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782 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Interradials one or three in the first row, followed by one or two in the 
second, all forming a part of the ventral disk.. The large anal plate of the 
dorsal cup is generally followed at the tegmen by two rows of three plates 
each, and these by a large number of minute pieces, which enclose the anus. 
The anal opening is directed laterally and placed near the upper end of the 
anal area. The posterior oral occupies a central — or nearly central — posi- 
tion; it is highly protuberant, and very large compared with the other four, 
which are small, scarcely convex, and pushed to the anterior side; but 
sometimes they may be unrepresented altogether, In this case, small cover- 
ing pieces follow the sides of the posterior oral; but when all the orals are 
represented, generally large radial dome plates of a first and second order 
take the place of the covering plates. 
Column round, small; axial canal minute. 
Istribution. — Probably restricted to the age of the Warsaw and St. Louis 
eroups. 
Type of the genus: Talarocrinus cornigerus (Shumard). 
femarks. — Talarocrinus forms a transition between Dichocrinus and Ptero- 
tocrinus. It preceded P/erotocrimus in geological time, while Dichocrinus, 
although surviving Zularocrinus, reached its climax before the latter was 
introduced. The species upon which the genus was founded were originally 
described by Shumard and Casseday and Lyon under Dichocrinus, whence 
S. A. Miller removed them to Pterotocrinus. 
Tularocrinus differs from Dichocrinus in the more massive plates, and in 
having but one costal to the ray. The latter is the case also in Pterotocrinus, 
but the distichals in that genus are comparatively large, and form an import- 
ant part of the calyx; while those of Yalarocrinus are small, and retain the 
form of free arm plates. Besides, Péerotocrinus has large, wing-like appendages 
fastened to the surface of the test, like which nothing is found in Tularo- 
crus ; the corresponding plates of the latter are much smaller and are 
inserted between the other plates, instead of resting against their beveled 
outer edges. 
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