Contributions to Palaeontology. 



193 



GENUS PEMPHIGASPIS ( n. g.). 



Generic characters. The general form of the part of the 

 shield known is semielliptical, rounded behind, nearly 

 straight in the middle in front, and becoming rounded 

 towards the outer margin ; distinctly trilobate. Axis 

 narrow, straight, and slightly narrowing posteriorly; 

 distinctly annulated : annulations direct. Lateral lobes 

 ovate, extremely gibbous or ventricose, rising much 

 above the axis : margins at the sides abruptly incurved. 



PEMPHIGASPIS BULLATA (n.s.). 



Three individuals of this species have been examined : the lar- 

 gest is about one-fifth of an inch in width, and a little less in length. 

 The axis is marked by seven annulations, besides the posterior one : 

 the lateral lobes are smooth, ovate, and very ventricose. The 

 anterior extremity of the middle lobe, with a small area on the inner 

 anterior face of the lateral lobes, may have been articulating faces. 

 The lateral margins are abruptly incurved, flat below, with a narrow 

 elevated ridge just without the inner edge. 



The specimens are casts of the interior, and the character of the 

 exterior surface is unknown. The figures are six times enlarged. 



Fig. 1. The upper surface, Fig. 2. The lower surface. 



Fig. 3. A profile view from the posterior extremity. 



GENUS AMPHION"? 



A single glabella, much resembling in its lateral lobes 

 the glabella of a Calymene, has been found in a specimen 

 from the lower beds near Trempaleau. 



Although not entirely corresponding with Amphion, I 

 refer it, for the present, to that genus. 



[ Trans. v.~\ 25 



