184 PTILOTA. 



section they are very similar in this respect, although shorter, 

 and composed of fewer joints. These organs are, however, 

 in general very short, and com}H>sed of three or four joints ; 

 and in many groups they are entirely wanting in the larva 

 state. 



The eyes of larva; are not, like those of the perfect insect, 

 formed of an innumerable series of hexagonal lenses, hut con- 

 sist of a small numher of simple granular tubercles, placed at 

 the side of the head, in the same situation that the eyes of 

 the future insect are to be developed ; they are, therefore, 

 more analogous to the simple eyelets of many insects, 

 subsequently described under the name of ocelli; many 

 larva; are, however, entirely destitute of them. Their num- 

 bers, when present, seldom exceed six on each side, which is 

 the number possessed by the caterpillars of butterflies (fig. 20, 

 a). The larvae of the dragon-flies have eyes somewhat re- 

 sembling those of the perfect insect. 



The mouth of the majority of larva; consists, like the mouth 

 of the perfect insect, of an upper lip (fig. 20, c), a pair of 

 horny jaws (fig. 20, d), a second or lower pair of jaws of Irx 

 firm consistence (fig. 21, e), furnished with an articulated pal- 

 pus (fig. 21, /), and a lower lip (fig. 21, g), furnished also 

 with a pair of articulated palpi (fig. 21, A A). Here, how- 

 ever, it is to be remarked, that the structure of the mouth of 





