195 



The siphuncle of this species is larger than that of the other. The 

 transverse sections differ in being more narrowly rounded on the 

 ventral than on the dorsal aspect in 0. tjjpica, while in C. Mercurius 

 both the ventral and dorsal sides have the same form of convexity. 



The specimens are, however, very imperfect, and further, discoveries 

 may render some modifications of the descriptions of these two remarkable 

 cephalopods necessary. 



The dorso-ventral diameter of one of these specimens next to the 

 chamber of habitation is 9 lines ; lateral diameter 6 lines ; dorso-venti-al 

 diameter of the siphuncle in the same specimen 4 lines ; lateral diameter 

 3 lines. 



Locality and Formation. — Point L^vis ; limestone of the Quebec 

 group. 



Collectors.— R. Bell, T. C. Weston. 



DiKELOCEPHALUS DbVINEI. (N. Sp.) 



Fig. 180. 



Pig. 181. 



Pig. 180. — Dikelocephalus Devinei. The glabella. 



181. — Pygidium supposed to belong to this species. 



Description. — Head large, moderately convex, and apparently with a 

 flat margin, the width of which has not been ascertained. Glabella oblong, 

 convex, its outhne on a side view uniformly arched from the front, back- 

 wards, to about the mid-length, then nearly straight ; sides straight and 

 converging towards the front, which is also nearly straight, or gently 

 convex, and about one-fourth narrower than the base ; neck furrow wide, 

 but somewhat obscure, deepest on each side of the middle, a little turned 

 forwards at the ends, which do not quite reach the dorsal furrows ; 

 posterior glabellar furrows, with their anterior extremities, just behind the 

 mid-length, directed obliquely backwards and inwards at an angle of 45° ; 

 two anterior pairs of furrows, all very obscure ; neck segment wide, 



