RORQUALS 147 



ing table shows the numbers for a series of 

 individuals : 



B. muscuhts C. 7 D. 15 * L. 14 or 15 t Ca. 26. 



B. borcalis C. 7 D. 13 or 14 L. 13, 14, or 16 Ca. 19. 



B. rostrata C. 7 D. 1 1 L. 12 Ca. 17. 



B. sibbaldii C. 7 D. 1 5 L. 1 5 Ca. 28. 



It is the rule for the whales of this genus to 

 have all the cervical vertebrae free from each other, 

 not ankylosed in the typical whale fashion. But 

 occasionally two or three are partially fused. This 

 is described by Flower as occurring in B. rostrata. 

 Nor is this occasional peculiarity confined to the 

 species Rostrata. It has been mentioned as occurring 

 in B. borcalis. 



As to the number of vertebrae, it is noteworthy 

 that it bears some relation to the size of the 

 creatures. Thus the smallest species B. rostrata 

 has the smallest number of vertebrae, and the 

 largest species B. sibbaldii the largest number of 

 vertebrae. 



It is a feature of this genus for the first rib to be 

 bifid. This structural feature, as has been pointed 

 out, occurs in other Cetacea, and has been made use 

 of for systematic purposes. The late Professor van 

 Beneden, how r ever, observes that it is wrongly that 

 " zoologists have thought it their duty to attach a 

 certain importance to this arrangement, which is 

 purely individual." But it is very general. Thus 



k I have seen only 14 lumbars in a specimen at the British Museum, 

 but 15 on another, 

 t A sixteenth rib has been described (by Sir J. Struthers). 



