650 Bulletin American Museum of Natural History [Vol. XLVI 



If the above conclusions are correct, i.e., that a single subspecies of 

 C. ventralis extends from Yuma, Arizona, to La Paz, Lower California, it 

 seems preferable to introduce the name gabbii in spite of the very in- 

 adequate description of Cope in 1900. Cope had specimens from north- 

 ern Lower California (the type locality) before him, at least the National 

 Museum specimens above mentioned and probably also the original 

 specimens collected by Gabb on which his manuscript name in 1875 was 

 based. 



I do not find any characters in the type and paratype of C. carmenen- 

 sis which warrant its distinction from C. gabbii. 



In seventy-eight specimens from Tucson, I find a mean tail-length 

 of .54 of the total, and the length of the hind leg .86 of that of the body, 

 the average of femoral pores higher (17.4) and the proportion of speci- 

 mens with the occipital separated from the supraorbital semicircles a 

 minority, instead of a majority, as in the Lower Calif ornian series. 



Turning to the description of C. ventralis myurus (Richardson, 1915, 

 p. 408), I find that he has compared the proportionate tail-length in 

 myurus from Pyramid Lake, Nevada, with the tail-length of a series of 

 ventralis from Yuma, Arizona, and San Diego County, California, with an 

 average of .55 for the former and .58 for the latter. (I have transposed 

 his figures for body/tail to tail/body and tail, for comparison with mine.) 

 It will be seen that the Yuma specimens agree with the Lower Calif ornian 

 ones, while myurus has a tail of practically the same length as Tucson 

 ventralis, from which it is distinguished, therefore, chiefly by the lower 

 number of femoral pores. As the type locality of ventralis is 

 "New Mexico west of the Rio Grande" (including Arizona in 1852), I 

 believe I am justified in regarding the Tucson specimens as typical 

 ventralis, distinct from the form at Yuma. 



Additional evidence on this question is furnished by the character 

 of the occipital, which may be more or less broadly in contact with the 

 supraorbitals or separated from them by a row of scales. In our series 

 of C. v. gabbii as above defined, twelve specimens have the supraorbitals 

 in contact with the occipital and forty-three have an intercalated row of 

 scales. In the seventy specimens examined from Tucson, the proportions 

 are reversed, fifty-one specimens having the supraorbitals and occipital 

 in contact, while nineteen have them separated. Dr. Stejneger has 

 kindly examined a series of specimens in the National Museum from west 

 of the mouth of the Colorado River in this respect, and states that out of 

 fifty-seven specimens, seventeen have the supraorbitals and the occipital 

 in contact, six have them in contact on one side, separated on the other, 



