. The elasmobranch fishes. Chondrichthyes. 242 THE ELASMOBRANCH FISHES. For convenience of description we may consider the facial nerve as made up of two groups of fibers. One of these supplies the sensory canal system; the other belongs to the facial i)roper. Three great nerves are in the service of the sensory canal system. These are : the ophthalmicus superficialis {, figs. 220 and 221) which goes to the supraorbital canal and associated ampullae of Lorenzini; the buccalis, to the infraorbital canal and associated ampullae of Lorenzini; and the external mandibular, a branch of the hyo
. The elasmobranch fishes. Chondrichthyes. 242 THE ELASMOBRANCH FISHES. For convenience of description we may consider the facial nerve as made up of two groups of fibers. One of these supplies the sensory canal system; the other belongs to the facial i)roper. Three great nerves are in the service of the sensory canal system. These are : the ophthalmicus superficialis {, figs. 220 and 221) which goes to the supraorbital canal and associated ampullae of Lorenzini; the buccalis, to the infraorbital canal and associated ampullae of Lorenzini; and the external mandibular, a branch of the hyomandibular nerve. This supplies the hyomandibular and the mandibular canals (figs. 220 and 245), and ampullae of Lorenzini. The ophthalmicus su- perficialis of the facial {) is a somewhat large nerve which arises from a large ganglion (figs. 220 and 221) and runs forward into the or- bit. Generally it enters the orbit through the or- bital fissure in common with the trigeminal, but in certain types (Mus- ielus henlei) it may enter through its o^\^i foramen above and in front of the orbital fissure. As it passes through the orbit superficially, it gives off numerous branches dorsally to the supraorbital canal and associated ampul- lae and leaves the orbit by a large anterodorsal foramen. It extends forward giving off a large branch which passes downward in front of the eye to supply the lower part of the supraorbital canal and numerous small branches which pass toward the tip of nose. The buccalis may arise from a large ganglion which is continuous with that of the ophthalmicus superficialis VII {Acanthias, fig. 220, ). In Mus- telus californicus these two ganglia are distinct but the ganglion of the buc- calis is in close relation to the ganglion of the external mandibular nerve. The buccalis, as was previously mentioned, runs across the floor of the orbit closely associated with the maxillaris of the fifth. In the anteroventral angle of the orbit it divides into tw
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