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trematic + pharyngeal branch, and a lower R. post- 
trematicus. The former passes forwards, and divides into 
two rami, both of which at once turn downwards and back- 
wards. These are the R. pharyngeus (ph. zw. 1) and the R. 
pre-trematicus (pre. 1). The pharyngeus courses down- 
wards and immediately breaks up in the mucous mem- 
brane of the roof of the mouth. ‘The pre-trematicus 
reaches the first branchial arch, lying just internal to the 
undivided post-trematicus ix. When the latter divides it 
thereafter accompanies the ventral division of it, but 
curves round the inner aspect of the elbow formed by the 
epi- and cerato-branchials. 
The R. post-trematicus (post. 1.) gives off below just 
at its origin a motor branch, and shortly afterwards curves 
downwards, outwards and backwards to reach the second 
branchial arch. ‘here it divides into two branches, just 
as in the ixth, and these bend externally round the epi- 
and cerato-branchial elbow, one lying above the cerato- 
branchial and the other below it. Thereafter their course 
resembles that of the post-trematicus 1x. 
2.—T. branchialis secundus Vagi (¢. wv. 2). 
The ganglion of this division is more or less massed 
with the remaining vagus ganglia (g. xv. 2-5), and their 
boundaries are difficult to determine. The truncus arises 
from the internal surface of the ganglionic mass, like the 
first. A small mixed plexus of communis and motor 
fibres, not shown in the chart, may be described here. It 
arises by 3 roots—one from the second branchial ganglion, 
and two from the third. These three roots form a plexus 
from which 3 nerves arise, two of which pass forwards and 
inwards and break up in the roof of the pharynx, whilst 
the third also passes forwards as a purely motor 
nerve, 
