100 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS Type.—Holotype, 1,290, one specimen, C. C. Branson collection, <strong>University</strong> <strong>of</strong> Missouri, Columbia. Genus PTYCHOBLASTUS Fay, 1960 Type-species, by original designation.—Ptychoblastus pustulosus FAY, 1960. Generic diagnosis.—Spiraculate blastoids with nine spiracles, or eight spiracles and anispiracle located between an epideltoid and hypodeltoid, radials abutting against deltoids, hydrospire plate present, two pores to each side plate and along deltoid and radial margins, one hydrospire fold on each side <strong>of</strong> an ambulacrum, lancet covered at aboral end but gradually exposed to one-third <strong>of</strong> its width near the adorai end; shape <strong>of</strong> calyx ellipsoidal. Mississippian, Missouri. Remarks.—The genus Ptychoblastus was probably derived from Poroblastus by infolding <strong>of</strong> the poral canals along the deltoid margins to form two pores to each side plate, and downward migration <strong>of</strong> the deltoid plates so that they abut against the radials. PTYCHOBLASTUS PUSTULOSUS Fay Plate 42, figures 4-7, 9-10 Ptychoblastus pustulosus FAY, 1960, pp. 1198-1201, text-fig. 1. Description.—A detailed description is given in the above article and is not here repeated. Of importance is the presence <strong>of</strong> two pores to each side plate along the deltoid margins and radials abutting against the deltoids. Occurrence.—Upper Mississippian, Warsaw Limestone, 12 feet below the top, SW1/4 NW1/4 SW1/4 sec. 9, T. 44 N., R. 5 E., just below level <strong>of</strong> St. Louis & San Francisco RR tracks, Keyes Summit, St. Louis County, Missouri. Types.—Holotype, 3,643; paratypes, 3,644 (a thinsection), and 3,645 (six specimens and one thin-section with fragment), Geology Department, <strong>University</strong> <strong>of</strong> Oklahoma, Norman. Genus SCHIZOBLASTUS Etheridge & Carpenter, 1882 Pype-species, by subsequent designation (ETHERIDGE & CARPENTER, 1886).—Pentremites sayi SittimARD, 1855. Generic diagnosis.—Spiraculate blastoids with 11 openings around the mouth, consisting <strong>of</strong> ten spiracles and separate anus, which is located between an epideltoid and hypodeltoid, lancet exposed along main food groove, one pore between side plates along deltoid and radial margins, deltoids moderately long, deltoids overlapping radials, two hydrospire folds on each side <strong>of</strong> an ambulacrum; form <strong>of</strong> calyx ellipsoidal. Mississippian, Iowa, Missouri. Remarks.—The genus Schizoblastus was probably derived from a genus approaching Schizotremites, in which the deltoid septa moved out to form ten spiracles with anus separate, cryptodeltoids fused with superdeltoid to form an epideltoid, and lancet moved out and down while the hydrospires atrophied to two folds on each side <strong>of</strong> an ambulacrum. SCHIZOBLASTUS SAYI (Shumard) Plate 46, figures 1-2; text-figs. 207-208 Pentremites sayi SHUMARD, 1855, p. 185, pl. B, figs. la-d. Cri broblastus sayi HAMBACH, 1903, p. 42, pl. 5, fig. 14. Schizoblastus sayi var. sayi CLINE, 1936, p. 269, pl. 44, figs. 17-22. Description.—The holotype is fragmentary. Calyx calcitic, 12 mm. long by 16 mm. wide, crushed on one side, in limestone matrix. Base slightly concave. Shape <strong>of</strong> calyx widely elliptical in side view. Deltoids overlap radials and extend below the periphery for about threefourths the length <strong>of</strong> the specimen. Spiracles apparently ten, separate from anus, with anus between an epideltoid and hypodeltoid plate. Ambulacra five, linear, each 19-20 mm. long by 1.5 mm. wide, recurved below, with lancet exposed along the middle one-fifth <strong>of</strong> its width along the main food groove, and 32 side plates in a space <strong>of</strong> 10 mm. along an ambulacrum. The anal opening is covered on the aboral side by a low adorai projection <strong>of</strong> the hypodeltoid plate. Each deltoid plate has three longitudinal ridges extending toward the adorai tip, one in the mid-line <strong>of</strong> the plate and two marginal ones. The surfaces <strong>of</strong> the calyx plates are ornamented by fine growth lines subparallel to plate margins, with a tendency toward granulation. EXPLANATION OF PLATE 33 FIGURE PAGE 1-9. Placoblastus angularis (LvoN), plesiotypes, 13,890 (figs. 1-6), Gurley coll., Univ. Chicago, Middle Devonian, Hamilton Group, Charlestown, Ind., 19,052 (figs. 7-9), Falls <strong>of</strong> the Ohio, near Jeffersonville, Ind.; 1-3, oral, "D" ambulacral, and aboral views <strong>of</strong> average specimen, (X2.9); 4-6, oral, "D" ambulacral, and aboral views <strong>of</strong> a gerontic specimen (X2.2); 7-9, oral, "D" ambulacral, aboral views <strong>of</strong> four-sided specimen in which the "A" ambulacrum failed to develop, thus with only four radials and four deltoids (X7) 95
JNIVI RSITY OF KANSAS PALFONTOLOGICAL CONTRIBUTIONS FCHI NODER MATA, A RTIÇI. E 3 PI.ATF 3 3