REPTILES OF THE PACIFIC COAST. 225 



Poui'teeii to seventeen superior and fourteen to eighteen 

 inferior labials, first pair of latter meeting in front of a 

 single pair of geneials. Three to five rows of scales 

 between supralabials and eye. Scales in twenty-five or 

 twenty-seven rows, keeled except sometimes in one or 

 two rows of each side. Gastrosteges varying from one 

 hundred and fifty-eight to one hundred and ninety- 

 eight. Urosteges seventeen to twenty-seven, a few of 

 the posterior sometimes divided. 



The general color is white, gray, yellow, vinaceous-cin- 

 namoii, or salmon-red, minutely dotted with black or 

 brown, and with a series of indefinite brown, black, or red 

 blotches along the back. These dots and dorsal blotches, 



as well as smaller blotches which sometimes are present 

 on the top of the head and on the sides, may be so faint 

 as to cause the animal to be called the White Rattle- 

 snake, or so dark as to produce a blackish effect; the 

 blotches, however, never have definite outlines, appear- 

 ing only as darker portions of the general " pepper and 

 salt " style of coloration. A dark band sometimes runs 

 down and back from the eye. The tail is gray, with 

 black cross-bars. The lower surfaces are white or yellow, 

 usually more or less clouded with brown. 



Leugth to amis 710 770 810 840 870 930 



Length of tail to rattle 6-2 74 72 60 71 90 



Distribution. — This rattlesnake has been found in the 

 Colorado Desert, near Mountain Springs, San Diego 



