220 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



and Le Hon to Gilbertsocrijius. The following species are too little known to 

 be recognized : R. spinosus Hall, B, gracilis Hall, B. varsoviensis Hall, and 

 R. rectus Hall. 



Rhodocrinus Wortheni Hall. 

 Plate XL Fig. 6, and Plate XII. Figs. 7a, h, c. 



1858. Hall; Geol. Hep. Iowa, Vol. I., Part II., p. 556, Plate 9, Pigs. 8a, b, c. 

 1881. W. and Sp. ; Revision Palaeocr., 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. Eadials 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 2X10 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, wdiich 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, low^a. 



Type in the lUinois State collection, Springfield. 



Remarks. — Specimens apparently of this species, are found in the 

 Waverly group of Cuyahoga Co., 0., 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. nrceolatus (PI. XII. Figs. 8, h). The typical form 

 resembles R. watersianus W, and Sp., and R. Wachsmuthi Hall ; from which 



