364 



width strongly convex sides straight, gradually tapering backwards ; 

 pleurae with a very wide groove. Pygidium and moveable cheeks un- 

 known. 



The cheeks and glabella are very convex ; the glabella separated from 

 the cheeks by a deep groove ; the margin in front of the glabella is ele- 

 vated into a strong rounded cord-like rim between which and the apex of 

 the glabella there is a wide and deep groove. These characters shew 

 that it is closely allied to both B. conicus and B. Cordai. On compari- 

 son with these, it is seen that B. conicus differs in having the glabella 

 more narrowed forwards and in the form of the space between the apex 

 and marginal rim, that is to say, convex next to the glabella and concave 

 close to the margin. B. Cordai has the glabella proportionally more elon- 

 gated. The eye also in B. gregarius seems to be further forwards and 

 more distant from the glabella than it is in the other two. 



The surface characters cannot be made out from the casts. 



Locality and Formation. In the primordial slates holding Paradoxides 

 Bennetti (Salter) at St. Mary's Bay in the south part of Newfoundland. 



Collectors. The specimens were procured by Mr. D. E. McKay of 

 Montreal, who furnished me with a cast holding four individuals in a space 

 of three inches square. 



BATHYURUS PERPLEXUS. (N. sp.) 



Fig. 350. Pygidium of B. pcrplexus. 



Description. Pygidium semi-elliptical or sub-triangular, strongly con- 

 vex ; anterior margin gently convex, nearly straight ; sides gently convex 

 and converging to form a somewhat narrowly rounded apex ; axis eylindro- 

 conical, strongly convex, extending the whole length very nearly, rounded 

 and rather abruptly elevated at the apex, with three distinct segments in 

 the anterior half (besides the half-segment at the anterior margin), the 

 posterior half apparently smooth. Side lobes with a narrow smooth 

 border all round, and three depressed convex segments each, separated 

 by narrow grooves. The anterior segment has a pleural groove close to 

 the margin. These three pairs of segments occupy, with their inner 

 extremities, the length of the anterior half of the axis being separated 

 therefrom by the linear dorsal furrows. Behind the third pair there 

 appears to be a fourth alongside of the posterior half of the axis, and con- 



