86 THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS angle 180 degrees, base flat, and summit flat. Stem round, 0.75 mm. in diameter, crenellar, with small round central lumen. Basal circlet 1.5 mm. in diameter, pentagonal in aboral view, confined to small aboral surface, with three normally disposed basais. Radials five, each 2.5 mm. long by 2.5 mm. wide, recurved onto aboral surface, with short sinus 1 mm. long by 1 mm. wide. Deltoids overlap radials. Deltoids four, each 9 mm. long by 4 mm. wide, with smooth triangular middle portion 2.5 mm. wide at base along radiodeltoid suture, bordered on either side by lenticular portions that have aligned lobes even with each side plate, each row slanting at an angle <strong>of</strong> about 100 degrees, measured from the mouth as origin and the line <strong>of</strong> the food groove as base. The disposition <strong>of</strong> the anal plates are the same as in Nucleocrinus elegans. In two specimens, one polished, one with orals removed, the hidden superdeltoid was seen. There are two hydrospire folds on each side <strong>of</strong> an ambulacrum, with a short hydrospire canal. Ambulacra five, linear, recurved below, each 11 mm. long by 1 mm. wide, with lancet covered by side plates, and 36 side plates in a space <strong>of</strong> 10 mm. along an ambulacrum. Side plates disposed as in Nucleocrinus elegans. Orals five, subtriangular, covering peristome, interambulacral in position, and arranged as in Nucleocrinus ekgans. Occurrence.—Middle Devonian, coral zone <strong>of</strong> Widder beds, Hungry Hollow Formation, near Thedford and Arkona, Ontario. Types.—Plesiotypes, 3,662, 3,662a (used for above description), two specimens, from Thedford, Geological Survey <strong>of</strong> Canada, Ottawa; 102,707, one specimen, from tile yard, Thedford, Charles Southworth collection, U. S. National Museum, Washington; E148, three specimens, one polished, from Thedford, and E8,244, one specimen, from tile yard, Thedford (identified as N. lucina), Southworth collection (1933), E15,939, two specimens, from tile yard, Thedford, Southworth collection (1943), and E21,120, nine specimens, from tile yard, Thedford and Hungry Hill, Arkona, Southworth collection, Buffalo FIGURE 178. Nucleocrinus meloniformis (BARRis), Middle Devonian, Hamilton Group, Moscow, New York (Buffalo Soc. Nat. Sci., no. E8,244); aboral view <strong>of</strong> basais and adjoining plates, showing ridges, X15. [Explanation. —"A," amb.; Z, azygous basal.] Society <strong>of</strong> Natural Sciences, Buffalo, New York. All these specimens, except one, have been labelled as Nucleocrinus elegans and obviously are misidentified. Genus ORBITREMITES Austin & Austin, 1842 Type-species, by subsequent designation (Bather, 1899).—Pentremites derbiensis SOWERBY, 1825. Generic diagnosis (emend. FAY, 1960).—Spiraculate blastoids with five spiracles, or four spiracles in addition to an anispiracle, with a superdeltoid, two FIGURES 179-187. Species <strong>of</strong> Orbitremites AUSTIN & AUSTIN, Lower Carboniferous, England. 179-182. 0. derbiensis (SowERBy), Middle Limestone, Yorkshire (H. H. Beaver coll., nos. 4, 328); 179, summit and anal areas (no. 328), X15; 180, anal area <strong>of</strong> acidetched specimen, X15; 181, cross section <strong>of</strong> "E" ambulacrum, oral view (no. 4), X15; 182, part <strong>of</strong> "E" ambulacrum, showing side plates (no. 4), x45. 183-185. 0. cam panulatus (M'CoY), "Devonshire [ ?Derbyshire], England (Univ. Chicago, no. 1,633); 183, basal area, X15; 184, cross section <strong>of</strong> "D" ambulacrum, oral view, X15; 185, part <strong>of</strong> "E" ambulacrum, showing side plates, X45.-186, 187. 0. ellipticus (SowERsy), Clitheroe Limestone, Yorkshire (H. H. Beaver coll.); 186, summit area, X15; 187, part <strong>of</strong> "A" ambulacrum, showing side plates, X45. [Explanation.—"A," amb.; An, anal opening; Bf, brachiolar facet; Bp, brachiolar pit; "C," amb.; C, canal (radial); CR, cryptodeltoid; "D," amb.; D, deltoid; H, hydrospire; HD, hypodeltoid; HP, hydrospire plate; L, lancet; 0, oral opening; OSp, outer side plate; P, pore; Pf, pore furrow; S, spiracle; Sp, main side plate; Su, superdeltoid; Z, azygous basal.]
BLASTOID STUDIES 87 183 187 nn•nn