126 BRITISH LIZARDS 



In L. I'iridis, the green lizard, the yellow lateral 

 stripes which are found in the young persist in some 

 of the old females, just as similar markings do in some 

 of the skinks. 



The general conclusion, therefore, is that colour 

 variation in lizards is mainly to be accounted for by 

 the influence of the two factors of age and sex. It 

 must not be supposed, however, that these two factors 

 are exclusively concerned in the matter, for many 

 lizards exhibit variations which can only be explained 

 by attributing them to individual peculiarities, whilst 

 others, the sand lizard for example, have considerable 

 local variations. The wall lizard, too, has a great 

 number of colour varieties, some of which are un- 

 doubtedly local in origin, such as the variety on the 

 Faraglione Eocks, near Capri, which is the colour of 

 the rock on its upper parts, blue underneath. This is 

 a matter of protective colouration, and it is in con- 

 sidering these varieties that the two questions of 

 colour variation and protective colouration overlap. 

 The object here, as we explained at the outset, has 

 been to account for the variations found in a given 

 species, irrespective of whether that species was pro- 

 tectively coloured or not. In either case, these varia- 

 tions are chiefly sexual or a matter of age, while some 

 are due simply to individual peculiarities not affecting 

 more than the particular specimen under observation. 



For the benefit of those who would like to look 

 more deeply into the matter, we append the following 



