198 JOUENAl, OF ENTOMOLOGY AND ZOOLOGY 



geal. The ]n'oniinoiit ceiilialir and eaudal masses of cells seem 

 from the position of the nerve trunks and the arrangement of 

 the tihers to be largely associated with the o]itic and mandibnlo- 

 rostral nerves respectively. 



The snheso]ihageal ganglion is rather nniformly covered with 

 rather thick masses of cells ventrally, there is bnt little indica- 

 tion of more marked masses where the leg nerves are given off. 

 The lateral parts of the ganglion are also covered with nerve 

 cells and these reach up dorsally except where nerve trunks arise. 

 On the dorsal side there are few nerve cell groups towards the 

 middle line except at the cephalic and caudal ends. 



DisTRiBUTinisr OF FiBKR TitACTs. In the brain there are few 

 large commissures, one large band is sometimes made out ven- 

 trally, Init there are many cross fiibers not definitely located in 

 distinct bundles. 



In the subesophageal ganglion there are two main commis- 

 sures usually evident connecting lateral parts. The more dorsal 

 of these is especially marked in the cephalic regions of the 

 ganglion and iu jilaces appears as an arched band just dorsal 

 to the central region. Towards the lower end of the ganglion 

 the more ventral commissure often appears divided. 



Fibers from the brain run in long and shorter tracts and 

 connect the brain with lower levels. Some of these fibers run 

 into the long dorsal and ventral tracts which run the length of 

 the ganglion similar to those described and figured by Haller '12. 

 The dorsal tract probably connects wider areas ; it seems to have 

 a large part of the fibers of the abdominal nerves. Fibers from 

 and to the l)rain connect the dorsal tract to posterior regions, 

 and ventral tracts are broadly connected with the anterior region 

 of the brain. Short connectives are found in all ])arts, cells in 

 each region do not send their fibers straight in to the central 

 part of the ganglion in every case, but may act as connecting 

 cells for neighboring i)arts. Tlie brain is closely connected to 

 the rest of the central nervous system and short connections are 

 found as well as the longer ones mentioned. In the lower regions 

 there are many connections from one area to the next. 



