Memoirs of the Museum of Victoria 54(2): 243-269 (1994) 31 December 1994 https://doi.org/10.24199/j.mmv.1994.54.12 EARLY SILURIAN TRILOBITES FROM THE BROKEN RIVER AREA, NORTH QUEENSLAND

David J. Holloway

Department of Invertebrate Palaeontology, Museum of Victoria, 328 Swanston Street, Melbourne. Victoria 3000, Australia

Abstract

Holloway, D. J., 1 994. Early Silurian trilobites from the Broken River area, north Queens- land. Memoirs of the Museum of Victoria 54: 243-269. A Late Llandovery (Telychian) trilobite fauna is described from the Poley Cow Formation in the Broken River Province of north Queensland. Taxa recorded are Kosovopeltis, Proetus (s.l), WarburgeUdl, Otarion, Mauwtarion, Seharvia, Youngia, Sphaerexochus, Sphaeroco- ryphe, Coronocephalus? aff. urbis Strusz, 1980. Ceratocephala, the new encrinurid genus Prpstrix, and the new species Prostrix amnicola, Batocarafritillum, Gravicalymenel vaccina and Gaotania bimusa. Youtlgia and Gaotania are recorded from Australia for the first time.

Batocara Strusz, 1 980 is considered to be a senior subjective synonym of Pacifieurus Rams- kold, 1986a. Keywords: Trilobita, Early Silurian, Queensland, new taxa.

Introduction S2 on their fig. 144, not SI as stated in the text. In addition to the trilobites, the fauna from The Poley Cow Formation (Withnall et al., PL1906 also includes brachiopods, bivalves, 1988; Withnall, 1989) is part of the Early Silu- gastropods, nautiloids, ostracodes and rian to earliest Devonian Graveyard Creek abundant disarticulated crinoid remains, all preserved Group in the Broken River Province (Arnold as

and Henderson, 1 976) of north Queensland. The formation, which consists of up to 550 m of feld- spatholithic siltstones, mudstones and polymic- Pandanus tic conglomerates, unconformably overlies Creek Ordovician volcanics and clastic sediments of Homestead ^ownsville the Judea Formation, and is conformably overlain by limestones and clastic sediments of the Jack Formation (Fielding, 1993). Fossils are not common in the Poley Cow Formation, but a few scattered localities have yielded shelly faunas as well as graptolites and conodonts indicative of a Late Llandovery (Telychian) age (turriculalas-griestoniemis and celloni Bio- zones; Jell et al., 1988; Jell and Talent, 1989). The trilobites described herein were collected from the Poley Cow Formation at Museum of Victoria (NMV) invertebrate fossil locality

PL 1906 (Fig. 1), situated in the bed of a creek approximately 1.2 km south-east of where the track from Jessey Springs to Wando Vale crosses the Broken River, and approximately 400 m due east of the track (grid reference 703434 on the Burges 1:100,000 sheet 7859). This is the locality reported to yield the richest fauna from the clastic sequence of the Graveyard Creek Group b; Jell et al. (1988: 116), who gave a Figure 1. Locality map showing where trilobites were slightly different grid reference, Jell and by and collected from the Poley Cow Formation near Broken Talent (1989: 200), who marked the locality as River crossing, north Queensland.

243 244 DAVID J. HOLLOWAY

suggested Pickett, internal and external moulds in thinly-bedded, Boree Creek Formation, as by of early Wenlock age; fine micaceous siltstones. The trilobites are dis- 1982, this fauna may be of these faunas are articulated and commonly broken, indicating Bischoff, 1 986). The first two Poley Cow For- that they arc not preserved in situ but have been very different from that of the transported or reworked. All the faunal elements mation. The trilobite assemblage of the "Illae- effaced styginid are represented by specimens of relatively small nus" band is dominated by the dalmanitids and a pha- size, suggesting that sorting may have occurred. Thomastus together with the Poley This evidence is consistent with the views of copid, all of which are absent from Withnall (1989) and Fielding (1993) that the Cow Formation. The Richea Siltstone fauna Poley Cow Formation was deposited in a shal- includes Decoroproetus, Eatiproetus?, Trimerus, low, off-shore marine shelf environment affec- Acernaspis, Dalmanites, Anacaenaspis and Gravica- ted by storm or wave activity. Dicranurus, as well as Maurotarion and The trilobite assemblage from PL 1906 is con- lymene which are shared with the Poley Cow sistent with the Late Llandovery age indicated Formation. The Rosyth Limestone contains by graptolites and conodonts. Youngia is not Ananaspis, Trochurus, Batocara and Youngia, known to range above the Llandovery, and the the last not being recorded by Fletcher (1950) last species of Kosovopel'tis and Gaotania are closely though present in his collections; the two related to K. yichangensis Chang and G, ovata genera are shared with the Poley Cow Forma- Chang, respectively, from the Upper Llandovery tion, but the species of Batocara is not very of China. similar to B. frit ilium sp. nov. The only trilobites previously described from the Broken River Province are the effaced sty- Systematic palaeontology ginid Rhaxeros pollinctrix. the cheirurid Sphaer- Styginidae Vogdes, 1 890 exochus, Encrinurusl, a possible warburgellinc and an indeterminate calymenid (Lane and Tho- Kosovopeltis Snajdr, 1958 mas, 1978, 1980), from Late Llandovery strata of the Quinton Formation, a lateral equivalent Type species. Kosovopeltis svobodai Snajdr, of the Poley Cow Formation in the Gray Creek 1958. from the Ludlow of Bohemia; original des- area, some 25 km north of the Broken River. ignation. Effaced styginids have not been found in the material of the Poley Cow Formation, and the Kosovopeltis sp. other taxa recorded by Lane and Thomas is mostly too fragmentary for useful comparison. Figure 2A Opik (in White, 1965: 43) identified Encrinwus, Material. An incomplete cranidium comprising the two species of undetermined scutelluids (= sty- left part of the glabella and most of the tixigena. ginids). Praetutf, and Sphaerexochus or Onyco- pyge from the Quinton Formation in the same Remarks. The low convexity of the cranidium, area, though the horizon was incorrectly given as the preglabellar furrow that is very shallow lat- the Wairuna Formation, which is of Ordovician erally and appears to weaken further adaxially,

age. Arnold and Henderson ( 1 976) reported that and the rounded (exsag.) anterolateral border the present whereabouts of these specimens are suggest assignment to Kosovopeltis. A distinctive unknown, and a search of the collections in the feature is the deep and rather sharp furrow (lat- Australian Geological Survey Organisation eral border furrow?) running subparallel to the failed to locate them (D. L. Strusz, personal cranidial margin on the front of the fixigena, and

communication), so it is not possible to verify meeting the axial furrow just behind the widest Opik's identifications. part of the frontal lobe. This feature is also pres-

The only other Llandovery trilobite faunas ent in K yichangensis Chang ( 1 974, pi. 80, fig. 2) previously described from Australia are those of from the lower Upper Llandovery of south-west the "Illaenus" band in the Heathcote district of China, suggesting that the two species may be central Victoria (Opik, 1953), the Richea Silt- closely related. K. yichangensis differs from the stone in the Tiger Range of south-western Tas- present species in lacking a shallower furrow mania (Holloway and Sandford, 1993), and the (epiborder furrow?) in front of the very deep one Rosyth Limestone near Borenore in central on the front of the fixigena, the axial furrow is western New South Wales (Fletcher, 1950; if the more abaxially-concave in outline in front of the Rosyth Limestone correlates with the Quarry occipital furrow, the anterior branch of the facial Creek Limestone and with the lower part of the suture diverges more strongly forwards, and the EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 245

frontal lobe is poorly differentiated from the Remarks. This species is characterised by an anterior and lateral borders. elongate, gently forwardly tapering glabella that is well rounded anteriorly; occipital lobes that Proetidae Salter, 1864 are weak or absent; no preglabellar field; an apparently weakly forwardly diverging anterior Proetinae Salter, 1 864 branch of the facial suture; a librigenal field that Proetus Steininger, 1831 is narrower than the lateral border; a short genal spine; and a pygidium with a poorly defined bor- Type species. Calymmene concinna Dalman, der that expands strongly posteromedially. The 1827, from the Wenlock of Gotland; original elongate shape of the glabella has probably been designation. exaggerated by deformation. The weak or absent occipital lobes would exclude the species from Proetus (s.l.) sp. Proetus (Proetus) sensu Owens (1973: 11). No

Figure 2B-F, 1 similar species has previously been recorded from the Silurian of Australia. Material. A cranidium. a librigena and 2 pygidia.

