BATOCRINIDZ&. A471 
vonian of the Eifel, and there is another species at Colle, Spain, at a horizon 
which is generally recognized as Upper Devonian. 
Type of the genus: Aorocrinus immaturus W. and Sp. 
Remarks. —The species for which we propose the genus were referred 
heretofore by us and others to Dorycrinus, except Aorocrinus Cassedayi which 
had been placed under Genneoerinus. It approaches Dorycrinus, differing 
from it, however, in having single arms, and in not having the long spines 
upon which Roemer principally formulated his genus. 
Aorocrinus precedes Dorycrinus in time, and has essentially the character- 
istics of an immature Dorycrinus. The peculiarities of that genus are fore- 
shadowed, but have not acquired their full development, 
Aorocrinus immaturus W. and Sp. 
Plate XIV. Figs. Za, b. 
1890. Doryerinus immaturus — W. and Spr.; Geol. Rep. Illinois, Vol. VIII, p. 175, Plate 16, Fig. 5, and 
Plate 17, Figs. 6 and 17. 
1890. Dorycrinus immaturus —S8. A. Minturn; N. Amer. Geol. and Paleont., p. 240, Fig. 290. 
Below medium size; crown measuring from 30 to 40 mm.; height of 
calyx from 10 to 14, by 10 to 12 wide. Dorsal cup higher than the ventral 
disk, gradually spreading to the arm bases, the sides a little convex. Teg- 
men depressed conical, crowned with a subcentral elongate node or short 
spine. Plates of the dorsal cup moderately convex, their surface more or 
less rugose, the suture lines distinctly grooved. Color of specimens rather 
dark. 
Basals short, somewhat projecting beyond the column, their lower ends 
bending abruptly inward and forming a well defined concavity. Radials 
large, almost as wide as long, the lower margin but slightly convex, the 
upper face concave in the middle and truncated at the outer sides. Cos- 
tals very short, and not much more than half the width of the radials; the 
first quadrangular ; the second pentangular. Distichals 2 x 2, in form re- 
sembling the radials, but only half their size. In some specimens all the 
second distichals are axillary and support palmars, in others those of the 
anterior ray support the arms, which vary in number from eighteen to 
twenty. Arms stout, single, biserial, and arranged in groups, the tips 
incurving and flattened; the interspaces between the rays deeper than 
those between their subdivisions, and in the anal interradius nearly three 
