30 University of Michigan 



labials in two specimens and 8 in two. The infralabials are 9 

 in one and 8-9 in three. Three females have 173, 175 and 177 

 ventral plates, and one male has 169. The subcaudals are y2 

 and 79 in two females. Two females have a total length of 

 975 mm. and 870 mm., and a tail length of 216 mm. and 214 mm. 

 respectively. In every specimen the greatest head width in 

 the supraoccular region is one-half or a little more of the 

 distance from the end of the snout to the posterior end of the 

 parietal suture. The colors could not be determined accurately 

 as most of the specimens were about to shed when captured, 

 but they may be generally described as brownish olive above 

 and yellow beneath. In one brightly colored specimen the 

 ventral surface was pale orange yellow anteriorly, becoming 

 much paler posteriorly ; in the others the posterior part of the 

 abdomen and the tail are also orange yellow. 



The status of vetustum and flaviventris have not been sat- 

 isfactorily determined and our material is not sufficient to 

 throw much light on the cjuestion. It should be pointed out, 

 hoAvever, that in the apparently strong tendency to have less 

 than 17-15 scale rows, the Nevada specimens differ from 

 typical 5. constructor and from specimens of B. c. flavi- 

 ventris from the Great Plains region. It is probable also that 

 the head is slightly broader in B. c. vetustuin. 



This racer was found in numbers on a stony slope just be- 

 neath the northern peak of the Cortez Range, in an area about 

 one-fourth of a mile square. One specimen was taken and 

 another seen among the grass and bushes in the Humboldt 

 Valley, and one was taken on the margin of the valley and 

 mountain slopes. These observations indicate a wide range 

 of habitat. The individuals seen were very agile, and in the 

 mountains rushed away to the shelter of the rocks when 

 alarmed. 



