36 



Graphiocrinus. The species here described is distinguished 

 from Scaphiocrinus simplex, by having twelve arms instead of 

 ten, which is a good specific distinction but not of generic 

 importance. It is distinguished again from S. simplex, which 

 has six azygous plates or more, that rise above the calyx, by 

 having only one azygous plate confined between the plates of 

 the calyx. This may be of generic importance, but we are 

 not willing to found a new genus upon differences of doubtful 

 importance, when they are known to belong to only a single 

 species. In each case the first azygous plate truncates a sub- 

 radial and the difference consists, in the additional plates, 

 that separate the second radials and first arm plates, in one 

 species, that do not exist in the other. We prefer, at present, 

 to regard this as of specific importance only. The distinction 

 made by Prof. Hall between Scaphiocrinus and Poieriocrinus is 

 a good one and all the species he referred to Scaphiocrinus 

 properly belong there, as well as some that others have de- 

 fined. None of them belong to Graphiocrinus. 



Found in the Kinderhook Group, at LeGrand, Iowa, and 

 now in the collection of Wm. P. E. Gurley. 



Family AGASSIZOCRINID^E. 



AGASSIZOCRINUS OVALIS, n. sp. 



Plate II, Fig. 13, an entire specimen viewed opposite to azygous 

 area; Fig. 14, azygous side, of another calyx. 



Species large, contracted at the top of the calyx. Calyx 

 somewhat obovoid; surface smooth; sutures distinct. No evi- 

 dence of a column. Height and greatest diameter subequal. 



Basal plates small and forming a low cup with a subacute 

 point below and having upper sutures slightly concave for the 

 reception of the subradials. Subradials longer than wide, 

 showing expanding to the superior lateral angles, and each of 

 them gently rounded. First radials pentagonal, about one- 

 half wider than high, and curving inward, so that the great- 

 est diameter of the calyx is but little above the inferior angle. 

 They are truncated the entire width above and separated from 

 each second radial by a gaping suture. Second radials small- 

 er than the first, curve gently inward and are slightly con- 



