FOSSILS OF THE NIAGARA GROUP. 129 



a narrow summit, while in this one it is broad, and flattened for a space 

 equal to two-thirds the breadth of the body below. 



Formation and locality : In limestone of the age of the Niagara group, at Springfield, 

 Ohio. Collection of Prof. E. Orton. Presented by Charles Cline, Esq. 



EUCALYPTOCRINUS CRASSUS. 

 Plate 6, fig. 11. 

 Eucnlyptocrinus C7'assus, Hall; Trans. Alb. Inst., Vol. IV., p. 197. 

 Body narrowly obconical, the height below the bases of the arms equal 

 to the greatest diameter of the cup ; sides straight, or slightly convex ; base 

 truncate. Ba;Sal plates small, concealed within the cavity for the attach- 

 ment of the column ; first radial plates of moderate size, forming about 

 one-fourth of the height of the calyx; second radials quadrangular, 

 widest below, the height a little greater than the breadth; third radials 

 pentangular, truncated above by the small intersupraradial plate, and 

 supporting on each sloping face a supraradial plate, which in turn 

 supports the plates from which the arms rise. Interradial plates large, 

 half as high again as wide, and supporting two elongate interbrachial 

 plates. Arms and interbrachial plates not seen. Surface of the plates 

 of the calyx, so far as can be ascertained from a fragment of the matrix, 

 apparently smooth. 



The specimen being only an internal cast, the entire characters can 

 not be obtained. It has the general appearance and structure of E. cras- 

 sus, as above cited, and the form of one of the narrow or elongate varie- 

 ties of that species, which is very variable in the proportions of height 

 and breadth of the cup, and, consequently, in the proportion of diameters 

 of the plates composing it. 



Formation and locality : In the limestones of the upper part of the Niagara group 

 (Guelph beds), at Cedarville, Greene county, Ohio. Collected by Prof. E. Orton. 



BLASTOIDEA. 



Genus PENTREMITES, Say. 

 Pentremites sub-cylindriga (n. sp.). 



Plate 6, fig. 13. 

 Body elongate, very gradually tapering from the base of the ambu- 

 lacral areas downward to the lower end of the radial plates, and more 

 rapidly below that point to place for the attachment of the column; 

 9 



