64 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS by side plates at aboral end and gradually exposed to one-third <strong>of</strong> its width near the adorai end, with one pore between side plates along deltoid and radial margins; radials overlapping deltoids; calyx subglobular. Mississippian, Illinois, Missouri, Kentucky, Alabama. Remarks.—The genus Diploblastus was probably derived from a form similar to Schizotremites in which the lancet plates extended downward and the form became subglobular. There should be more intermediate forms. DIPLOBLASTUS GLABER (Meek & Worthen) Plate 48, figures 1-12; plate 49, figures 1-9; text-figs. 113-119 Granatocnnus glaber MEEK & WORTHEN, 1869, p. 91. Granatocrinus glaber MEEK & WORTHEN, 1873, p. 537, pl. 20, fig. I l. Description.—Observations here recorded are based mainly on one <strong>of</strong> the original syntypes. Calyx calcitic, worn, flattened spheroidal in side view, rounded pentagonal in top view, 5 mm. long by 6 mm. wide, with periphery at mid-height. The stem is round, crenellar, attached to a raised hexagonal base in the middle <strong>of</strong> the basal circlet, with small round central lumen. Basal circlet pentagonal in basal view, flat, 2.75 mm. in diameter, with three normally disposed basals. In one specimen from Kentucky the azygous basal is in the "DE" instead <strong>of</strong> "AB" position, but this specimen may belong to another species. Radials five, pentagonal in side view, recurved below, each 4.5 mm. long by 3.25 mm. wide, with long, narrow, shallow sinus 4.5 mm. long by 1 mm. wide. Radials overlap deltoids. Deltoids four, short, each 2 mm. long by 2 mm. wide, broadly lanceolate, each with a paired spiracle at the adorai tip. Four deltoid plates are present on the anal side—a superdeltoid, two cryptodeltoids, and a hypodeltoid. The V-shaped superdeltoid is adjacent to the oral opening and has two deltoid septa that are continuous in position with the cryptodeltoids. The adorai end <strong>of</strong> the paired anispiracle is excavated in the superdeltoid. Immediately aboral to the two septa and aligned with them are two subquadrangular cryptodeltoids, located on either side <strong>of</strong> the anal opening. The broad pentagonal hypodeltoid rests on the cryptodeltoids and covers the aboral part <strong>of</strong> the anal opening. The anal opening is partly fused with the adjacent hydrospire canals, thus forming a paired anispiracle on the anal side. Therefore, five spiracles surround the oral opening —four paired spiracles and a paired anispiracle. In weathered specimens these openings are separate and a variable number appear to be present from specimen to specimen. There are two hydrospire folds on each side <strong>of</strong> an ambulacrum, without a hydrospire plate. Ambulacra five, linear, recurved below, each 7.5 min. long by 0.75 mm. wide, with the median one-third <strong>of</strong> the lancet exposed near the adoral end, but near the aboral end the lancet is covered by the side plates. There are 45 side plates in a space <strong>of</strong> 10 mm. along an ambulacrum. Th primary side plates are dumbbell-shaped with one large pore between adjacent plates at the abmedial margin <strong>of</strong> the lens-shaped outer side plate, with pores located along radial and deltoid ambulacral margins. The surfaces <strong>of</strong> the basal and radial plates are ornamented with fine growth lines parallel to plate margins and the deltoids have aligned granules along growth ridges. Remarks.—There is regional and stratigraphic variation among various specimens assigned to this species. The basal circlet is convex, flat, or slightly concave in different specimens, and on this basis alone one may distinguish various species. The object <strong>of</strong> the present work is to define genera, and therefore this problem will have to be considered by later investigators. The variation in shape <strong>of</strong> specimens from the St. Louis Group <strong>of</strong> Illinois and the Ste. Genevieve Limestone <strong>of</strong> Kentucky should be called to attention. Occurrence.—Mississippian, St. Louis Limestone, Hardin County, Illinois (syntypes, X-363) and Brown County, Illinois (E1,498). Ste. Genevieve Limestone, Crittenden County, Kentucky (1,303). Gasper Formation, Huntsville, Alabama (71,650). Warsaw Formation, Florence, Alabama (S3,782). Types.—Syntypes, X-363, three specimens, one 4- sided, A. H. Worthen collection, old Illinois State Museum no. 10,096, now in Department <strong>of</strong> Geology, <strong>University</strong> <strong>of</strong> Illinois, Urbana. Plesiotype, E1,498, one specimen, labelled Mesoblastus kirkwoodensis, A. H. Worthen collection, <strong>University</strong> <strong>of</strong> Illinois. Plesiotypes, 1,303, seven specimens, one polished section, one thin section, and five EXPLANATION OF PLATE 17 FIGURE PAGE 1-3,7-9. Astrocrinus benniei (ETnERIDGE), plesiotypes, 362, Harvard Mus. Comp. Zoology, Lower Carboniferous Limestone Group (shale above no. 2 limestone), Carlops Quarry, Peebleshire, Scotland; 1,3, oral and aboral views with "A" ambulacrum toward top <strong>of</strong> page in fig. / ( X 10.6) ; 2, 9, "C" ambulacral and aboral views <strong>of</strong> another specimen (approximately X14), 7,8, aboral and oral views <strong>of</strong> specimen with "D" side directed downward ( X17.0) 21 4-6. Pleuroschisma ontario REIMANN, topotype, 35,033, Southworth coll., Univ. Michigan; Devonian, Hungry Hollow Formation (coral bed), Ausable River valley northeast <strong>of</strong> Arkona, Ontario; oral, "D" ambulacral, aboral views (all X9.1) 42
UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS FCIIINODERMATA, ARTICLE 3 PLATE 17 5 6 FAY-BLASTOID STUDIES