286 PROCEEDINGS OF THE ACADEMY OF [March, 



THE VARIATIONS OF EUTSINIA IN THE PACIFIC SUBREGION, 



BY ARTHUR ERWIN BROWN, 



The portion of the Pacific coast of North America occupied by the 

 garter snakes extends from about latitude 50° in British Columbia 

 to the neighborhood of 33° in southern California/ and exhibits great 

 variety of soil and climate, especially in the extremes of dryness and 

 humidity. The annual rainfall at Puget Sound has reached a hundred 

 and thirty inches, while at Yuma, in southeastern California, the aver- 

 age is little more than three. Under these circumstances, and having 

 in mind the ease with which color in reptiles is acted upon by external 

 conditions, of which there is reason to believe that moisture is one of 

 the most active, it is not surprising that color variation should reach 

 a maximum in a group of snakes which, through diversity of habit, 

 occupy practically every station open to their kind. Many species 

 and subspecies have been established from this region upon examples 

 so few in number as to form an altogether inadequate foundation in 

 a genus where the range of variation is as great as it is known to be 

 in Eutcenio — or is known, at least, to all but those naturalists who 

 estabhsh uniformity by the easy process of attaching a name to every 

 difference, without regard to its nature or its biological significance. 



Efforts to bring these supposed forms into some sort of order have 

 been made in late years by Mr. G. A. Boulenger,^ Mr. John Van Den- 

 burgh^ and the present writer,'* but it must be admitted that the assign- 

 ment of some intermediates has been accomplished in part b}" the exer- 

 cise of that mode of judgment which has been termed "the naturalist's 

 instinct." Some material now in my possession bears directly upon 

 the questions of identity involved in E. elegans and E. infernalis, 

 and their interesting character has led me to review all the garter 

 snakes of the region in question. 



The list following contains the names of all the species and subspe- 

 cies within my knowledge, with the date of establishment and the 



^ Eutwnia eques Reuss. has been found in the peninsula of Lower California, 

 and others may yet be taken in tliat little-known region. 



^ Catalogue of Snakes in British Museum, Vol. I, p. 192, et seq. (1893). 



^ Occasional Papers California Academy of Sciences, V, p. -199, et seq. (1S97). 



* Proceedings Academy of Natural Sciences of Philadelphia, 1901, p. 18, et seq. 



