5G2 PALAEONTOLOGY OF ILLINOIS. 



SCAPHIOCRraUS CAKBONAKIUS, M. and W. 



PL 24, Fig. 2. 



J'titeri'irriiniii ( Kcaphiocrimtg ?) carbo'itariug, MKKK IUM! WOUTHEN, 18C1. Proceed. Acad. Nat. Sci., PhiTa., 

 p. 140. 



BODY small, depressed or basin-shaped below the sum- 

 mit of the subradial plates; rounded and concave below, 

 composed of thick, convex, smooth plates, which are con- 

 nected by distinctly impressed sutures. Base small, con- 

 cave, and pentagonal in outline. Subradial plates a little 

 larger than wide, comparatively rather large, directed ob- 

 liquely outward from the base, and curved upward at their 

 extremities; all pentagonal, excepting one on the anal side, 

 which is a little truncated at the upper extremity, for the 

 reception of one of the anal pieces; upper angle of each 

 rather salient. First radials nearly twice as large as the 

 subradial pieces, wider than long, pentagonal or sub-pen- 

 tagonal, the upper side being truncated, and concave in its 

 outer slope. Second radial pieces nearly twice as long as 

 wide, pentagonal in outline, rounded on the outer side, and 

 distinctly constricted around the middle; supporting the 

 first divisions of the arms upon their superior sloping sides. 



Hight of body to the summit of first radials, 0.15 inch; 

 breadth of do., 0.28 inch. 



We are in some doubt in regard to the generic relations of this little 

 species, not being acquainted with the number and arrangement of its 

 anal plates and superior parts. It agrees with the group ticaphiocrinus 

 in the number of its radial pieces, the elongated and constricted charac- 

 ter of its second radial pieces, as well as in having the suture between 

 the first and second radials widely gaping. It differs, however, from 

 the typical species of that group, in having a distinctly concave base, as 

 in Zeacrinus. Others, however, have referred to the genus Scaphiocrinu* 

 species with a concave base. There are also some appearances of an 

 interradial piece between each two of the second radials, but we are not 

 quite sure they are such. 



Locality and position Upper Coal Measures ; Springfield, Illinois. 



