60 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS Genus CRIBROBLASTUS Hambach, 1903 Type-species, by subsequent designation (Bass ler, 1938).—Pentremites cornutus MEEK & WORTHEN, 1861. Generic diagnosis.—Spiraculate blastoids with eight spiracles in addition to anispiracle, which is located between epideltoid and hypodeltoid, two hydrospire folds on each side <strong>of</strong> an ambulacrum, lancet covered by side plates with single pore between side plates along radial and deltoid margins, hydrospire plate present, radials overlapping deltoids, deltoids with high coronal processes; calyx ellipsoidal in side view. Mississippian, Illinois, Missouri. Remarks.—The genus Cri broblastus may have been derived from a form similar to Carpenteroblastus in which the deltoids developed coronal processes, the pores remained simple, and the base became concave. CRIBROBLASTUS CORNUTUS (Meek & Worthen) Plate 46, figures 6-11; text-figs. 95-97 Pentremites cornutus MEEK & WORTHEN, 1861, p. 141. Granatocrinus cornutus (MEEK & WORTHEN), 1866, p. 276, pl. 20, fig. 1. Description.—Calyx calcitic, subspherical, with concave base, rounded summit, 13 mm. long by 12 mm. wide, periphery near mid-height, and adoral ends <strong>of</strong> deltoids extended into high coronal processes. Stem not visible. Basal circlet small, hidden in basal concavity, 2 mm. wide. Radials five, each elongate hexagonal, 10 mm. long by 7 mm. wide, strongly recurved below in basal concavity, with broad shallow sinus 10 mm. long by 3 mm. wide, limbs flared into broad raised ridges; radials overlapping deltoids. Deltoids four, arrow-shaped, each 5 mm. long by 3 mm. wide by 3 mm. high, the adoral tips <strong>of</strong> each extended ventrally into a high hornlike coronal process. Two spiracles are found on the adorai end <strong>of</strong> each deltoid, separated by a wide medium septum at the marginal base. On the anal side the large oval anispiracle is located between a small adorai epideltoid and a large pentagonal aboral hypodeltoid. Two hydrospire folds occur on each side <strong>of</strong> an ambulacrum, with a hydrospire plate, but only a single pore between side plates along the radial margins. Pores are present along the deltoid margins. Ambulacra five, linear, each 13 mm. long by 1-1.25 mm. wide, lancet covered by side plates, and 30 side plates in space <strong>of</strong> 10 mm. length along an ambulacrum. Side plates and pores normally disposed, with one large pore between adjacent side plates along radial and deltoid margins <strong>of</strong> ambulacra. The surfaces <strong>of</strong> the calyx plates are worn smooth. Occurrence.—Upper Mississippian, St. Louis Limestone, Brown County, Illinois (holotype); ?Warsaw Limestone, Fenton, Missouri (plesiotypes). Types.—Holotype, X-361, specimen in rock, Illinois State Museum, old no. 10,058, Department <strong>of</strong> Geology, <strong>University</strong> <strong>of</strong> Illinois, Urbana. The above description is primarily based on this specimen. Plesiotypes, S3,771, 13 specimens in three slabs <strong>of</strong> rock (one slab cut and polished), Springer collection, U. S. National Museum, Washington. Genus CRYPTOBLASTUS Etheridge & Carpenter, 1886 Type-species, by original designation.—Pentremites melo OWEN & SHUMARD, 1 850. Generic diagnosis.— Spiraculate blastoids with eight spiracles in addition to anispiracle, located between epideltoid? and hypodeltoid, possibly with two deep cryptodeltoids, lancet exposed along middle onethird <strong>of</strong> its width except near aboral end, two hydrospire folds on each side <strong>of</strong> an ambulacrum, hydrospire plate present, pores absent along deltoid margins, radials overlapping deltoids except at extreme adorai tip <strong>of</strong> the radial limbs where deltoids project slightly over the radials, base slightly concave; calyx ellipsoidal in shape, with depressed interradial sutures. Mississippian, Iowa, Missouri. Remarks.—The genus Cry ptoblastus was probably derived from Tanaoblastus by slight overlap <strong>of</strong> deltoids on adorai tips <strong>of</strong> radial limbs, the interradial sutures having been depressed, and the base becoming concave. EXPLANATION OF PLATE 15 FIGURE PAGE 1-2. Orophocrinus conicus WACHSMUTH & SPRINGER, metatypes, S3,226, Springer Coll., U.S. Natl. Mus.; Lower Mississippian, Kinderhook Group, Le Grand, Marshall County, Iowa; I, side view (X3); 2, side view <strong>of</strong> another specimen (X2.6) 37 3-8. Orophocrinus fusiformis (WAcHsmin-H & SPRINGER), metatypes, S3,226 (fig. 3), S3,227 (figs. 4-8), Springer coll., U.S. Natl. Mus.; Lower Mississippian Kinderhook Group, Le Grand, Marshall County, Iowa; 3, side view <strong>of</strong> specimen ( X3.6); 4, side view <strong>of</strong> another specimen ( X2.2); 5, side view <strong>of</strong> another specimen ( X2.5); 6, side view <strong>of</strong> another specimen ( X3); 7, side view <strong>of</strong> another specimen (X2.5); 8, detail view <strong>of</strong> an ambulacrum <strong>of</strong> specimen shown in fig. 7 ( X14.6) 37
UNIVERSITY OF KANSAS PALFONTOI OCICAL CONTRIBUTIONS FCIIIN0DFRMATA, ARTICLE 3 Pr ATE I FAY- BLASTOID STUDIES