New Species of Crinoibea and other Fossils. 219 



of those just described : the anchylosed edges are distinctly depressed, 

 while the exterior margins are prominent. Surrounding the whole 

 there is a narrow granulose (shagreen) border which is entire on its 

 onter margin. 



This body thus constituted seems to resemble the Echinidre of suc- 

 ceeding geological periods more than the Crinoidea, Cystid?e or 

 Asterid^ of the Palaeozoic formation, and in the minutise of its 

 structure becomes an object of interest. 



The specimens which I have observed do not appear to have been 

 parasitic ; and no -indication of such a character is given by the 

 authors of the genus. From the manner of their occurrence I con- 

 sider them to have been floating bodies ; the disc composing the 

 solid portions of the animal, and from which may have depended a 

 fleshy or cartilaginous sac. 



Formation and locality. In a soft shaly seam in the Trenton 

 limestone, near Saratoga, New York. 



Cycloctstoides anteceptus n. sj>. 



The specimen consists of a subovate ring of strong plates, which 

 are narrow on their inner faces, or somewhat wedge-form, the trans- 

 verse diameter the greater, and the height greater than the length. 

 Their surfaces are strongly granulose, separated at the sutures as for 

 the intervention of muscular attachments. 



The marginal plates have been removed, and nothing is known of 

 the character of the disc. 



Formation and locality. In the upper part of the Trenton 

 limestone, or base of the Hudson-river group, on the Escanaba 

 river, in Michigan. 



Genus — CK ANI A Retziits. 



Crania Tkentonensis n. sj). 

 Plate 7, figs. 11, 12. 



Shell of medium size, strongly convex on the upper valve ; width 

 a little greater than the length, greatest width below the middle of 

 the shell. Beak of dorsal valve small, pointed towards, and situated 

 near, the cardinal border. 



Surface marked by strong concentric lines of growth. No striae 

 or radiating: lines are visible. Transverse diameter eleven-twentieths 

 of an inch ; length half an inch. 



This species bears considerable resemblance to C. Hainiltonensis 

 in its general form and in surface characters, but difi"ers in having 

 the beak so near the cardinal border. 



Formation and locality. In Trenton limestone, Middleville, IS ew 

 York. 



