900 The American Naturalist. [November, 
No genus of Batrachia is peculiar to it, and the following 
divisions are wanting: Proteida, Trachystomata, Amphiu- 
moida, and all Pseudosauria, except Amblystomide (one spe- 
cies). The genus Bufo is the only one that is well represented. 
The following genera of reptiles are peculiar to it: 
Uta, Anota, 
Uma, ; Lichanura, 
Sauromalus, Phyllorhynchus, 
Callisaurus, Chionactis, 
Dipsosaurus, Chilomeniscus. 
It shares the following genera with the Central American 
subregion of the Neotropical Realm only: 
Ctenosaura. 
Eublepharis (also in the Indian region). 
Phyllodactylus (also in the Columbian Neotropical). 
Heloderma. 
Hypsiglena. 
Salvadora. 
Rhinechis (also Holarctic of Eurasia). 
Trimorphodon 
Tantilla (also in Brazilian Neotropical). 
Cinosternum (also in Brazilian Neotropical). 
The following genera of the Sonoran subregion enter the 
Texan district of the Austroriparian subregion: 
Holbrookia, - Hypsiglena, 
Crotaphytus, | Rhinochilus, 
Phrynosoma, | Cinosternum. 
Gerrhonotus, 
Many species are peculiar to this subregion, as will be shown 
later on. . 
The Western subregion is distinguished by the absence of 
most of the types of fishes of the humid part of the continent, 
and the presence of afew. Thus, the Ginglymodi, Haleco- 
morphi and Catostomide are absent, while Percomorphi are 
present. The Batrachian fauna lacks the Proteida, Trachys- 
tomata and Amphiumoidea, while Pseudosauria are abundant, 
