204 



specimen, it is difficult to perceive the line of separation between the body 

 and the tail. 



" The eyes and free cheeks are absent in all specimens. 



" Affinities — in form and number of pleuras it resembles Cyphoniscus 

 socialis (Salter), but diffiars from it in details of structure ; the pleurae 

 are of a different type, having the groove running along the middle, 

 straight outwards, and not obliquely outwards and downwards, as in 

 Salter's figure. The pygidium is entire, but it is as deep grooved as the 

 pleurae, the Avhole form is not so convex, and the pleura are not facetted. 

 It appears from the outward edge of the fixed cheeks that the facial 

 suture cuts the margin in front and posterior mai"gin far outward. The 

 head of Menocei^halus Salteri resembles closely that of Bathyurus 

 Saffoi'di, in the flat arched border in front of the glabella and in the 

 three convex lobes into which the head is divided. 



" Dedicated to J. W. Salter, Esq., Palaeontologist of the Geological 

 Survey of Great Britain. 



" This beautiful little crustacean was found at Point L^vis in the Quebec 

 group of rocks, in the same band of limestone as Olenus Logani.'' 



Bathyurus strenuus. (N. sp.) 



Fig. 188. Fig. 189. Fig. 190. 



Fig. 188. — Bathyurus strenuus. The head. 



189. — B. arcuatus. Side view of the head. Fig. 190. — Upper side of 

 the same. 



Description. — Head convex, broadly rounded in front, with short poste- 

 rior spines ; length nearly two-thirds the width. Glabella large, oblong, 

 nearly as long as the head, convex, most elevated just in front of the 

 neck furrow, thence arched down to the front margin ; sides parallel ; 

 front angles rounded, front margin somewhat straight in the middle ; 

 neck furrow narrow, well defined all across and continued on the checks 

 beyond the eyes ; dorsal furrow slightly impressed but distinct along the 

 sides of the glabella to the front margin ; neck segment depressed convex, 

 widest in the middle. Eyes moderate, rcniform ; their length nearly half 

 the Avidth of the glabella ; about one-third or one-half their own length 

 from the sides of the glabella ; their anterior angles close to a line drawn 



