1903] Description of a species of Cardioceras. 67 



Shell, at least in its immature stag"e, compressed, shallowly 

 and rather widely umbilicated, with a small and minutely crenu- 

 lated keel. Whorls about five, increasing rather rapidly in size 

 and rather strongly embracing, about one-half of the sides 

 of the inner ones being covered by the overlap of those that 

 succeed them. Umbilicus occupying about one-third of the entire 

 diameter, on each side, though its margin is rounded and very 

 indistinctly defined ; peripheral carina neither very prominent nor 

 distinctly compressed. 



Surface of each side of the outer volution marked with a few 

 comparatively large and distant but narrow and acute primary 

 radiating ribs, that commence at the suture and terminate about 

 half way across, in a small pointed tubercle. Of these ribs there 

 are about ten in the specimen figured. Besides them there are 

 rather more than twice as many small short secondary ribs, that 

 are little more than narrow, transversely elongated, compressed 

 and acute tubercles, on the outer half of each side. The primary 

 ribs almost bifurcate from a median tubercle, and seem to occa- 

 sionally alternate with an intercalated secondary rib, but the 

 secondary ribs are not quite continuous with any of the primaries. 

 Between the secondary ribs, also, and parallel to them, there are 

 a few fine radiating raised lines. 



Sutural line unknown, as are also the exact shape and sculp- 

 ture of the adult, and the contour of the outer lip. 



Judging by Meek and Hayden's figures, specimens of C cordi- 

 fonne of about the same size as the fossil collected by Mr. Mc- 

 Evoy, have much smaller and more numerous radiating ribs, that 

 are devoid of tubercles. 



The discovery of a species of Cardioceras in the Crows 

 Nest Coal fields is of considerable interest, as tending to show 

 that the grits m which it was found are probably of Jurassic age. 

 Associated with Cardioceras in these grits, there are fragments of 

 guards of a rather slender belemnite. 



Ottawa, June 6, 1Q03. 



