REPTILES OF THE PACIFIC COAST. 199 



Distribution. — The Desert Gopher Snake occupies the 

 Mojave and Colorado Deserts and those parts of the 

 Great Basin which lie within California, Nevada, and 

 perhaps southern Idaho and eastern Oregon. 



Habits. — Unknown, but similar, doubtless, to those of 

 P. catenifev. 



Genus 36. THAMNOPHIS. 



ThamnophiA, Fitzinoer, Syst. Kept., 1843, p. 26 (type saurita); 

 Eulainia, B. & G., Cat. N. A. Kept., Pt. I, Serp., 1853, p. 24 

 (type saurita). 



The body is more or less elongate, usually rather 

 slender, with moderately long, tapering tail, and head 

 distinct from neck. The cephalic plates are normal. 

 The nasals never unite. One or two (rarely three) pre- 

 oculars, two to four postoculars, and a loreal are present. 

 Temporals are normally 1-2, but may be 1-1, 1-3, or 

 2-3. A loreal is present. The scales are keeled, in 

 seventeen to twenty-three rows. The anal plate is un- 

 divided. Urosteges are in two series. The eye is 

 moderate or small, with round pupil. 



Although the several species and subspecies may often 

 be distinguished at a glance by one familiar with their 

 several characters, the amount of individual variation 

 is so great that it is quite impossible to make a key 

 which will properly refer all specimens. The following 

 synopsis will, I believe, usually serve its purpose, but 

 should not be trusted too implicitly. 



SYNOPSIS OF SPECIES.^ 

 a. — Upper labials seven; posterior geneials much longer than anterior. 



* If ray estimate of the status of the various western members of this genus differs 

 rather radically from that of recect authors (the latest American review of this genus 

 admits seventeen species and subspecies from the territory under discussion), I may, 

 perhaps, be pardoned on the ground that I have carefully examined more than three 

 hundred fresh alcoholic specimens besides rather hastily inspecting the material in the 

 National Museum. 



