186 J. B. Johnston 
the trigeminus. The hyomandibularis certainly innervates the ventral 
cutaneous area of this segment. It is to be expected that the same 
will be found in other eyelostomes and in selachians, and it is not 
surprising to find in a ganoid (Amia) this component persisting in the 
VII* root. 
In the glossopharyngeus we apparently have a primitive condition, 
the general cutaneous component from the spinal V*" traet inner- 
vating the skin of the first branchial segment. 
As in other vertebrates, a general eutaneous component is found 
in the root of the vagus, and several spinal nerves contribute such 
fibers to the vagus trunk. They are distributed to the skin of the 
lateral and ventral region by way of the branchial nerves just as in 
the case of the VII!" and IX. The arrangement of the spinal 
and branchial nerves is of importance chiefly with regard to seg- 
mentation and they will be referred to again. 
The Speeial Cutaneous System. 
The position and arrangement of the preauditory portion of the 
neuromast system is probably to be explained by its development. 
The supraorbital row of organs, its ganglion and nerve arise from 
a placode which overlies the profundus ganglion in early stages. This 
accounts for the presence of neuromast fibers in the profundus gan- 
glion and root. The infra-orbital line and its ganglion arise from a 
placode overlying the trigeminus ganglion. The position of these 
placodes far cephalad seems to account for the position of the gan- 
glion in front of the auditory capsule and near the trigeminus gan- 
glion. Allthese facts are in agreement with the suggestion made in 
a recent communication (23) that the lateral line system in its original 
eondition extended forward one or two segments in front of the 
auditory pit. The small ganglion connected with the hyomandibular 
ramus lies at nearly the same transverse level as the acusticus 
ganglion and is perhaps to be regarded as a derivative of the audi- 
tory pit placode. 
The interesting variation in the relations of the VII—X anasto- 
mosis to the lateral line, vagus and glossopharyngeus nerves has 
been noticed in the description. A suggestion may be made here 
as to the possible representative of this anastomosis in the true 
fishes. It is that the row of organs and ramus have been much 
reduced and are represented in fishes by the ramus otieus and the 
organs innervated by it. 
