62 



wolf extends throughout the northern hemisphere ; the same may be 

 said of the fox, the ermine, and, perhaps, of the beaver. It is not 

 improbable that our buffalo {Bos americanus) is a variety only of the B. 

 bison of the Old World, and that the grizzly bear ( Ursus horribilis) bears 

 the same relation to the European brown bear {U. arctos). There are 

 also certain corresponding or representative species ; thus, our red fox 

 {Vulpesfulvus) is nearly related to the European fox (F. vulgaris), and 

 the red squirrel {scnirus hudsonicus) to the S. vulgaris of Europe. The 

 elk and moose {Cervus canadensis and Alces americanus) respectively 

 answer to the C. elaphus and Alces europaeus. 



The majority of American deer belong to a peculiar group {Cariacus) 

 mainly characteristic of the Nearctic realm ; while the species of the 

 orders Eodentia and Insectivora are mostly of characteristically distinct 

 species or higher groups. 



Among birds, similar relations prevail. The singing-birds are the 

 most characteristic of any continent, and here we find in North America 

 the greatest number of species, genera, and families of birds which 

 ditt'er from those of the Old World. Of the latter, true thrushes, swal- 

 lows, shrikes, and crows occur, but in limited numbers ; while the genera 

 of finches are mostly distinct, and the vireos, tanagers, w^ood-warblers, 

 Icteridae, and mock-thrushes, which form the bulk of our avifauna, do 

 not exist in the Old World. On the other hand, starlings, flycatchers, 

 and warblers are absent from North America. 



As we direct our observation to birds of extended flight, as the 

 Accipitres and water-birds, cases of identity of species of opposite con- 

 tinents become more frequent. This is mostly confined here, also, to 

 the northern regions. The marsh-hawk {Circus cyaneus), peregrine 

 falcon, fish-hawk, and golden eagle are examples among Falconidae. 

 Among owls, the cases are still more numerous ; such are Nyctea nivea, 

 Surnia ulula, Otus brachyotus, Strix Jlammea. Some of these present 

 geographical varieties. Corresponding species are common here, e. g., 

 the American — 



Haliaetus leucocephalus to H. albicilla of Europe ; 

 Buteo swainsonii to B. vulgaris ; 

 Falco sparverius to F. tinnunculus ; 

 Falco columbarium to F. aesalon; 

 Bubo virginianus to B. maximus ; 

 Otus vilsonianus to 0. vulgaris ; 

 etc., etc. 



