MAMMALS 187 



animals of the world. The Blue Rorqual (Balaenoptera 

 sibbaldi), which reaches a length of over 80 fit., is the 

 largest living creature — recent or extinct. 



Before reviewing the principal Whales in order, a glance 

 at their general structure may be advisable. Even to-day 

 many educated persons find it difficult to accept the Whales 

 as mammals, since the wholly aquatic life has led them to 

 adopt a fish-like form that is best suited to rapid transit 

 in water. 



The average Whale's skeleton presents many unique 

 features. Though ponderous and heavy it is relatively 

 buoyant, being honeycombed with cells filled with oil. 

 The flippers, stripped of their flesh, are revealed as hands, 

 but the digits have an abnormal number of bones, rendering 

 them very flexible. When an otter or seal takes to the 

 water it will be seen that the hind limbs are held close 

 together in order to obviate resistance. The Whale, 

 abandoning this principle altogether, has practically dis- 

 pensed with them, only the vestigial thigh bones remaining 

 buried deep within the abdominal muscles. 



The skull is of unique shape and usually of immense 

 size, especially in the toothless whale-bone Whales, who 

 require enormous mouths with which to engulf the vast 

 quantities of small creatures on which they subsist. Whales 

 habitually spend considerable periods submerged, and since 

 the top of the head cuts the water first upon rising, the 

 nostrils are situated far up on the head resting just in 

 front of the eyes. In some species the external nasal 

 openings are paired, in others they are united. The bones 

 which go to make the bony tube of the typical mammalian 

 ear are in Whales modified to form a huge semi-globular 



