PROVINCIAL MUSEUM HALIFAX, N. S. PERKINS. 161 



ington, for the same purpose. Here Dr. True was most help- 

 ful, as has already been noted. A series of photographs of the 

 periotic of the Vermont specimen was examined by him, and 

 he reports as follows : " The periotic of D. vermontanus appears 

 to indicate that the species is distinct from leucas. The prin- 

 cipal differences are that in the former the petrosal is larger, 

 the poms acusticus interims also larger and differently shaped, 

 the posterior process of the petrous portion much longer and 

 more pointed, the anterior process more rounded, the fenestra 

 cochleae larger. I cannot see that the vertebrae of vermontanus 

 present any tangible differences of importance. The neural 

 arch of the axis appears to be differently shaped, but this is 

 probably due to its imperfect condition. The vertical .foramina 

 in the sides of the centra of the caudals appear smaller, but 

 there is considerable variation in this character. The coracoid 

 process of the scapula is narrow at the end, but this is also 

 variable. I think the ulna is straighter. It is really necessary 

 in identifying such material to exami'ne the SDecimens them- 

 selves." 



As to what Dr. True notices in respect to the neural arch of 

 the axis, it may be well to say that this vertebra in the Vermont 

 specimen does not seem to have been broken to any such extent 

 as to change its form, especially that of the upper border of the 

 spine, from that of D. leucas to that which it now has. 

 In all specimens of the recent species which I have seen, the 

 upper portion of the spine slopes rapidly from back down to the 

 front, while in D. vermontanus it is nearly horizontal, that is, 

 it has little slant from the back to the front edge. 



The hyoid, too, is much more cylindrical in the thyrohyal 

 portion. Of course it may be said that most or all of these 

 characters are subject to individual variation in the cetacea, but 

 allowing for this it seems probable that some at least of these 

 characters are constant and may be regarded as at least varietal 

 if 'not specific. It appears, then, that Thompson was justified 

 in establishing the species vermontanus. 



