VARIATIONS OF GARTER-SNAKES. 57 



by an obscurity of these markings. In 1892 he apparently recog- 

 nized this fact and the near relationships of these forms, as he 

 describes them all as forms of macrostcinma, evitlently including 

 insigniarum specimens wdth obscure markings both of the yellow (3) 

 and black (2) phases, since he states that the type of macrostemma 

 is intermediate in color between insigniaruni and favilahris. In 

 1900 he carried this farther and reduced fiavilabris and insigniarum 

 to the standing of varieties, but defined jnacrostemma {insigniaimm) as 

 being larger, darJcer colored and having the spots and bands indistinct 

 and the parietal spots generally absent, as distinguished from 

 favilahris with its brighter colored ground, yellow labials, stripes, 

 belly, and parietal spots. As we have shov.n in the description of 

 the color phases, the ground color in the original insigniaruni form is 

 yellow, so that although Cope was justified in combining insigniarum 

 and niacrostenima, as all intermediate color phases occur, he has 

 limited liis description to include only the dark forms, phase 1 and 2, 

 and placed the name insigniarum in the synonymy of niacrostemma, 

 but at the same time excluded the color phase to which it was 

 originally given, putting these specimens with favilahris. That this 

 is actually the case is further shown by tlie fact that he subsequently 

 labeled several specimens of the yellow phase (3) as favilahris. 



As a matter of fact it is absurd to attempt to distinguisli subspecies 

 on these color phases, and, indeed, impossible to do so and still observe 

 geographic probability. If we ignore all questions of nomenclature 

 and examine the color phases, it will be found that numbers 1, 2, 

 and 3 may all occur in the same locality and intergrade perfectly, 

 but seem to be quite distinct from phase 4, with its more distinct 

 markings. If we examine the range of the specimens, however, we 

 will find that the color phases 1, 2, and 3 are only represented in the 

 southern part of Mexico, and that they include all of the specimens 

 taken about the lakes in this region (Patzcuaro, Clialco, Xochimilco), 

 while phase 4 is found to the north in Arizona, Chihuahua, Durango, 

 and Guanajuato, and in Veracruz and Piiebla. They can therefore 

 hardly be classed as either iiuUvidual or racial variations, and since 

 they are not sexual, males and temales being found of either color, 

 the suggestion arises at once that they may be due more or less to 

 local environmental influences. This exj^lanation is enforced b}' the 

 fact that the specimens taken about the lakes Chalco and Patzcuaro 

 (the forms with obscure markings) represent the aquatic forms whose 

 habits have been described, while those in the more arid regions are 

 the phase 4. This ex])lanation must be taken with extreme caution, 

 however, for in very few cases is there data with individual specimens. 

 It is advanced principally to call attention to the need of detailed 

 study on this point. 



Enough has been said to establish the homogeneity of the form 

 megalops tlu-oughout its range. Tliis uniformity, which is in har- 



