198 JOURNAL OF ENTOMOLOGY AND ZOOLOGY 
geal. The prominent cephalic and caudal masses of cells seem 
from the position of the nerve trunks and the arrangement of 
the fibers to be largely associated with the optic and mandibulo- 
rostral nerves respectively. 
The subesophageal ganglion is rather uniformly covered with 
rather thick masses of cells ventrally, there is but 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 candal ends. 
DistrrputTion oF Freer Tracts. In the brain there are few 
large commissures, one large band is sometimes made out ven- 
trally, but there are many cross fibers 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 in places 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 712. 
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 brain 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 parts, 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 parts. The 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. 
