256 THE MAMMALIA. 



and, therefore, the whales may, in the widest 

 sense of the word, be classed with the primary 

 Hoofed Animals, which still possessed five toes and 

 differed as much, and even more, from the present 

 group as the primeval horses from the horses of 

 our day. 



The period when whales were most abundant 

 was that of the Middle Tertiary, when, as already 

 stated, the present Europe-Asiatic continent was 

 for the most part under water. Brandt gives a 

 very graphic description how the Cetacea of those 

 temperate zones may have ceased to exist with the 

 disappearance of that ancient ocean. And as the 

 account is of general importance we will quote his 

 words : * The dying out of marine animals appears 

 at first sight more strange than the dying out of 

 land animals. We are apt to imagine that the in- 

 habitants of the sea in their far-reaching element 

 animated everywhere more or less by living creatures 

 have a better opportunity of withdrawing from 

 such external influences as affected them injuriously, 

 without thereby experiencing a want of food, par- 

 ticularly if the hurtful changes were not sudden. 

 As an example of an earlier ocean of this kind, 

 extending from Western and Southern Europe to 

 Central Asia, we may take the immense ocean 



