RHODOCRINID &. 225 
to adjoining plates. Radials nearly as large as the basals, but the ridges less 
conspicuous. First costals smaller than the second, convex; the second as 
large as the first. The second distichals support the free arms, which are 
not preserved. Interradial areas not depressed below the level of adjoining 
brachials ; composed of the interradial plate, and about nine interbrachials, 
of which the upper ones are very small. The anal area has one or two 
additional plates. Ventral disk small; its diameter scarcely two thirds the 
width of the dorsal cup at the widest part; composed of numerous very 
small, highly convex plates. Anus subcentral. Column round. 
Florizon and Locality. — Keokuk group ; Harrison Co., Indiana. 
Remarks.— We did not have access to the specimens to illustrate this 
species, and were obliged to make our description after Miller. 
Rhodocrinus nodulosus Hatt. 
Plate XII. Fig. 8. 
1862. Rhodocrinus (Acanthocrinus) nodulosus — Hatt; 15th Rep. N. Y. State Cab, Nat. Hist., p. 126; 
ibid., 1872, Bull. I., Plate la, Fig. 8. 
1881. Rhodocrinus nodulosus —W. and Sp.; Revision Paleocr., Part IT., p. 212. 
Of medium size. Dorsal cup more rapidly spreading to the top of the 
second costals than from there to the arm bases; height and greatest width 
about equal ; interradial and interdistichal spaces depressed. Plates convex, 
the surface covered with obscure radiating ridges, and the central portion in 
most of them produced into a small node. 
Infrabasals small, but plainly visible beyond the column; the bottom 
somewhat depressed for the reception of the column. Basals larger than 
any of the other plates, longer than wide; the lateral upper faces longer 
than the lateral lower ; the upper faces rather narrow. Radials larger than 
the costals; three of them pentagonal, the two posterior ones hexagonal ; 
the costals slightly narrower and shorter. The distichals support the free 
arms; five to six of them take part in the calyx, of which the three lower 
ones are subquadrangular and twice as wide as long, the two or three suc- 
ceeding ones cuneate, and slightly interlocking. The free distichals are less 
convex and shorter than those of the calyx; the succeeding arm plates 
strictly biserial, and very short. Arms rather stout at the proximal ends, but 
the size decreases rapidly with each bifurcation. There are-two bifurcations 
in the free arms, and the branches are widely divergent. The large plates 
29 
