CONSTITUTION AND DEVELOPMENT OF TERMITES. 67 



commissures between the fourth and fifth ganglia are rela= 

 lively very long. 



There is a small frontal ganglion connected as usual with 

 the supra-oesophageal ganglion. From it there comes off an 

 azygos nerve which turns back to run along the oesophagus ; 

 along it is a series of small ganglia, some before the point 

 where the CBSophagus begins to dilate, another in the first 

 thoracic segment where it is somewhat dilated, and lastly, one 

 in the third thoracic segment where it is much dilated. This 

 supra-oesophageal nerve gives off numerous small twigs to the 

 oesophagus. There are special nerves to the salivary glands, 

 but I have not been able to determine their origin. More 

 minute researches will probably lead to the detection of other 

 ganglia in the neighbourhood of the oesophagus ; I simply 

 suppose them to exist. 



The eyes are compound and euconic; there is a retinal 

 ganglion (ganglionic lamina). The cones and rhabdoms 

 are very short, and the cornea very thin. Ocelli are absent. 



The anterior portion of the alimentary canal (PI. 19, fig. 3) 

 is very narrow at its commencement, with well-marked longi- 

 tudinal folds. It begins to dilate from about the posterior 

 margin of the head, and the folds become less distinct. About 

 the beginning of the mesothorax it becomes very large, often 

 after presenting a slight constriction, and the folds are no 

 longer discernible. It persists in this condition to the seg- 

 ment mediaire, where it again becomes very narrow by an 

 almost sudden constriction to finish a little further on. Four 

 longitudinal folds arise at the point of constriction, and are 

 continued back over a short and narrow tract, where they are 

 intercalated with others. The anterior three fourths of this 

 tract are free, and the hinder fourth is invaginated into the 

 chylific ventricle. The cuticle lining the dilated portion of the 

 fore-gut is spinose. 



The chylific ventricle is enlarged in front and narrowed 

 posteriorly. Like the oesophageal portion it runs straight, and 

 is continued to the seventh abdominal segment. Its epi- 

 thelium is cylindrical, with a striated cuticular margin, and at 



