ASYMMETRY OF SKULL 



349 



anything to do with the 

 aquatic life is not so clear. 

 It also characterises the 

 Sirenia, more or less, and 

 the Otters ; l)ut, on the other 

 hand, the terrestrial Bears 

 show the same structure as 

 do also some Ungulates. It 

 must be borne in mind, too, 

 that the kidneys of foetal 

 ^\Ian are lobulated. 



The liver is a compact 

 organ not showing such lobu- 

 lation as is common, but not 

 universal, among mammals. 



The bones of Whales have 

 a somewhat loose structure, 

 and are much impregnated 5^ 

 with oil. In many features 

 the skeleton of Whales is 

 highly distinctive of the 

 order. 



The brain case is small 

 proportionately and rounded. 

 The " face " is therefore long, 

 and in some cases, especially 

 among the fossil forms of 

 riatanistidae, the rostrum 

 is extraordinarily elongated. 

 The asymmetry of the 

 Whale's skull is one of its 

 most reniarkaljle features ; 

 this, however, is entirely 

 limited to the Toothed 

 AVhales, and among them 

 is more pronounced in some 

 forms than in others. Thus 

 the Platanistidae and many 

 Ziphioids are not nearly so 

 asymmetrical as the Dol- 