1»1

" W P4ffi- I

-';"31 i if

Figure 2. A, Kosovopeltis sp., cranidium NMV P 1 34800, latex cast of external mould, dorsal view, X 4. B-F, I, ProetUS (s.l.)sp- B. cranidium NMV PI 34801, latex cast of external mould, dorsal view, X 10. C, pygidium NMV mould, dorsal view. X 10. D, E, librigena NMV P 134803. internal mould and F 1 34805, latex cast of external latex cast of external mould, dorsal view, X 9. F, I, pygidium NMV PI 34804, internal mould and latex cast of external mould, X 7. G, H,J-L, Warburxellasp.G, cranidium NMV PI 34809, internal mould, dorsal view, X 8. H. cranidium NMV P134808. internal mould, dorsal view, X 8. .1, K, librigena NMV PI348I0, latex casts of counterpart moulds, ventral and dorsal views, X 6. L, pygidium NMV P1348I I, internal mould, dorsal view, X 9. 246 DAVID.I. HOLLOWAY

in "general Warburgcllinae Owens, 1 973 members of the Aulacopleuridae proportions", the prominent, fully isolated LI, Warburgella Reed, 1931 the number of thoracic segments ( 14 as opposed broad Type species. AsaphusStokesii Murchison, 1839, to 8 or 9 in rorringtoniids), and the short, from the Wcnlock of England; original desig- pygidium with only the first pairs of pleural and nation. interpleural furrows well defined. Other similar- ities with aulacopleurids are the width of LI, Warburgella! sp. which is much narrower than the adjacent median part of the glabella instead of being Figure 2G, H, J-L approximately the same width as in rorrington- Material Two cranidia, a librigena and a pygidium. iids; the distance of the palpebral lobe from the axial furrow, which is greater than it is in ror- Remarks. These speeimens are tentatively ringtoniids; the median swelling on the posterior assigned to Warburgella because of the strongly part of the preglabellar field, which is also devel- waisted glabella with deep SI and shallow S2 oped in Olarion (see Adrain and Chatterton, and S3, the rather narrow, subparallel-sided LI 1994, fig. 12.5-12.7% Songkania (see Ludvigsen with long axis oblique to the sagittal line, the and Tripp, 1 990, pi. 8, fig. 3) and more weakly in long palpebral lobe, and the comparatively long Maurolarlon (see Thomas, 1 978, pi. 8, fig. la, b): pygidium with narrow axis (the narrowness is and the anterior border furrow that is flexed possibly exaggerated by deformation). Features medially. that arc not typical of Warburgella. however, are Reasons cited by Adrain and Chatterton the lack of occipital lobes; the absence of a pre- ( 1 993: 1637) for the assignment of Goodsiraspis glahcllar field, transverse preglabellar ridge and to the Rorringtoniidae are the deep S2, the ros- tropidium; and the weak forward divergence of tral plate that does not taper to a point poster- the anterior branch of the facial suture. Some of iorly, the genal spine that is flattened at its base these features arc characteristic of Warburgella and carries extensions of the lateral and pos- (Anambon) Landrum and Sherwin, 1976, a sub- terior border furrows, the absence of a "lobatc" genus so far recorded only from the Lower eye socle, and the apparent absence of posterior Devonian (see also Chatterton and Perry, 1977). spines on the hypostome. None of these points A distinctive feature of the librigena is a weak provides grounds for exclusion of the genus from depression on the field, running subparallel to the Aulacopleuridae. S2 appears to be very vari- the lateral margin and curving adaxially poster- able in development in Goodsiraspis; in most iorly (Fig. 2K); a similar depression is present in specimens of the type species, 6'. packardi. it is some species of Prantlia (see P. grindrodi Owens, certainly wider (tr.) and deeper than is normal 1973, pi. 15, figs 3-5). for aulacopleurids, but in other specimens it is The present cranidia resemble the proetinc weak (e.g., Adrain and Chatterton, 1993, pi. 1, Cyphoproetus but differ in the rather short (sag., fig. 1, pi. 2, fig. 9). S2 is also very weak in "liar- exsag.) occipital ring with no lateral lobes and pulelkr butorus Holloway and "Cyphaspis" median tubercle not forwardly placed. If the novella Barrande. both of which were assigned to librigena and pygidium arc correctly associated Goodsiraspis with question by Adrain and Chat- with the cranidium. the poorly defined lateral terton, and which I consider to be undoubtedly border furrow, weak depression on the librigcnal congeneric with G. packardi. The rostral plate field and the long pygidium with narrow axis does not taper to a point posteriorly in all aula- also suggest that this species does not belong to copleurids; in Rhinotarion (see Whittington and ( 'yphoproetus.

Campbell, 1967, pi. 4, fig. 1 1) and possibly also The present pygidium is too poorly preserved in Maurotarion for comparison with the warburgelline pygidium axitiosum (Campbell, 1977: 16, pi. 3, fig. 2c) the posterior ends of the connective figured by Lane and Thomas ( 1 978, pi. 2, figs m, suture arc widely separated, as in Goodsiraspis. p) from the Quinton Formation in the Gray The flattening of the genal Creek area of the Broken River Province. spine in G. paekardi appears to be at least partly due to collapse under post-depositional compression, as shown by the Aulacopleuridae Angclin, 1854 presence of longitudinal fractures and/or Remarks. Adram and Chatterton (1993) depressions along most spines (e.g., Adrain and

1 included their new genus Goodsiraspis in the Chatterton, 993, pi. 1 , figs 1 , 4. 5, 7, 8, pi. 2, figs Rornngtoniidae Owens in Owens and Ham- I, 4). Fracturing also seems to account for the niunn. 1990 but acknowledged that it resembles apparent extension of the lateral border furrow ,

EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 247

onto the genal spine in Adrain and Chatterton's (Whittington and Campbell, 1967) from the pi. 1, fig. 7; the true lateral border furrow is seen Upper Wenlock or Ludlow of Maine. Compared to meet the posterior border furrow in front of with those species, the anterior borders of the the spine base, and only a single furrow extends present cranidia are more convex (sag., exsag.) along the spine, as is common in aulacopleurids. and upturned, especially medially, and the Adrain and Chatterton (1993, 1994) did not anterior border furrow is deeper, but these dif- explain their use of the terms "lobate" and "bilo- ferences may be due to slight deformation by bate" for the eye socle of aulacopleurids, but longitudinal compression. Librigenae assigned "bilobate" apparently refers to a socle that is to this species differ from those assigned to Otar- considerably wider and/or more convex anter- ion sp. in having the lateral margin only weakly iorly and posteriorly than at midlength (exsag.). incurved at the base of the genal spine, and the The socle of G packardi is poorly defined but facial suture crossing the posterior border far- does not appear to be bilobate. The socle in ther from the genal spine. Rhinotarion is not bilobate either but parallel- Maurotarion rhaptomyosa (Sun, 1990) from sided (Whittington, 1992, pi. 102, figs A, C, D), the Rainbow Hill Marl Member (Ludlow) of the indicating that a bilobate socle is not a synapo- Yass Basin, New South Wales, differs from the morphy of Aulacopleuridae as indicated by present species in having a more elongated and Adrain and Chatterton (1993, fig. 2) in their anteriorly-rounded glabella, a larger LI. a less cladogram. Finally, the only hypostomes of G'. steeply inclined preglabellar field, a shallower packardi known are too incomplete to be certain anterior border furrow and a flatter anterior bor- that posterior spines are not present. der. M. bowningense (Mitchell. 1887) from the Goodsiraspis is consequently here assigned to Lochkovian of the Yass Basin appears to be the Aulacopleuridae and is considered to be similar to the present species but the published most closely related to Maiirotarioit. Characters illustrations are very poor. M. bowningense was uniting these two genera, and collectively differ- based on a single specimen (Mitchell, 1 887: 438. entiating them from all other aulacopleurids. are pi. 16, fig 3; Chatterton, 1971, pi. 24, fig. 10), the moderate cranidial convexity, the subtrape- which is thus the holotype: the designation of a zoidal or parabolic glabella that is not markedly different specimen as lectotvpe bv Chatterton indented laterally at the front of LI. the rela- (1971: 96) is invalid. tively short (sag.) preglabellar field, the position of the eye with its midlength (exsag.) opposite Otarion Zenker, 1833 the outer end of SI, and the pygidium with the Type species. Otarion diffraction Zenker, 1833, axis as wide anteriorly as the pleurae. from the Ludlow of Bohemia; by monolypy.

Maurotarion Alberti, 1969 Remarks. Adrain and Chatterton (1994) have revised Otarion and sought to distinguish it from Type species. Harpidella maura Alberti, 1967, the closely related Cyphaspis Burmeister, 1 843. from trie lower Ludlow of Morocco; original des- Evaluation of their concepts of both taxa must ignation. await publication of their forthcoming work on Diagnosis, See Holloway and Sandford (1993). Cyphaspis.

Maurotarion sp. Otarion sp.

Figure 3A, B, E-G, 1 Figure 3C, D, H, J-L

Material. Four cranidia and 4 librigenae. Material. Four cranidia and 4 librigenae.

Remarks. In the subquadrate glabella with more Remarks. Distinctive features are the moder- or less transverse anterior outline, the small LI ately inflated glabella that narrows weakly for- the anterior border furrow that is uniformly wards in front of LI and is broadly rounded curved in dorsal view instead of having maxi- anteriorly, the very small and laterally projec- mum curvature medially, and the anterior bor- ting LI, the weakly curved SI, the convex and der that is not expanded medially, the cranidia steeply inclined preglabellar field that is resemble those of Maurotarion christyi (Hall. approximately equal in length (sag.) to the 1864) from the Wenlock of Indiana (see Hall, anterior border plus anterior border furrow, the 1879, pi. 32, figs 5-7), M. hama (Snajdr, 1984) rather dense cranidial sculpture of fine from the Wenlock of Bohemia and M. plautum tubercles, and the librigena with wide (tr.) field 248 DAVID J. HOLLOWAY

