806 13. COLUBRIDJE 



Banos, Gadwall, Snelling), San Joaquin (Banta), Contra 

 Costa (Walnut Creek), Alameda (Berkeley), Santa Clara 

 (Palo Alto, Castro, San Jose, Uvas Creek), Santa Cruz 

 (Glenwood), Monterey (Pacific Grove, Seaside, Carmel, 

 Mt. Mars), San Luis Obispo (Edna), San Bernardino 

 (Ontario, Colton), Los Angeles (Los Angeles, Bixby), and 

 Riverside (Riverside) counties. 



The following localities are represented each by one 

 specimen. The material being so limited one cannot state 

 positively to which subspecies of sirtalis these specimens 

 should be referred, but it is probable that they belong here. 

 Willow Lake, Tehama County, Susanville, Lassen County, 

 and Fallen Leaf Lake, El Dorado County, California, and 

 Nixon, Washoe County, Nevada. 



It probably will prove to be impossible to draw any 

 very definite limits to the areas occupied by this form and 

 by T. sirtalis concinnus. This must be so, for one gradually 

 changes into the other. The area of intergradation is a 

 broad one, individual variation is great, and opinions may 

 easily differ as to geographical limits. Our own views are 

 expressed in the lists of localities given under each subspecies. 

 These indicate that to T. sirtalis concinnus are referred 

 snakes from Del Norte, Siskiyou, Shasta, Humboldt, Men- 

 docino, Sonoma, Napa, and Marin counties, while those from 

 elsewhere in California are regarded as T. sirtalis infernalis. 



Remarks. This subspecies differs from both T. sirtalis 

 parietalis and T. sirtalis concinnus in having a greater num- 

 ber of gastrosteges and urosteges. This is clearly shown 

 in the following table of average counts: 



