SNAKES OF THE GENUS PITUOPHIS 



87 



mainland specimens is the only differentiating character. It is possi- 

 ble, however, that ui a large series of specimens this character may 

 prove sufficiently constant to warrant the separation of the Cerros 

 specimens as a distinct subspecies. 



Some degree of sexual variation is evident in some of the char- 

 acters, which may be summarized as follows from an analysis of the 

 specimens examined: Dorsal scale formula varying from 29-31-23 to 

 32-35-25 in males and from 29-33-23 to 35-35-25 in females; ventrals 

 237 to 249 (average 242.3) m males and 238 to 262 (average 248.7) 

 in females; caudals 62 to 69 (average 64.7) in males, 51 to 67 (average 



13 



258 

 256 

 254 

 252 

 250 

 248 

 246 

 244 

 242 



240 

 238 

 236 



Region No. 1 2 3 4 5 6 7 



FiQUEE 44.— Geographic variation in number or ventrals in Pituophis oertebralis. 



61.1) m females; supralabials average 8.8 in males, 8.9 in females; 

 infralabials average 12.8 in males, 13.1 in females; postoculars average 

 3.3 in males, 3.5 in females; number of body spots averages 43.7 in 

 males, 45.1 in females; tail spots average 12.2 in males, 11.3 in females; 

 proportionate tad length averages 0.135 in males, 0.128 in females. 



Range. — This species ranges throughout Lower California, and as 

 far north in California as Jim Grey, San Bernardino County. It 

 occurs also on the outlying islands of Cerros, Margarita, andMagdalena. 



Specimens have been examined from the following localities: 