Figure 3. A. B. E-G, I. Maurotarion sp. A. cranidium NMV P1348I6. internal mould, dorsal view X 6 5 B G eranidium NMVP13481 internal 7, mould and latex cast of external mould, dorsal views, X 8 E librigenaNMV PI 348 1 9, latex cast of external mould, dorsal view, X 10. F, librigena NMV P134835 latex cast of natural mould, ventral view. X 9. 1, librigenaNMV P134821, latex cast of external mould, dorsal view X 8 C D H J- L. Oianon sp. C, librigena NMV PI 348 1 latex 4, cast of external mould, dorsolateral view, X 8 D 'librigena NMV PI 348 5. latex cast of external 1 mould, ventrolateral view, X 8. H, L. cranidium NMV PI 348 12 internal mould and latex cast ol counterpart mould, dorsal views, X 10 and X 1 1.5. J, cranidium NMV PI 34802 latex cast of external mould, dorsal view, X 9.5. K, cranidium NMV P1348I3. latex cast of external mould "dorsal Scharyta sp CTani - M - dium NMV PI 34823. S, »,, ^~P\ internal mould, dorsal view, X 12. N pygidium NMV PI 34825. latex cast of external mould, dorsal view, X 12. O, pygidium NMV P134824 latex cast of external mould, dorsal view, X 12. P. Aulacopleuridae indet., pygidium NMV PI34822 internal mould dorsal EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 249 and with the lateral margin strongly incurved at Owens (in Owens and Hammann, 1990) trans- the base of the genal spine. In these features ferred it to the Brachymetopidae. I follow there is a similarity to species such as Otarion Adrain and Chatterton ( 1 993) in regarding Scha- brauni Perry and Chatterton. 1979 and O. hud- ryiidae as a separate family within the Aulaco- dyi Adrain and Chatterton, 1994, both from the pleuroidca. Wenlock of Canada, and O. coppinsensis Adrain and Chatterton, 1994 from the Wenlock of the Scharyia Pfibyl, 1946 Australian Capital Territory. The present Type species. Proetus micropygus Hawle and material, however, is inadequate for detailed Corda, 1 847, from the Ludlow of Bohemia; orig- comparison with other species. Otarion coppinsensis was based on specimens inal designation. considered by Chatterton and Campbell (1980: 87) to be closely related to or possibly conspe- Scharyia sp. cific with Cvphaspis horani Etheridge and Mit- Figure 3M-0 chell (sec Chatterton, 1971: 95, pi. 24, figs 1-6; Material. cranidium and 2 pygidia. Chatterton and Campbell, 1980, pi. 11. figs 13, A 14). from the Ludlow of the Yass district. New Remarks. The conical glabella lacking furrows, South Wales. Adrain and Chatterton ( 1 994: 320) the long preglabellar field, and the rather long stated of horani that it "has 1 1 thoracic seg- pygidium indicate that these poorly preserved ments, a strongly inflated, but not elongate, gla- specimens belong to Scharyia. The pygidia bella, and a pygidium which is narrow relative to resemble that of 5. redunzoi Perry and Chatter- its length, bears three axial rings, and has both ton. 1979 from the Wenlock of Canada in having rings and posterior pleural bands ornamented interpleural furrows that are much deeper than with single rows of relatively coarse tubercles. the pleural furrows (except for the first pleural All of these make its assignment to Cyphaspis furrow; see Fig 30), a prominent border and a unambiguous, and serve to differentiate it from deep border furrow; S. redunzoi differs, how- the older Coppins Crossing species" (i.e. O. cop- ever, in that the axis extends closer to the border pinsensis). However, no complete (or even furrow posteriorly, the border does not expand incomplete) thoraces of coppinsensis are known, posteromedially, and the posterior margin is not so the number of thoracic segments is indeter- subangular medially. minate: there is no appreciable difference from of the glabella horani in the length and inflation Cheiruridae Hawle and Corda, 1847 or in the width of the pygidium; the number of pygidial axial rings is the same as in horani: and Acanthoparyphinae Whittington and Evitt, rows of tubercles are present on the axial rings 1954 and posterior pleural bands of both species. Youngia Lindstrom, 1885 Hence none of these features can be used to dis- tinguish horani from coppinsensis, or to justify Type species. Cheirurus trispinosus Young, assignment of these species to separate genera. 1 868, from the Llandovery of Scotland; sub- sequent designation of Vogdes (1917: 115). Aulacopleuridae indet. Remarks. Several species previously included in Figure 3P Youngia were reassigned by Ramskold (1983) and Chatterton and Perry (1984) to Hyrokybe Remarks. The only aulacopleurid pygidium Lane, 1 972. There has been confusion in the dis- outline, with found is transversely lenticular in crimination of these genera because they share anteriorly as the pleurae an axis that is as wide similar cephalic morphology and because no six or possibly and narrows strongly backwards, pygidia are known for either type species. New pleural furrows, and a seven axial rings, four diagnoses for Youngia and Hyrokybe were given It is uncertain as to which poorly defined border. by Chatterton and Perry (1984) on the basis of this pygidium of the two preceding species new material of a number of species, most rep- belongs. resented by both cephala and pygidia. The pygidia of species they assigned to Hyrokybe Scharyiidae Osmolska, 1957 have two pairs of marginal spines of almost Remarks. Thomas and Owens (1978) included equal size, and are very different from the the Scharyiinae in the Aulacopleuridae, but pygidia assigned to Youngia which have the sso DAVID J. HOLLOWAY

outer pair of spines greatly elongated and the wards with its posterior edge opposite SI, and inner pair very reduced in size. Although Chat- the lateral border furrow is indistinct near the tcrton and Perry did not list differences between genal angle (Lane, 1971, pi. 16, figs 1-4,7-9, 11, the two genera, comparison of their diagnoses 13). and discussion suggests that, in addition to the Of the species assigned to Youngia by Chat- form of the pygidial spines, they considered terton and Perry (1984) from the Upper Llan- Hywkybe to differ from Youngia in that the dovery of Canada, those most closely resembling occipital and gcnal spines are commonly the present one are Y. boucoti, Y. kalhyae and Y. shorter, there are two pairs of secondary spines steineri. These three species, considered by on the lateral fixigenal border in front of the Chatterton and Perry to belong to a single evol- genal spine, the hypostome is commonly fused utionary lineage, differ from the Poley Cow to the rostral plate, and the posterior margin of species in that SI does not meet the occipital the hypostome has a series of blunt spines medi- furrow, the fixigenae are narrower so that the ally. Secondary spines on the lateral fixigenal genal spine arises closer to the occipital ring, and border are apparently not present, however, in the palpebral lobe is situated farther forwards the type species of Hywkybe. H. pharanx Lane with its posterior edge opposite SI. The hypos- pi. (1972, 64, figs 1 -3). Species assigned by Chat- tome of Y. boucoti is unknown, but those of Y. terton and Perry to Hywkybe also differ from kathyae and Y. steineri differ from the hypos- those assigned to Youngia in that the glabella tome of the Poley Cow species in having more (excluding the occipital spine) is always wider pronounced tubercles on the anterior lobe of the than long in dorsal view (in Youngia the glabella middle body. is commonly as wide as long or slightly longer than wide, but in Y. johnsoni it is wider than Sphaerexochinae Opik, 1937 long), and the middle furrow of the hypostome is Sphaerexochus Beyrich, 1 845 weaker and directed transversely or slightly obliquely forwards rather than obliquely back- Type species. Spaerexochus [sic] minis Beyrich, wards. The differences in the cranidium are not 1845, from the Wenlock of Bohemia; by mono- always consistently developed, so that in the typy. absence of hypostomes or pygidia unequivocal assignment to Youngia or Hywkybe may not be Sphaerexochus sp. possible. Figure 5A-G, I, J

Youngia sp. Material. Eight cranidia, a hypostome, an incomplete thoracic segment and a pygidium. Figure 4 Remarks. Numerous Sphaerexochus species Material. A cephalon. 6 cranidia, 3 isolated fixigenae. have been 3 librigenae. and a hypostome. named from the Silurian but their dis- crimination is made difficult by conservatism in Remarks. S3 is distinguishable on only one of cephalic morphology (Holloway, 1980: 38) and the cranidia (Fig. 4L), in which, however, S2 is variability in the pygidium. Pygidial variation obliterated by a fracture. S3 is more anteriorly has in some cases been attributed to dimorphism directed than SI and S2, and meets the axial fur- (Perry and Chatterton, 1977; Ramskold, 1983; row at the abaxial end of the preglabellar fur- Chatterton and Perry, 1 984) and in other cases row. to the type of preservation or to changes during This species, which in the absence of pygidia is ontogeny (Thomas, 1981). These factors, not formally named, is assigned to Youngia together with the poor preservation of the pres- rather than to Hywkybe because the glabella is ent material and the paucity of pygidia, make approximately as wide as long (sag.) in dorsal reliable comparison with other species imposs- view, the occipital and genal spines are relatively ible. large, the hypostome has a well-defined middle Nevertheless, several species resemble the furrow that is directed obliquely backward, and present one in having a relatively broad pygid- the posterior margin of the hypostome is not spi- ium with very short marginal projections and nose medially. The type species, Y. trispinosa, distinct pits in the axial furrow near the front of differs from the present one in having longer the terminal lobe. Such species include S. britan- occipital and genal spines, the occipital spine is nicus Dean, 1971 from the Wenlock of England thicker at its base, the eye is situated farther for- (if this is distinct from 5. mints; see Thomas, EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 251

Figure 4. Young/a sp. A, cranidium NMV PI 34828. latex cast of external mould, external view, X 5. B, cran-

idium NMV F 1 34830, internal mould, dorsal view. X 4. C, fixigena NM V P 1 34834, latex cast of external mould, oblique view (posterior border at bottom of photograph), X 6. D. librigena NMV PI 34839. latex cast of external mould, oblique view, X 10. E, F, cranidium NMV PI 34827, latex cast of external mould, oblique and external views, X 6. G, librigena NMV PI 34838, latex cast of external mould, oblique view, X 6. H, L-N, incomplete

cephalon NM V P 1 34826; H, L, N, latex cast of external mould, dorsal, lateral and oblique views (anterior lateral glabellar furrow in Lis S3), X 3; M, internal mould, oblique view, X 3. 1, cranidium NMV PI 34832, latex cast of external mould, oblique view, X 4. J, hypostomeNMV PI 34840, latex cast of external mould, ventral view, X 2. K, cranidium NMV PI 34829, latex cast of external mould, dorsal view. X 4. 252 DAVID J. HOLLOWAY

1 98 1), S. glaber Holloway. 1 980 from the Wen- backwards distally; the narrow, transverse pos-

lock of Arkansas and Oklahoma, ,S'. scahridus terior pygidial margin between the second pair

Angelin. 1 854 from the Wenlock of Gotland (see of spines; and the deep pygidial axial furrow

