REVISION OF THE KING SNAKES. 83 



pies from western and southern California, and that these higher 

 averages are bridged by a gradual change, through central Arizona, 

 from yumensis in the south. (2) Proceeduig west from Tucson there 

 is an increase in number of ventrals to the average and approximate 

 extremes characteristic of hoylii west of the Sierras, while the number 

 of rings, already the same as the average for hoylii as soon as yumensis 

 was differentiated from splendida, remains the same. The break 

 from Yuma to San Diego County is slight. (3) North from here 

 there is a progi'essive decrease in number of ventrals and increase in 

 annuli to the vicinity of Los Angeles. Specimens from this region 

 are sometimes distinguishable on sight by the evidently more nu- 

 merous and narrower white bands — about one scale wide dorsally, 

 and three on the first row of scales. It seems probable that these 

 specimens are also more often brown than black, but all those we 

 have examined were preserved. It should also be mentioned here 

 that two examples from Santa Cataltna Island are strikingly charac- 

 teristic of those from the adjacent mainland — ^with a high number of 

 rings and a low number of ventrals. (4) The vicinity of Los Angeles 

 is doubtless west of the direct route of migration, as the normal 

 number of ventrals and rings is exhibited by specimens from 

 Kern County. (5) Thirty examples from the immediate vicinity of 

 San Francisco show that the form is characteristically developed 

 there, but leaves unexplained the high averages of the Fresno speci- 

 mens. (6) A small number of specimens from the vicinity of Shasta 

 County indicate that the tendency here is toward a decrease in 

 number of ventrals and an increase in rings (like Los Angeles speci- 

 mens). In fact, no specimen from here has even as many ventrals 

 as the average for San Francisco, while the lowest number found here 

 is not reached elsewhere in CaUfornia, except by a single aberrant 

 individual from San Diego County. 



The situation with respect to the labials is shown by figure 19. 

 This indicates that on the west coast there is a uniform decrease in 

 niunber of infralabials from south to north. In this there may be 

 some significance. The change from Ymna to San Diego County is 

 too slight to be very significaiit, but from this region northward a 

 distinct retrograde tendency is evident attaining in northern Cali- 

 fornia the 7-9 formula characteristic of the genus; southward there 

 is an increase in the lower series that seems to have become distinctive 

 in individuals from the Cape Region. Specimens from Arizona are 

 too few to indicate the tendency northward from the range of 

 yumensis. 



Further confirmation of the distinctness of the east section of 

 hoylii from the west is to be had by an examination of the pattern and 

 markings. Specimens from the east section retain the head markings 

 essentially as developed in yumensis. The white markings are 



