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Show 1895.] ON SOME CRANIAL CUABACTEES OF THE SALMONOIDS. 299 Fig. 2. Diagrammatic view of the sensory canal system in the head of Amiurus. (Lettering as above.) Fig 3. Figure showing the series of canal-bones, c.b., in Amiurus, which connect the main canal of the head with the operculo-mandibular branch. From the series of canal-bones, c.b., the canal passes first into a portion of the hyomandibular, hyom., then into the preoperculum, p.op., and finally into the quadrate, qu. Fig. 4. Diagrammatic view of the sensory canal system in the head of Pimelodus. (Lettering as before.) Fig. 5. Dendritic branches and grooves from the sub-orbital and operculo-mandibular branch of the main sensory canal of Pimelodus. Fig. 6. Lateral view of the head of Callichthys littoralis, showing the distribution of the sensory canal system. Fig. 7. Lateral view of the head of Labeo dussumieri, showing the distribution of the sense-organs. X 1. (Drawn by M r . F. W . Crispe.) Fig. 8. Longitudinal section through one of the flask-shaped sense-organs in Labeo dussumieri, showing the pore, p., and the sensory filaments, s.fl., arising from the walls of the cavity. The nerve innervating the sense-organ is shown at the base, n.f. Fig. 9. Sensory filament, highly magnified ; the nerve fibre, n.f., passes up the filament for nearly two-thirds of its length and then divides into a number of very fine branches, which terminate around the disc, d. Fig. 10. Diagrammatic view of the sensory canal system in the head of Esox and distribution of the trigeminal and facial nerves. Fig. 11. Lateral diagrammatic view of the same. Fig. 12. Diagram illustrating the distribution of the mandibular branches of the trigeminal and facial nerves in Esox. Fig. 13. Lateral diagrammatic view of the sensory canal system in Salmo. Fig. 14. Dorsal view of the same. The sensory canals are coloured yellow. Those canals which are no longer functional and pass through the cranial elements are indicated by a double black line. