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22 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS FIGURES 4, 5. Brachyschisma corrugatum (RErmaNN), Middle Devonian, New York (Buffalo Soc. Nat. Sci., no. E15,982). 4. Plates around oral opening and near summit on anal amb.; "C," amb.; "D," amb.; D, deltoid; Dc, deltoid crest; side, X13. 5. "AB" deltoid and adjoining elements, HD, hypodeltoid; Hs, hydrospire slit; 0, oral opening; X13. [Explanation.—"A," amb.; An, anal opening; "B," RI, radial limb; Su, superdeltoid; Sub, subdeltoid.] G FIGURES 6, 7. Brachyschisma corrugatum (REIMANN), Middle Devonian, New York (Buffalo Soc. Nat. Sci., nos. E15,407, E15,982). 6. Vertical section of subdeltoid of "C" ambulacrum, X15. 7. Main and outer side plates of part of "D" ambulacrum, E15,407, X45. [Explanation.—Bf, brachiolar facet; Bp, brachiolar pit; HD, hypodeltoid; OSp, outer side plate; R, radial; Sp, main side plate; Sub, subdeltoid.1 7 plates in 10 mm. length. The pentagonal primary side plates alternate with large adorally disposed pentagonal outer side plates, each pair with a brachiolar facet for the reception of one brachiole. Remarks.—The genus Brachyschisma appears to have been derived from a form like Decaschisma by atrophy of hydrospire slits on the left side of the anal opening in the subdeltoid and adjacent radial limb. Occurrence.—Devonian, Onondaga limestone, near Williamsville (Vogelsanger quarry), New York. Types.—Topotypes, E15,407, seven specimens collected by Fred W. Wattles, 1941; E15,982, one specimen collected by Mr. Wattles, 1943; E21,134, three specimens, one of which was used for the above description. Buffalo Society of Natural Sciences Museum, Buffalo, New York. Genus CODASTER M'Coy, 1849 [=Codonaster ROEMER, 1851 (obj•)] Type-species, by original designation.—Codaster acutus M'Coy, 1849. Generic diagnosis.—Fissiculate blastoids with eight exposed hydrospire fields, epideltoid, ?hypodeltoid, lancet covered by side plates, flat summit, rounded base, lancet not adjacent to mouth, and radials over-
BLASTOID STUDIES 23 lapping deltoids, with broad sinuses. Lower Carboniferous, England. CODASTER ACUTUS M'Coy, 1849 Plate 12, figures 1-7, 9; text-figs. 8, 9 Codaster acutris M'Coir, 1849, pp. 250-251. Description.—Calyx calcitic, cup-shaped in side view, pentagonal in oral view, 14 mm. long by 11 mm. wide, slightly compressed, with flat summit and rounded base. Stem round, crenellar, with small round lumen. Basal circlet cup-shaped in side view, rounded pentagonal in basal view, large, 6.5 mm. long by 9 mm. wide, with a prominent bluntly rounded median ridge on each basal plate. Radials five, pentagonal in side view, wide, each 9 mm. long by 8 mm. wide, with flat truncated top bearing sinuses so that the ambulacra are almost invisible in side view. Each radial sinus is 2 mm. long by 5.5 mm. wide, with deltoids overlapped by thickened radial limbs. Deltoids four, short, lancet-shaped, each 6 mm. long by 3 mm. wide, confined to summit, with low crests, and with approximately eight hydrospire slits exposed on each side of an ambulacrum except in anal area where they are lacking. The slits extend to the adjacent radial limbs. Approximately 16 cover plate sockets occur on each side of each deltoid lip. On the anal side, the thick horseshoeshaped epideltoid, adjacent to the oral opening, surrounds the adorai portion of the anal opening on three sides and is overlapped by the radial limbs. The aboral part of the anal opening was presumably covered by a pentagonal hypodeltoid which is missing, probably as a result of disturbance of sediment in which it was buried, judging from the worn nature of the theca. Hydrospire slits are lacking on anal side and therefore only eight hydrospire fields are developed. Ambulacra five, short, petaloid, confined to summit, each 3.75 mm. long by 1.75 mm. wide, with the adorai end of lancet 2 mm. from oral opening and exposed between side plates for a short distance aborally, but generally covered by side plates. Primary side plates subquadrangular, 30 in a length of 10 mm., with a subtriangular secondary side plate on the adoral-abmedial corner of each primary side plate. The brachiolar area of attachment is shared equally between a primary side plate and its associated secondary side plate. Approximately four main cover-plate sockets correspond to each side plate along the main food groove and three side cover-plate sockets along either side of each side food groove. Surfaces of calyx plates are ornamented with fine growth striae parallel to plate margins. Remarks.—The genus Codaster is a specialized form that, as now understood, should be restricted to fossils known from the Lower Carboniferous of England. It was probably derived from a form like Trionoblastus of the Devonian, in which the superdeltoid and subdeltoid plates are fused to form the epidcltoid. Occurrence.—The labels on the specimens are generalized and merely indicate unspecified Lower Carboniferous strata of Yorkshire, Lancashire, and Derbyshire, England. Types.—Plesiotypes 367, six specimens, Harvard Museum of Comparative Zoology, Cambridge, Mass. The description was based mainly on characters of one of these specimens, with an old name "Pentremite asteria" and number 2319, Malham, Yorkshire, England, on the label. Plesiotypes 96,267, three specimens, Carboniferous limestone, Yorkshire, England, labelled Codaster acutus; S3,200, three specimens, Carboniferous limestone, Lischowney, Derbyshire, England, labelled Codaster acutus, Springer collection; S3,218, two specimens, Carboniferous limestone, Lancashire, England, labelled Codaster trilobatus, Springer collection; S3,219, three specimens of the Hambach collection, Carboniferous limestone, Lischowney, Derbyshire, England, labelled Codaster trilobatus in the Springer collection; and S3,220, two specimens, Carboniferous limestone, Settle, Yorkshire, England, labelled Codaster trilobatus var. acutus, Springer collection, U. S. National Museum, Washington. Genus CONOSCHISMA Fay, n. gen. FIGURES 8, 9. Codaster acutus M'CoY, Lower Carboniferous, England; part of "A" ambulacrum showing main and outer side plates seen in two specimens (Harvard Mus. Comp. Zoology, no. 367, fig. 8, X45; U. S. Natl. Mus., no. S3,218, fig. 9, X37.5). [Explanation.—Bf, brachiolar facet; Bp, firachiolar pit; OSp, outer side plate; Sp, main side plate.] Type-species, by original designation (herein).—Codarter (Cryptoschisma?) iaeviusculus ROWLEY, 1900. Generic diagnosis.—Fissiculate blastoids with ten exposed hydrospire fields, an epideltoid and hypodeltoid, broad radial sinuses, lancet covered by side plates, ambulacra extending down sides of theca; form of calyx conical in side view. Mississippian, Missouri.
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