UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS PLATE 12 <strong>ECHINODERMATA</strong>, ARTICLE 3 FAY-BLASTOID STUDIES
BLASTOID STUDIES 49 Deltoids four, arrow-shaped, with moderately high coronal processes, and seven or eight exposed hydrospire slits on each side <strong>of</strong> an ambulacrum, extending to adjacent radial limbs. On the anal side there are three deltoid plates. The hexagonal superdeltoid is adjacent to the oral opening and the horseshoe-shaped subdeltoid rests on the inner aboral surface <strong>of</strong> the superdeltoid. The subdeltoid limbs curve around the sides <strong>of</strong> the anal opening and meet the truncated radial limbs. It is assumed that a hypodeltoid plate was present on the aboral side <strong>of</strong> the anal opening, where a facet is present. Hydrospire slits are lacking on anal side; thus there are eight exposed hydrospire fields. Ambulacra five, linear, each 3.5 mm. long by 0.5 mm. wide, with approximately 50 side plates in 10 mm. The primary and secondary side plates are pentagonal and almost equal in size, with four or five cover-plate sockets to each side plate along the main food groove. The surfaces <strong>of</strong> the calyx plates are ornamented with fine growth lines parallel to plate margins. Occurrence.—Middle Devonian, Partridge Point Formation, Partridge Point, Michigan. Types.—Plesiotypes, E21,142, 12 specimens, Reimann collection, Buffalo Society <strong>of</strong> Natural Sciences, Buffalo, New York. TRIONOBLASTUS PYRAMIDATUS (Shumard) Plate 4, figures 7-9; Plate 12, figure 8; text-figs. 67, 68 Codaster pyramidatus SHUMARD, 1858, p. 238, pl. 9, figs. la-c. Description.—Calyx silicified, obconical in side view, pentagonal in oral view, 12 mm. long by 8 mm. wide, with vault 2 mm. long, pelvis 10 mm. long, pelvic angle 45 degrees, and periphery at radial lips well above midheight. Basal circlet rounded in aboral view, broadly triangular near area <strong>of</strong> stem attachment, 3.5 mm. long by 4 mm. wide, with three normally disposed basals. Stem round, 1 mm. in diameter, with small round lumen. Radials five, each broadly pentagonal in side view, 8 mm. long by 4 mm. wide, with broad flat sinus 3 mm. long by 3.5 mm. wide, and low limbs. The interradial sutures are in depressed areas flanked by a double or triple row <strong>of</strong> parallel ridges on either side; radials overlapping deltoids. Deltoids four, arrow-shaped, with low crests, and seven hydrospire slits on each side <strong>of</strong> an ambulacrum, extending to adjacent radial limbs. On the anal side there are three deltoids. The arrow-shaped superdeltoid is adjacent to the oral opening. The subdeltoid is horseshoeshaped, adjacent to the aboral surface <strong>of</strong> the superdeltoid, with limbs that extend on both sides <strong>of</strong> the anal opening and meet the adjacent radial limbs which overlap the subdeltoid limbs. It is assumed that a small hypodeltoid plate covered the aboral part <strong>of</strong> the anal opening and abutted against the radial limbs. Hydrospire slits are absent on anal side; therefore there are eight hydrospire fields. Ambulacra five, linear, each 4.5 mm. long by 1 mm. wide, with lancet covered by side plates, and 50 side plates in 10 mm. The side plates appear to be normally disposed. The surfaces <strong>of</strong> the calyx plates appear to be ornamented with fine growth lines parallel to plate margins. Remarks.—The flat summit and ridges parallel to the interradial sutures serve to characterize this species. The variously described species <strong>of</strong> Trionoblastus may readily be distinguished by the number <strong>of</strong> hydrospire slits in each field, and the relative height <strong>of</strong> the deltoid crests. Occurrence.—Middle Devonian, Onondaga (Columbus) Limestone, Columbus, Ohio. Types.—Plesiotypes, 37,759, eight specimens, U. S. National Museum, Washington; E21,071, seven specimens used for the above description, Buffalo Society <strong>of</strong> Natural Sciences, Buffalo, New York. Order SPIRACULATA Jaekel, 1918 Blastoids with hidden hydrospire slits that open into hydrospire canals, haying definite spiracles and hydrospire pores. Silurian -Permian, North America, Europe, Timor, Australia, Asia, North Africa. EXPLANATION OF PLATE 12 FIGURE PAGE 1-7,9. Codaster acutus M'Cov, plesiotype (figs. 1-3), S3,218, Springer coll., U.S. Natl. Mus., Lower Carboniferous limestone, Lancashire, England; plesiotypes (figs. 4-7,9), 367, Harvard Mus. Comp. Zoology, Lower Carboniferous limestone, Malham, Yorkshire, England; 1-3, oral, "D" ambulacral, aboral views (all X3.7); 4-6, oral, "D" ambulacral, aboral views (all X4.6); 7, enlarged view <strong>of</strong> "E" ambulacrum <strong>of</strong> another specimen ( X16); 9, thin sec. <strong>of</strong> anal area <strong>of</strong> a third specimen, showing epideltoid against radial limbs (anal area in white) ( X16) 23 8. Trionoblastus pyramidatus (SHumARD), plesiotype, 37,759, U.S. Natl. Mus.; Devonian, Onondaga Limestone, Columbus, Ohio; oral view, for comparison with Codaster, showing subdeltoid plate on adorai side <strong>of</strong> anal opening, adjacent to superdeltoid plate, with distinct suture between the two plates ( 7) 49