XIV DISTRIBUTION 633 



total number of species, and in the very large proportion of endemic 

 species. The islands have evidently been peopled by waifs and 

 strays from other lands, at periods so remote that most of the 

 immigrants have assumed the character of distinct species, 

 or even, especially in the isolated Sandwich Islands, of distinct 

 genera. 



On the whole, the affinities of the Polynesian fauna are dis- 

 tinctly Australian ; they present, however, certain American char- 

 acteristics, especially in the occurrence of Lizards, belonging to the 

 American family of the Iguanidse, in Fiji. Amongst the most 

 notable endemic forms are the Dodo-like Pigeon, Didunculus, in 

 Samoa ; the Kagu ( Bhinochetus), a remai'kable genus of Grallse, in 

 New Caledonia, and the Brepajiidw, a family of Passerines allied 

 to the American Greenlets, in the Sandwich Islands. Polynesia 

 cannot be said to form a well-defined region, the islands composing 

 it being united largely on the ground of convenience. 



In the Neotropical Region we have once more an immense 

 tract of land, presenting such well-defined faunal characteristics as 

 make it one of the best-marked of all the zoo-geographical regions. 

 And this in spite of the fact that it is in free connection with the 

 Nearctic region, the two being separated by an ill-defined tran- 

 sition-region formed by the northern part of Mexico. The Neo- 

 tropical region includes, therefore, the tropical part of North 

 America, as well as the whole South American Continent, the 

 Antilles or West Indies, the Galapagos Islands, the Falkland 

 Islands, and Juan Fernandez. Both geological and zoological 

 evidence point to a complete separation of the two Americas 

 during the Miocene and Pliocene periods. 



The endemic animals of the region are very numerous and 

 characteristic. They include, among Mammalia, the Prehensile- 

 tailed Monkeys {Gehidce) and the Marmosets {Hapalidce) ; the 

 Chinchillas and Cavies, two peculiar families of Rodents ; 

 the Jaguar ; the Llamas, and Peccaries, and a species of Tapir ; the 

 Sloths, Armadillos and Ant-eaters — three entire families of Eden- 

 tata. The Opossums {Didelphyidm) are also very characteristip, 

 though not actually endemic since they extend into the Nearctic 

 region. A single Diprotodont Marsupial (Ccenolestes) has been 

 found in the extreme south. Among Birds the chief endemic 

 forms are the three species of Rhea, constituting the entire order 

 Rhese; the Tinamous, forming the order Crypturi;the Toucans, 

 Screamers, Oil-bird (Steatornis), Hoatzin (Opisthoconuis), and 

 many others. The Humming-birds, although extending into the 

 Nearctic Region, are a characteristic group. Boas, Rattlesnakes, 

 Iguanas, Crocodiles, and Caimans are abundant, and among the 

 fresh-water Fish are the Electric Eel (Gymnohis), and Lepidosiren, 

 one of the three existing genera of Dipnoi. 



