30 



Graphiocrinus. The species here described is distinguished 

 from Sca]>hiocrinus simplex, by havinij twelve arms instead of 

 ten, whicli is a ^nod 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. Tliis may be of generic importance, but Ave 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 ])late truncates a sub- 

 radial and the difference consists, in the additional jilates. 

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

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

 to regard this as of specific importance only. Tlie distinction 

 made by Prof. Hall between Scaphiocrinus and Poteriocrinus 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 (Jroup, at Tje(!rand, Iowa, and 

 now in the coUccfiou of Win. V. E. (uirley. 



F.AMii.v A(;ASSIZ0CRINID/E. 



.\C!ASSTZOCUINrS OVALTS, n. sp. 



Plate II, Fig. !'■>, an entire specimen viewed opposite to (izjjyons 

 area; Fig. 14, azi/gous 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 UTid ha\ing u|)]ii'r sutures slightly concave for the 

 recej)tion of tiie suljradials. Subradials long(>r than wide, 

 showing expanding to the suix'rioi- lateral angles, and each of 

 them g(Mitly rounded. l<'irst i-adials pentagonal, alout one- 

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

 est diamelfU' of liu; calyx is l)ut little above the inferior anghv 

 They are ti-uiicated the entii-e width al)ov(^ and .separated fi-oni 

 each second i-adial by n gaping sutui-(>. Second radials small- 

 er tlian the first, cuive gently inward and are slightly con- 



