504 University of California Publications in Zoology [Vol. 12 



collected ; these comprise twenty species. Habit notes were recorded at 

 time of observation. The Turtle Mountain work was undertaken for 

 the purpose of studying a definite fauna in an arid locality, where 

 animal habitats are reduced nearly to simple topographical terms. 

 (See map, pi. 19.) 



All the specimens obtained have been added to the collection of the 

 California Museum of Vertebrate Zoology, and it is under the numbers 

 of this Museum that they are individually referred to in this paper. 

 To the Director of this institution, Dr. Joseph Grinnell, the writer 

 wishes here to express appreciation for criticism and general super- 

 vision during the preparation of the manuscript. 



The color names used in this paper are taken from Ridgway's 

 (1912) Color Standards and Color Nomenclature. 



The desert bordering the lower Colorado River, its tributaries and 

 distributaries, is not subject to the low winter temperatures prevalent 

 in other continental parts of the United States, and it seems reasonable 

 to suppose that this high winter (as well as summer) temperature 

 might account for the greater number of species of lizards in the 

 Colorado Desert than in the higher and colder Mohave Desert, the 

 more enclosed and colder Death Valley region, and the plateaus of 

 Nevada and Utah, farther north. Certainly the climate of the regions 

 mentioned appeal's to differ in no other decided respect than in winter 

 temperature, and this makes it seem likely that the latter must be 

 reckoned as an important control in the distribution of saurians. 

 Climatic characteristics of the Colorado Valley are: moderate winter 

 and very high summer temperatures, during both night and day, 

 scanty and sporadic rainfall, very low relative humidity and much air 



CLIMATOLOGICAL TABLE 



(Compiled from Bulletins L and W, U. S. Weather Bureau) 



Altitude Mean annual Mean Mean 



(feet) rainfall annual Mean July 



above r~ ■ — K > temperature relative temperature 



Locality sea level inches from F.° humidity F." 



Yuma, Arizona 141 3.31 1S70-1007 



(57% 8 a.m.) 



" |36%8p.m.J yu " 



Parker, Arizona .... 375 4.12 1894-1907 71.0 92.5 



Needles, California 477 3.49 1892-1908* 73.0 94.0 



Mohave, California 2751 4.79 1877-1900 



Mammoth Tank, California 257 1.99 187S-1908 76.0 98.5 



(79% 8 a.m.) 



Los Angeles, California 293 15.86 1878-1909 60.3 \ C ,L \ 67.4 



D (64% 8 p.m. ( 



* There are at Needles only eleven days in the year on the average with .01 

 inches or more of rain. 



