16 



The pygidium found in the same fragment of stone with one of the spe- 

 cimens of the glabella of this species is in all general characters that of a 

 Bathyurm. It is semicircular, convex, axis cylindrical, strongly convex, 

 terminating behind with an abruptly rounded descent, six annulations, the 

 first three or four most strongly defined. The lateral lobes have four 

 segments each, separated by strong rounded furrows ; there is a narrow 

 entire margin all round with a distinct groove inside, which appears how- 

 ever to be interrupted at the end of the axis. 



The dimensions of the most perfect specimens are as follows : 



Glabella, length 3J- lines ; width at neck segment 1J line, at the 

 front 2 lines ; distance of the eye from the side of the glabella 1J line. 

 The eye appears to be about f of a line in length. 



Pygidium, length 3 lines ; width at anterior margin 5 J lines ; width 

 of axis 1 line. 



Locality and Formation. Anse au Loup, on the north shore of the 

 Straits of Belle Isle. Limestone of the Potsdam group. 



Collector. J. Richardson. 



BATHYURUS PARVULUS. (N. sp.) 



Fig. 21. 



Description. Glabella cylindrical, strongly convex, much elevated 

 above the fixed cheeks, uniformly arched from the front margin for half 

 the length backwards, very slightly narrower at neck segment than at 

 front margin, sides straight, nearly parallel, and distinctly defined by the 

 dorsal furrows. Neck furrow extending all across, posterior glabellar 

 furrows indicated by a barely perceptible indentation on each side, no 

 anterior furrows. Front of head surrounded by a narrow flat margin. 

 Eyes distant from the sides of the glabella about the width of the neck 

 segment. 



On a side view the head has a convexity equal to about one quarter of 

 a sphere. Length of head 2f lines ; width of glabella 1J line ; width of 

 the flat border surrounding the front of the head about J of a line. 



A line drawn across the head at about one third of the length from the 

 posterior margin of the glabella would pass through the centres of the 

 eyes. The eyes appear to be about J of a line in length. 



This species differ from B. senectus in the almost total absence of 

 glabellar furrows ; and in the nearly equal width of the glabella through- 

 out its whole length. 



Locality and Formation. Anse au Loup, on the north shore of the 

 Straits of Belle Isle. In limestone of the Potsdam group. 



Collector. J. Richardson. 



