264 



width from one-fifth to one-fourth of the length of the glabella. On a side 

 view the head is rather strongly convex, the outline gently arched along 

 the median line of the posterior two-thirds of the glabella, and then 

 descending with a convex slope to the smooth anterior margin, which is 

 slightly concave between the apex of the glabella and the edge of the 

 head. There is scarcely a marginal rim to the head of this species so far 

 as yet observed. 



The pygidium, represented by fig. 250, has a strongly convex and 

 rather acutely conical axis, a little less than half the whole length, and a 

 little less than one-third the whole width. The side lobes have three or 

 four short and very obscure furrows near the anterior margin, but else- 

 where, are smooth, and descend with a concave slope to the margin. The 

 anterior angles seem to be abruptly bent downwards, and just behind the 

 deflected portion there is a short curved groove, the convex side forwards, 

 deeper than the others. This groove dies out before reaching the axis on 

 the one hand, and, on the other, before reaching the margin. There is, 

 however, an obscure rounded fold, in front of the groove, which reaches 

 the margin. 



No perfect specimens of this peculiar pygidium have been discovered, 

 but as nearly as can be ascertained, its form is obscurely sub-quadrate, 

 the posterior margin obtusely rounded, the sides somewhat parallel, but 

 diverging from each other forwards. The central portion next the 

 anterior margin is strongly convex, and the peculiar slope of the wide 

 margin gives it a shape resembling that of a duck's bill. 



Length of the largest pygidium collected 6 lines; width about the 

 same. Length of the largest glabella 4 lines. 



Locality and Formation. F, G, and H, Port aux Choix, and Keppel 

 Island, Newfoundland ; Quebec group. 



Collector. J. Richardson. 



BATHYURELLUS MARGINIATUS. (N. sp.) 



Fig. 248. 



Description. Glabella cylindro-conical, narrowly rounded in front, 

 rather strongly convex, uniformly arched along the median line ; width, 

 a little more than half the length ; neck segment depressed convex ; neck 

 furro^ narrow, extending all across. The front of the head has a flat 

 horizontal margin its width equal to one-sixth the whole length of the 

 head. From this to the glabella, there is a convex ascent the width of 

 the margin and ascent being one-third the whole length of the head. The 

 glabella is two-thirds the whole length of the head. Eyes and cheeks, 

 unknown. 



