72 



The game-birds of the Central region are larger than those of the 

 Eastern. Such are the sage-cock, Centrocercus urophasianm ; the Pedi- 

 oecetcs jihasianellKS, or cock of the plains: the Tetrao obscurus ; several 

 I)tarmigan {Lar/oinis); and Bonasa ; the last three Palaearetic genera 

 also. 



The reptiles are not numerous, and tortoises are especially rare. 

 Besides the genera of lizards characteristic of the Eastern district, it 

 adds Phrynosoma, Crotaphytus, and Rolhroolia. Among snakes, no 

 genus is peculiar, and the moccasins and Flaps are wanting. There is 

 but one, possibly two, species of rattlesnake. Batrachians are few; 

 most of the genera of Anura are found, except Eyla. Among sala- 

 manders, the oul^- genus is Amhlystoma ; but this is abundant, its large 

 larvae de\"eloping in the temporary jiools of many arid regions. The 

 burrowing-frog, Spea homhi/rons, ranges the same region, and breeds in 

 much the same way. l^o genus of Batrachians or Beptiles is peculiar 

 to the Central region. 



Fishes are few in families and species, largely in consequence of the 

 poverty of the region in rivers and streams. In the Western Colorado 

 and tlie Humboldt, perch, pike, Siluridae, herring, cod, eels, gar, dog- 

 fish, and sturgeon are entirely wanting. Cyr>rinidae, Catostomidae, Sal- 

 monidar, and Cottidae are the only families abundant in individuals and 

 species. The same remarks apply in great part to the Columbia Eiver, 

 where, however, the Salmonidae have a great development. These sal- 

 mon are principally marine species, which ascend the river to deposit 

 their spawn. They belong to many species, all peculiar to the region, 

 and embrace incredible numbers of individuals. 



The Pacific region is nearly related to the Central, and, as it con- 

 sists of only the narrow district west of the Sierra Nevada, might be 

 regarded as a subdivision of it. It, however, lacks the mammalian 

 genera Bos and Antilocapra, and possesses certain peculiar genera of 

 birds, as Geococcyx (ground-cuckoo or chaparral-cock), Chamaea, and 

 Oreortyx (mountain-partridge). Of marine mammalia, there are several 

 peculiar types, as the eared seals {Otariidae) and sea-otter (Enhydra). 

 There are some genera of reptiles, e. g., Charina, related to the Boas, 

 Lodia, Anklla, Gerrhonotus, and Xantusia, which do not occur in the 

 Central subregion. There are three characteristic genera of Batrachia, 

 all salamanders, viz, Ana ides, Batraclioseps, and Bicamptodon ; while the 

 Eastern genera Plethodon and Biemyctylus re-appear after skipping the 

 entire Central district. The other types of Eastern Anura are found 

 here, there being two species of Hyla. 



