New Fossils from the Winnipeg Limestones. 395 



This species bear some resemblance to A. Bohemieum of 

 Barrande, particularly in size and in the general style of 

 its surface markings. The ribs or riblets of this Bohemian 

 species, however, are represented as finer and very much 

 more numerous. Thus, according to Lindstrom, in A. 

 Bohemieum there are as many as twenty-two riblets in a 

 length of five millimetres, and hence, presumably, forty- 

 four to a centimetre, but in the present species there are 

 only from seven to nine ribs to a centimetre. Among 

 Canadian species, A. costulatum would seem to be nearest to 

 A. Canadense, Billings, the type of Hyatt's genus Billing sites, 

 and hence may be referable to that genus. The surface 

 markings of A. Canadense, however, are still unknown, 

 or at least not preserved in any of the specimens in the 

 Museum of the Geological Survey. 



Cyrtoceras laticurvatum. (Nov. sp.) 



Shell large (attaining to a length of about twelve 

 inches, as measured along the convex and presumably 

 ventral curve), narrowly fusiform and broadest at a short 

 distance from the body chamber, elongated, slender, and 

 so much curved as to form a broad semi-circular arch, 

 which is straighter anteriorly than posteriorly: sides 

 compressed, the outline of a transverse section of the 

 broadest part being elliptical : body chamber compressed 

 cylindrical, more than twice as long as broad, and occupy- 

 ing about one- third of the entire length. 



Surface markings unknown, though there are indications 

 of faint longitudinal ribs on one of the casts. 



Longitudinal sections show that the septa (thirty- five 

 of which can be counted in one specimen) are strongly 

 concave and about seven or eight millimetres apart near the 

 body chamber, but much closer together at the posterior 

 end, also that the siphuncle is almost cylindrical, but 

 slightly contracted at the septa, exogastric and placed at 



