: 
HEXACRINID ZA. 783 
Talarocrinus cornigerus (Suvm.). 
Plate LX XVIII. Figs. Ga, b, and 7a, 6. 
1856. Dichocrinus cornigerus —Suumarp; Trans. St. Louis Acad. Sci., Vol. I., p. 72, Plate 1, Figs. 
1865. fos kaetes cornigerus — SHUMARD; Catal. Paleoz. Foss. N. Amer., p. 393. 
1877. Pterotocrinus cornigerus-—S. A. MitteR; Catal. Amer. Palwoz. Foss. (1st Edit.), p. 89. 
1881. Talarocrinus cornigerus — W. and Spv.; Revision Paleocr., Part II., p. $7. 
1883. Zalarocrinus cornigerus —S. A. Mitiur; Catal. Amer. Paleoz. Foss. (2d Edit.), p. 288. 
Calyx ovate, the base slightly truncated and excavated at the bottom. 
Dorsal cup a little lower than the ventral disk, and somewhat shorter than 
wide; the plates strong, moderately convex, but without other markings; 
suture lines distinctly grooved. 
Basals forming a shallow cup, which is transversely elongated, and occu- 
pies about one third the height of the dorsal cup; it is concave at the lower 
face, and the cavity is only partly filled by the column. Radials sub- 
quadrangular, slightly increasing in width upward, their length equal to the 
greatest width; the plates are a little tumid, the greatest convexity being at 
two thirds their height, whence they slope considerably to the upper margin, 
producing a moderate depression or constriction beneath the arm regions. 
Anal plate considerably longer than the radials, its upper face on a level with 
the top of the distichals, its lower face angular, the lateral faces parallel. 
Costals and distichals very small, the former trigonal, often not visible 
externally, and the distichals appear as if they rested upon the radials, as 
described by Shumard; they bend slightly outward, and are wider than 
high, their upper faces concave, forming a sharp angle. First palmars 
narrower and shorter than the distichals, rounded like arm plates; the two 
outer ones touching the radials. Arm openings four to the ray. .The arms 
are not preserved in any of the specimens. Ventral disk highly elevated 
and bulging; the interambulacral spaces depressed, and the plates flat. 
The radial dome plates strongly tuberculous, the other disk plates con- 
vex. Posterior oral strictly central and of extreme size, forming a large 
ovate tubercle, the shorter diameter facing the posterior and anterior 
sides. The other orals quite small and scarcely convex. Four of the 
interambulacral spaces narrow, and the plates elongate; arranged 1, 2, 2, 
with sometimes one or two small accessory pieces interposed between them. 
The posterior interradius is wide, being composed above the anal plate 
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