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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 points 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 (Cebidce) and the Marmosets (Hapalidce) ; the Chin- 

 chillas 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 Edentata. 

 The Opossums (Didelphyidce) are also very characteristic, though 

 not actually endemic, since they extend into the Nearctic region. 

 A single additional Marsupial (CcBnolestes) of uncertain affinities 

 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 (Opisthocomus), 

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

 the Nearctic Region, are a characteristic group. Boas, Rattle- 

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

 the fresh- water Fish are the Electric Eel (Gymnotus), and Lepido- 

 siren, one of the three existing genera of Dipnoi. 



The negative characteristics of this region are also very remark- 

 able. Except in Central America and the West Indies, there are 

 no Insectivora ; Civets, Oxen, Sheep, Antelopes, and true Swine 

 (Suince) are altogether absent, and there are very few species of 

 Deer ; Crows and Ravens are also practically unrepresented. 



In the West Indies there are no Edentata, Monkeys, or Car- 

 nivora, and there occurs a peculiar Insectivore, Solenodon, 

 belonging to the Centetidae, otherwise found only in Madagascar. 

 The Galapagos Archipelago, a group of oceanic islands, about 600 

 miles to the west of the continent, has at the most two Mammals, 

 a Bat and a Mouse ; its Birds are very different from those of 

 the mainland, and include many endemic species ; and among the 

 Reptiles are the gigantic Tortoises (Testudo), of which different 

 species occur in the various islands, 



