CHAP. XIV.] THE NEOTROPICAL REGION. 9 



highly specialized forms out of some ancestral swift-like tjrpe . 

 how complete and long continued the isolation of their birth- 

 place to have allowed of their modification and adaptation to 

 such divergent climates and conditions, yet never to have per- 

 mitted them to establish themselves in the other continents. 

 No naturalist can study in detail this single family of birds, 

 without being profoundly impressed with the vast antiquity ot 

 the South American continent, its long isolation from the rest of 

 the land surface of the globe, and the persistence through countless 

 ages of all the conditions requisite for the development and 

 increase of varied forms of animal life. 



Passing on to the parrot tribe, we find the peculiar family of the 

 Conuridae, of which the macaws are the highest development, very 

 largely represented. It is in the gallinaceous birds however that 

 we again meet with wholly isolated groups. The Cracidse, in- 

 cluding the curassows and guans, have no immediate relations 

 with any of the Old World families. Professor Huxley considers 

 them to approach nearest to (though still very remote from) the 

 Australian megapodes ; and here, as in the case of the marsu- 

 pials, we probably have divergent modifications of an ancient 

 type once widely distributed, not a direct communication between 

 the southern continents. The Tinaraidse or tinamous, point to a 

 still more remote antiquity, since their nearest allies are believed 

 to be the Struthiones or ostrich tribe, of which a few repre- 

 sentatives are scattered widely over the globe. The hoazin of 

 Guiana (Opisthocomus) is another isolated form, not only the 

 type of a family, but perhaps of an extinct order of birds. Pass- 

 ing on to the waders, we have a number of peculiar family types, 

 aU indicative of antiquity and isolation. The Cariama of the 

 plains of Brazil, a bird somewhat intermediate between a bustard 

 and a hawk, is one of these ; the elegant Psophia or trumpeter of 

 the Amazonian forests ; the beautiful little sun-bittern of the 

 river banks {Eurypyga) ; and the horned screamers (Palamedea), 

 all form distinct and isolated families of birds, to which the Old 

 World offers nothing directly comparable. 



Reptiles. — The Neotropical region is very rich in varied forms 

 of reptile life, and the species are very abundant. It has six 



