740 THE CEINOIDEA CAMERATA OF NORTH AMERICA. 



Horizon and Locality. — Niagara group ; Perry Co., Tenn. 



Types in the Mineralogical Museum at Breslau, Germany. 



Remarks. — Roemer's figures are misleading. The calyx is not symmet- 

 rical, as he represented it, and the interbrachial pieces bend but slightly 

 inward, even at the four regular sides. Neither do we find the small plates 

 at their sides, nor the linear ambulacral slits ; the spaces between the upper 

 ends of the interbrachial plates are occupied by several small pieces, which 

 are probably covering plates of the ambulacra. He also fails to represent 

 the costals ; they are plainly seen in two of the four specimens in our collec- 

 tion occupying the part which in Eoemer's figure appears as if constituting 

 a projection of the radials. 



