufficient to pay one year’s printing commitments. Whilst there is no cause for alarm, it would be prudent to raise subscriptions for 1976. Publications. Four parts of Volume 17 were published during 1974; they contained 49 papers and 4 short communications consisting of 971 pages and 126 plates. Despite the effects of the three-day week and industrial disputes which delayed the publication of Volume 1 7, part 1 until April and part 2 until September, part 4 was published on time in November. Two Special Papers have been published during the year. Special Paper 13 ‘Graptolite studies in honour of O. M. B. Bulman’ was published in October and Special Paper 14 ‘Palaeogene Foraminiferida and palaeoecology, Hampshire and Paris Basins and the English Channel’ was published in December. Meetings. Seven meetings were held during 1974. The Association is indebted to Professor B. C. King (Bedford College, London), Professor F. W. Shotton (Birmingham University), and Professor D. L. Dineley (Bristol University) for granting facilities for meetings, to the leaders of the field excursions, and to the local secretaries for their efficient services in organizing the meetings. a. The Seventeenth Annual General Meeting was held in the Lecture Theatre of The Geological Society of London on 6 March 1974. Professor Dr. M. Lindstrom of Philipps-Universitat, Marburg delivered the Seventeenth Annual Address on ‘The conodont apparatus as a food-gathering mechanism’. The address was published in Palaeontology, 17, 729-744. b. A Colloquium on molluscan phylogeny was held at Bedford College, London on 3-4 April 1974. Over P 890 THE PALAEONTOLOGICAL ASSOCIATION 1 00 delegates from 1 2 countries attended to hear some 33 contributions. The colloquium was organized by Drs. J. D. Taylor and N. J. Morris, British Museum (Natural History). c. A Field Demonstration Meeting was organized by the Carboniferous Group on the ‘Belgian Dinantian’ and led by Professor R. Conil, Dr. H. Pirlet, and Dr. E. Grossens. The meeting was held on 25-28 April and was well supported. d. A Field Demonstration Meeting on the ‘Wenlock Limestone of Wenlock Edge, Shropshire’ was held on 11-12 May 1974 and led by Dr. T. P. Scoffin (University of Edinburgh). About 35 members attended. e. An extra Field Demonstration Meeting on a temporary exposure in the Bagshot Beds at Virginia Water, Surrey was held on 14 September 1974 and led by Mr. D. W. J. Bosence (Goldsmiths’ College) and Dr. R. Goldring (Reading University). /. An International Symposium on the Ordovician System was held at Birmingham University on 17-20 September 1974, attended by nearly 200 delegates from 25 countries. Symposium field excursions were conducted to the Ordovician sections in Wales and the Welsh Borders (10-17 September) and to Northern England and Southern Scotland (20-25 September). The symposium was organized by Professor A. D. Wright (Queen’s University, Belfast) assisted by Dr. D. A. Bassett, Dr. J. K. Ingham, and Dr. Isles Strachan. The Proceedings of the Symposium are to be published for the Association by the University of Wales Press. g. The Annual Christmas Meeting on the ‘Recognition of brackish water assemblages in the fossil record’ was held at Bristol University on 16-18 December 1974. About 100 members attended. Two field excursions were organized to local sections and led by Dr. D. Hamilton, Dr. A. B. Hawkins, Dr. S. C. Matthews, and Dr. J. W. Murray. The local secretary was Dr. J. W. Murray. Council. The following were elected members of Council for 1974-1975 at the A.G.M. on 6 March 1974: President: Professor C. H. Holland; Vice-Presidents: Dr. R. Goldring, Dr. W. D. I. Rolfe; Treasurer: Dr. J. M. Hancock; Membership Treasurer: Dr. E. P. F. Rose; Secretary: Dr. C. T. Scrutton; Editors: Dr. J. D. Hudson, Dr. D. J. Gobbett, Dr. L. R. M. Cocks, Dr. C. P. Hughes, Dr. J. W. Murray (Dr. C. B. Cox was co-opted as an Editor in October 1974 after the resignation of Dr. D. J. Gobbett); Other members: Dr. M. G. Bassett, Dr. D. D. Bayliss, Dr. M. C. Boulter (Circular Reporter), Dr. C. H. C. Brunton, Pro- fessor D. L. Dineley, Dr. J. A. E. B. Hubbard, Dr. J. K. Ingham, Dr. C. R. C. Paul, Dr. J. E. Pollard, Dr. P. F. Rawson, Dr. A. W. A. Rushton, Professor D. Skevington, Dr. P. Wallace. Circulars. Four Circulars, Nos. 75-78 were distributed to Ordinary and Student Members and over 100 Institutional Members on demand during 1974. Consideration was given to the airmailing of Circulars to overseas members but was rejected as a blanket proposal on grounds of cost. It was agreed, however, that Overseas Members due to visit the United Kingdom could receive Circulars on request, by airmail, immediately prior to their visit. A marked increase in Ordinary, and particularly Student, membership together with Special Papers subscriptions followed revision of the Association’s Information and Member- ship Application leaflets and their distribution to all members with the October Circular. Thanks are due to those members who used the leaflets to introduce new applicants. A coloured Subscription Reminder form was first issued with the February Circular. Many members then in arrears with subscription payment responded promptly, considerably reducing the time and cost involved in collecting dues. A discount Sales Order form was first issued with the March Circular. Subsequent sales to members through the Membership Treasurer maintained the record levels of 1972 and 1973, more than treble the previous annual average number of transactions. Both forms will be issued annually in future, and also a publicity leaflet/sales order form for each Special Paper on publication, as in 1974. Council Activities. As the result of suggestions emanating from the stimulus committees of previous years, a Planning Committee was set up during 1974 to undertake the detailed consideration of proposals affecting the Association’s future policies and activities. The members of the Committee are Dr. W. D. I. Rolfe (Vice-President), Dr. J. M. Hancock (Treasurer), Dr. C. T. Scrutton (Secretary), Dr. D. D. Bayliss, Dr. M. C. Boulter, Dr. C. H. C. Brunton, and Dr. A. W. A. Rushton. The Committee looked first at the future utilization of the Association’s financial resources and detailed proposals are currently before Council for consideration. The procedure for election of Council was also given early attention. This has resulted in a proposal for changes in the Constitution to allow a postal ballot when nominations exceed vacancies; THE PALAEONTOLOGICAL ASSOCIATION 891 guide-lines for the conduct of a ballot have now been agreed by Council. At the same time it is proposed to write into the Constitution the terms of office for Officers agreed by Council last year. An informal meeting has been held between representatives of the Association and the Geological Society of London to discuss matters of common interest. The meeting resulted in a useful exchange of views and ideas covering among other things publications, promotional activities, arrangements for meetings, the Geological Society’s Library, and geological conservation. As well as arranging the Association’s established annual programme of events, Council continues to review suggestions for additional indoor and outdoor meetings. Following the success of the International Symposium on the Ordovician System, Council is actively exploring the organization of future symposia on similar lines. Dr. C. A. Fleming retired from his post as Overseas Representative for New Zealand at the end of 1974. Dr. G. R. Stevens (New Zealand Geological Survey) has agreed to serve in his place. Thanks are due to Dr. Fleming for his long service to the Association. 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