Ramskold, 1 983), and Ramskold's ( 1 983, pi. 28, behind the second ring. In the pygidial charac-

figs la, b, 6a. b) pygidial dimorph B of S, lo.ll- ters listed above there are similarities with Dei- frons Angelin, 1854, from the Ludlow of Got- p/ton, a genus generally considered to have been land. The last of these is perhaps the most derived from Sphaerocoryphe (Lane, 1971; Hol- but, similar compared with the present species, loway and Campbell. 1 974; Chatterton and the glabella of S. latifrons seems to be much Perry, 1984; Pribyl et al., 1985). The present wider adaxial to LI (Ramskold, 1983, pi. 27, fig. species is assigned to Sphaerocoryphe rather

12b). Pygidia of S. bfitarinicus and .S'. scahridus than to Deiphon because the fixigena is not have a more convex (sag.) axial terminal lobe markedly reduced in size, there is a well devel- that is semiclliptical or bulbous rather than sub- oped posterior cephalic border, and the subgenal triangular, and the third marginal projection is notch is only very shallow. Further assessment longer. In addition, the hypostomc of ,S". scahri- of relationships must await the availability of dus has a more convex anterior margin, a lateral better material. border not expanding as strongly backwards, A short, third pair of pygidial spines is present and a deeper, more concave-forwards posterior inmost, if not all, deiphonines (Holloway, 1980) border furrow (Ramskold, 1983, pi. 27, figs 7, 8). but has not been seen on the present pygidium. The pygidium of ,S'. glaber has a more convex In Deiphon and at least some species of Sphae- (sag.) terminal lobe, and the third pleural rib rocoryphe these spines are ventrally directed and does not project distally at all. consequently are not visible unless the entire Chatterton and Campbell (1980) described posterior margin of the pygidium is excavated. two Australian species, Sphaerexochus molon- Such excavation was considered inadvisable in gloensis from the Wenlock of Canberra and ,S'. the case of the present pygidium because of brum from the Ludlow of the Yass Basin, New likely damage to the internal mould of the dorsal South Wales. The former is the more similar to surface. the present species but appears to have a longer The only previous record of Sphaerocoryphe pygidium with a more distinct pseudo-articulat- from strata younger than Ashgill was by Thomas ing half ring on the second segment, and a longer and Lane (1983: 62), who mentioned its occur- third marginal projection. rence at an unspecified horizon in the Silu- rian. Deiphoninae Raymond, 1913 Encrinuridae Angelin, 1854 Sphaerocoryphe A n ge I i n , 1854 Encrinurinae Angelin, Type species. Sphaerocoryphe denlala Angelin, 1854 1854, from the Upper Ordovieian of Sweden; Prostrix gen. nov. ICZN Opinion 614 (Bulletin of Zoological Etymology. Latin pro, Nomenclature 18: 357). forward, and stri.x, fur- row, referring to the deep longitudinal median furrow on the frontal lobe of the type species. Sphaerocoryphe sp. Gender feminine. Figure 5H, K Type species. Prostrix amnicola sp. nov., from Material. Internal moulds of a cranidium and a pygid- the upper Llandovery of north Queensland. ium, on the same piece of rock. Diagnosis. Glabella of low convexity; LI con- Remarks. Distinctive features are the glabellar tinuous across glabella; SI -S3 and prcglabcllar bulb that is wider than long; the very short (sag.) furrow deep and slit-like abaxially but weak the LI ; widely divergent genal spine (very poorly medially; frontal lobe with deep longitudinal preserved as an external mould of the ventral median furrow anteriorly. Glabellar tubercles surface); the stout, downwardly directed profix- weak on external surface but distinct internally, igcnal spine (preserved as a pit in Fig. 5H; the longitudinally paired on L2-L4; anterior cranid- slightly smaller pit to the right of it is not another ial border with a few small, weak tubercles. Pal- spine); the shallow subgenal notch; the relatively pebral lobe long (exsag.), situated close to gla- long and weakly curved first pygidial marginal bella with posterior edge opposite median part spine; the second marginal spine that is flexed of occipital furrow and anterior edge opposite EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 253

external mould, dorsal view, X Figure 5. A-G. I, J, Sphacrcxochu.ssp. A, cranidium NMV PI 34842, latex cast of and dorsal views, X 5. B, F, cranidium NMV PI 3484 1, internal mould and latex cast of external mould, oblique 5.5. C, G, cranidium NMV PI34843, internal mould, oblique and dorsal views, X 5. D, hypostome NMV anterior PI 34849, latex cast of external mould, ventral view (ridge extending forward from median part of oblique view, X 6. J, margin is preparation mark). X 6. E, thoracic segment NMV PI 34850, internal mould, 1, pygidium NMV P134851, latex casts of counterpart moulds, dorsal and ventral views, X 9. H, K, Sphaeroco- rrphesp. H, cranidium NMV PI 34853, internal mould, dorsal view, X 4. K, pygidium NMV PI 34854. broken internal mould, dorsal view, X 5.

S3, with small circular pit at midlength; palpe- for Encrinurinae (e.g., presence of preglabcllar bral furrow almost exsagittally aligned except furrow and longitudinal median furrow, abax- anteriorly and posteriorly. Fixigenal field with- ially slit-like lateral glabellar furrows, LI con- out distinct tubercles; genal spine absent. tinuous across glabella rather than obsolete Hypostome with poorly defined rhynchos. medially, glabellar tubercles longitudinally Pygidium with 12+ axial rings and 9 or possibly paired on L2-L4), so that their presence in other 10 pleural ribs not projecting strongly distally. taxa(e.g., Cromus Barrande, 1852, Penyus Gass Doublure sloping steeply downwards and and Mikulic, 1 982; see Edgecombe and Chatter- inwards towards front of pygidium. ton, 1992) is not necessarily indicative of close relationship.

Strusz, 1 980, to Remarks. The genus is known only from the Prostrix differs from Batocara rather poorly preserved type species, whose which most other Australian Silurian encrinu- the relationship with other encrinurines is uncer- rines are assigned herein (see below), in that is less convex, the glabellar and pregla- tain. With the discovery of additional species, glabella some characters included in the preceding diag- bcllar furrows are wider (tr.) and slit-like abax- nosis may prove to be significant only at species ially, the longitudinal median furrow is well are not tuberculiform but have level. Other characters included arc primitive defined, L2-L4 254 DAVID J. HOLLOWAY

longitudinally paired tubercles, the tubercula- Prostrix amnicola sp. nov. tion is weak on the exterior of the glabella (Fig. Figure 6 6A, K) and on the anterior cranidial border, the palpebral lobe is situated very close to the gla- Etymology. Latin amnicola, inhabitant of or by a bella and to the posterior border furrow, the river, referring to the proximity of the type fixigenal field lacks distinct tubercles, the hypos- locality to the Broken River; noun in apposi- tome has a poorly defined rhynchos, and there tion. are fewer axial rings in relation to the number of Type material. Holotype:cranidiumNMV PI34833A, pleural ribs. B (counterparts). Fig. 6F, K. Prostrix resembles some of the Chinese Llan- Paratypes: NMV PI 34855, P134857. PI 34862 dovery encrinurine species that have been (cranidia); NMV P 1 34859-PI 3486 1 (hvpostomes); assigned to Encrinuroides Reed, 1931, but NMV P134863-P134865 (pygidia). whose affinity with that genus was considered Diagnosis. As for genus. dubious by Edgecombe and Chatterton ( 1 990a). The greatest similarity is with species such as Description. Glabella flat-topped in transverse "Encrinuroides" abnormis Chang, 1974, "£." profile and weakly convex in lateral profile, enshiensis Chang, 1974 (both revised by Chang, expanding gently forwards in front of occipital 1986), "2T." guangyuanensis Chang, 1986 and ring, approximately 1.5 times as wide at frontal "£." renhuaiensis Yin in Yin and Lee, 1978. lobe as at LI . Occipital ring decreasing slightly in Similarities include the abaxially slit-like glabel- length (exsag.) abaxially, with a slight node dis- lar and preglabellar furrows, the moderate-sized tally; occipital furrow deep and gently arched glabellar tubercles that in some species are longi- forwards. Preglabellar furrow not as deep as gla- tudinally paired on L2-L4, and the absence of bellar furrows abaxially, not defined medially on genal spines (in species with the genal angles pre- external surface. L1-L3 successively longer served). The Chinese species differ from Pros- exsagittally; frontal lobe comprising half pre- trix, however, in having stronger tuberculation occipital length of glabella, lateral extremity on the glabella and anterior cranidial border, the partly isolated in holotype by short, weak eye is situated farther from the glabella and from depression directed forwards from S3 (Fig. 6F). the posterior border furrow, there are prominent Glabellar tubercles arranged in transverse row tubercles on the fixigenal field, and the pygid- on medial part of L2 and posterior part of frontal ium has a greater number of axial rings in lobe; arrangement on L3 apparently more vari- relation to the number of pleurae. able (Fig. 6E, F). Palpebral lobe occupying most Langgonia Kobayashi and Hamada, 1971, of fixigena, steeply upturned; palpebral furrow known from three species (probably synony- narrow and deep. Posterior cranidial margin mous) from the upper Llandovery or lower Wen- deflected backwards at fulcrum and recurved lock of West Malaysia, was originally placed in forwards distally; posterior border furrow longer the Dalmanitidae but was transferred to the (exsag.) and deeper than occipital furrow adax- Encrinuridae by Holloway (1981). Langgonia ially. shallowing distally. resembles Prostrix in the abaxially slit-like gla- Hypostome with elliptical, moderately con- bellar and preglabellar furrows, the distinct vex middle body; rhynchos poorly defined, pro- longitudinal median furrow on the front of the jecting over anterior border furrow but not glabella. LI that is continuous across the gla- bounded laterally by furrow; macula distinct. bella, the weak tuberculation on the glabellar Pygidium approximately as wide as long exterior, the closeness of the eyes to the glabella, (sag.), subtriangular, rounded posteriorly. Axis and the absence of genal spines. Langgonia dif- well-rounded (tr.), approximately as wide as fers from Prostrix in that the glabella is more pleural lobe anteriorly; ring furrows deep lat- convex across the frontal lobe, the palpebral lobe erally, shallower medially; sagittal tubercle pres- is situated farther forward and more obliquely ent on sixth and possibly third rings. Pleurae on the cheek, there are nodular lobes on the pos- curving downwards abaxially from axial furrow; terior part of the fixigena adjacent to the axial pleural ribs flat-topped, first one projecting furrow, and the pygidium is semi-eiliptical slightly distally, remainder not projecting; inter- rather than subtriangular in outline, with rib furrows much shorter (exsag.) than ribs. broader pleural lobes and fewer axial rings in Doublure divided into a flattened, steeply relation to the number of pleural ribs. inclined outer portion and an upwardly flexed EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 255

