INTRODUCTION 



Of the great class Insecta, probably no section has been the subject of more careful 

 and systematic study than that which includes the Lepidoptera, or scale-winged insects, 

 popularly known as Butterflies and Moths. The Rhopalocera or Butterflies are somewhat 

 unevenly distributed over the globe. Tropical America possesses by far the greatest number 

 of described forms. Tropical Asia and the Indo-Malayan region come next in order, whilst 

 Africa is comparatively poor in species. The latest complete work on the African 

 Rhopalocera, that of Aurivillius, gives some 1,613 species, not including the Hesperidae, 

 and with the present rapid exploration of this continent the number has already been 

 considerably increased. Many years of patient and laborious work on the part of naturalists 

 both at home and abroad have resulted, especially in recent years, in a better comprehension 

 and definition of the relations existing between the various forms, and of the families and 

 genera into which they may be separated. 



The study of mimetic relationship which forms the subject of this work necessitates 

 a knowledge of classification, and it is desirable therefore to give some account of the system, 

 which, though subject to slight variations according to the views of different authorities, 

 will nevertheless enable those who have not previously studied the subject to understand 

 the terms used when differentiating between the various families, sub-families, and genera. 

 The whole division Lepidoptera is divided into two sections, namely the Rhopalocera or 

 those having clubbed antennae, and which are commonly known as Butterflies, and the 

 Heterocera, which have the antennae of various other forms, and which are known as Moths. 



The undesirability of having the larger of the two sections thus distinguished by 

 a negative character has been outweighed by the convenience of the terms, though morpho- 

 logically speaking the differences in the antennae are by no means so important as other 

 though less superficially obvious distinctions.^ 



The body of a butterfly is divided into three principal parts, the head, thorax, and 

 abdomen. The head varies considerably in size, and carries, bilaterally placed, the large 

 and conspicuous compound eyes. These are formed of many facets, each of which is prac- 

 tically a single eye or lens. The outer surface of the eye is more or less hemispherical, but 

 each lens or facet appears to direct the light to one internal point so that the numerous 

 images produced are coincident upon the retina. There are sometimes in addition two 

 simple eyes placed on the back of the head and between the compound eyes. As these are 

 generally covered with hairs, they probably have no visual function, but serve only to 

 distinguish between light and shade. 



The antennae are more or less elongated and many-jointed organs arising from the 

 upper and anterior part of the head. They are of considerable importance in classification. 

 What the precise function of these organs may be does not appear to have been satisfactorily 

 elucidated, but it would seem almost certain that they have something to do with the 



1 I am aware that it is now proposed to revive 

 the term Phalaenae proposed by Linnaeus for this 

 section, but I have in this case retained the terms 



here given as being more in accordance with common 

 usage at the present time. 



