VARIATIONS OF GARTER-SNAKES. 35 



As in the case of the dorsal stripe, tlie position of the hiteral eoh)r 

 bands has been made the basis of specific diagnoses, for it was appar- 

 ently recognized quite early that the position of these strij)es was con- 

 stant in the different forms. Thus, Baird and Girard (lS5o) noted 

 that in the ribbon-snakes its position was on the third and fourth 

 rows, in distinction from the other forms then known, in which it was 

 upon the second and third rows;" while Cope, Brown, Stejneger, and 

 others have continued to make use of it as a distinctive character as 

 the genus became enlarged. 



The position of this stripe has been reported by Taylor (1892, 320) 

 to be subject to occasional variations (apparently meaning here in- 

 dividual variation), but this conclusion may probably be taken as a 

 result of an attempt tt) group specimens of apparently similar but in 

 reality distinct forms, for there can be no doubt of the really remark- 

 able fixity of this trait. In not a single specimen in the 3,000 that 

 have lieen examined has the position of the lateral stripe varied as 

 much as a single row from the normal for the form.'' 



There seems to be some evidence that the position of this stripe is 

 affected by the factors that influence the dorsal, for in northeastern, 

 northwestern, and southwestern United States, and the moimtains of 

 eastern Mexico there is a tendency toward a narrowing and loss of the 

 lateral stripe in certain forms, that closely parallels similar conditions 

 in the dorsal band. This is not other than is to be expected, from 

 the fact that the stripes ver}" probably have the same physiological 

 significance, but, be this as it may, the extent of the modifications is 

 so decidedly less in the case of the lateral stripe that there are but 

 two forms (angustiro,stru and i^heMax) known at the present time in 

 which it is characteristically absent, none in wliich it is on other tluin 

 the second, third, and fourth rows, two (marcianus, hutleri) in which 

 it is difficult to say whether it is upon the second and third or third 

 and fourth rows, and but one (hutleri) of the latter in which there can 

 be nmch question as to which of the two positions it is to be referred. 



The })osition of the lateral stripe is thus apparently a very good 

 and reliable specific character, owing to its constancy within the 



« Baird and Girard erred in classing radix (the only form listed in the Catalogue of 

 North American Reptiles besides the ribbon-snakes that has the stripe on the third 

 and fourth rows) with those having the bands on the second and third rows. 



ft Hay (1892, b522) records a specimen of sauritus from Wabash County, Indiana, 

 which had the stripe on the fourth and fifth rows. It should be noted, however, that 

 this snake had also 21 scale rows, which is such an unusual number among the ribbon- 

 snakes that in the large numbers examined we have never observed a specimen with 

 over 19. It is thus very probable that the individual was abnormal as regards the 

 arrangement of the dorsal scale rows, and the possibility is at once suggested that an 

 extra row may have been added on either sider below the lateral stripe, which would 

 be a decided abnormality. 