Figure 6. Prostrix amnkola gen. nov., sp. nov. A, B, cranidium NMV PI 34856, latex cast of external mould and internal mould, dorsal views, X 7. C, cranidium NMV PI 34862, internal mould, dorsal view, X 9. D, hyposlome NMV PI 34860, latex cast of external mould, ventral view, X 7. E. cranidium NMV PI 34855, internal mould, dorsal view, X 4.5. F, K, cranidium NMV PI 34833, internal mould and latex cast of external mould, dorsal views. X 4.5. latex V P I 1 , cast G, hypostome NM 3486 of external mould, ventral view, X 8. 1 1, 1, pygidium NMV P134864, internal mould, dorsal and lateral views, X 7. J, M, N, pygidium NMV PI 34863, latex casts of counterpart moulds, ventral, dorsal and lateral views, X 4. L, pygidium NMV PI 34865, latex cast of external mould, dorsal view, X 6. O, cranidium NMV PI 34857, internal mould, dorsolateral view, X 6.

inner portion; outer portion very high anteriorly Type species. Encrinurus Bowningi Foerste, (Fig. 61, N) but diminishing rapidly posteriorly; 1888, from the upper Ludlow of New South inner portion with shallow embayment poster- Wales; original designation. iorly (Fig. 6J). Diagnosis. See Ramskold ( 1 986b: 559; diagnosis Batocara Strusz, 1980 of Enertnut us (Australurus)).

(= Pacificums Ramskold, 1986a, pro Australurus Remarks. Strusz (1980) assigned most Aus- Ramskold, 1986b, turn Jell and Duncan, 1986) tralian and some Asian Silurian cnerinurine 256 DAVID J. HOLLOWAY

species to his Encrimirus mitchelli plexus but bella include 1-1,(2); 11-1,2; 111-1,2,3; iv-l; dis- excluded "Enaimirus" bowningi, for which he tal tubercles on L2-L4 not significantly erected Batocara as a monotypic genus. Rams- enlarged. Axial furrow wide. Fixigenal field kold (1986a, 1986b) subsequently proposed strongly inflated adaxially, with tubercles adjac- Pacificurus for the mitchelli plexus sensu Strusz. ent to axial furrow not enlarged; 2-3 tubercles Batocara shares diagnostic characters of Paciji- situated between posterior edge of palpebral CUms (LI continuous across glabella, bearing lobe and axial furrow. Librigcnal field appar- tubercles adaxially and usually abaxially; L2-L4 ently with only a few tubercles. Pygidium with tuberculiform and alternating with adaxial up to 21 axial rings and 7-10 (usually 9) pleural tubercles on fixigena; abundant tubercles on ribs plus postaxial ridge. genal field and precranidial lobe of librigena; Description. Glabella slightly narrower at L2 eyes not stalked; genal angle without spines; than at LI and narrower at L3 than at occipital pygidium relatively large, non-mucronate, with ring; widths at occipital ring, L2 and L4 approxi- broad pleural lobe), suggesting that bowningi mately in ratio 1.7:1:2. Occipital ring well shares a common ancestor with species of the rounded (sag., exsag.), decreasing in length mitchelli plexus rather than originating in a sep- (exsag.) distally abaxial to LI; occipital furrow arate lineage as proposed by Strusz (1980, text- deep. S1-S3 continuous across glabella, S3 very fig. 9). Strusz ( 1 980) considered Batocara to be shallow medially; distal tubercle on LI (if pres- distinguished partly by the coarseness and ent) small and low. Frontal lobe strongly crowding of the cranidial tuberculation, but inflated, comprising half sagittal length of gla- amongst species included in Pacificurus this bella in dorsal view, bearing fairly dense character is shared with "Encrinurus" silverdal- tubercles that are of two sizes (Fig. 7B) and not ettSiS Etheri.dge and Mitchell, which also resem- arranged in distinct rows. Preglabellar furrow bles bowningi in the prominent median indistinct or undefined medially; anterior cran- tubercles and well developed sagittal band on idial border complete only on holotype (Fig. 7E), the pygidial axis (Strusz, 1980, pi. 5, figs 8-16, lateral third with 5 tubercles that decrease in size pi. 6, figs 5- 1 4). As bowningi is evidently closely adaxially, median third lacking related to silverclalensis and the other Australian distinct tubercles. Palpebral lobe upturned, anterior species, 1 consider its separation from them in a edge opposite L4 and posterior monotypic genus to be unjustified. Hence bow- edge opposite L2; palpebral furrow shallow and broad. ningi is here included in the mitchelli plexus, and Eye ridge distinct on internal moulds (Fig. 7E), Pacificutus is regarded as a junior subjective crossing axial furrow obliquely opposite L4 synonym of Batocara. The synonymy of Bato- and with prominent tubercle at abaxial edge of cara and Pacificurus was also suspected by Fdge- axial furrow. Anterior branch of facial suture not con- combe and Chatterton (1990b: 4). who listed verging as strongly forward as eye ridge; similarities (some interpreted as synapomor- pos- terior branch transverse adaxially, phics) between the two genera, and concluded thereafter flexed postcrolaterally in concave-forward curve that Batocara is "sister group to Pacificurus (if subparallel to part of posterior not part of the ingroup)". cranidial margin. Posteromedial part of fixigenal field standing higher than glabella opposite, with Batocara fritilium sp. no v. dense tubercles and intervening pits; largest tubercles Figure 7 adjacent to palpebral furrow; fixigenal tubercles very subdued on exterior of large Etymology. Latin fiitil/as, spotted, referring to specimens (Fig. 7A). Genal angle the tuberculate ccphalon. rounded. Librigenal field wider (tr.) than height of lat- type material. Holotype: cranidium P134868A, NMV eral border, bearing only a few large tubercles. It (counterparts). Fig. 7B. E. Base of eye socle higher than precranidial lobe, I'aratvpes: NMV PI 34869 (cephalon): NMV defined by rather deep furrow. Lateral border I* 1 34870, PI 34871 (cranidia); NMV PI 34872 (iso- behind precranidial lobe with a single lated flxigena); NMV P134884. PI34885 (librigenac); row of subdued tubercles; anterior NMV PI34852, PI 34873-PI 34882 (pygidia). furrow poorly defined; precranidial lobe shorter (exsag.) than Diagnosis. Glabella markedly constricted at L2, librigcnal field. expanding very strongly forwards in front of L2; Pygidium slightly longcrthan wide, posterola- front of glabella and anterior cranidial border teral margins weakly concave in outline. Axis very steep. Tubercles on posterior part of gla- 0.25-0.3 times maximum pygidial width anter- EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 257

m

Figure 7. Batocarafritillum sp. nov. A. cranidium NMV PI 34870, latex cast of external mould, dorsal view, X 4.5. B, E. holotype. cranidium NMV PI 34868, latex cast of external mould and internal mould, dcrsal views, X 6.5 and X 5.5. C, pygidium NMV PI 34873, latex cast of external mould, dorsal view, X 4. D, pygidium NMV PI 34874, latex cast of natural mould, ventral view, X 6. F, pygidium NMV PI 34875. internal mould, dorsal view, X 6. G, pygidium NMV PI 34852, latex cast of external mould, dorsal view, X 5. H, cephalon NMV PI 34869, internal mould, dorsal view, X 4. 1, N, pygidium NMV PI 34876, latex cast of external mould, lateral and dorsal views, X 4. J, librigena NMV P134884, internal mould, exterior view, X 10. K, librigena NMV P134885, latex cast of external mould, exterior view, X 7. L, pygidium NMV P134877, internal mould, dorsal view, X 7. M, pygidium NMV PI 34878, latex cast of external mould, dorsal view, X 8. 25X DAVID.I. HOLLOWAY

