492 



THE SENSORIAL FUNCTIONS. 



This system in the larva (Fig. 442) has the same 

 simple form as in the Annelida, or in the Talitrus, 

 for it consists of a longitndinal series of ganglia, 



444 443 



442 



usually twelve or thirteen in number, connected in 

 their whole length by a double filament. By de- 

 grees the different parts of which it consists ap- 



forvvards. The last four (8, 9, 10, 11) of the abdominal ganglia 

 remain, with but little alteration, in all the stages of metamorphosis: 

 in the larva, they supply nerves to the false feet. The nerves (12, 13) 

 which supply the wings of the imago, are very small in the larva; 

 and they arise by two roots, one derived from the cord, and one from 

 the ganglion. The nerves sent to the three pair of anterior, or true 

 legs, are marked 14, 15, 16, 



The nervous system of the larva is exhibited in Fig. 442, that of 

 the pupa in Fig, 443, and that of the imago in Fig. 444. It will be 

 seen that in the pupa the abdominal ganglia are but little changed ; 

 but those situated more forward (6, 7) are brought closer together by 

 the shortening of the intervening cord, preparatory to their final ob- 



