220 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
and Le Hon to Gilertsocrinus. The following species are too little known to 
be recognized: R. spinosus Hall, R. gracilis Hall, R. varsoviensis Hall, and 
R. rectus Hall. 
Rhodocrinus Wortheni Hatt. 
Plate XI. Fig. 6, and Plate XII. Figs. 7a, b, ¢. 
1858. Hat; Geol. Rep. Iowa, Vol. I., Part IL., p. 556, Plate 9, Figs. 8a, 8, e. 
1881. W. and Sp.; Revision Paleocer., Part II., p. 213. 
A small species. Calyx depressed-globose, a little concave at the bottom; 
plates delicate, flat and perfectly smooth. Infrabasals of moderate size, the 
tips slightly projecting beyond the column; forming a pentagon. Basals very 
large, a little wider than long. Radials nearly as large as the basals, angular 
below, narrowly truncated above ; their lateral faces parallel. Costals two, 
generally anchylosed, the two together smaller than the radials, and only 
half their width; the first quadrangular. Distichals 2 X 10 in the calyx, 
those of the lower row nearly as large as the costals, the upper smaller, and 
excavated to form the arm bases, which do not project. Ambulacral open- 
ings small, slitlike, directed upwards, and arranged in pairs around the disk. 
Arms delicate and cylindrical; they branch twice above the calyx, and are 
uniserial to the first bifurcation, then turning into biserial, with short inter- 
locking pieces. The five plates interposed between the radials are consider- 
ably smaller than the basals, and but little larger than the two succeeding 
interbrachials, which are followed by two rows of two small plates. At the 
anal side, the first interradial plate is larger than those of the regular 
sides, and followed by three plates. Ventral disk very small, and following 
the general curvature of the calyx. Column small, round; the upper joints 
rounded at their edges; the axial canal minute. 
Horizon and Locality. — Lower Burlington limestone, Burlington, Iowa. 
Type in the Illinois State collection, Springfield. 
vemarks. — Specimens apparently of this species, are found in the 
Waverly group of Cuyahoga Co., O., as natural moulds; the calyx, however, 
appears to be more depressed, and larger in proportion to the length of the 
arms. Similar specimens, but decidedly more urn-shaped, occur in the 
Burlington beds of Lake Valley, New Mex., for which we propose the name 
Rhodocrinus Wortheni, var. wrceolatus (Pl. XII. Figs. 8, b). The typical form 
resembles FR. watersianus W. and Sp., and R. Wachsmuthi Hall; from which 
