VARIATIONS OF GARTER-SNAKES. 195 



produce dwarfing in the larger forms, such as radix, . elegans, and 

 megalops. In selecting material for such work, however, the appa- 

 ently more variable forms of the Radix and Elegans groups should 

 be chosen in preference to the less variable ones of the Sirtalis or 

 Sauritus groups. Properly handled, these snakes should furnish 

 the best material not only for the investigation of the problems 

 peculiar to the order, but also for the study of general problems of 

 heredity and evolution. 



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