100 
IOWA ACADEMY OF SCIENCES. 
lis superior rapidly ascends to the longissimus dorsi muscle 
and passes back to the posterior end of the body within the 
dorsal portion of the muscle. The ramus lateralis 
medius (7) on leaving the ganglion at first turns ventrally 
to the level of the emergence of the remaining vagus 
trunk (ramus inferior) and runs parallel with it on its 
median border as far as the ganglion of the third spinal 
nerve. From this point the ramus lateralis medius as- 
cends to the level of the longissimus dorsi muscle and in 
company with the ramus lateralis posterior of the seventh 
cranial nerve passes to the posterior region of the body, 
the greater part of the distance within the ventral portion 
of the muscle. The remaining trunk (8) given off from the 
vagus ganglion is by far the largest of the eight. Between 
the ganglia of the second and third spinal nerves it divides 
into three main branches. The first of these after passing 
ventrally and receiving a branch from the first spinal nerve 
divides into the ramus intestinalis and a branch running 
along the outer border of the first branchial artery. A 
second division becomes the ramus lateralis inferior sup- 
plying the ventral series of the lateral line sense-organs. 
A third anterior portion divides into two parts, one sup- 
plying the dorsotrachealis muscle and the other running 
along the inner border of the first branchial artery. 
In agreement with Kingsley I find that the hypoglossal 
nerve arises by four roots. The two dorsal and the anterior 
ventral roots are very rudimentary in the specimen studied. 
I found no ganglion cells on the hypoglossal. They had 
evidently degenerated along with the atrophy of the dorsal 
roots. The principal hypoglossal trunk runs posteriorly in 
the longissimus colli muscle and finally enters into close 
relationship with that branch of the ramus inferior of 
the vagus that gives rise to the ramus intestinalis. At one 
point there seem to be a few fibers passing from the vagus 
to the hypoglossal, but I was able to trace the hypoglossal 
as a distinct trunk through the vagus complex to the outer 
border of the sternohyoid muscle. 
The main trunk of the first spinal nerve runs posteriorly 
to the level of the posterior border of the third spinal 
