VARIATIONS OF GARTER-SNAKES. 6 



attains to a wider si<i:niii('aiu'o tliau it lias previously enjoyed. Hith- 

 erto, as the result of the application of analytical methods to tax- 

 onomy, it has been largely static in its nature, as it concerned itself 

 princijially with the determination of the present distribution of the 

 forms as if this arrangement were fixed, thus affording only a descrip- 

 tion of the present conditions. In connection with the synthetic 

 method, however, it is more comprehensive and essentially dynamic 

 in its nature, for it not only takes note of the present distribution of 

 the forms but at the same time recognizes the close relations that 

 exist between this arrangement and the en\dronment, and its conse- 

 quent unstability, and by the determination of the laws of change 

 furnishes a powerful aid to the interpretation of the past history of the 

 present forms, without a knowledge of which it is impossible to explain 

 the present conditions. 



THE TAXONOMY OF THE GARTER-SNAKES. 



PRESENT STATUS OF THE GENUS. 



As an example of the confusion into which a group may be throwTi 

 by systematists who see in every association of traits a species, prob- 

 ably no better could be found than that of the common garter-snakes of 

 North and Middle America, composing the genus Thatyinophis Fitzinger. 

 This genus has long stood in the minds of herpetologists as a sjmonyin 

 for chaos, and has been a source of trouble to those who attempted 

 to compile local lists, for specimens may be found in almost any 

 locality which can not be referred exactly to any described form, or 

 doubtfully to two or three. The result has been that in the attempt 

 to express these difi'erences the method of analysis has been carried 

 to the extreme, and something like sixty-five forms have been 

 described. 



This has not solved the problem, however, for, owing to the extent 

 of variation and the fact that descriptions have been based on differ- 

 ent combinations of traits without an adequate knowledge of the 

 variations, it has been practically impossible to define accurately any 

 of these forms. In nearly every species the characters often seemingly 

 grade ofl" in different directions independently of one another, and it 

 has happened more than once that a diagnosis has been subsequently 

 shifted from the form represented by the type-specimen to an entirely 

 different one, by the author of the species himself. Anything approach- 

 ing a natural key was not to be thought of, and a worker was fortunate 

 if he could devise an artificial one that would sufficiently define the 

 forms in particular regions so that they could be recognized. It is an 

 instance where the insufficiencies of the methods applied have been 

 thrown prominently into the foreground by the nature of the material, 



