. The elasmobranch fishes. Chondrichthyes. THE ELASMOBRANCII FISHES 279 poral canal is supplied by a few twigs of the supratemporalis IX (Chlamydo- selaehus, Laemargus, Squalus acanthias, fig. 245, ) and the most anterior part of this segment is supplied by a few fibers from the ramus oticus VII. The supraorbital canal is supplied by branches from the ophthalmicus superficiaJis of the facial nerve, and the infraorbital by the buccalis nerve, while the nenromasts of the hj-omandibular and mandibular canals are sup- plied by the external mandibular division of the seventh nerve. FUNCTION OF
. The elasmobranch fishes. Chondrichthyes. THE ELASMOBRANCII FISHES 279 poral canal is supplied by a few twigs of the supratemporalis IX (Chlamydo- selaehus, Laemargus, Squalus acanthias, fig. 245, ) and the most anterior part of this segment is supplied by a few fibers from the ramus oticus VII. The supraorbital canal is supplied by branches from the ophthalmicus superficiaJis of the facial nerve, and the infraorbital by the buccalis nerve, while the nenromasts of the hj-omandibular and mandibular canals are sup- plied by the external mandibular division of the seventh nerve. FUNCTION OF SENSORY CANAL SYSTEM The function of tlie sensory canal system has l)een made the subject of many studies. It was observed by early workers that the pores contained mucus. The. Fig. 245. Innervation of the Sensory canal system and certain of the pit organs, Squalus acanthias. (From Norris and Hughes.) , buccalis nerve; cc, suprateniporal canal; , ramus dorsalis of tenth nerve; liinc, hyomandibular canal; ioc, infraorbital canal; U., lateral line canal; , lateral line nerve; mc, mandibular canal; , external mandibular nerve; , ophthalmicus superficialis of seventh nerve; po., pit organs; soc, supraorbital canal; , supratem- poralis of ninth nerve; , supratemporalis of tenth nerve. system was therefore taken to function in the production and distribution of mucus and the pores were therefore called mucous pores. Later study also demonstrated the relation of these organs to the nervous system. It has been shown by G. H. Parker (1904) that a shark which has been de- prived of hearing and sight responds to wave movement, like that produced by throwing a stone into the water, so long as the nerves to the lateral line are intact. When these nerves are cut, however, no further response is given. Ampullary Organs The ampullary sense organs, as in Heptanchus, are confined to the head and are generally arranged in four or five groups. These are, in Squ
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