534 University of California Publications in Zoology [Vol. 12 



back indistinct, brown; sides gray; a few scales surrounding darker 

 patches on back, bluish gray ; underparts whitish ; a broad light sub- 

 ocular stripe including six of the upper labials. 



No. 5541 has more red in the coloration of the sides, and the lighter 

 dorsal bands are flesh pink. Gray predominates in the dorsal colora- 

 tion, and the pink ground color becomes tawny on the posterior end 

 of the body. Distinct reddish brown bands on posterior third of 

 the body ; anteriorly each of these bands splits into three transverse 

 blotches, the outer two being small, and the middle one large as in 

 tigris. Belly white ; lateral edges of gastrosteges in median abdominal 

 region speckled with red and gray. Light area below eye, covering 

 five upper labials. No. 5544 is in the red phase. The coral red of the 

 top of the head and back almost obscures every other marking, but the 

 dorsal bands can be made out because of their darker shade, near rus- 

 set vinaceous. The pink color becomes yellowish near the tail; the 

 latter is marked by seven fairly distinct blackish bands which do not 

 meet below. The sides and top of the head are obscurely stippled with 

 gray. No light markings below or behind eye. In all three specimens 

 the sides of the head do not exhibit the postocular stripe common to 

 so many species of rattlesnakes (see Stejneger, 1895, pp. 423-424). 



Only the three pallid rattlesnakes taken were seen; two of these 

 were in a rocky wash at the Horn Mine, and one ( no. 5541 ) was beneath 

 a dead palo verde in a wash about a mile from the foot of the moun- 

 tains. The stomach of no. 5544 contained a Stephens canon mouse 

 (Peromyscus crinitus stephensi). Since this rodent is wholly noc- 

 turnal, the instance might be taken as showing nocturnal habits on the 

 part of the snake. 



Crotalus cerastes Hallowell 

 Sidewinder 



One horned rattlesnake (no. 5542) was captured in the drifting 

 sand near Blythe Junction. This specimen has the anterior and pos- 

 terior nasal plates divided on the right side and united on the left. 

 One internasal is present on each side. There are 13 superior and ]3 

 inferior labials, 143 gastrosteges, and 24 urosteges of which the pos- 

 terior four are divided. The total length to the base of the rattle is 

 504 millimeters, and the tail length 39 millimeters. There is a wart- 

 like growth on one side near the neck, consisting of eight elongated 

 scales arranged in rosette fashion. 



