RHODOCRINID^. 221 



it differs in the mode of branching of the arms, and the fact that the latter 

 has convex calyx plates; also in its basal concavity being much deeper^ 

 the column larger, and calyx higher. 



Rhodocrinus Wortheni, var. urceolatus W. and Sp. 



Plate XII. Figs. 8a, h. 



Differing from the typical form of R Wortheni in the form of the calyx, 

 which is urn-shaped instead of globular, higher than wide and rounded at 

 the bottom, while that is flattened. The infrabasals are convex, and on 

 a level with the basals. The greatest width of the calyx is across the first 

 costals, whence it contracts rapidly to near the arm bases, which slightly 

 project outward, giving to the tegmen a decidedly pentangular outline. 

 Ventral disk almost fiat, wider than in the typical form, and the plates less 

 numerous. Anus subcentral, and not protuberant. The plates of the calyx 

 flat and without ornamentation. 



IIorizo7i and Locality, — Age of the Lower Burlington limestone, Lake 

 Valley, New Mexico. 



Types in the collection of Wachsmuth and Springer. 



Rhodocrinus watersianus W. and Sp, 

 Plate XIL Fig. 9. 



1889. W. and Sp. ; Geol. Rep. Illinois, Vol. VIII., p. 184, Plate 17, Fig. 10. 



A small species of the type of Rhodocrinus Wortheni, from which it differs 

 in the more concave base, the proportionally smaller size of the basals, in the 

 more elongate form of the calyx, and in the arm structure. Calyx from 

 sub-globose to sub-ovoid, truncate at the bottom and narrowly concave; 

 plates very slightly convex, and without ornamentation. 



Infrabasals small and concealed by the column. Basals moderately large, 

 their lower ends abruptly deflected inward, their upper portions curving out- 

 ward and upward. Eadials somewhat smaller than the basals; as wide as 

 long. Only the proximal distichals take part in the calyx ; they are followed 

 by five to six slightly cuneate free plates, of which the upper one is axillary, 

 and supports two arms, which remain simple. Arms twenty, rounded on the 

 back, slender, very little tapering, and biserial from the last bifurcation ; the 

 joints moderately high and a little convex. Pinnules stout for the genus. 

 The first interradial plate as large as the radials ; followed by five to six 



