FOSSILS OF THE BURLINGTON GROUP. 449 



posed of quadrangular pieces, the first of which is nearly as 

 long as Avide, and the others about half as long as wide, 

 with scarcely any tendency to assume a wedge shape. Sur- 

 face merely riiiely granular. 



Hight of body to the top of first radial pieces, measuring 

 to their inner edges, 0.14 inch; breadth, 0.40 inch; breadth 

 of column, 0.08 inch. 



This species will be distinguished from the last by its more depressed 

 body, which has its under side between the top of the first radial pieces 

 and the column, slightly convex in outline instead of concave, which 

 results from the greater prominence of the basal and subradial pieces 

 of the latter. The species under consideration likewise has its radial 

 pieces proportionally wider particularly the second radials, which also 

 dift'er in being broadly rounded, instead of angular, on the dorsal side, 

 and not constricted on their lateral margins. Its arm pieces are also 

 flat, instead of convex, on their outer side. 



Owing to the fact that the column entirely hides the very small base 

 of this sj>ecies, and the sutures between the subradials, or first range of 

 pieces around the summit of the column, are rather obscure, and really 

 look as if there were only three, instead of five of these pieces, we were 

 led to suspect that these might be the basal pieces, which would remove 

 the species entirely from the genus Erisocrinus. On removing the col- 

 umn, however, we have been able to see what we believe to be five 

 minute basal pieces within the first series surrounding the end of the 

 column, which would necessarily have to be succeeded by five pieces in 

 the next range. Hence, we think we can scarcely be mistaken in sup- 

 posing the appearance of only three suture lines between the plates, 

 we regard as the subradials, as merely an abnormal condition, resulting 

 from two of the suture lines being anchylosed, or accidentally obliter- 

 ated. This supposition is also strengthened by the near specific rela- 

 tions between this and the last described species, in which all the basal, 

 subradial and other plates are clearly and distinctly seen. 



In case our genus Erisocrinu* is not distinct from Philocrinus, with 

 which we have already suggested it may be identical, then the names 

 of the species here described will have to be written Philocrinus an- 

 tiquus and P. Whitei. 



The specific name of this species is given in honor of Dr. C. A. WHITB, 

 the able State Geologist of Iowa. 



Locality and position Upper division of the Burlington group, at 

 Burlington, Iowa. Lower Carboniferous, Mr. WACHSMUTH'S collec- 

 tion. 





