THE BALJiNOIDEA. 



337 



a. In the BaZmnoidea the nasal chambers communicate 

 with the exterior by two apertures, which are capable of being 

 shut at the will of the animal, and are called spiracles. These 

 are not connected with any saccular dilatations of the nasal 

 passages, situated between the skull and the integument. 



In the spinal column, no rib has a complete neck and capi- 

 tulum, the heads of even the most anterior ribs being united 



EQ 



Sta. IM.— Lateral and snperlor views of the skull of a foetal Whale (Salcma AusfraHt)j— 

 Thejugal bones are absent, and the ^ure does not sufficiently Indicate the outward 

 oarratnre of the ramus of the mandible (Mn.). 



1.5 



