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, produc- 

 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. 



Tt/pes in the collection of Wachsmuth and Springer. 



Rhodocrinus coxanus Wokthen. 

 Plate XIII. Figs. 6 and 7. 



1883. VTorthen; Geol. Eep. Illinois, Vol. VII., p. 305, Plate 28, Fig. 7. 

 1885. W. and Sp. ; Revision Pala^ocr., Part III., p. 99. 



Syn. Rhodocrinus ])olydadylus Worthen; 1883, Geol. Rep. Illinois, Yol. YIL, Plate 27, Fig. 5. 



The two specimens figured by Worthen as RJiodocrinus 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; \i\\i R. jpolydactylus, ^Q,Q,o\dS.wg to Worthen's figure, has an additional 

 bifurcation in one of the ray divisions, i. e., 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 R. polydactylus a synonym of 

 R. coxanus: 



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 Hall. 

 Plate XIII Figs 5a, I, c, d, and Plate XV. Fig. 7. 



1861. Hall ; Prelim. Descr. of New Spec, of Crinoidea, Albany, p. 18. 

 1881. W. and Sp.; Revision Palaiocr., Pt. II., p. 213. 



Somewhat larger than the three preceding species. Calyx subovoid, 

 flattened at both poles, the proximal end abruptly and deeply impressed, 



