266 



a little less. Just outside of the eyes is an obscure linear groove, which 

 forms a semicircle round them and the front of the glabella. 



Thorax, with nine segments ; axis strongly convex, semi-cylindrical, less 

 than one-fourth the whole width, with straight sides, slightly converging 

 backwards. Pleurae flat, apparently falcate at their extremities ; the 

 genal angle at about half the length ; the pleural groove running along the 

 middle of the ribs, nearly to the extremity. 



Pygidium much less convex than the head, semicircular, with a wide 

 smooth slightly concave border ; axis short, conical, half the length of the 

 pygidium, obscurely defined at the apex ; two or three obscure ribs near 

 the anterior margin ; side lobes, with obscure indications of ribs near the 

 axis. 



The whole surface appears to be smooth. 



The head of this species is somewhat like that of B. marginatus, but 

 differs in the form of the margin. It is closely allied, but still distinct. 



Length of the largest specimen observed about 11 lines ; length of the 

 head 4 J lines ; of the glabella 3 lines ; of the eye 1J- lines ; width of the 

 head 6 lines ; length of the thorax 3 lines ; length of the pygidium 3i 

 lines. 



Locality and Formation. P, Cow Head, Newfoundland ; Quebec 

 group. 



Collector. J. Richardson. 



BATHYURELLUS FORMOSUS. 



Fig. 250. 



Description. This species has a strongly convex head, terminating 

 with strong and long posterior spines, and with a narrow concave border. 

 The form of the head is precisely the same as that of B. nitidus, with the 

 exception of the spines and the difference in the width of the margin. 

 The eye is also smaller. From B. validus, it is distinguished by the 

 greater convexity and straightness of the sides of the glabella. 



In B. nitidus all the space in front of the glabella is concave, forming 

 what I have designated the wide concave border. In B. formosus only 

 one-third of the same space, next the margin, is concave ; the remainder, 

 extending to the glabella, has a convex upward-slope. 



In both B. fraternus and B. validus the border is, also, narrow and 

 concave, but the glabella in the anterior two-thirds is scarcely at all ele- 

 vated above the general convexity of that part of the head, whereas in 

 B. formosus it is strongly convex. 



