430 REPORT ON THE STATE CABINET. 



base, first and second radials. Both specimens are casts of the interiors 

 of the fossil, and show not only the real structure, but the obscurely 

 angular form of the lower part of the body. 



AcTiNOcRiNUS (Saccocrinus) whitfieldi, Hall. 



(Page 370.) 



An examination of the figure, and a subsequent examination of a 

 specimen labelled Megistocrinus marcouaniis^ in Prof. Marcy's collection, 

 and which appears to have been the original of the figure given, leaves 

 no doubt regarding its identity with A. whitfieldi. The bifurcations of 

 the rays take place in precisely the same manner in the two individuals ; 

 and differences as great as those indicated in the plates and form of the 

 body, can be detected between many of the individuals from Waldron, 

 and are of no specific importance. Prof. W. points out a difierence in 

 the number of interradial plates, stating that they are always less than 

 fifteen. But in the two interradial areas of his specimen which show 

 plates, on either of them can be counted fifteen plates, or even more 

 than this number, if we enumerate the smaller ones in the upper part of 

 the area. In one of the areas, sixteen plates can be distinctly counted. 



Megistocrinus infelix, W. & M., is only a smaller individual of the pre- 

 ceding species, possessing all the characters of the Waldron specimens 

 and none othei's. The number of interradial plates may appear less, as 

 those of the upper part of the area are too small to be counted in a cast 

 of the interior, especially since this cast is very indistinctly preserved 

 in some of its parts. The constrictions of the interradial and anal areas 

 between the arm-bases is a character common to all the Waldron speci- 

 mens, when preserving the margin of the dome. This feature is well 

 shown in Saccocrinus speciosus* figured by Rcemer. The bifurcation of 

 the rays take place at the same height^ as in the Waldron species of the 

 same size ; the ridges along the radial series are subject to much varia- 

 tion, but these differences are of no specific value. Both Prof Winchell's 

 figure and specimen leave no doubt of the identity of this form with 

 Actinocrinus whitfieldi. 



Megistocrinus necis, W. & M. The specimen communicated by Prof. 

 WiNCHELL, under this name, I should regard as A. (^S.) whitfieldi with the 

 summit unusually constricted , but showing no marks of specific distinction. 



* The fossil referred by Dr. Rcemeb to Saccocrinus speciosus is probably not of that species, but 

 more likely identical with the Waldron species. 



