GEOGRAPHICAL DISTRIBUTION OP ANIMALS 301 



is an essential unity of life over this vast area, and the rec- 

 ognition of North America as a separate (nearctic) realm, 

 which some writers have attempted, seems hardly practi- 

 cable. 



The Neotropical or South American realm includes 

 South America, the West Indies, the hot coast lands of 

 Mexico, and those parts of Florida and Texas where frost 

 does not occur. Its boundaries through Mexico are not 

 sharply denned, and there is much overlapping of the north 

 temperate realm along its northern limit. Its birds espe- 

 cially range widely through the United States in the sum- 

 mer migrations, and a large part of them find in the North 

 their breeding home. Southward, the broad barrier of the 

 two oceans keeps the South American fauna very distinct 

 from that of Africa or Australia. The neotropical fauna is 

 richest of all in species. The great forests of the Amazon 

 are the dreams of the naturalists. Characteristic types 

 among the larger animals are the snout or broad-nosed 

 (platyrrhine) monkeys, which in many ways are very distinct 

 from the monkeys and apes of the Old World. In many of 

 them the tip of the tail is highly specialized and is used as 

 a hand. The Edentates (armadillos, ant-eaters, etc.) are 

 characteristically South American, and there are many 

 peculiar types of birds, reptiles, fishes, and insects. 



The Indo-African realm corresponds to the neotropical 

 realm in position. It includes the greater part of Africa, 

 merging gradually northward into the north temperate 

 realm through the transition districts which border the 

 Mediterranean. It includes also Arabia, India, and the 

 neighboring islands, all that part of Asia south of the limit 

 of frost. In monkeys, carnivora, ungulates, and reptiles 

 this region is wonderfully rich. In variety of birds, fishes, 

 and insects the neotropical realm exceeds it. The monkeys 

 of this district are all of the narrow-nosed (catarrhine) 

 type, various forms being much more nearly related to 

 man than is the case with the peculiar monkeys of South 



