INTRODUCTION. XXXV 



Further observations on the senses of insects are much 

 needed. There is no doubt that the two classes of eyes 

 function in different ways, and some insects have a much 

 more powerful sight than others. That most insects are 

 capable of recognising colours is certain ; and considering 

 the complicated character of their visual organs, it is, to say 

 the least of it, premature to argue, as some entomologists 

 have recently done, that the sight of Butterflies is so imperfect 

 that Nature can only appear to them as through a thick veil. 

 All considerations of probability, and even practical observa- 

 tions, seem to be quite opposed to such an idea. Attempts 

 have been made, with more or less success, to discover homo- 

 logies between the eyes of insects and those of vertebrate 

 animals ; but we have not space to enter upon these questions 

 in detail. 



The antennae, often called horns or feelers, are two long 

 jointed organs, situated in front of the head, between the eyes, 

 and before the ocelli, when the latter are present. We will 

 defer discussing their structure in Moths to another volume ; 

 in Butterflies they are generally about half as long as the body, 

 or a little more, and are nearly always conspicuously thickened 

 towards the end. Sometimes this thickening is more or less 

 gradual, in which case (especially in the Skippers), the antenna 

 often terminates in a slight hook, and sometimes the antenna 

 is suddenly thickened into a knob at the end. This character 

 is so universal throughout Butterflies, and so exceptional in 

 Moths, that it has always been considered as one of primary 

 importance, Butterflies being called Rhopalocera (Club-Horns), 

 and Moths Heterocera (Different Horns). This distinction 

 may be conveniently applied to separate the first few 

 families of Lepidoptera from the others, especially as we have 

 two such different popular names for them as "Butterflies" 

 and " Moths." In most Continental languages they have only 

 one principal word for both, and simply prefix " day " and 



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