136 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th See. 



of the eastern states, and parietalis, of the western, intergrade. 

 It is upon their authority that trinomials are used here. Inter- 

 gradation, it seems, occurs chiefly in the vicinity of the ninety- 

 fifth (90° to 100°) Meridian. Thamnophis sirtalis parietalis 

 ranges west from this area of intergradation. The snakes of 

 the northwest coast of Oregon and Washington have been 

 recognized by many authors as a distinct race, under the names 

 Thamnophis parietalis pickeringii or, more properly, Tham- 

 nophis sirtalis concinnns. 



Several names have been based upon individuals of these 

 races. Thus, parietalis was originally described by Say in 1823 

 from material collected at Camp Missouri near Council Blufif. 

 Blainville's Coluber infernalis, 1835, from California, is based 

 upon a garter-snake belonging to this group, and Cope's 

 Eiitcenia sirtalis tetratcsnia, from Pitt River, California, also is. 

 Hallowell's type of concinnus (1852) was from Oregon Terri- 

 tory. It represented the dark northwest-coast form which 

 Baird and Girard soon afterwards (1853) named Eutainia 

 pickeringii from material secured at Puget Sound. Cope, in 

 1892, proposed the name E. sirtalis trilineata for specimens 

 from Port Townsend, Oregon, and Fort Benton, Montana. 



General Discussion 



While the northwestern coastal snakes thus were distin- 

 guished from parietalis at an early date, and have since been re- 

 corded by most authors under a different name, no one has 

 claimed that these two races showed any distinctive characters 

 other than those of coloration. Ruthven states that "there is 

 no character which will constantly distinguish specimens of 

 concimms from parietalis. The narrow dorsal stripe and lateral 

 interspaces of the former will usually do so, but these may be 

 exactly as in parietalis. Still, the fact that nearly all specimens 

 from Washington and northern Oregon, west of the Cascade 

 Range, are characterized by a marked predominance of black 

 pigment and a narrow dorsal stripe justifies their recognition 

 as a separate form." This was the opinion reached as the result 

 of earlier studies set forth in "The Reptiles of the Pacific Coast 

 and Great Basin," and now, with nearly 400 of these snakes 

 before us, this opinion is unchanged. Although there is much 

 variation in the amount of dark pigment and in the width of 



