1922] Schmidt, Amphibians and Reptiles of Lower California 615 



genera and species suggests a different and somewhat earlier stage in this 

 distributional process, Trimorphodon lyrophanes and Phrynosoma solare 

 being the best examples (see below) . 



Nelson (loc. cit., p. 117, PL xxxi) finds a division of the peninsula 

 into faunal districts, independent of the "life zones," useful in discussing 

 the fauna. The extent of his divisions is shown in the accompanying 

 copy of his map (Fig. 1). The San Diegan, the San Pedro Martir, and the 

 Colorado Desert districts at the north are continuous with faunally 

 similar areas in California. The Cape district, occupying nearly the 

 southern half of the peninsula, has by far the most distinct fauna. The 

 Vizcaino Desert, intermediate in position between the Colorado Desert 

 and San Diegan districts at the north and the Cape district at the south, 

 has an intermediate fauna, with a number of peculiar forms. In the 

 northward extension of the San Lucas fauna to nearly the middle of the 

 peninsula and the adoption of an intermediate district, these faunal sub- 

 divisions appear to present a distinct advance. Their agreement with 

 the distribution of the herpetological fauna can now be examined in 

 detail. 



The San Pedro Martir district of Nelson, coinciding very nearly 

 with the transitional zone, is characterized herpetologically by the ex- 

 treme poverty of its fauna. Sceloporusgraciosusvandenburgianus appears 

 to be confined to this area in Lower California, but otherwise it is scarcely 

 more than an impoverished appendage of the San Diegan fauna. This 

 area is therefore united with the San Diegan for the present discussion. 



The San Diegan and San Pedro Martir faunae, so far as recorded 

 from Lower California, consist of the following forty-three species. 



Amphibians 

 Plethodon croceater Bufo boreas halophilus 



Aneides lugubris lugubris Hyla regilla 



Bairachoseps attenuatus Hyla arenicolor 



Batrachoseps leucopus Rana aurora draytonii 



Scaphiopvs hammondii 



Reptiles 



Crotaphytus wislizenii *Lichanura roseofusca 

 Callisaurus ventralis gabbii Coluber flagellum piceus 



Sceloporus occidentalis bi-seriatus Coluber lateralis 



*Sceloporus graciosus vandenburgianus Salvadora hexalepis 



*Sceloporus rufidorsum Arizona elegans 

 *Sceloporus orcutti Pituophis catenifer rutilus 



*Uta mearnsi? * Pituophis catenifer annectens 



*Species confined, or nearly so, to the area discussed. 



