1922] Schmidt, Amphibians and Reptiles of Lower California 619 



talus, Thanmophis megalops, Crotalus atrox atrox, Crotalus mitchellii, and 

 Crotalus cerastes. Nine more have been recorded from the Cape dis- 

 trict but are as yet unknown from the Colorado Desert district in Lower 

 California: Bufo punctatus, Phyllodactylus tuberculosus, Crotaphytus 

 wislizenii, Sauromalus obesus, Siagonodon humilis, Chilomeniscus ephip- 

 picus, Chilomeniscus cinctus, Sonora episcopa, and Salvadora hexalepis. 

 Eleven species remain unrecorded from this area in Lower California, 

 most of which may be expected as additions to its fauna in the future: 

 Bufo cognatus cognatus, Bufo alvarius, Bufo woodhousii, Rana pipiens, 

 Phrynosoma ?n , callii, Thamnophis marcianus, Sonora occipitalis, Lampro- 

 peltis getulus boylii, Arizona elegans, Testudo agassizii and Kinosternon 

 sonoriense. 



The occurrence of Xantusia vigilis at San Matias Pass, where it is 

 associated with a species of tree yucca as in the Mohave Desert, indicates 

 a more or less distinct fauna bordering the Colorado Desert district in 

 Lower California on the eastern slopes of the San Pedro Martir Moun- 

 tains. The distribution of Uta mearnsi has been mentioned above. The 

 peculiar case of Phrynosoma solare, which is absent in California and re- 

 appears at Las Animas Bay, Lower California, a third of the distance 

 down the Gulf side of the peninsula, seems to indicate a somewhat recent 

 "invasion" of the Colorado Desert into a less arid area. Unfortunately, 

 the eastern escarpment of the Sierra Juarez and San Pedro Martir is so 

 precipitous that there is little hope of tracing a continuous zone through 

 this area. 



The Vizcaino Desert district of Nelson's map occupies the area 

 between the three districts just discussed and the Cape district. It 

 should include, in my opinion, the Magdalena Plain. Its fauna is im- 

 perfectly known and this area quite certainly offers a most interesting 

 field for further herpetological exploration. 



In view of this lack of information, it is not possible to present a list 

 of the amphibians and reptiles of this area. Four species are character- 

 istic of and confined to it, as far as known : Callisaurus crinitus, Phryno- 

 soma jamesi, Cnemidophorus bartolomas, and Cnemidophorus rubidus. 



There is a "crossing over" of the Sonoran desert fauna in this area, 

 cutting off a remnant of the San Diegan fauna on Cedros Island. My 

 inference that the fauna of the Magdalena Plain is to be directly asso- 

 ciated with that of the Vizcaino Desert is based primarily on the distribu- 

 tion of Callisaurus crinitus, the close relations between Cnemidophorus 

 rubidus and C. bartolomas, and the presence of Verticaria hyperythra 

 beldingi. It would be of great interest to know whether Cnemidophorus 



