98 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS gins along ambulacra to form two pores to each side plate, reduction <strong>of</strong> hydrospire folds to two on each side <strong>of</strong> an ambulacrum, and formation <strong>of</strong> a concave base. POROBLASTUS GRANULOSUS (Meek & Worthen) Plate 40, figures 7-12; plate 41, figures 1-12; plate 42, figure 8; text-figs. 203-205 Pentremites (Granatocrinus?) grantdosus MEEK & WORTHEN, 1865, p. 165. Granatocrinus grantdosus MEEK & WoRTHEN, 1873, p. 508, pl. 15, fig. 10. Schaoblastus? granulosus ETHERIDGE & CARPENTER, 1886, p. 223. Cribroblastus gramdosus HAMBACH, 1903, p. 40. Cryptoblastus grantdosus CLINE, 1937, p. 643, pl. 88, figs. 11-16. Description.—The holotype is 7 mm. long by 7 mm. wide, subspherical, complete, and similar to the following described specimen. Calyx calcitic, 7.5 mm. long by 7 mm. wide, flattened elliptical in side view, rounded pentagonal in top view, with concave base, and periphery at mid-height near radiodeltoid suture. Stem impression not seen. Basal circlet pentagonal in basal view, in basal depression, 1.5 mm. wide, with three normally disposed basals. Radials five, each pentagonal in side view, 5 mm. long by 4 mm. wide, moderately long, extending to midheight, recurved below, with a 135 degree angle formed by radial limbs at radiodeltoid suture with center at interradial suture. Radials overlap deltoids. Deltoids four, elongate, lancet-shaped, each 4.5 mm. long by 3 mm. wide, with two spiracles notched in the adorai end <strong>of</strong> each, adjacent to the ambulacra. On the anal side there are two deltoids, a short V-shaped epideltoid adjacent to the oral opening, and a long pentagonal hypodeltoid on the aboral side <strong>of</strong> the anispiracle. The hypodeltoid projects ventrally above the anispiracle a short distance, forming a low hood. Thus there are nine openings surrounding the oral aperture—eight spiracles and the anispiracle. One hydrospire fold occurs on each side <strong>of</strong> an ambulacrum, ending admedially in a hydrospire plate. Ambulacra five, linear, recurred below, each 9.5 mm. long by 1 mm. wide, with lancet covered by side plates along the aboral one-half and exposed one-third <strong>of</strong> its width at the adoral end, with 30 side plates in a space <strong>of</strong> 10 mm. along an ambulacrum. The side plates are normally disposed, with five or six main cover-plate sockets to each side plate along the main food groove. Approximately two pores to each side plate are present along the radial ambulacral margins and one pore to each side plate along the deltoid margins. The surfaces <strong>of</strong> the calyx plates are ornamented by fine granules and growth ridges subparallel to plate margins. Remarks.—The presence <strong>of</strong> one pore to a side plate along the deltoid margins distinguishes this genus from Ptychoblastus and Granatocrinus, which have two pores to each side plate along the deltoid margins. Also, Granatocrinus is large when mature but Poroblastus small. In Ptychoblastus the radials and deltoids abut against each other, and in Granatocrinus and Poroblastus the radials overlap the deltoids. Occurrence.—Lower Mississippian, upper part <strong>of</strong> Burlington Limestone, locality 21 <strong>of</strong> WELLER, Springfield, Missouri (described specimen); locality 20 <strong>of</strong> WELLER, same. Keokuk Group, Warsaw, Illinois (the holotype). Upper part <strong>of</strong> the Burlington Limestone, Burlington, Iowa (S3,720). Keokuk formation, Jersey County, Illinois (S3,717). Keokuk Group, near Warsaw, Illinois (S3,719). Warsaw Formation, Otterville, Illinois (S3,716). Warsaw Formation, fourth horizon, geode bed, one mile above Warsaw, Illinois (also numbered S3,719). Types.