316 ■ EIGHTEENTH REPOKT ON THE STATE CABINET. 



Among the Cystideans of the same group in Wisconsin, there are several 

 specimens which preserve the structure and general features of this genus ; 

 but they are for the most part obscure. 



HEMICOSMITES SUBGLOBOSUS (n. s.). 



General form subglobose, a little longer than wide, somewhat narrower 

 T above than below ; the ovarian aperture above the middle of the length : 



scarcely produced at the base, which is sometimes subtruncate or even 



a little depressed. [This latter feature is probably due to accident.] 

 In the lower range the plates are short ; and the second range consists of 



comparatively wide plates, giving it a greater proportional width than 



the typical species of the genus. 

 The mouth is at the summit, but it cannot be determined whether it is or 



is not proboscidiform. The ovarian aperture is situated above the second 

 * range of plates, and is apparently more nearly at the summit of the plate 



on the right, which has a somewhat different form from the corresponding 



plate in Hemicosmites pyriformis. 

 The plates of the body are granulose and marked by striae parallel to the 



margins, having the centre elevated in a low node from which there are 



radiating ridges to the angles of the plate. 



Formation and locality. In the Racine limestone (Niagara group), Ra- 

 cine, Wisconsin. 



Among the collections from Racine, and associated with the preceding 

 species, there are several specimens of a peculiar form, apparently cysti- 

 deans, but of different structure from any described genus, which, from the 

 nodes or spines upon the surface of the species known, I propose to name 



ECHINOCYSTITES. 



GENUS ECHINOCYSTITES (nov. gen.). 



Body subspheroidal, composed of four ranges of plates. The basal plates 

 are probably four, and are succeeded by two ranges of five plates each and 

 a series of dome plates. The mouth is central, with an excentric or lateral 

 > ovarian aperture. 



ECHINOCYSTITES NODOSUS (n. s.). 



Body subglobose, base slightly protuberant in the centre ; basal plates 



short. The five plates of the second range are large, forming part of the 



basal curve, and extending up the sides ; they are furnished with strong 



nodes which are directed obliquely downwards. In the third range the 



plates are of equal size with the second range, and nodose in like manner ; 



the sides of the body between the nodes being nearly straight in the vertical 

 12 



