BRANCHES — BRANCHIAL NERVES OF FISHES 141 



yngeus runs forward ventral to the pharyngobranchial of the 

 first branchial arch, and can be traced to the transverse plane of 

 the foramen for the ramus palatinus facialis. The ramus pre- 

 trematicus internus reaches the internal (concave) surface of 

 the first branchial arch and continues onward in that position, 

 lying along the posterior surface of the internal edge of the 

 branchial bar. A third branch, also accompanied by sympathetic 

 fibers, is the ramus pretrematicus externus, which runs forward 

 and reaches the external (convex) surface of the first branchial 

 arch, distal to the surface of insertion of the levator muscle of 

 that arch. There it passes internal to the ramus posttrematicus 

 posticus of the nervus glossopharyngeus and joins the ramus 

 posttrematicus medius, where it continues onward lying close 

 against the posterior surface of the latter nerve. The remaining 

 three branches of the first vagus together form the ramus post- 

 trematicus, and they may be called, because of their relations 

 to each other, the rami anticus, medius and posticus, the ramus 

 anticus receiving a bundle of sympathetic fibers. The rami 

 anticus and medius are both wholly sensory nerves, and run 

 outward external, and hence anterior, to the levator muscle of 

 their arch, the ramus posticus, which contains all the motor 

 fibers of the nerve and but few, if any, sensory fibers, running 

 outward posterior to the latter muscle. All three of these 

 nerves run downward along the external (convex) surface of the 

 branchial bar of the second branchial arch, the ramus anticus 

 lying anterior to the efferent artery of that arch, and the rami 

 medius and posticus posterior to that artery. The ramus 

 medius, while still in the upper (proximal) half of its arch, gives 

 off a ramus posttrematicus internus, this nerve being a wholly 

 sensory one which runs downward along the anterior surface of 

 the epibranchial of the arch, sends a recurrent branch upward 

 along the internal edge of that bar, and then itself reaches the 

 internal edge of the ceratobranchial of the arch. There it sends 

 a large branch downward anterior to the adductor muscle of 

 the arch, along the anterior surface of the ceratobranchial, and 

 itself passes posterior to the adductor muscle, along the internal 

 edge of the ceratobranchial, where it is joined by, and closely 