chilorhodus iorly. tapering backwards rather strongly over Ramskold, 1986b), suggesting that that genus first 2-3 segments, thereafter more gently; sagit- may be more closely related to Batocara. tal band distinct but crossed by shallow medial (though not belonging to it) than to parts of ring furrows, especially anteriorly. Up to 3 median axial tubercles distinguishable on Coronoeephalus Grabau, 1924 some pygidia but subdued on exterior; lirst tubercle on ring 3 or 4, second on third next ring, Type species. Kncrinurus (Coronoeephalus) rex last on third or fourth next ring. Pleural ribs on Grabau, 1924, from the Upper Llandovery anterior segments curving strongly backwards (Temple and Wu, 1990) of China; by mono- abaxially, on posterior segments becoming more typy. exsagittally aligned and acquiring sigmoidal shape as distal ends turn outwards slightly; ends Coronoeephalus! all', urbis Strusz, 1980 Of ribs form blunt projections (Fig. 7D). Some internal moulds with sparse tubercles along ribs Figure 8A-F, H-J, L-N (Fig. 7F). Inter-rib furrows narrower than ribs Material. Five cranidia, an isolated fixigena, 2 libri- external surface. doublure widening on Pygidial genae and 5 pygidia. slightly posteriorly towards V-shaped notch Coronoeephalus urbis, from the Wen- (lig. 71)). Remarks. lock of the Canberra district, was excluded from Remarks. The librigena on a poorly preserved Coronoeephalus by Chang (1983: 203, 223) ccphalon of liuiocura fritillimi has the tubercles because it has a distinct preglabellar furrow, a 00 the field arranged in a single row close to the shallow longitudinal median furrow on the front base of the eye (Fig. 7H), whereas two isolated of the glabella, and numerous small tubercles on librigenae lack this arrangement of tubercles on the librigenal margin. However, these characters the held (Fig. 7.1, K). Despite this difference, the are primitive homologues of derived states pres- isolated librigenae are assigned to li. fritillum ent in most f 7;TO/;ort7>//a/M.vspecics(prcglabellar rather than to I'rostrix amnicola because the eye and longitudinal median furrows weak or appears too small to match the palpebral lobe on effaced, single row of large denticles on libri- the latter species. genal margin) and do not preclude a close Batocara fritillum is easily distinguished from relationship with that genus. Consequently urbis most other species of the genus by the marked is here assigned to Coronoeephalus with ques- constriction of the glabella at F2, the inflated tion. frontal lobe that is very steep anteriorly, the The present specimens resemble Coronoee- wide axial furrow not overhung by enlarged phalus'! urbis in the long genal spine, the wide adaxial tubercles on the lixigena, and the sparse (tr.) anterior cranidial border with a double row tuberculalion on the librigenal held. li. fritillum of tubercles, the shallow longitudinal median resembles li. bowniflgi (see Strusz, 1980. pi. 6, furrow (Fig. 8L), the broad palpebral area, the figs 5-14) in the constriction of the glabella at densely tuberculate librigena with a narrow 1.2, but there arc so many other differences field, and the relatively short pygidium with dis- between the two species that they are not con- tinct sagittal tubercles. The specimens differ sidered to be closely related. from topotypes of verbis in having fewer pygidial "I'iici/icurii.s" chilorhodus Edgecombe and axial rings (about 14 instead of about 20) and Ramskold, 1992 from the Telychian (not Shein- pleural ribs (9-10 instead of 10-11), a distinct woodian; ( i. I). Edgecombe, personal communi- anterior furrow on the librigena (Fig. 8C), and cation) of Canada resembles Batocara fritillum possibly in the glabellar tubercle pattern (e.g., in several respects, notably the constriction of the presence of tubercles ii-0 and iii-0oriii-l in the glabella across L2, the distal tubercles on L2- some cranidia). The Poley Cow species thus 14 that are not significantly enlarged, and the appears distinct from urbis but the material non-enlarged adaxial lixigenal tubercles. (especially of cranidia) is considered inadequate "R."chilorhodus differs from li. fritillum, and for formal naming.

1 from all other members of Batocara, in having Coronoeephalus". thailandicus (Kobayashi SI merging with the occipital furrow medially, a and Sakagami, 1989), from the upper Wcnlock pygidium with a low ratio of axial rings to or lower Ludlow of Thailand, was considered by pleura] ribs, and distinct paired tubercles on the Edgecombe and Ramskold (1992: 261) to be pygidial axial rings. These characters are shared closely related to urbis, and shares many of the with Balizoma (sensu Holloway, 1980 and similarities between that species and the present EARLY SILURIAN TRILOB1TES FROM NORTH QUEENSLAND 259

Figure 8. A-F, H-J. L-N. Coionoivplialus'! aft", urbis Strusz. A, B, cranidium NMV P 1 34886. internal mould and lalexeasl of external mould, dorsal views, X 7.C, librigena NMV P134892, latex cast of external mould, exterior view. X 7. D, pygidium NMV 1*134893. internal mould, dorsal view. X 8. E. cranidium NMV PI 34887. latex cast of external mould, dorsal view. X 6. F. cranidium NMV PI 34888. internal mould, dorsal view, X 5. H,

pygidium NMV PI 34894, latex cast of external mould, dorsal view. X 8. 1. cranidium NMV PI 34889, latex east of partly testiferous mould, dorsal view, X 5. J. fixigena NMV PI34890, internal mould, dorsal view. X 5. L, small cranidium NMV PI 3489 1, latex cast of external mould, dorsal view, X 10. M. pygidium NMV PI 34895, latex cast of external mould, dorsal view, X 6.5. N, pygidium NMV P134896, internal mould, dorsal view. X 6. G, K. encrinurid hypostomes indet. G. NMV PI 34897. internal mould, ventral view, X 7. K, NMV PI 34898, latex cast of external mould, ventral view, X 6. O. encrinurid pygidium indet., NMV P134899. latex cast of external mould, dorsal view, X 4.

one. C? lhailandicus is most readily dis- that projects strongly anteriorly and is bounded tinguished from the present species by its longer laterally by deep furrows, but in one specimen pygidium with a greater number of axial rings. the rhynchos is conical (Fig. 8K) whereas in the

other it narrows weakly forwards, is broadly encrinurid hypostomes indet. rounded anteriorly and slightly concave in out- line laterally (Fig. 8G). The specimens also differ Figure 8G. K. in the length (sag.) of the posterior border and Remarks. These two hypostomes differ mark- the curvature of the posterior margin. edly from each other and clearly belong to sep- It is not possible confidently to match these arate taxa. Both hypostomes have a rhynchos hypostomes with the two preceding species. Cor- 260 DAVID.I. HOLLOWAY

onocephalus! urbis has a conical rhynchos, as do character at the generic level. Price therefore most species of Batocara. However. Batocarasil- placed Slhenarocalymene in synonymy with venlalense (Etheridge and Mitchell) has a rather Gravicalymene. Until the relationships of caly- weakly tapering rhynchos (Strusz, 1980, pi. 5, menids of Apocalymene and Sthenarocalvmene fig. 14), suggesting that the present hypostome type are clarified, I prefer to assign such species with this character may belong to B. frilillum. to Gravicalymene with question.

encrimirid pygidium indet. Gravicalymene? vaccina sp. nov.

Figure 80 Figure 9

Remarks. A single encrinurid pygidium, which Etymology. Latin vaccinas, of cows, referring to is incomplete posteriorly, differs from the others the Poley Cow Formation. known from the Poley Cow Formation. The

specimen resembles pygidia of Batocara frit il- Type material. Holotypcrcranidium NMV IM38830A, ium in overall proportions but has a wider and B (counterparts). Fig. 9A, B. Paratypes: PI 3883 1 -PI (cranidia); more strongly tapering axis, fewer axial rings NMV 38838 NMV PI34883, P 1 38839-P1 38842 (librigenae); and pleural ribs, ring furrows containing ellipti- NMV P134867, PI 38843-PI 38847 (hypostomes); cal apodemal pits laterally, and wider (exsag.) NMV P138848-PI 38856 (pygidia). inlcr-rib furrows. Diagnosis. Anterior cephalic border as long Calymenidae Milne Edwards, 1840 (sag.) as occipital ring, gently upturned. LI large, almost as wide as adjacent median part of gla- Flexicalymeninae Siveter, 1977 bella, with anterior edge opposite glabellar mid- (= Mctacalymcninac Pfibyl and Vanek, 1977) length. Midlength of palpebral lobe opposite S2 or slightly farther forward. Hypostome with Remarks. Flexicalymeninae and Metacalymeni- broad posterior border spines having abaxial nac are considered here to be synonymous. and adaxial margins convex in outline, separ- Although Pfibyl and Vanek's publication estab- ated by sharp notch. Pygidium with narrow, lishing Metacalymeninac is dated 1975, the date gently taping axis of 6-7 rings, 5 sharply of issue given inside the front cover of the vol- impressed pleural furrows, and no vincular fur- ume is December 1 977. Dr Siveter has informed row. me that his publication was issued in April 1977. Flexicalymeninae thus has priority over Metaca- Description. Glabella bell-shaped, widest lymeninac towards back of LI and approximately 0.6 times as wide across frontal lobe; front of glabella flat- Gravicalymene Shirley, 1936 tened in outline medially, level with front of fixigenal field or projecting slightly farther for- Type species. Gravicalymene convolva Shirley, wards. Occipital ring decreasing in length abax- 1936, from the lower Ashgill of south Wales; ially behind LI , flexed forwards original designation. slightly distally; occipital furrow increasing greatly in depth Remarks. The following species belongs to the behindLl.Ll ovate; posterior branch of SI shal- group for which Chatterton and Campbell lowing abruptly opposite middle (exsag.) of LI (1980) proposed the genus Apocalymene. The but extending to occipital furrow. L2 subcircular difficulty of classifying such species was dis- or elliptical, half as long (exsag.) as LI and not as cussed by Holloway (1980), who concluded that distinctly separated from median part of gla- present knowledge of calymenid relationships bella. L3 nodular, half as long (exsag.) as L2; S3 does not enable the discrimination of Apocaly- narrow (tr.), shallow and situated at 0.25 times mene from Slhenarocalymene Siveter, 1977. glabellar length. Axial furrow containing Sthenarocalvmene was considered by Siveter anterior pit just behind anterolateral extremity (1977) and Holloway (1980) to differ from of frontal lobe; preglabellar furrow not as deep as Gravicalymene in the form of the anterior axial furrow but recessed slightly beneath front cephalic border. Price (1982), however, pre- of glabella. Anterior border flattened (sag., sented evidence that the form of the anterior exsag.) behind strongly rounded crest; anterior border is too variable to be used to distinguish border furrow shallow and well-rounded in cross between these two genera, lending support to section. Fixigenal field convex (exsag.), sloping doubts raised by other workers (e.g., see Price, steeply forwards in front of palpebral lobe; 1982: 58) on the taxonomic usefulness of this anterior edge of palpebral lobe opposite S3, pos- EARLY SILURIAN TR1LOBITES FROM NORTH QUEENSLAND 261

