SSS SS —————— ‘ — eenatniei eae aS - 
SSS Se 3 z ————Se SS a ae — ~ 
ae aes ie ae <= -- = ———= ——— —_" SS 
786 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Talarocrinus symmetricus Cass. and Lyon. 
Plate LXX VITI. Figs. 4a, b, and 6. 
1860. Dichocrinus symmetricus —Cassnpay and Lyon; Proceed. Amer. Acad. Arts and Sci., Vol. V., p. 21., 
1866. Dichocrinus symmetricus —SuuMaARD; Catal. Paleeoz. Foss. N. Amer., p. 367. 
1877. Dichocrinus symmetricus —S. A. Minter; Catal. Paleoz. Foss. Amer. (1st Edit.), p. 76. 
1881. Talarocrinus symmetricus —W. and Sr.; Revision Paleocr., Part I1., p. 87. 
1888. Talarocrinus symmetricus —8. A. Mituer; Catal. Pal. Foss. Amer. (2d Edit.), p. 288. - 
Syn. Dichocrinus elegans — Lyon and Cass.; Proceed. Amer. Acad. Arts and Sci., Vol. V., p. 22. 
Syn. Zalarocrinus elegans —W. and Sp.; Revision Paleocr., Part II., p. 87. 
This species is closely allied to the preceding one, but somewhat smaller ; 
the dorsal cup is more depressed, the form of the ventral disk more conical, 
less contracted at the periphery, and the anal area wider. Dorsal cup semi- 
globose, slightly lobed as seen from above or below, the plates without 
ornamentation ; suture lines distinctly grooved. 
Basal cup quite shallow, widest at right angles to the interbasal suture. 
Radials spreading rapidly to the middle, less rapidly in the upper portions ; 
the superior faces a little excavated, and their outer edges slightly truncated. 
Anal plate longer than the radials, widest in the middle, the upper end 
inflected, making the lateral faces convex. Costals and distichals very small; 
not exposed upon the surface; they are hidden by the two inner palmars of 
the first row, which overlap them. The two outer palmars of the first row 
rest upon the radials, their lateral faces support an interbrachial, which 
also slightly touches the radials. Palmars four in the calyx, in contact later- 
ally, short and rather deeply excavated for the reception of the higher 
brachials, which are not preserved in the specimens, The arms of the same 
ray are equidistant, while those of different rays are farther apart and sepa- 
rated by a shallow groove. Ventral disk higher than the dorsal cup. The 
interambulacral spaces filled by one and two narrow plates followed by the 
orals; the first radial dome plate is conical. The large anal plate supports 
three plates, of which the middle one is considerably wider than high and 
somewhat depressed, the two others quite narrow. The second row also con- 
sists of three pieces, and these are succeeded by numerous smaller ones, 
which form an elongate rounded ridge containing the anus. This ridge, 
which is bounded laterally by a shallow groove, extends to the posterior oral 
in an almost vertical line. The primary radial dome plates alternate with 
the orals; they are large and either spinous or strongly tuberculous. The 
secondary radial dome plates are elongate and enclose a large interdistichal. 
