386 INSECTS AT HOME. 



the simpler word ' ray,' as analogous with the fin-ra^s of 

 fishes. He is undoubtedly justified in considering that ' ray 

 is the better word, but as in all scientific accounts of the Lepi- 

 doptera the word ' nervure ' is used, I have employed it, leaving 

 the reader to substitute the word ' ray ' if he should prefer it. 



The reader will notice the enormous size of the eye-masses, 

 as shown in Fig. 1, this great size and bold projection being 

 rendered necessary by the fact that these insects are all day- 

 fliers, perpetually on the wing, and, consequently, very con- 

 spicuous. Now, there are many creatures — certain birds, for 

 example, dragon-flies, and other predacious foes — which are very 

 fond of Butterflies, and would wofully thin their numbers did 

 not their multitudinous eyes enable them to see the approach- 

 ing enemy in time for their broad wings to carry them out of 

 danger. The form of the proboscis is also shown in Figs. 1 

 and 2, the former representing it as it appears when coiled up 

 so as to be out of harm's way, and the latter showing it as 

 partly uncoiled, as it appears when the insect is about to take 

 food. 



"We now proceed to take in their order some typical examples 

 of British Butterflies. The first family is called Papilionidae, 

 and may be distinguished by having the first pair of legs formed 

 for walking, the tip of the antennae not hooked, and the dis- 

 coidal cell of the hind wings quite closed. Only one genus 

 inhabits this country, and only one species, the beautiful 

 Swallow-tail Butterfly (Pajpilio Machaon), which is si. own in 

 the frontispiece. 



In the genus to which this Butterfly belongs, the hind wings 

 are tailed, and the caterpillar, or larva, is furnished with a 

 forked appendage called the ' nuchal horn ' because it issues 

 from the neck. In this species the horn is only used in 

 moments of irritation, and is concealed within the body, its 

 place being only marked by two dots. If, however, the cater- 

 pillar be irritated or hurt, it immediately throws out the horn, 

 which can be produced to the length of half an inch or so. 

 Many naturalists suppose that this horn is intended for the 

 purpose of driving away the ichneumon flies when they attack 

 iLs larva. I can, however, scarcely accept this theory, oecause 

 the ichneumon flies are terribly injurious to many other jater* 



