72 THE BUTTERFLY VIVARIUM. 



especially those of some exotic kinds destined to 

 live under the hark of trees, the pressure of which 

 they are enabled to resist hy this defence. The larva 

 of our native Moth, the Cossus Ligniperda, has a 

 horny clothing of similar character, which protects 

 it while eating its way through the trunks of trees. 

 These characteristics are, however, rare. 



Most larvae are opaque, though some, even among 

 those of the Lepidoptera, are nearly transparent; 

 and the body of a water larva, that of Tipula Crys- 

 tallina, is positively as clear as glass, insomuch that 

 it is scarcely distinguishable from the element in 

 which it lives. 



The segmental divisions of the body are com- 

 mon to classes of larvae in general, all the various 

 kinds having their bodies more or less distinctly 

 marked transversely by the joints of these segments 

 or divisions. In some of the earth larvae, and 

 others of the Grub class, however, the wrinkles of 

 the soft skin conceal the marks of these articu- 

 lations, which are generally twelve in number, ex- 

 clusive of the head. These segments are individually 

 of much larger proportion in some species than in 

 others, as the form of the larva exhibits a long and 

 slender, or robust and compact form. The general 

 form of larvae is cylindrical, though some are much 



