MAMMALIA. 443 



even a first and a fifth, where now there is no trace of either. 

 Here belong also the ass, the zebra and the tapir. 



Suborder (c) Proboscidca (with proboscis). Two living 

 and many extinct species of huge Placentalia with five digits, 

 each with a distinct hoof. The nose is much developed into 

 a prehensile organ, with corresponding changes in the skull 

 for attachment of muscles. The upper incisors grow enor- 

 mously, forming the tusks characteristic of the group. No 

 canines; molars very complex. Two thoracic teats. The 

 largest of the land mammals, the elephants and the extinct 

 mastodon and mammoth, belong here. They are now con- 

 fined to the tropical regions of Asia and Africa, though in 

 geological times they seem to have had a world-wide range. 

 The tusks of species of elephants, both living and extinct, fur- 

 nish the ivory of commerce. 



Order 5. Carnivora (flesh-eaters). The Carnivora are 

 four- or five-toed animajs with the digits ending in claws. The 

 canines are well developed, strong and curved. The other 

 teeth are often pointed and adapted to holding or tearing. 

 Muscles of mastication are especially well developed. Mammae 

 are numerous, occurring along the entire abdomen. There are 

 two types of Carnivora terrestrial and marine. To the first 

 belong the bear family, which is perhaps the least specialized 

 group; the dog family, including dogs, wolves, foxes, jackals; 

 the cat family, including lions, tigers, leopards ; many fur- 

 bearing animals as otters, weasels, minks, martens, etc. 

 The seals and walruses belong to the marine group. In these 

 forms the appendages have become adapted to the water habit, 

 the digits bearing intervening webs. The order embraces 

 many very powerful and intelligent animals which are well 

 adapted to win in the struggle for life, if it were not for human 

 interference. In the presence of man, however, all those which 

 are not suited to domestication are gradually disappearing; 

 some because of their dangerous qualities, others because of 

 the value of their products. The group is not used to any 

 considerable extent as food. 



