266 ALUS. [Vol. XVIII. 



branch r. gh, above considered, runs forward along the dorsal 

 surface of Meckel's cartilage to the point where that cartilage 

 enters the ramus of the dentary. There the nerve leaves the 

 cartilage, and, instead of entering the ramus of the dentary, runs 

 mesial to that bone and receives from, or sends an anastomising 

 branch to, the mandibularis internus facialis, exactly as in Amia. 

 The nerve then breaks up into several terminal branches, some of 

 which enter the dentary, one of them traversing that bone and 

 coming to its external surface. A branch is apparently sent from 

 this part of the nerve to the imperfectly developed intermandib- 

 ularis muscle. 



The Truncus Hyoideo-Mandibularis Facialis (hiuf) arises 

 from the hind end of the trigemino-facial ganglionic complex. 

 Running backward and laterally it traverses the facial foramen 

 through the cranial wall and issues in the trigemino-facial chamber 

 of the petrosal. There it turns backward and issues from the 

 chamber by its posterior or facial opening. Turning laterally and 

 tipward, along the side wall of the skull, it traverses the adductor 

 hyomandibularis, at its origin, and then runs laterally along the 

 dorsal surface of that muscle to the inner opening of the facial 

 canal through the hyomandibular. 



While traversing the foramen through the petrosal, and also 

 while still inside the trigemino-facial chamber, it presents a well 

 marked ganglionic swelling. In the chamber it gives off the ramus 

 palatinus facialis, which runs downward and slightly forward 

 through the palatine canal in the petrosal. The truncus then 

 passes through the loop in the large sympathetic nerve that trav- 

 erses the trigemino-facial chamber, as already described, and 

 then, as it issues from the chamber, receives from, or gives to the 

 nervus glossopharyngeus a communicating branch, which will be 

 considered in describing the latter nerve. As it reaches the dorsal 

 surface of the adductor hyomandibularis, it gives off two branches, 

 one directed forward and the other backward. The former 

 pierces the adductor hyomandibularis and innervates it and un- 

 doubtedly also the adductor arcus palatini, though the fibres of the 

 nerve were not traced definitely to the latter muscle. The other 

 branch runs backward and laterally on the dorsal surface of the 

 dorso-posterior portion of the adductor hyomandibularis, and 



