222 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
interbrachials in two or three rows. The anal side has the same number of 
interbrachials, but these enclose a longitudinal row of three rather large anal 
plates. Ventral disk small, somewhat receding from the dorsal cup, produe- 
ing an offset or groove around the margin; it is convex, and composed of 
small irregular plates. Column circular; the joints rounded at the edges; 
the nodal joints a little wider and higher. The internodes at~about three 
inches from the calyx consist of six pieces, and the same number apparently 
persists throughout the rest of the column. Like most of these stems, it 
tapers considerably downward, and near the distal end is provided with com- 
paratively stout cirri or rootlets, irregularly given off from the sides. 
Horizon and Locality.— Kinderhook group, Le Grand, Marshall Co., Iowa. 
Types in the collection of Wachsmuth and Springer. 
Rhodocrinus coxanus WorrHEN. 
Plate XIII. Figs. 6 and 7. 
1883. Worrnen; Geol. Rep. Illinois, Vol. VIL, p. 305, Plate 28, Fig. 7. 
1885. W.and Sp.; Revision Paleocr., Part IIL., p. 99. 
Syn. Rhodocrinus polydactylus WortTHEN ; 1883, Geol. Rep. Illinois, Vol. VII., Plate 27, Fig. 5. 
The two specimens figured by Worthen as Rhodocrinus coxanus and 
R. polydactylus are too much crushed and distorted to admit of critical com- 
parison or satisfactory description. Both appear to have smooth plates, and 
these, so far as we can ascertain, are arranged substantially in the same 
way; but &. polydactylus, according to Worthen’s figure, has an additional 
bifureation in one of the ray divisions, 7. ¢., five arms to the ray. Whether 
this is a persistent character cannot be ascertained from the specimens, 
and until this is proved we prefer to regard FR. polydactylus a synonym of 
R. coranus. 
Horizon and Locality.— Upper part of the Geode bed in the Keokuk 
group ; Hamilton, Ills. 
Types in the collection of L. A. Cox of Keokuk. 
Rhodocrinus Wachsmuthi Hatt. 
Plate XIII. Figs 5a, b, c, d, and Plate XV. Fig. 7. 
1861. Hatu; Prelim. Deser. of New Spee. of Crinoidea, Albany, p. 18. 
188]. W. and Sp.; Revision Paleocr., Pt. II., p. 213. 
Somewhat larger than the three preceding species. Calyx subovoid, 
flattened at both poles, the proximal end abruptly and deeply impressed, 
