CRT ACE A. 



767 



arterial blood in different parts of the body, may be asso- 

 ciated with the aquatic life. 



The cervical vertebrae are thin, and more or less fused. 

 There is no union of vertebrae to form a sacrum, for the 



FIG. 412. Left fore-limb of 

 BaZanoptera. 



Sc., Scapula with spine (.$/*.) ^* 

 humerus ; ./?., radius ; /., ulna ; 

 C., carpals embedded in matrix ; 

 Me., metacarpals; Pk.> phal- 

 anges. 



FIG. 413. Fore-limb 

 of whale (Megaptera 

 longimand]. After 

 Struthers. 



hind -limbs are at most very rudimentary. Under the 

 caudal vertebrae there are wedge-shaped chevron bones. 



The brain -case is almost spherical; the supraoccipital 

 meets the frontals and shuts out the parietals from the roof 

 of the skull ; the frontals arch over the orbit ; the snout or 

 rostrum of the skull is composed of premaxillae, maxillae, 



