no. 2078. REPTILES OF NORTHWESTERN NEVADA— RICHARDSON. 409 



fuse to form cross bars. Tail lighter, with a greater admixture of 

 white. Fore legs lightly suffused with blue-gray; hind legs barred 

 and mottled with darker markings, with three definite bars on each 

 tibia. Posterior surface of each femur with one bhie-gray bar 

 extending across it longitudinally. Throat white, mottled with 

 gray; gular patch with a slight purple tinge. Belly and ventral 

 surface of legs, white; on each side of belly a long blue patch, crossed 

 obliquely by two triangular-shaped black bars, the posterior one 

 largest. Tail, underneath, white with three black spots near the 

 base and live black bands occupying a more distal position and 

 forming complete annuli. 



mm. 



Length of head 13 



Width of head 14 



Foreleg 39.5 



Hind leg 71 



Base of fifth to end of fourth toe 33 



Length, snout to anus 76.5 



Length of tail 92 



Ratio, length of body to tail . 831 



The Oallisaurus from the vicinity of Pyramid Lake, Nevada, pre- 

 sents some well marked deviations from the typical Oallisaurus cen- 

 tralis (Hallo well) which entitle it to a name. These differences 

 involve the ratio between the length of body (from snout to anus) and 

 tail, the number of femoral pores and the dorsal coloration. The 

 average ratio of body to tail in 45 individuals picked at random from 

 a large series compared with the same ratio in 30 specimens of typical 

 O. ventralis (22 from Yuma, Arizona, 6 from Fish Springs, and 2 from 

 Oak Grove, San Diego County, California), shows that this character 

 is very distinct. In Oallisaurus v. myurus, the ratios range from 0.727 

 to 0.864 with an average of 0.807, while in Oallisaurus ventralis the 

 range is from 0.678 to 0.826, the average 0.728. Females of both 

 forms are smaller than the males, but the ratios are the same. The 

 following table shows the variation of femoral pores in a number of 

 series. It will be seen that the range of variation and the average 

 number of femoral pores in the Nevada series are lower than in any 

 other except the one from Fairbank and Fort Lowell, Arizona, in 

 which the range of variation is smaller. The femoral pore counts for 

 the series from Tucson, Arizona, are taken from Ruthven (1907, pp. 

 518-523). In this series as in the series from Fairbank and Fort 

 Lowell, Arizona, the average number of pores on each thigh is greater 

 than in the others. 



