VOL.X] 



VAN DENBURGH— VARIATION IN GOPHER-SNAKES 



Fig. 2 



upper curve (1) represents the counts in the snakes we called 

 P. catenifer catenifer, the middle curve (2) those for P. caten- 

 ifer annectens, and the lower curve (3) the same counts for P. 

 vertebralis. That there is a very real difference between the 

 first group and the others is evident. 



Turning now to a consideration of ^he number of dorsal 

 blotches between the head and tail (at a point over the anus), 

 we find that the snakes which have fewer gastrosteges are not 

 all alike. Those from near the coast have more blotches than 

 those from the interior. The same is true of the snakes with 

 more numerous gastrosteges. The coast snakes have more 

 numerous blotches than those from the interior. Figure 3 

 shows the number of blotches on the body in gopher-snakes 

 from several geographical areas. The upper two curves (1 

 and 2) represent the snakes with fewer gastrosteges, which we 

 called Pituophis catenifer cataiifer. It will be seen that there 

 is a marked difference between these two curves. The upper 

 curve (1) represents the snakes from the coast valleys and 

 ranges from Oregon to Santa Barbara County, California. 

 The second curve (2) shows the number of blotches in the 

 snakes of this group from the Klamath-Modoc region, the 

 Sacramento Valley, the western slope of the Sierra Nevada, 



