. The elasmobranch fishes . Fig. 202. Branches of the facial nerve, HeptancMis maculatus. (W. R. Dennes, orig.) , buccalis of facial; , chorda tympani; limd., hyomandibular (postspiracular) division of seventh nerve; , superior and inferior branches of external mandibularis of seventh; , internal division of mandibularis of seventh; , ophthalmicus super- ficialis of seventh nerve; , palatinus; , postspiracular twigs; , prespiracular nerve; sp., spiracle. facial nerve {) passes from the brain stem just dorsal to the maxillary division of the fifth
. The elasmobranch fishes . Fig. 202. Branches of the facial nerve, HeptancMis maculatus. (W. R. Dennes, orig.) , buccalis of facial; , chorda tympani; limd., hyomandibular (postspiracular) division of seventh nerve; , superior and inferior branches of external mandibularis of seventh; , internal division of mandibularis of seventh; , ophthalmicus super- ficialis of seventh nerve; , palatinus; , postspiracular twigs; , prespiracular nerve; sp., spiracle. facial nerve {) passes from the brain stem just dorsal to the maxillary division of the fifth (). In the orbit it divides much like the maxillary division of the fifth. It goes to supply the infraorbital canal and the ophthal- mic and buccal groups of ampullae. The palatine division of the seventh (, fig. 202) leaves the main stem of the hyomandibular nerve and passes ventralward, dividing into an anterior and a posterior branch, to the palate of the mouth. The most posterior division of the facial, the hyomandibular {hmd., figs. 200a and 202), after giving off the palatine branch, passes sharply backward around the spiracle, downward around the angle of the jaw and forward along the mandible. It first gives a prespiracular branch (, fig. 202) to the anterior wall of the spiracle; other twigs () are next given off to the posterior wall of the spiracle. Back of the angle of the jaw a superficial branch runs forward toward the angle of the jaw, and two branches () pass along the external side of the mandible to the hyoman- dibular canal and mandibular groove (hmc. and mg., fig. 228). A deep branch (, fig. 202) given off at the angle runs along the body of the hyoid, and another branch, the chorda tympani (), passes forward between the hyoid and the mandible. The auditory or eighth nerve in Heptanchus (VIII, figs. 200a and 200b) is more or less clearly separated from the seventh. It has a large ganglion from
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