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Show 1895.] SENSOEY CANAL SYSTEM OF FISHES. 297 Trigeminal. Ramus ophthalmicus superficialis Ramus buccalis Ramus oticus In Amiurus the ramus oticus supplies the upper part of the opercular portion of the operculo-mandibular branch. In Amiurus the ramus ophthalmicus superficialis supplies the cluster-pores. In Conger the ramus maxillaris may supply posterior part of the sub-orbital branch. Ramus mandibularis. M a y either supply mandibular portion of the operculo-mandibular branch (Amiurus) or no portion of the canal system (other types). Facial. Supplies the operculo-mandibular branch. In Conger also supplies a sensory organ in lateral canal. Glossopharyngeal. M a y either innervate a portion or the whole of the main canal or the occipital commissure only, or it may not supply any portion of the canal system (Amiurus ?). Vagus. M a y or may not by anterior branches supply the initial portion of the main canal of the head. It will be seen, from the above tabular view of the nerves, that the innervation proceeds very largely from tbe trigeminal group of nerves. I have pointed out in previous papers (3 and 4) that in the Elasmobranchii the canal system was supplied solely by the facial group; in the Ganoidei the same feature still obtained, with the addition of a larger innervation from the ramus oticus, and also a portion of the system in Polyodon was supplied by the ramus mandibularis of the trigeminal. In most of the species examined the glossopharyngeal nerve innervated some portion of the main canal or the occipital commissure (excepting Amiurus ?), replacing the branch of the vagus lateralis marked 1' in Polyodon (cf. 3. pi. 40. fig. 11). With the exception of Amia, in which Allis (1) states that the glossopharyngeal nerve innervates a single sense-organ and a series of what he terms "'pit-organs "-probably synonymous with what I have called "primitive pores"-the Physostomi are the most generalized class of fishes in which such a condition is found. The innervation of any portion of the canal system by the glossopharyngeal nerve is certainly a characteristic feature in Teleostean fishes. Amia is probably the only Ganoid in which such a condition obtains. VIII. BlBLIOGEAPHY. 1. ALLIS, E. P.-"The Anatomy and Development of the Lateral Line System in Amia calva." Journ. Morphology, 1889, vol. ii. pp. 463-569, pis. xxx.-xlii. 2. BBIDGE, T. W., and H A D D O N , A. C - " Contributions to the Anatomy of Fishes.-II. The Air-Bladder and Weberian Ossicles in the Siluroid Fishes." Phil. Trans. 1893, pp. 65- 333, pis. 11-19. 3. COLLINGE, W A L T E E E . - " The Sensory Canal System of Fishes. Pt. I. Ganoidei." Quart. Journ. Micros. Sci. 1894, vol. xxxvi. pp. 499-537, pis. 39, 40, I Fairly constant, supplying main canal and | the supra- and sub-orbital branches. |
