63 



The Nearctic realm possesses a peculiar family, the Cathartidae 

 (turkey-buzzards), which the Old World lacks, but has no vultures 

 properly so-called. 



There are several wading-birds common to the two contineuts ; and 

 cases of identity among the ducks, gulls, and divers are relatively still 

 more numerous. The Gallinae are, on the other hand, entirely distinct, 

 though not without a few corresponding species. 



Among lower Vertebrata, specific identity is unknown, except in one 

 frog {Bana temporaria) and a few marine fishes, with one of fresh-water, 

 the northern pike {Esoa; Indus). The numerous tortoises of Korth 

 America remind one especially of Eastern Asia and India, but the 

 western regions of our continent are as deficient in this form of animal 

 life as the corresponding part of the Palaearctic region. Ghelydra is 

 peculiarly North American, and the Cinosternidae are Mexican in 

 character. 



The principal Crocodilian is our alligator, which presents only minor 

 differences from the South American caimans. The lizards are all 

 of Neotropical families, except the seines {Eumeces), which are found 

 elsewhere chiefly in Africa and Australia. The genera are nearly all 

 peculiar, or extend a short distance into the northern parts of the Neo- 

 tropical, Mexico, and the West Indies. Some families have, however, a 

 correspondence with those of the Old World, as follows : The Nearctic — 



Teiidae to Lacertidae ; 



Gerrhonotidae to Zonuridae; 



Iguanidae to Agamidae. 

 The Batracfiia present relations to the Europeo- Asiatic fauna in the 

 species of one genus {Rana) of frogs, and one genus (Roto'plithalmus) 

 of salamanders. In other respects, the Nearctic batrachiau fauna is 

 highly peculiar. The cosmopolitan genus Hyla (tree-frogs) exists in 

 numerous species, several of which are terrestrial. The burrowing-frogs 

 {ScapMopidae) are nearly all peculiar to this fauna. The toads are 

 of a peculiar division of the all but cosmopolitan genus Bufo. The 

 salamanders present the greatest i)eculiarities. The large family of 

 Plethodontidae is represented by various forms, mostly terrestrial ; while 

 the genei-a Desmognathus and Amhlystoma, each alone in its family, 

 present curious structural modifications. To the latter belong the Sire- 

 dons, or larval Aniblystomae, which reproduce without regard to their 

 metamorphosis, sometimes completing it and sometimes remaining 

 unchanged. 