Figure 9. Gravicalymene'! vaccina sp. nov. A, B, holotype, cranidium NMV P138830, internal mould and latex cast of external mould, dorsal views, X 3.5. C, cranidium NMV P 138831. latex cast of external mould, dorsal view. X 5. D, H, cranidium NMV P138832. latex cast of external mould, lateral and dorsal views, X 5. E, cranidium NMV P138833, internal mould, dorsal view, X 5. F, cranidium NMV P138834, internal mould, dorsal view, X 5. G, pygidium NMV PI 38848. latex cast of external mould, dorsal view. X 3. 1, J. left librigena NMV P138839, latex casts of counterpart moulds, dorsal and ventral views. X 3.5. K. left librigena NMV PI 38840. latex cast of natural mould, ventral view, X 3.5. L, pygidium NMV PI 38849, latex cast of natural mould, ventral view, X 3.5. M, hypostomc NMV PI 34867. latex cast of external mould, ventral view, X 8. N, cranidium NMV P138835. internal mould, dorsal view. X 10. O, pygidium NMV P138850, internal mould, dorsal view, X 6. P, hypostome NMV PI 38843, latex cast of external mould, ventral view, X 7. Q, hypostomc NMV PI 38844. internal mould, ventral view, X 7.5. R. pygidium NMV PI 3885 1, latex cast of external mould, dorsal view. X 3. S. pygidium NMV PI 38852, internal mould, dorsal view, X 3. T, cranidium NMV P138836. latex cast of external mould, dorsal view, X 4. U, cranidium NMV PI 38837, internal mould, dorsal view, X 4.5. 262 DAVID J. IIOLLOWAY tcrior edge opposite outer end of SI. Anterior to be the least deformed specimen. A very small branch of facial suture mostly subparallel to sag- cranidium (Fig. 9N), 1.9 mm in length, differs ittal line or converging weakly, curving strongly from larger cranidia in having a broader, more inwards across front of anterior border furrow; subquadrate glabella and a shorter (sag.), sharply posterior branch of suture (interpreted from upturned anterior border, although these differ- librigena) directed laterally or even slightly for- ences could again be due to deformation. LI is wards from s, flexed more strongly backwards subtriangular; SI is rather shallow at the axial about half way to lateral border furrow. Libri- furrow, the anterior branch is very weak and gena with gently convex field, shallow lateral transverse, and the posterior branch is deep but border furrow, and broad and well-rounded bor- dies out abruptly just in front of the occipital der; doublure flattened, inner edge lying close furrow. S2 and S3 are transverse and narrow, S3 beneath inner part of border. being very shallow; L2 is not separated from the Hypostomc approximately as wide across median part of the glabella. The cranidium is shoulders as long (sag.), about 1.5 times wider rather coarsely granulose and there is a median across anterior wings: anterior margin broadly tubercle on the occipital ring. y rounded, lateral margin subparallel between Gravical\>mene'. vaccina is very similar to G? anterior wing and shoulder; notch between pos- hetera Gill, 1 945 and G? kilmorensis Gill, 1 945. terior spines extending forwards to posterior both from the Ludlow of central Victoria, and border furrow. Anterior lobe of middle body G? coppinsensis (Chatterton and Campbell. elliptical, rising steeply to a central prominence; 1 980) from the Wenlock of the Australian Capi- posterior lobe crescentic, slightly inflated, wider tal Territory. G? hetera and G? kilmorensis, (tr.) than anterior lobe; middle furrow deepest which are probably synonymous (Holloway and abaxially and medially, median part lying Neil, 1982), differ from G? vaccina in having a opposite shoulder; maculae inconspicuous. more upturned anterior cephalic border and Anterior border flexed ventrally to form a sharp slightly more posteriorly placed palpebral lobes, flange separated from middle body by a long with their midlength opposite L2 ratherthan S2. (sag., exsag.), poorly delimited depression; G? coppinsensis has a smaller LI than G? vac- anterior wing with deep pit. Lateral border cina, slightly narrower posterior hypostomal strongly convex (tr.), of uniform width except spines separated by a broader median notch, a towards shoulder where it expands slightly; lat- more strongly tapering pygidial axis, less sharply eral border furrow firmly impressed. Posterior impressed pygidial pleural furrows (except the spines flattened; posterior border furrow first), and interpleural furrows that are more dis- increasing in depth abaxially and medially. tinct abaxially. G? cooiamundrensis (Gill, 1940), Pygidium 1.5-1.6 times as wide as long, len- from strata in New South Wales previously ticular to rhombic in outline. First axial ring assigned a Late Silurian age but now known to be flexed slightly forwards distally and with weak Early Devonian (Adrian, 1 978), is also similar to node; rings 2 and 3 with pseudo-articulating half G? vaccina but has a slightly more upturned rings medially; all except last ring furrow deepest anterior border, a somewhat smaller L 1 , coarser abaxially. Axial furrow very shallow behind axis. cranidial granulation, and pygidial pleural and Pleural lobes gently convex (tr.); posterior mar- interpleural furrows that are deeper abaxially. gin arched upwards towards sagittal line. Pleural Gravicalymenel changyangensis (Chang, furrows shallowing abaxially but distinguishable 1974) from the Silurian of south-west China is to almost margin; interpleural furrows weak. distinguished from G? vaccina by its less bell- most distinct abaxially; posterior pleural band shaped glabella with much smaller LI. on fifth segment depressed abaxially. bounding The incomplete calymenid pygidium figured gently convex (tr.) postaxial region. Doublure by Lane and Thomas (1978, pi. 2, fig. o), from narrow and sharply rounded in cross section. the Quinton Formation in the Grey Creek area External surface of cranidium. librigena, of the Broken River Province, differs from hypostomc and pygidium with traces of granu- pygidia of Gravicalymenel vaccina in having lose sculpture. longer (exsag.) pleural furrows that curve more strongly backwards abaxially Remarks. The preserved shape of the glabella of and extend closer to the pygidial margin, Gravicalymenc'! vaccina and the degree to which and interpleural furrows that are deeper abaxially. the anterior border is upturned vary due to deformation of the specimens (e.g., compare Fig. 9A, C, H). The holotype (Fig. 9A. B) appears EARLY SILURIAN TRILOB1TES FROM NORTH QUEENSLAND 263

Odontopleuridae Burmeister, 1 843 instead of being separate. Partial fusion of these

spines is, however, variably developed within Odontopleurinae Burmeister, 1 843 some other odontopleurid genera; among Remarks. A number of odontopleurid genera species assigned by Ramskold and Chatterton to were assigned by Ramskold and Chatterton Meadowtownella, these spines are partly fused in (1991) to the Acidaspidinae Salter. 1 864, a sub- Primaspis ascita Whittington (1956: 199, pis I, family previously considered synonymous with 2) and Acidaspis trentonensis Hall (see Ross, the Odontopleurinae. Ramskold and Chatterton 1979: D8, pi. 4, figs 8-11) but not in Acidaspis stated that their concept of the Acidaspidinae is girvanensis Reed ( 1 9 1 4: 33, pi. 5, figs 8-10, pi. 6, new but did not give a full diagnosis as details are figs 1-3). This suggests that partial fusion of to be presented elsewhere. Pending the publi- pygidial spines may develop independently cation of these details, the Acidaspidinae is not within lineages and should be used with caution recognised here. in adducing relationships. Species assigned to Gaotania also differ from those assigned to Gaotania Chang, 1974 Stelckaspis in that the occipital lobes are very Type species. Gaotania ovata Chang, 1974, from weak or absent and the pygidial pleural ridge is the upper Llandovery of south-west China; orig- more poorly defined along its adaxial edge. inal designation. Globulaspis is even more poorly known than Gaotania, the type and only known species, Glo- Remarks. Gaotania is not well known, morpho- bulaspis prominens (Reed, 1931) from the lower logical information on the genus having been Llandovery of Scotland, being represented only derived mostly from the cephalon and pygidium by several fragmentary' cranidia (Howells, 1982. of the type species illustrated by Chang( 1 974, pi. pi. 15, figs 8, 12, 13). The narrow frontal lobe, 82, figs 7, 8). Another Chinese species, G. pul- the absence of L3, the relatively weak isolation ehella Chang, 1974, is based on a very poorly of S2 from the median glabellar lobe and the preserved dorsal cxoskeleton. and has also been narrow, rather inflated part of the fixigena adax- recorded from poorly preserved material by Wu ial to the palpebral lobe and eye ridge are simi- (1977: 103, pi. 2, figs 15, 16; note that the num- larities with Gaotania and Stelckaspis, and the bering of figs 12 and 16 is transposed on Wu's apparent absence of occipital lobes suggests a plate 2). Poorly preserved specimens assigned to greater similarity with the former. G. prominens G. ovata by Chang and Meng ( 1 986: 5 1 3, pi. 3, differs from species assigned to both Gaotania figs 8-12) apparently do not belong to that and Stelckaspis in having a functional facial species, as the major border spines on the pygid- suture. Globulaspis may eventually be judged to ium are not greatly inflated. be a senior synonym of one or both of these gen- Ramskold and Chatterton (1991) considered era, but until the discovery of more complete Gaotania to belong to a monophyletic group of material of G. prominens, including pygidia, I genera that also includes Globulaspis Reed. consider that Globulaspis should be restricted to 1931, Slelckaspis Chatterton and Perry, 1983 that species. and Vriarra Chatterton and Campbell, 1980. Vriarra, known only from the type species U. Gaotania is extremely similar to Stelckaspis and kausi Chatterton and Campbell, 1980 from the was considered to be a senior synonym of that Wenlock of the Australian Capital Territory, genus by Lane (1988). Characters shared by the resembles Stelckaspis and Gaotania in most of two genera include: glabella narrower than the the cephalic characters shared by those genera cheeks; frontal lobe not expanded laterally; L3 but differs in having S2 strongly separated from absent; L2 weakly separated from the median the median glabellar lobe, a longer (sag.) occipi- lobe; facial suture apparently fused in holas- tal furrow, secondary spines along the dorsal pides; eyes situated posteriorly and very close to edge of the genal spine and a pygidium with only the glabella: anterior and lateral cephalic border one pair of median secondary border spines furrows joining in a curve; genal spines rela- between the major spines. tively short and stout; and pygidium with two pairs of median secondary border spines between the major spines. Ramskold and Chat- Gaotania bimusa sp. nov. terton (1991: 356) stated that the pygidium of Figure 10A-M, N, O. Q, R Gaotania differs from that of Stelckaspis in having the lateral pair of median secondary bor- Etymology. Latin bi-, two, together with the gen- der spines partly fused with the major spine pair eric name of the banana, in reference to the 264 DAVID. I. HOl.LOWAY EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 265

