Vol. IX] 



VAW DENBURGH & SLEVIN— GOPHER-SNAKES 



201 



The transition from the number characteristic of the coast 

 snakes to that of the desert snakes is complete and more or 

 less gradual. Nevertheless, these counts are of great use in 

 the separation of the two subspecies. 



i r < T T~T i i i i I J i ; ■ I 1 : i : 1 ■ • i ■ ! i 



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The specimens which we have studied show gastrostege 

 counts ranging from 200 to 263. No sexual difference is ap- 

 parent in the counts. We believe that specimens having 

 fewer than 220 gastrosteges may, on that basis alone, be re- 

 ferred to Pifuophis catenifer catenifer, and that any specimen 

 with more than 231 gastrosteges may be considered to belong 

 to the other subspecies, which has been called Pifuophis sayi 

 bcllona or Pitiiophis catenifer deserticola, properly to be 

 known as Pitiiophis catenifer annectens (Baird & Girard). 



The tvpical specimens of Pitiiophis catenifer catenifer with 

 fewer than 220 gastrosteges are from northern California and 

 western Oregon. Specimens of Pitiiophis catenifer annectens 

 M'ith more than 231 gastrosteges have been found only in 

 southern California, northern Lower California, Arizona, 

 Nevada, and Utah. 



A large number of specimens have gastrostege counts vary- 

 ing from 220 to 231. Most of these are from central Cali- 

 fornia and the San Diegan Fauna. They represent geographic 

 intergradation and, to some extent, the extremes of individual 

 variation. A majority of the specimens with 220 to 225 gas- 

 trosteges are from the more northern localities and may be 

 referred to Pitiiophis catenifer catenifer. Most of those hav- 

 ing counts of 226 to 231 gastrosteges are from the range of 

 Pitiiophis catenifer annectens, and may be so called. 



On the accompanying map specimens having from 200 to 

 220 gastrosteges are indicated by round spots ; those having 

 from 231 to 263 by square spots; those with 221 to 225 by 

 half-round spots ; and those with from 226 to 230 gastrosteges 



