1916 1 Camp: Amphibians and Reptiles 533 



least three black cross-bars on the nape, and no. 5545 has a series of 

 lighter scales in regular transverse intervals down the back on the 

 anterior half of the body. Both specimens are heavily marked with 

 brown and red spots about the face, neck, and throat. 



The red racer seems to be the most generally distributed snake on 

 the Colorado Desert. It occurs on mountain and plain alike, and is 

 far swifter in movement than any other desert snake. The two present 

 examples were taken at the Horn Mine near a tent floor under which 

 they had apparently been living. 



Crotalus mitchellii (Cope) 

 Pallid Rattlesnake 



Three specimens (nos. 5540, 5541, 5544) of this desert species were 

 captured near the Horn Mine. In seutellation and coloration these 

 examples show departure from some of the typical characteristics of 

 mitchellii and seem to approach to a certain extent those of tigris. In 

 no. 5540 the rostral is in contact with the anterior nasals on both sides. 

 but on the left a small scale has started to split off from the nasal be- 

 tween the latter and the rostral. In the other two specimens the ros- 

 tral is separated from the anterior nasals by one row of three scales on 

 each side. Rostral higher than wide in no. 5540, equilateral in no. 

 5544, and wider than high in no. 5541. Scales on body all keeled ; in 

 23 rows in no. 5541, and in 25 rows on the other two specimens. Supra- 

 oculars striate and rugose. Three rows of scales between suborbital 

 chain and labials. Other characters as follows : 



Museum Number 5540 



Rows of scales between supra-oculars 7 



Superior labials 17 



Inferior labials 16 



Gastrosteges 179 



Urosteges 18t 



Total length (in millimeters) 653 



Tail length (in millimeters) 41 



t Last one divided. 



t First and last three divided. 



The color varies widely. In no. 5540 the transverse bands of 

 ground color are light pink, the muzzle greenish, the top of the head 

 pinkish yellow speckled with yellow, and the sides of the head gray 

 over the temporal region and corner of the mouth ; dark patches on 



