3 o INTRODUCTION 



same species as the handsomely spotted Coluber 

 sauromates ; and yet, if we compare the young of 

 these two snakes we find them to be absolutely 

 identical in their markings, and, in the absence of 

 any structural differences, we are forced to conclude 

 that they only represent two forms of the same 

 species, of which the latter is the more primitive. 



It is nevertheless a fact that, with a few excep- 

 tions, the markings, however variable they may be, 

 are reducible to certain fundamental patterns to 

 which the innumerable variations may be traced 

 back, and their derivation followed and scientifically 

 explained. Let us consider, for instance, another 

 species of Coluber, highly variable in its markings : 

 C. leopardinus, of which the typical form, so called 

 from having been the first described and named, is 

 not by any means to be regarded as the most 

 primitive. 



First, we must take for granted that the markings 

 of all such snakes, whether consisting of spots, 

 stripes, or bars, start from a regular arrangement, 

 which may be theoretically represented by four 

 paired longitudinal series on the head and body : 

 (i) Dorsal series (D) ; (2) Dorso-lateral (DL) ; (3) 

 Lateral (L) ; (4) Ventro-lateral (VL). The first 

 starts from the middle line of the head, and is con- 

 tinued along the spine ; the second occupies the 

 space between the first and third, which originates 

 at the tip of the snout, passes through the eye, and 



