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Soutlierri Neotropical realms. But one mammal (the cougar, Felis con- 

 color), aud no reptiles, batracliians, nor fresh-water fishes, extend into 

 Brazil ; but a number of birds are permanent residents throughout both 

 realms. These are mostly waders, as follows : 



Ralhis crepitans. 

 Limosafedoa. 

 Tryngites rufescens. 

 Actiturus hartramius. 

 Heteroscelus hrevipes. 

 Symphemia semipalmata. . 

 Ereunetes petrificatus. 

 Aeglalitis vilsonius. 

 Xyctherodlus violacem. 



To these must be added the turkey-vulture, Caihartes aura. Then 

 certain marine birds and a few fishes extend along the coasts of both 

 regions, but their number is comparatively small. 



The number of species of the Nearctic realm which occur in the Mex- 

 ican region is rather greater. The red lynx and raccoon are examples 

 of mammals, and several species of wood-warblers, vireos, and hawks 

 represent the birds as far south as the Isthmus of Darien. The only 

 reptiles are the snapping-tortoise and the ringed snake OpMbolus dolia- 

 tvs ; the only batrachian is the Rana halecina herlandieri. A few other 

 species, as Eutaenia sirtalis, extend for a shorter distance into the same 

 region. 



In the higher groups of the genus and lamily, we have greater com- 

 munity with the Neotropical realm. But few genera of Batrachia aud 

 Eeptilia extend to its Brazilian region, but there are a few common 

 genera of Mammalia [Mephitis, Procyon, Ursus, Sciurtis, Hesperomys, and 

 Bidelpkys), and a number of birds, especially among the lower orders, and 

 the scansores, syndactyli, and clamatores, particularly the Tyrannidae. 

 The number of genera which enter Mexico and Central America is much 

 greater, and I select the following from the mammals, reptiles, and 

 batrachianS; as these are incapable of the migrations performed by birds. 

 '!j Cosmopolitan genera and those common to both the American realms 

 i are omitted. 

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