73 



A single species of tortoise {Chelopus marmoratus) exists in the Pacific 

 region. 



Tiie fresh-water fish-fauna is much like that of the Central district in 

 being poor in types. It adds the viviparous Pharyngognathi of the fam- 

 ily of Embiotocidac, which is represented by a number of species. The 

 marine fauna differs from that of the east coast in the great number 

 of species of Salmo and Sehastes and the variety of types of Cottidae. In 

 its northern regions, the genus Chirus and allies have their peculiar hab- 

 itat. The singular genus Blei)sias (related to Coitus) exists on the same 

 coast, and several valuable species of cods [Gadiis auratus, G. periscopus, 

 and Brachygadus minutus), with the peculiar form Bathymaster, belong 

 especially to the northern coasts. 



The So)ioran region is strongly marked among the faunae already de- 

 scribed. It is deficient in the species of ruminating Mammalia found 

 in the Central, and possesses a smaller number of species of mammals 

 than any of the others. Of birds, a few genera and several species are 

 different from those of the Central ; such are CalUpepla (partridge), Cich- 

 lopsis, Mitrephorus (Tyrannidae), Campylorliynchus, and Geococcyx. Most 

 of these genera occur in Mexico, and the last-named in California also. 

 I It is in Reptiles that the great peculiarity of this region appears. The 

 following genera are not found in any of the other regions described : 



Lizards. 



Heloderma. 

 Sauromalus. 

 Uma. 

 Coleonyx. 



Serpents. 



Gyalopium. 



Chionactis. 



Sonora. 



Bhinoehilits. 



Chilopoma. 



Eight other genera of Eeptilia are peculiar to this fauna and that of the 

 Lower Californian region, under which they are enumerated. Heloder- ■ 

 ma, Coleonyx, and allies of Gyalopium of the above list are more largely 

 developed in species and individuals in the Mexican region of the Neo- 

 tropical realm. Every one of the tive genera of serpents of the Sonoran 



