94 



NEKVOUS SYSTEM OF INSECTS. 



FIG. 412. ACHERONTIA ATROPOS. 



kind of cry, the manner of producing which is not well known ; 

 such is the Acherontia Atropos, known under the name of the 



Death's-head Moth. 

 (ANIM. PHYSIOL. 

 676679). 



670. The Ner- 

 vous system of In- 

 sects shows the 

 general arrange- 

 ment, and the chief 

 part of the modifi- 

 cations, which we 

 have already described in treating of the Sub-kingdom, to which 

 these animals belong ( 652). It is principally composed of a 

 double series of ganglia, which are united together 

 by longitudinal cords ; the number of these ganglia 

 corresponds with that of the segments ; and they are 

 sometimes at nearly equal distances, and extend from 

 one end of the body to the other, whilst in other in- 

 stances several of them are connected together in such 

 a manner as to constitute a single mass. The cephalic 

 ganglia present a very high development, and give 

 origin to the nerves of the Antennae and of the Eyes, 

 &c. The first pair of ganglia below the oesophagus 

 supplies the nerves of the mouth ; and the cords which 

 unite these nervous centres to the cephalic ganglia, 

 and which pass round the oesophagus, give off on 

 each side a nerve which goes back to the stomach ; 

 and which joining itself with that of the opposite 

 side, forms a single trunk, running on the central 

 line above the digestive canal, and having two gan- 

 glia in its course. The three pair of ganglia on the 

 ventral cord, following those which are situated im- NERVOUS SYS- 

 mediately beneath the oesophagus, belong to the three TEM QF n 

 rings of the thorax, and are the points of departure of the nerves 

 of the feet and the wings ; in general they are very close together, 

 and are much larger than the succeeding pairs, which belong to 

 the abdomen. 



