UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS PLATE 36 FCHINODERMATA, ARTICLE 3 FAY- BI ASTOID STUDIES
BLASTOID STUDIES 105 Type.-Holotype, 7,225/1, Woodman collection, American Museum <strong>of</strong> Natural History, New York. Genus TROOSTICRINUS Shumard, 1866 Type-species, by subsequent designation (ETHERIDGE & CARPENTER ; 1882).-Pentremites reinwardti TROOST, 1835. Generic diagnosis.-Spiraculate blastoids with five paired spiracles, consisting <strong>of</strong> four paired spiracles and a paired anispiracle, with a superdeltoid, two cryptodeltoids, and a hypodeltoid, edges <strong>of</strong> the cryptodeltoids slightly exposed; lancet covered by side plates, one pore between adjacent side plates along ambulacral margins, radials overlapping deltoids; ambulacra short, directed outward and downward, with three to five hydrospire folds on each side <strong>of</strong> an ambulacrum; pelvis long, deltoids not visible in side view but hypodeltoid visible in side view, and steeply obconical in side view. Silurian, Missouri, Oklahoma, Tennessee, Kentucky, Indiana, Illinois, Ohio. Remarks.-The genus Troosticrinus may have been derived from a form similar to Polydeltoideus in which the sinuses closed, or both <strong>of</strong> these genera may have come from an unknown group <strong>of</strong> echinoderms with diverse structures that early differentiated the Fissiculata from the Spiraculata. An Ordovician group <strong>of</strong> echinoderms that may have given rise to the blastoids is the newly distinguished class Edrioblastoidea, proposed in an article to appear in the "Journal <strong>of</strong> Paleontology." The only genus known in this group is Astrocystites, which has many regular thecal plates and deep infolds crossing the sutures, with five regular straight petaloid or widely linear ambulacra. TROOSTICRINUS REINWARDTI (Troost) Plate 19, figures 1-5; text-figs. 218-221 Pentremites reinwardti TROOST, 1835, P. 224, pl. 10, figs. 10-11. Pentatrematites reinwardtii ROEMER, 1851, p. 373, pl. 6, figs. 13a-c; 1860, p. 60, pl. 3, figs. 2a-c; 1876, pl. 11, fig. 10. Troosticrinus reinwardti SHUMARD, 1866, p. 385, footnote. Troostocrinus reinwardti ETHERIDGE & CARPENTER, 1886, p. 193, text-fig. 7, p. 194, pl. 12, figs. 11-12, pl. 17, fig. 17; BATHER, 1900, p. 87, fig. 8; WOOD, 1909, pp. 13, 17, pl. 3, figs. 2-4; SPRINGER, 1913, p. 170, fig. 264; JAEREL, 1918, p. 107, fig. 101; SPRINGER, 1926, p. 141, pl. 33, figs. 1-8; WANNER, 1933, p. 495, fig. 32; AMSDEN, 1949 (as Troosticrinus), pp. 82-83, pl. 12, figs. 5-7, text-fig. 29. Description.-The holotype is obconical in side view, 23 mm. long by 8 mm. wide, vault 5 mm. long, pelvis 18 mm. long, pelvic angle 30 degrees; periphery at radial lips above mid-height, and rounded pentagonal in top view. Basal circlet conical in side view, 9 mm. long, with three normally disposed basals. Radials five, each approximately 14 mm. long by 5 mm. wide, with short radial limbs and linear sinuses. The radial limbs on the anal side are shorter than those on the other sides. Radials overlap deltoids. Deltoids four, short, externally appearing as an inverted V, each with a paired spiracle elongate in its medial portion. Deltoids not visible in side view except along sinus areas. On the anal side are four anal deltoids. The small superdeltoid is adjacent to the oral opening, and the two elongate cryptodeltoids rest on the aboral face <strong>of</strong> the superdeltoid, separating the anal opening from the adjacent hydrospire canals internally and partly externally. The pentagonal hypodeltoid almost covers the cryptodeltoids but the suture between these plates is visible along sinus margins in well-preserved specimens. The elongate hypodeltoid is visible in side view and abuts against the short radial limbs on the anal side. The cryptodeltoids reach the exterior slightly and therefore a paired anispiracle is present, in which the anal opening and adjacent hydrospire canals are incompletely fused. Thus, five paired openings surround the mouth, consisting <strong>of</strong> four paired spiracles and a paired anispiracle. There are three to five hydrospire folds on each side <strong>of</strong> an ambulacrum, distinguishing this genus from Metablastus, which has four or five hydrospire folds, and Tricoelocrinus, which has three small folds in the substance <strong>of</strong> the radial plates. EXPLANATION OF PLATE 36 FIGURE PAGE 1-3. Tanaoblastus missouriensis (SuumARD), hypotype, 3,576, Carl C. Branson coll., Univ. Missouri; Lower Mississippian, Chouteau Limestone, quarry near Sweeney, Mo.; oral, "D" ambulacral, aboral views <strong>of</strong> specimen figured by Peck (1938, pl. 26, fig. 39) (all X6.9) 104 4-6. Tanaoblastus tennis (HANIRAGH), hypotype, 3,572, Carl C Branson coll., Univ. Missouri; Lower Mississippian, Chouteau Limestone, near Providence, Mo.; oral, "D" ambulacral, aboral views <strong>of</strong> specimen figured by Peck (1938, pl. 26, figs. 16,22) (all X7.2) 105 7-12. Tanaoblastus roemeri (SHUMARD). 7-9. Hypotype, 1,143, Blair coll., Univ. Missouri; Lower Mississippian, Chouteau Limestone, near Sedalia, Mo.; oral, "D" ambulacral, aboral views <strong>of</strong> specimen figured by Peck (1938, pl. 26, figs. 24,28,32) (all X8.5).-10 12. Plesiotypes, 19,106, Gurley coll., Univ. Chicago; Lower Mississippian, Chouteau Limestone, Sedalia, Mo.; 10, polished cross section <strong>of</strong> summit showing cryptodeltoids adjacent to anal opening ( X9.6); 11, oral view <strong>of</strong> polished cross section with "A" ambulacrum upward, showing two hydrospire folds on each side <strong>of</strong> ambulacrum ( X6.6); 12, oral view <strong>of</strong> another specimen showing lack <strong>of</strong> pores along margins <strong>of</strong> deltoid plates (X7.5) 102