320 



ZOOLOGY. 



maxillae, and labium. The mandibular nerves project for- 

 ward and arise from the anterior part of the ganglion, near 

 the origin of the supra-cesophageal commissures, while the 



maxillary and labial nerves are directed downward into 

 j_i 



The sympathetic ganglia are three in number ; one situ- 

 ated just behind the supra-oesophageal ganglion (Fig. 273, 

 as), resting on the oesophagus, and two others situated each 

 side of the crop, low down. Each of 

 the two posterior ganglia is supplied 

 by a nerve from the anterior ganglion. 

 Two nerves pass under the crop con- 

 necting the posterior ganglia, and 

 from each posterior ganglion a nerve 

 is sent backward to the end of the 

 proventriculus. A pair of nerves pass 

 under the oesophagus from each side 

 of the anterior sympathetic ganglion, 

 and another pair pass downward to a 

 round white body, whose nature is 

 unknown (Fig. 273, ). 



Fig. 280 represents an enlarged 

 view of the braip and sympathetic 

 nerve of a moth.* The heart is a long 

 * be !y in g in th e abdomen, dilating 

 at six P laces alon g its course, and 

 eopt. endin g in a conical point near the 

 nerve; r.azygos trunk of the* end of the abdomen; it is held in 



visceral nervous system ; r', . * 



its roots arising from the place by tine muscular bands. 



eupra-eisophageal ganglion ; -n , -i ,-, > . 



g, paired nerve with Its gangii- All insects breathe by means of a 

 After C Bran! e t e fro1n *Gegen^ complicated system of air-tubes rami- 

 fying throughout the body, the air 



entering through a row of spiracles, or air-holes, or breath- 

 ing-holes (stigmata), in the sides of the body. There are in 

 loctlsts two pairs of thoracic and eight pairs of abdominal 

 spiracles. The Erst thoracic pair (Fig. 281) is situated on 

 the membrane connecting the prothorax and mesothorax, 

 and is covered by the hinder edge of the protergum (usually 

 called prqthorax). The second spiracle is situated on the 



