in SPECIAL ADAPTATIONS 185 



themselves to such an explanation. The 

 fish-like form of the whole creature the 

 provision of an enormous mass of oily 

 fat, called blubber, completely enveloping 

 the internal organs, for the double pur- 

 pose of protecting from cold those organs 

 which are dependent on a warm Mam- 

 malian blood, and of so adjusting the 

 specific gravity of the whole creature as 

 to facilitate flotation on the surface of 

 the ocean, where alone respiration can 

 be effected by the Mammalian lung the 

 development of a caudal appendage which 

 does not represent the Mammalian tail, 

 but is constructed on an entirely different 

 type the assigning to that tail a function 

 which it never serves in the Mammalia 

 that of propulsion in the medium which 

 is its habitat all these, together with 

 the baleen in the mouth, constitute an 

 assemblage of characters departing so 

 widely from the whole Mammalian class, 



