162 J. B. Johnston 
to distinguish nerve fibers. There can be little doubt, however, that 
these branches are destined to the neuromasts which lie farther . 
forward in the direction in which the nerves are going. As indicated 
on the plate, a number of organs are found between sections. 220 
and 280. None are found between 280 and 340. 
The ramus hyomandibularis ineludes, therefore, a very small 
faseiculus communis component to the first demibranch, a larger motor 
component for the constrietor muscles, and much larger general 
cutaneous and neuromast components for the skin and neuromasts 
of the ventro-lateral surface of the head behind the mouth. 
The smaller ramus goes directly caudad from the base of the 
ramus hyomandibularis, inclines mesially beneath the caudal part 
of the auditory ecapsule, passes beneath the ganglia of IX and X, 
takes up a position between the notochord and the mucosa of the 
roof of the pharynx, and between the cardinal vein and the aorta, 
and continues to 780 where it is lost from view. During this long 
course its position is not always the same. It is constantly shifting 
in the sections to pass a cartilage, a muscle, or a bundle of fibrous 
tissue, but a detailed description of these changes of position is 
unnecessary. Two facts are of importance: one that at intervals it 
descends upon the inner surface of the mucosa and the two nerves 
lie at either side of the aorta; the other that in these places the 
nerve is enlarged and contains larger and more conspicuous nuclei 
than elsewhere. The last two of these enlargements, which are 
shown in the plate, lie in the plane of dorsal spinal nerves and 
undoubtedly contain ganglion cells. It is evident that this is the 
sympathetie trunk of the head and that it consists of a series of 
small ganglia and slender connectives. The ganglia lie upon the 
mucosa and the connectives run among the muscles, ligaments and 
blood vessels ventro-lateral to the notochord and the vertebral carti- 
lages. The connectives are so very slender in two places as to be 
almost lost, but the chain was traced without a break to a point 
behind the eighth dorsal spinal nerve. Behind that Icould not find 
it again nor could I find in these preparations the sympathetie ganglia 
of the trunk described by JuLın (24). No connection with the spinal 
nerves could be found. If any exist they must be very small and 
it is doubtful if they could be traced through the complicated course 
which they must take. The sympathetie itself varies from three or 
four to perhaps twenty fibers at the utmost, so that we should not 
expect the communicating rami with the spinals to have more than 
