Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 



271 



as many authors assert, if that nerve is a postspiraciilar and not 

 a prespiracnlar one. Ruge so considers it and says, moreover, 

 (Xo. 63, p. 214) that the ramus mandibularis n. faciaUs of most 

 reptiles, birds, and mammals seems "dem Trigeminus voUig ein- 

 verleiht worden zu sein." 



The Ramus Hyoideus Facialis (/?/), after it leaves the main 

 truncus hyoideo-mandibularis facialis, runs inward and down- 

 ward through the ventral end of the narrow space between the 

 hind edge of the hyomandibular and the anterior edge of the pre- 

 operculum, and reaches the inner surface of the latter bone. There 

 it runs downward, slightly posterior to the epihyal, then forward 

 and downward across the inner surface of the proximal end of 

 the ceratohyal, and then forward along the inner surface of the 

 branchiostegal rays, close to the postero-ventral edge of the cera- 

 tohyal. \Miile on the inner surface of the gill-cover the nerve 

 gives ofif two or three rather large branches. The first of these 

 branches leaves the nerve near the ventral edge of the exposed 

 inner surface of the preoperculum, and running backward crosses 

 the exposed surface of that bone, then the inner surface of the 

 pointed process at the anterior end of the suboperculum, and then 

 a short portion of the operculum immediately behind that process. 

 It then reaches the anterior edge of the body of the suboperculum, 

 and passes backward between the adjoining and overlapping edges 

 of that bone and the operculum. From this branch a branch is 

 sent downward between the adjoining and overlapping edges of 

 the preoperculum and interoperculum. The second branch, and 

 a third branch also when found, is sent backward along the inner 

 surface of the interoperculum, between that bone and the muscle 

 fibers that arise from the dorsal branchiostegal ray, and that form 

 the dorsal portion of the superior division of the hyohyoideus. 

 Anterior to these branches other branches are sent from the main 

 nerve to other portions of the superior division of the hyohyoideus, 

 the nerve continuing forward along the external surface of that 

 muscle, between it and the internal surfaces of the branchiostegal 

 rays, onto the external surface of the inferior division of the 

 muscle. Between the fourth and fifth branchiostegal rays, count- 

 ing from above downward, the nerve sends a branch outward onto 

 the outer surface of the superior division of the geniohyoideus. 