—Holotype, 713, one specimen, old Illinois State Museum no. 1,843, labelled Schizoblastus granulosus, Illinois Geological Survey, Urbana. Plesiotypes, 13,893, five specimens, one complete, from locality 20, Weller collection; and 13,894, three specimens, two complete, from locality 21, Weller collection, one specimen <strong>of</strong> which was used for above description, Walker Museum, <strong>University</strong> <strong>of</strong> Chicago. These specimens are also labelled Schizoblastus granulosus. Topotypes?, S3,719, one specimen, Springer collection, from the Keokuk near Warsaw, Illinois; also S3,719, 35 specimens, from the ?Warsaw (labelled Keokuk), 4th horizon, geode bed, one mile above Warsaw, Illinois, Springer collection, labelled Cryptoblastus granulosus; S3,716, 15 specimens, Springer collection; S3,717, one specimen, Springer collection; S3,720, 20 specimens, Springer collection, all <strong>of</strong> which are labelled Cryptoblastus granulosus; U. S. National Museum, Washington. POROBLASTUS CHOUTEAUENSIS (Peck) Plate 42, figures 1-3; text-fig. 206 Orbitremites chouteattensts PECK, 1938, p. 69, pl. 26, fig. 18. Description.—Calcitic, fragmentary, 9.5 mm. long by 9 mm. wide, subspherical, with periphery at mid-height, base sharply concave, with basal circlet 1 mm. in diameter in basal concavity. Radials five, each approximately 5 mm. long by 4.5 mm. wide, strongly recurved below, with sinus 5 mm. long by 1 mm. wide, and angle <strong>of</strong> 150 degrees formed by radial limbs along radiodeltoid suture with interradial suture as center. Radials overlap deltoids. Deltoids four, each 6 mm. long by 4 mm. wide, long, extending below periphery, with adorai tips <strong>of</strong> each notched by two small spiracles on the ambulacral margins. On the anal side the anispiracle is apparently placed between an epideltoid and hypodeltoid plate. Thus, apparently nine openings surround the oral aperture, consisting <strong>of</strong> eight spiracles and the anispiracle. The number <strong>of</strong> hydrospire folds is unknown.
BLASTOID STUDIES 99 Ambulacra narrow, linear, each 11 mm. long by 1 mm. wide, recurved below, with lancet covered by side plates in aboral one-half <strong>of</strong> each ambulacrum but gradually exposed to one-third <strong>of</strong> its width at the adorai end, with 30 side plates in a space <strong>of</strong> 10 mm. along an ambulacrum. Approximately two pores to each side plate are found along the radial ambulacral margins, and one pore to each side plate along the deltoid margins, with a hydrospire plate present along deltoid and radial margins. The surfaces <strong>of</strong> the calyx plates are ornamented by finely granular growth ridges subparallel to plate margins, and the side plates are normally disposed. Occurrence.—Lower Mississippian, Chouteau Limestone, near Providence, Boone County, Missouri. o 706 207 205 203 208 FIGURES 203-208. Species <strong>of</strong> Poroblastus FAY, D. gen., and Schizoblastus ETHERIDGE & CARPENTER. 203-205. P. granulosus (MEEK & WORTHEN), Lower Mississippian, Burlington Limestone, Springfield, Mo. (Univ. Chicago, nos. 13,893, 13,894); 203, summit and anal areas (no. 13,894), X15; 204, cross section <strong>of</strong> "C" ambulacrum, oral view (no. 13,893), X45; 205, part <strong>of</strong> "A" ambulacrum, showing side plates (no. 13,894), X45. 206. P. chouteauensis (PECK), Lower Mississippian, Chouteau Limestone, near Providence, Mo. (Univ. Missouri, no. 1,290); part <strong>of</strong> "A" ambulacrum, showing side plates, X45. 207, 208. S. sayi (SHumARD), Lower Mississippian, Burlington Limestone, Boone and Marion Counties, Missouri (U. S. Natl. Mus., no. S3,735); 207, basal circlet, arrow directed toward "A" ambulacrum, X2.5; 208, part <strong>of</strong> "A" ambulacrum, showing side plates, X20. [Explanation.—"A," amb.; An, anal opening; Bf, brachiolar facet; Bp, brachiolar pit; "C," amb.; C, canal (radial); "D," amb.; D, deltoid; ED, epideltoid; Fg, main food groove; HD, hypodeltoid; HP, hydrospire plate; L, lancet; 0, oral opening; OSp, outer side plate; P, pore; Pf, pore furrow; R, radial; S, spiracle; Sp, main side plate; Z, azygous basal.]
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