NO. sa), JZOSCLES AND NERVES IN AMIA CALVA: 695 
vagi tertii (~7v3), one of which, as on the other arches, crosses 
over the posttrematicus to reach its anterior side, and there 
anastomoses with other anterior branches distributed to the tis- 
sues along the anterior edge of the ventral surface of the arch. 
The main nerve separates, near the distal end of the cerato- 
branchial of its arch, into two portions, the posterior of which 
enters and supplies the deeper portion of the obliquus ventralis 
of the arch, while the anterior one enters and supplies the 
superficial bundle of that muscle, as on the second arch. 
The truncus branchialis tertius n. vagi separates, soon after 
leaving its ganglion, into two parts, one of which is a ramus 
pharyngeus, and the other what may be called the united pre- 
and posttrematic branches of the nerve. The pretrematic 
branch, however, contains both pharyngeal and pretrematic 
elements and corresponds, in its relation to the muscles and 
ligaments of the arches, to the entire ramus anterior of the two 
preceding vagus nerves. The ramus pharyngeus (v3) runs 
outward and downward, dorsal to the efferent artery of the third 
arch, turns backward and inward behind that artery, perforates 
the cartilage of the third infrapharyngobranchial immediately 
behind the hind edge of the ossified portion of that element, in 
front of, or under, the proximal end of the fourth epibranchial, 
and is distributed to tissues in the region of the pharyngeal 
bones. In one specimen it sent a branch to the posterior sur- 
face of the third arch, and in all the specimens examined it 
varied somewhat in its arrangement and distribution. The 
pre- and posttrematic branches of the nerve soon separate. 
The former sends an important branch, which corresponds to 
the pharyngeal branches of the two preceding vagus nerves, 
forward and inward through the opening between the ligaments 
uniting the third and fourth epibranchials, the rest of the 
nerve, the true ramus pretrematicus (v3), running outward 
and backward behind the levator of the third arch to the upper 
surface of that arch, where it is distributed as already described. 
The ramus posttrematicus n. vagi tertii (fsv3) runs outward, 
downward, and backward, sends a branch to the posterior sur- 
face of the levator of the fourth arch and, on the right side 
of the specimen used for illustration, another to the second 