major border spines on the pygidium. Noun in Thoracic segments with long (exsag.), convex apposition. pleural ridge and very short (exsag.) anterior Type material Holotype: pygidium NMV P138857A, articulating flange abaxially (Fig. ION, Q); B (counterparts). Fig. 10O, R. anterior pleural spine short, blunt and down- Paratypes: NMV PI 34837. PI 38858-P 138868 wardly directed; posterior spine long, stout and (cephala); NMV PI 38869. PI 38870 (thoracic seg- gently curved. ments); NMV P134807, P13887I (pygidia). Pygidium excluding border spines approxi- mately 2.7 times as wide as long. Axis with width Diagnosis. Pygidium with inflated major border across articulating half ring approximately 0.25 spines having distinct backward flexure at mid- times maximum pygidial width, slightly nar- length, and with two pairs of secondary border rower across second axial ring but much wider spines lateral to major spines. across first ring. First axial ring highly elevated and gently arched forwards; second ring much Description. Cephalon including genal spines lower, weakly separated from terminal piece of crescentic in dorsal view; anterior margin appar- axis, with a short (sag.), steeply inclined pseudo- ently flexed forward slightly directly in front of articulating half ring lying beneath posterior eye, more or less transverse in outline medially edge of first ring and separated from remainder (Fig. 10K). Glabella expanding slightly from of second ring by a deep furrow. Axial furrow occipital ring almost to front of LI, thereafter very deep lateral to second ring and terminal narrowing strongly. Occipital ring strongly piece of axis, not impressed adjacent to first ring arched (tr.). decreasing greatly in length abax- or behind axis. Pleural lobe with slightly raised ially behind LI; occipital furrow long (sag., anterior margin and broad, gently convex border exsag.) and shallow medially, deeper and more that slopes backwards between major border sharply impressed laterally. LI elliptical to spines. Pleural ridge short, extending obliquely ovate, separated from median lobe by deep, backwards from first axial ring and merging with oblique S 1 and less-sharply impressed longitudi- border in front of lateral part of major spine nal furrow. L2 much smaller than LI. not sep- base. Major spines extending backwards more arated from median lobe; S2 notching side of than twice sagittal length of pygidium; first glabella. Axial furrow deep alongside posterior (most anterior) secondary spine smaller than part of LI and in front of S2, shallow elsewhere. second, both curving backwards abaxially sub- Eye situated opposite LI. together with arcuate parallel to proximal part of major spine but eye ridge isolating a narrow, inflated sliver of directed more ventrally than it; third and fourth check adjacent to axial furrow; lateral and ante- secondary spines similar in size to second, rolateral to eye and eye ridge, cheek gently con- directed posterovent rally, third spines converg- cave (tr.) and inclined. Lateral border flattened ing slightly backwards, fourth spines subparallel or weakly concave (Fig. 10B), very wide poster- (Fig. 10O). Doublure divided into inner and iorly and narrowing strongly forwards; lateral outer bands by an angular, transverse ridge; border furrow shallow. Genal spine broad proxi- inner band expanding adaxially to a point in mally and tapering strongly distally. Cephalic front of major spine base and thereafter increas- margin with at least 16 blunt, downwardly- ing in slope. directed spines in a row extending from more or Exterior of cephalon and pygidium with gran- less directly in front of eye onto base of genal ulose sculpture. spine. Cephalic doublure with deep, exsagittally elongated depression situated adjacent to inner Remarks. Gaotania himusa is more closely margin at base of genal spine (Fig. 10K). related to G. ovata than to G. pulchella. Charac-

Figure 10. A-M, N.O. Q. R, Gaotania bimusa sp. nov. A. D, cephalon NMV PI 38858, internal mould and latex cast of external mould, dorsal view. X 8.5. B. F, H. cephalon NMV PI 38859. latex casts of counterpart moulds, oblique, dorsal and ventral views, X 8. C. cephalon NMV PI 38860, latex cast of external mould, dorsal view, X 7.5. E. cephalon NMV PI38861, latex cast of natural mould, ventral view. X 5. G, cephalon NMV P138862, latex cast of external mould, dorsal view, X 5. 1, cephalon NMV P138863, latex cast of external mould, dorsal view. X 7. J. cephalon NMV PI 38864. latex cast of external mould, dorsal view, X 7. K. cephalon NMV

PI 38865, latex cast of natural mould, ventral view. X 6. L, cephalon NMV P 1 38866. latex cast of natural mould, ventral view, X 5. N. Q, thoracic segment NMV PI 38869, latex casts of counterpart moulds, ventral and dorsal views, X 5. O, R. holotype, pygidium NMV PI 38857. latex casts of counterpart moulds, dorsal and ventral views, X 8. M, P, Ceratocephalasp. M. pygidium NMV PI 38872, latex cast of natural mould, ventral view, X 5. P. pygidium NMV PI 38873. latex cast of external mould, dorsal view. X 3. 266 DAVID J. HOLLOWAY

ters in which the first two species differ from the Corda, 1847) (redescribed by Snajdr, 1986) last are the inflated major border spines on the from the upper Ludlow to lowermost Pfidioli of pygidium. the secondary border spines that are Bohemia, C. vogdesi Etheridge and Mitchell, much smaller than the major spines, and the dis- 1897 from the upper Ludlow of the Yass Basin, tinct pygidial border abaxial to the major spines. New South Wales, and Ceratocephala n. sp. A of

The pygidium of 6'. bimusa differs from that of Chatterton and Campbell, 1 980 from the Wen- G. ovala in having only one secondary border lock of Canberra. Pygidia of these species differ spine lateral to the major spine rather than two, from the present specimen in having only one the major spine is not as distinctly flexed back- axial ring. wards at midlcngth. the posterior pair of second- "Ceratocephala" impedita Etheridge and Mit- ary spines diverge backwards instead of being chell, 1897, based on cranidia from the Ludlow subparallel, and the pygidial granulation is of the Yass Basin and revised by Chatterton apparently coarser. G. bimusa seems to have (1971), actually belongs to Miraspis, as shown by shorter, more strongly tapering genal spines than the SI that is directed obliquely backwards from either of the Chinese species, but cephala of all the longitudinal furrow instead of obliquely for- three species are too poorly preserved for further wards, and the median glabellar lobe that is useful comparison. widest at the inner end of SI instead of narrow- ing forwards from the occipital furrow. Ceratocephalinae Richter and Richter, 1925 Acknowledgements Ceratocephala Warder, 1838

I thank Dr J. S. Jell (University of Queens- Type species. Ceratocephala goniata Warder, land) for guiding me to the locality from which 1838, from the Silurian of Ohio; by mono- the material was collected; DrG. D. Edgecombe typy. (Australian Museum) for discussion on Prostrix Ceratocephala sp. gen. nov.; Ms P. L. Clark for printing most of the photographs; and Dr C. C. Lu for translating Figure 10M, P Chinese literature. The manuscript was Remarks. The more complete of two pygidia reviewed by Dr Edgecombe and Dr A. T. Tho- belonging to this genus lacks the left lateral mas (University of Birmingham, UK), both of extremity and the distal parts of the marginal whom made suggestions for its improvement. spines (Fig. I OP). The specimen seems to have been deformed by upward flexing of the anterior References portion along a transverse line passing between Adrain, J. M. and Chatterton, B. D. E., 1993. A new the second and third marginal spines. As a result, rorringtoniid trilobite from the Ludlow of Arctic the axis appears to slope very steeply backwards Canada. Canadian Journal of Earth Sciences 30: with respect to the remainder of the pygid- 1634-1643. ium. Adrain, J. M. and Chatterton, B. D. E., 1 994. The aula- Ceratocephala species with three, seven or coplcurid trilobite Otarion, with new species from nine marginal spines on the pygidium are known the Silurian of northwestern Canada. Journal of from the Silurian. In having seven spines and Paleontology 68: 305-323. Adrian, 1978. two axial rings, the present specimens most J„ Cootamundra Group. Pp. 1 10-122 in: H. Basdcn, .1. Adrian, D. S. closely resemble C plummeri Chatterton and L. Clil'l and R. E. Winchester, Geology of the Cootamundra Perry, 1 983 from the lower Wenlock of Canada, 1: 100.000 Sheet 8528. Geological Survey of New but the first second and marginal spines arc South Wales: Sydney. more laterally directed than in that species, the Alberti, G. K. B„ 1969. Trilobiten des jungercn Silu- barbs on the marginal spines are finer (to judge riums sowie des Outer- und Mitteldcvons. I . Mit from their broken bases), the exoskelelal granu- Bcitragen zur Silur-Devon Stratigraphie einige lation is less uniform in size, and there is a pair of Gebictc Marokkos und Oberfrankens. Ahhand- small tubercles on the first axial ring. The second lungen der Senckenbgrgischen Ngturforsckenden ring furrow appears to be much deeper and the Gesellschafi 520: 1-692. Angclin, N. P., 1854. Palaeontohgia terminal piece of the axis more depressed in the Scandinuvica. I C rustacca fonnationis transilionis. present material, but these differences can be Fasciculus 2. Academiac Regiae Scicntiarum Succanac: Hol- attributed to deformation. Other Silurian miae, i-ix, 21-92, pis 25-41. species of Ceratocephala with seven pygidial Arnold, G. O. and Henderson, R. A.. 1 976. Lower Pal- spines are marginal C rhabdophora (Hawle and aeozoic history of the southwestern Broken River EARLY SILURIAN TRILOBITES FROM NORTH QUEENSLAND 267

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