The Colouration of Insects. 73 



Hypodermal Colours. 



Blue ^ 



Green 



Yellow 



Milk-white ) Fading after death. 



Orange and 



shades between 

 Red 



The hypodermal colours are usually lighter than the epidermal, 

 and are sometimes changed by a voluntary act. Hypodermal and 

 epidermal colours are, of course, not peculiar to insects ; and, as 

 regards the former, it is owing to their presence that the changing 

 hues of fishes, like the sole and plaice, and of the chameleon are due. 



The great order Lepidoptera, including butterflies and moths, 

 seems to the non-scientific mind to be composed of members which 

 are pretty much alike, the differences being of slight importance ; 

 but this is not in reality the case, for the lepidoptera might, with some 

 accuracy, be compared to the mammalia, with its two divisions of the 

 placental and non-placental animals. Comparing the butterflies 

 (Rhopalocera) to the placental mammals, we may look upon the 

 different families as similar to the orders of the mammalia. Were we 

 as accustomed to notice the differences of butterflies as we are to 

 remark the various forms of familiar animals, we should no longer con- 

 sider them as slight, but accord to them their true value. "When in the 

 mammalia we find animals whose toes differ in number, like the three- 

 toed rhinoceros and the four-toed tapir, we admit the distinction to be 

 great, even apart from other outward forms. So, too, the seal and 

 lion, though both belonging to the carnivora, are readily recognized 

 as distinct, but the seals may easily be confounded by the casual 

 observer with the manatees, which belong to quite a different order. 



Thus it is with the Lepidoptera, for from six-legged insects, whose 

 pupae lie buried beneath the soil, like most moths, we pass to the 

 highest butterflies, whose fore-legs are atrophied, and whose pupae 

 hang suspended in the open air; and this by easy intermediate 

 stages. Surely, if six-legged mammals were the rule, we should 

 look upon four-legged ones as very distinct; and this is the case with 

 the butterflies. It is necessary to make this clear at starting, in 

 order that we may appreciate to its fall value the changes that have 

 taken place in the insects under study. 



