Nos. IAND2.] .^IX ATOMY OF SCOMBER SCOMBER. 275 



than one half the fibers of the entire root, but, nevertheless, form 

 a bundle that seems sufficiently important to represent the entire 

 motor component of the nervus. 



The ramus anterior of the nervus (agl) arises either directly 

 from the ganglion of the nervus, as a separate and independent 

 nerve, or as a branch of the single truncus of the nervus, close 

 to the point where the latter leaves the ganglion. It runs for- 

 ward, or upward and forward, along the side wall of the skull, 

 to the upper edge of the surface that gives origin to the external 

 levators of the first two arches and to the ligament that represents 

 the interarcualis dorsalis of the first arch. There it turns for- 

 ward, external to the muscle and ligament of the first arch, and 

 between the two heads of the muscle of the second arch, lying 

 immediately against the ventro-lateral surface of the jugular vein. 

 Anterior to the surface of origin of the two muscles the entire 

 nerve, in some specimens, turns downward internal to the mucous 

 lining of the posterior surface of the adductor hyomandibularis 

 (Fig. 66), and joins and fuses completely with the communicating 

 branch already described as coming from the nervus facialis. In 

 other specimens the glossopharyngeal nerve separates into two 

 strands one of which continues directly forward while the other 

 turns slightly downward, both of them joining and fusing com- 

 pletely with the communicating branch from the facialis; one of 

 them ho.wever seeming to run proximally into the communicating 

 nerve and the other distally with it. After this anastomosis of the 

 two nerves a single trunk continues downward to the anterior end 

 of the opercular gill, where it separates into two parts. One of 

 these parts turns forward along the ventral surface of the adductor 

 hyomandibularis, the other turning backward and laterally along 

 the ventral edge of the opercular gill. This gill, as already stated, 

 receives its blood supply from the arteria hyoidea. 



The anastomosis above described is certainly Jacobson's anasto- 

 mosis, and it seems to be formed by two nerves, one coming from 

 the nervus facialis and the other from the glossopharyngeus. The 

 ramus anterior glossopharyngei seems, in fact, to here separate 

 into its two divisions, the ramus pharyngeus and ramus pretre- 

 maticus. The ramus pharyngeus seems to run proximally into the 

 communicating branch from the facialis, and it may be that it is 



