18. CNEMIDOPHORUS 533 



confirms these views, this name, C. cethio'ps (Cope), will 

 replace C. mel&nostethus. 



It is probable that future collections will show inter- 

 gradation of this race with typical C. t. tessellatus. However, 

 the specimen from Gunsight is a typical one with black 

 throat and chest, while typical C. t. tessellatus was secured at 

 Ajo, Pima County, only about 40 miles away. 



Habits. Ruthven remarks: "At Tucson C. melanoste- 

 thus is common and of general distribution on the Grease- 

 wood plains. It is also found on the mesas, but more abund- 

 antly in the Creosote bush association in the arroyos, and 

 much less commonly in the Suaharo-Ocotillo association of 

 the hills. Its food, as shown by an examination of stomach 

 contents, seems to consist of insects exclusively ants, beetles, 

 grasshoppers and spiders being recognizable. It is in turn, 

 according to our observations, preyed upon by the Arizona 

 Racer (Eascamon flagellum frenatum) and the Leopard 

 Lizard ( Crotaphytus wislizenii ) . " 



113. Cnemidophorus dickersonae Van Denburgh & Slevin 

 DICKERSON'S WHIPTAIL LIZARD 



Cnemidophorus dickersonte VAN DENBURGH & SLEVIN, Proc. Cal. Acad. 

 Sci., Ser. 4, Vol. XI, No. 6, 1921, p. 97 (type locality, Isla Partida 

 near Angel de la Guardia Island, Gulf of California, Mexico). 



Description. Body long, with a very slender tail and 

 very long legs. Nostrils in large anterior nasal plates, latter 

 in contact on top of snout. Posterior nasal forming sutures 

 with anterior nasal, first, second, and third labials, loreal, 

 prefrontal, and frontonasal plates. Loreal in contact with 

 third and fourth labials, first subocular, preocular, first 

 superciliary, prefrontal, posterior nasal, and usually first 

 supraocular plates. Four supraoculars, fourth smallest. 



