WHITEAVES.] FOSSILS OF TRIASSIC ROOKS OF BRITISH COLUMBIA. 149 



AuLAoocERAS Carlottense, Whiteaves. 



Plate 19, fig. 6. 



Autacoceras Carlottense, AVhiteaves. — 1887. Dawson, Kep. Geol. Exam. N. part 

 Vane. I., &c. ; in Ann. Rep. Geol. Surv. Can. for 

 1886, p. 109 B. 



Guard elongated, in the more perfect though smaller of the only 

 two specimens collected, which may therefore be i-egarded as the type 

 of the species, narrowly conical and increasing very slowly in thick- 

 ness from the acutely pointed posterior end, whose apex is slightly 

 excentric; in the larger but less perfect example comparatively thick, 

 somewhat fusiform and bluntly pointed posteriorly, with the apex 

 distinctlj' excentric. Alveolus and jjbragmocone unknown. Outer 

 surface mai'ked by close-set, rounded, longitudinal ribs, which are 

 sej)ai-ated from each other by narrow but deep linear furrows. 



In 1878 six badly preserved specimens of the guards of one or more 

 sjjecies of Belemnites were collected by Dr. G. M. Dawson at Houston 

 Stewart Channel, in the Queen Charlotte Islands. Of these, the two 

 desciibed above are both longitudinally ribbed on the outside and 

 apparently belong to the genus Aulacoceras of Hauer. The smaller of 

 the two is a natural longitudinal section of the guard, about two 

 inches in length and not quite half an inch broad at the thickest end, 

 while the larger, which is only a badly preserved natural mould or 

 imj)ression of one side of a large specimen of the guard with part of 

 the test preserved at the j)osterior end, but which shows clearly one 

 of the lateral grooves as well as several of the longitudinal ribs that 

 are said to be characteristic of the genus, is nearlj^ five inches in 

 length and fully an inch and a half broad in the thickest part. Of 

 the other foui- specimens two are mere fragments which cannot be 

 determined either generieally or specifically, one being a very slender 

 guard about two inches and a half long and not quite a quarter of an 

 inch broad at the thicker end, whose surface markings are not pre- 

 served, while the other is a piece of the posterior or pointed end of the 

 guard of a small individual, about an inch and a quarter long and a 

 quarter of an inch broad at the thicker end, whose surface appears to 

 be perfectly smooth. 



