322 EVOLUTION AND ANIMAL LIFE 



of Africa, merging gradually northward into the north temper- 

 ate realm through the transition districts which border the 

 Mediterranean. It includes also Arabia, India, and the neigh- 

 boring 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 America. Some of these 

 (anthropoid apes) have much in common with man. To this 

 region belong the elephant, the rhinoceros, and the hippopot- 

 amus, as well as the tiger, lion, leopard, giraffe, the wild asses, 

 and horses of various species, besides a large number of rumi- 

 nant animals not found in other parts of the world. It is, in 

 fact, in the lower mammals and reptiles that its most striking 

 distinctive characters are found. In its fish fauna it has much 

 in common with South America. 



The Lemurian realm comprises Madagascar alone. It is 

 an isolated division of the Indo-African realm, but the presence 

 of many species of lemurs an unspecialized or primitive type 

 of monkey is held to justify its recognition as a distinct realm. 

 In most other groups of animals the fauna of Madagascar is 

 essentially that of neighboring parts of Africa. 



The Patagonian realm includes the south temperate zone 

 of South America. It has much in common with the neo- 

 tropical realm from which its fauna is mainly derived, but the 

 presence of frost is a barrier which vast numbers of species can- 

 not cross. Beyond the Patagonian realm lies the Antarctic 

 continent. The scanty fauna of this region is little known, 

 and it probably differs from the Patagonian fauna chiefly in 

 the absence of all but the ice-riding species. 



The Australian realm comprises Australia and neighboring 

 islands. It is more isolated than any of the others, having 

 been protected by the sea from the invasions of the character- 

 istic animals of the Indo-African and temperate realms. It 

 shows a singular persistence of low or primitive types of ver- 

 tebrate life, as though in the process of evolution the region 

 had been left a whole geologic age behind. If the competing 

 faunas of Africa and India could have been able to invade 

 Australia, the dominant mammals and birds of that region 



