The Cranial Nerve Components of Petromyzon. 169 
line nerve by blood vessels. Of course, no inference is drawn as 
to the occurence of such anastomoses in the trunk or tail region, 
where I have no preparations. Only one branch is given off from 
the lateral line nerve in this part of its course. This arises at 457, 
just behind the ganglion, runs dorsally close to the eranial wall and 
goes in the direction of the pit organ near the mid dorsal line in 
476. The branch is much larger tban is necessary for the inner- 
vation of one organ and it is possible that it continues caudad be- 
neath the skin and innervates the organs at 589 and 663. The 
small number of organs in this region makes it diffieult to determine 
their innervation but so far as our evidence goes, it favors the view 
that the lateral line nerve, contrary to what we should expect from 
its position, sends branches to the pit organs independently of the 
dorsal rami of the spinal nerves. I may say that in the branchial re- 
gion of the body the dorsal rami of the ventral nerves come into eloser 
relation with the lateral line nerve than do those of the dorsal nerves. 
Nervus glossopharyngeus. The caudal end of the auditory 
capsule is at 430. At 433 (Fig. 11) a ramus arises from the lateral 
surface of the glossopharyngeal ganglion, runs laterad, caudad and 
dorsad around the auditory capsule and in 445 unites with the 
VII—X anastomosis. This anastomosis is divided between the lateral 
line and the glossopharyngeal nerves, while in Zampetra it is divided 
between the lateral line and the vagus nerves. On the other hand 
the component of the vagus above described as root 7b goes to the 
glossopharyngeus in Zampetra. It may be said that there are many 
other differences in the number and composition of the roots, and 
in the form and position of the ganglia of the IXth and Xth nerves 
between the two species. These differences will be seen on com- 
parison with the account in the paper on the brain of Lampetra 
(p. 47). The branch of the VII—X anastomosis which joins IX has 
been drawn diagrammatically in the plate in order to avoid obscuring 
the roots and ganglia of the vagus, across which it would run if 
drawn in its actual position. 
At 445 the ganglion ceases and the trunk runs downward and 
backward, goes internal to a large blood vessel and a cartilage and 
reaches the mucosa. It gives off twigs to the mucosa, becomes en- 
wrapped in the large blood vessels at the base of the gills and 
sends more twigs to the mucosa. At 462 it gives off a large ramus 
visceralis mesially which continues backward along the base of tlıe gill 
lamellae and internal to the muscles until it reaches the caudal wall of 
