No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 693 
The ramus posterior, or ramus posttrematicus n. vagi primi 
(fsv'), runs outward and downward immediately in front of the 
levator arc. branch. ext. secundus, sends a branch to that muscle, 
and beyond it reaches the upper surface of the second arch, 
where, like the corresponding nerve on the first arch, it is the 
anterior and larger of four nerves that run outward and back- 
ward on that surface. From it, as on the first arch, a branch 
is sent downward across the anterior surface of the epibran- 
chial of the arch to the dorsal surface of the ceratobranchial, 
and, as also on the first arch, the second nerve of the four 
crosses over the first nerve at the outer end of the arch, and 
on the ventral surface of the ceratobranchial lies along the 
anterior edge of that bone, anastomosing with a branch of the 
larger nerve. The other nerves anastomose and branch irregu- 
larly, the main portion of the nerve so formed continuing for- 
ward and inward onto the ventral surface of the interarcualis 
ventralis of the arch. There it sends branches from its hind 
edge into the deeper and proximal portion of that muscle, and 
then, turning inward through the superficial and distal bundle 
of the muscle, or passing around the anterior and then the 
dorsal surface of that bundle, sends a branch to that bundle, 
and is then distributed to tissues near the basal line between 
the second and third arches. One of the branches of the 
united nerves is sent along the anterior edge of the arch to 
tissues between its arch and the next preceding arch. On 
each of the four complete arches a similar branch is found. 
In one specimen (Fig. 59, Pl. XXXV) what was apparently 
a second ganglion was found on the truncus primus n. vagi, be- 
yond the first ganglion, at the point where the truncus separated 
into its several portions. In this specimen four large nerves 
arose from this second ganglionic swelling, —a posttrematicus, 
a pretrematicus, and a pharyngeus, anda fourth nerve which ran 
directly to the ganglion of the glossopharyngeus, and had on its 
distal end, where it joined that ganglion, a marked swelling, 
ganglionic in appearance. No such nerve or ganglion was 
found in any other specimen. 
The truncus branchialis secundus n. vagi arises from the 
second vagus ganglion (gv?). It runs backward, downward, and 
