226 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
interposed between the radials are followed by two, three, and three inter- 
brachials at the regular sides; while the anal side has three in the second 
and four in the third row. Construction of ventral disk and anus not known. 
Interaxillaries three or more. 
Florizon and Locality.— Hamilton group ; Canandaigua and Ontario Cos., 
Noe 
Type in the New York State Cabinet of Natural History at Albany. 
Remarks. — This form differs from the other American species, except 
Rhodocrinus Kirbyi, in having interaxillary plates, and also in the details 
of the arm structure. Our description was made from Hall’s figure, and 
from a specimen in the collection of Prof. J. M. Clark, which is now in the 
New York State Cabinet. 
Rhodocrinus Kirbyi W. and Sp. 
Plate XII. Figs. 1a, b, ¢, d. 
1889. Geol. Rep. Illinois, Vol. VIII, p. 180, Plate 15, Fig. 10 and Plate 16, Fig. 3. 
Calyx barrel-shaped, a little longer than wide, excavated at the bottom, 
slightly swelling from the middle of the basals to the middle of the second 
costals, thence contracting to the margin of the tegmen. In some specimens 
the sides are almost cylindrical. Surface of plates convex, covered with 
obscure ridges passing from plate to plate; those following the radial series 
somewhat stronger, and increasing in prominence as they approach the arm 
bases, so as to give to the calyx an obscurely pentangular outline. 
Infrabasals concealed by the column, small, resting within a shallow con- 
cavity. Basals large; their lower margins abruptly bent inward; the 
middle portion forming a sort of rim on which the calyx rests. Radials 
smaller than the basals, about as wide as long. Costals two, of nearly 
uniform size, about half the size of the radials. Distichals five; the two 
lower ones incorporated into the calyx, smaller than the costals; the three 
upper ones free, very short and rounded exteriorly; the third axillary, 
giving off two branches, of which only the inner one branches again, gener- 
ally from the third plate, giving three arms to each main division of the ray, 
or thirty in all, with occasionally an additional arm in one or both posterior 
rays. Arms cylindrical, and only tapering at the tips; they are composed 
of a double series of rather short, interlocking pieces, with indented suture 
lines which give to the back of the arms a file-like appearance. Pinnules 
