No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 687 
levator arc. branch. int. anterior, which they innervate. As 
the nerve passes in front of the levator arc. branch. ext. primus 
it sends a nerve to that muscle, and immediately beyond the 
muscle is joined, on its anterior side, by the small branch 
that arises directly from the main ganglion, with which it 
anastomoses, as already stated. Immediately beyond this anas- 
tomosis a branch is given off on the anterior side of the united 
nerve, the branch being larger than the small anastomosing 
branch, and hence apparently containing fibres from the main 
nerve. This branch, shortly before reaching the outer end or 
angle of the arch, turns downward along the anterior surface of 
the epibranchial of the arch, reaches the dorsal surface of the 
ceratobranchial, and then runs forward and inward along the 
dorsal surface of that bone and of the hypobranchial as far 
as, or farther than, the distal end of the latter element. Many 
small branches are given off by it in its course. 
Immediately beyond the insertion of the levator arc. branch. 
ext. primus, the ramus posttrematicus glossopharyngei is joined, 
on its posterior side, by three branches of the ramus pretremati- 
cus vagi primi, and the four nerves continue side by side without 
anastomosis to the outer end of the arch. They all lie external 
to and superficial to the efferent artery of the arch, and internal 
to, that is, deeper than, the afferent artery, the same relations 
to the arteries being maintained on the ventral portion of the 
arch as well. At the outer end of the arch the anterior of the 
three branches of the first vagus crosses externally over the 
glossopharyngeus, and on the ventral aspect of the arch lies 
along the anterior side to that nerve. The three remaining 
nerves pass to the ventral surface of the ceratobranchial, and 
there anastomose completely, forming at first two nerves and 
then a single one. From these nerves, before and after the 
anastomosis, branches are given off on both sides, and, from 
these branches, branches are sent forward and backward along 
the entire length of the anterior and posterior edges of the 
arch. They form numerous anastomoses with each other, as 
shown in the figures, and anastomose also with that branch of 
the vagus that crosses externally over the glossopharyngeus to 
the anterior edge of the arch, The main portion or branch of 
