THE OTTAWA NATURALIST 



VOL. XXIII. OTTAWA, MAY, 1909 No. 2 



DESCRIPTION OF A NEW SPECIES OF AMMONITE OF 



THE GENUS STEPHEOCERAS, FROM SOME ROCKS 



OF PRESUMABLY JURASSIC AGE IN THE NICOLA 



VALLEY, B. C* 



By J. F. Whiteaves. 



The generic name Stepheoceras was proposed by Mr. S. S. 

 Buckman, in 1898, f for the Ammonites of the " Humphreys- 

 ianus-group " , which had previously been regarded as the most 

 typical section of Waagen's genus Stephanoceras. But, as Mr. 

 Buckman has pointed out, the latter name was "preoccupied % 

 when proposed by Waagen" in 1869, and "must lapse altogether 

 on account of prior use". Stepheoceras, as its author is careful to 

 say, is "only an alteration of the name Stephanoceras" , and per- 

 haps is not altogether free from objection on that account. Still, 

 the genus itself seems to be quite a natural one, and as such is 

 accepted as valid by Hyatt, in 1900, in his revision of the 

 Ammonoidea in the first volume of Eastman 's translation of 

 Zittel 's Text-book of Palaeontology. 



The type of Stepheoceras , which, so far as known, is an exclu- 

 sively Jurassic genus, is the Ammonites Humphreysianus of 

 Sowerby. In a well preserved specimen of that species, from 

 Dundry, in the Museum of the Geological Survey of Canada, 

 which is five inches and three-eighths in its maximum diameter, 

 there are at least six rounded and slender whorls; the ombilicus 

 is wide and open, exposing a considerable portion of each of the 

 inner whorls ; and the surface is marked with straight and trans- 

 verse ribs, which trifurcate from a tubercle on the middle of each 

 side. 



In 1876 Dr. G. M. Dawson made a collection of fossils from 



* Communicated by permission of the Director of the Geological 

 Survey of Canada. 



t Quarterly Journal of the Geological Society of London, vol. LIV, p. 

 454. 



I By Ehrenberg, in 1838, for a genus of Rotifera. 



