176 J. B. Johnston 
ramus which innervates sense organs in sections adjacent to 955, 
and a ramus musculo-cutaneous which supplies museles and skin as: 
do the previous rami. 
At 1040—1060 the fine fibered trunk has a ganglion, at 1080 
it bends down to the mucosa and at 1093 divides into visceral and 
lateral rami as do the branchial nerves. There are no sense organs 
behind the last gill sac and the visceral ramus is small. 
Returning now to the coarse fibered trunk at about 940, it con- 
tinues backward and slowly outward and downward so that it se- 
parates farther and farther from the fine fibered trunk. At about 
960 it receives the ventral ramus of the 12?" ventral spinal which 
comes close over the lateral surface of the fine fibered trunk without 
any interchange of fibers.. In 985 the ventral ramus of the 12th 
dorsal spinal reaches the fine fibered trunk, on the lateral surface 
of which it lies for a short distance. It then goes down and joins 
the coarse fibered trunk in 1010. The 13: ventral spinal can 
not be traced past the cardinal vein. The 13! dorsal and the 14!" 
ventral spinals send their ventral rami down over the outer surface 
of the cardinal and along the inner face of the muscles well sepa- 
rated from the fine fibered trunk and both reach the coarse fibered 
trank in the same sections, about 1040. No further spinal nerves 
could be traced to this trunk, although the 14! dorsal might be 
expected to reach it. The coarse fibered trunk continues backward 
and downward, curves round behind the last gill slit (1100) and 
bends forward dividing into one large and two or three small bran- 
ches. Small bundles are given off to the muscles and the chief 
ramus approaches the middle line. _ From 1000 forward-an irregular 
row of pit organs is found along the course of this branch. It is 
traced forward to 600 where it divides into such small bundles that 
they can not be followed. 
This ceoarse fibered trunk contains the fibers of root 7/5 minus 
such fibers as may go to the pit organs over the gill slits, a part of 
the ventral ramus of each of ten or eleven ventral spinal nerves be- 
ginning with sp.v. 4, and a certain number of general cutaneous 
fibers, certainly those derived from the 12'% and 13! dorsal spinals. 
The general cutaneous fibers are probably all distributed in the region 
of the last gill. The ventral recurrent part of the trunk then con- 
tains somatie motor fibers for the sub-branchial museles and speeial 
cutaneous component for the pit organs caudal to the territory sup- 
plied by the corresponding component in IX. 
