SPECIFIC CHAEACTERS OF BRITISH LIZARDS 83 



head scales (p. 86), the reader should endeavour to 



draw it himself from memory, so as to familiarise 



himself with the position of each scale. Then he 



should turn to the description of the specific scaling 



characters of each species and construct for himself 



a line drawing of the head of each species. This is 



even more important in the snakes than in the lizards, 



for the field naturalist who is familiar with the scahng 



of the heads of the adder and the ring-snake, can 



identify a specimen from the head alone, and is 



not misled by any considerations of size or colour. 



Whether this is the best possible manner that could 



be devised for classification, and whether weight should 



not be given to other characters more than it is, are 



questions which need not concern us here ; the point 



is, that scaling arrangements are specific characters, 



and as such should be known by every field naturalist. 



It is quite possible that originally the scales which 



cover the bodies of hzards were all alike, but a glance 



at one of the lizards of the present day will show that 



considerable differentiation has taken place between 



the scales of one part of the body and those of 



another. The scales of the head, back, limbs, and 



belly, have become different in shape, and in ti/pe of 



arrangement. For this reason those who have been 



responsible for making classifications of reptiles have 



found it best to take these as their guide. That is to 



say, the scaling becomes of the greatest importance in 



the distinction of one species from another, and of one 



