COLORATION AFFECTED BY THE BNVIBONMEKT. 61 



is true. These animals comprise representatives of all the 

 principal classes; and they are without exception of a uniform 

 sandy or " isabelline " hue. There are rats, birds, lizards and 

 snakes in this collection ; plenty of instances will occur to any 

 one at once which might have been exhibited, as well as those 

 that actually are. 



In relation to this matter Mr. W. W. Smith has remarked 

 that the prolonged drought recently experienced in New 

 Zealand produced pale-coloured varieties ; and that the 

 Lepidoptera of that country are generally paler on the plains 

 than on the hills ; " the higher we ascend the Alps," he 

 remarks, " the more humidity we meet with, and the greater 

 the darkening of the Lepidoptera, imtil we reach the summit,, 

 when they become perfectly black." 



Influence of Light. 



At one time light and heat were regarded as indispensable 

 for the development of colour, and the gorgeous hues of 

 tropical birds and butterflies were instanced as proving this 

 view. Mr. Wallace has, however, abundantly shown that 

 there is not necessarily an intimate connection between light 

 and colour. It is true, he admits, that there are more brilliantly 

 coloured animals in the tropics than elsewhere ; but then 

 there are more animals of all kinds ; animal life is at its 

 maximum in the tropics. Besides, there are plenty of dull- 

 coloured insects and birds. The temperate regions, too, pro- 

 duce some of the most brilliantly and diversely coloured 

 animals that are known. 



The metallic blue of our " Clifden Blue " rivals in brilliancy 

 of hue that of the " Morphos " of South America; there are 

 no insects in the tropics belonging to the same group more 

 brilliant in their coloration than the " Red Admiral." 



