84 THE BUTTERFLY VIVARIUM. 



have those of the Puss-moth tribe ; hut it is not 

 known how far they have the same powers to use 

 them for the same purposes. 



Some Caterpillars have the power of exuding 

 globules of a fluid which emits a fetid odour, 

 serving as a defence, and which is re-absorbed, to 

 serve on another occasion, directly the present 

 danger is over. In some of the larvae of the genus 

 Papilio the fork on the first segment only emits 

 an odour, without any fluid. 



In speaking of means of attack or defence, the 

 curious mask of the larva of the Dragon-fly should 

 not be omitted. This curious appendage conceals 

 the formidable jaws of the creature as it is stealing 

 upon its foe ; and being raised, not only gives them 

 full play when the moment for action arrives, but 

 also closes upon the victim Avhen seized, and pre- 

 vents the possibility of escape. 



The Spinning Power, by means of which the 

 cocoon is formed by the Silk-worm and many other 

 kinds of larvso, is generally situated in the head, but 

 in some at the otber extremity of the body. 



The Skin varies in hardness, as I have said 

 before. In some of the Grub kind it is very soft, 

 except at the head, or trunk segments ; in others, it is 

 horny, and in some, transparent. In true Caterpil- 



