Vol. X] VAN DENBURGH— VARIATION IN GOPHER-SNAKES 5 



The sixth curve, representing the snakes of Arizona, also 

 shows marked difference from all of the others of this group. 

 The number of blotches is much reduced and is similar to that 

 found in Pituophis vertehralis, shown in the seventh curve. It 

 would seem that the Arizona snakes also are entitled to sub- 

 specific rank. 



This leaves curves 4 and 5, which agree with each other and 

 with curve 2. Bearing in mind the fact that the snakes of 

 curve 2 {P. c. hcermanni) belong to the group having fewer 

 gastrosteges, it seems necessary to regard those represented by 

 curves 4 and 5 as deserving separate standing. 



It will be shown later that the snakes of Utah (curve 5) 

 differ from those represented by curve 4. For the latter, the 

 name P. catenifer deserticola would seem to be available. 



The number of blotches on the tail in these various races has 

 been charted in figure 4. The same differences and relation- 

 ships as are indicated by the blotches on the body are shown 

 by these data. 



Turning now to a consideration of the scale-rows we find that 

 the greatest number present on the body, although subject to 

 great individual variation, also shows geographic variation. 

 This is brought out in figure 5. Curves 1 and 2, representing 

 P. c. catenifer and P. c. heermanni, agree in showing 31 rows 

 as the most frequent number. The Ari^na specimens (curve 

 6) and those of P. c. amiectens (3), and P. c. deserticola (4) 

 agree, and show 33 as the most frequent number. P. verte- 

 hralis (curve 7) stands by itself in having 35 rows as the usual 

 number. At the other extreme stand the Utah (curve 5) speci- 

 mens, of which only 25 per cent have as many as 31 rows, while 

 the majority have only 29. These Utah snakes are thus quite 

 different from typical P. c. deserticola. 



In figure 6 are charted the number of urosteges in specimens 

 of these several races. Curves 1 and 3 are of interest as show- 

 ing that P. c. annectens (3) usually has more urosteges than 

 P. c. catenifer or any of the other races. Curve 4 indicates a 

 reduction in the number of urosteges in P. c. deserticola as com- 

 pared with Utah specimens and P. c. heermanni. 



In work upon groups such as this, where individual variation 

 is so great as almost to conceal geographic differences, I have 

 found that the latter may be thrown into greater relief by what 



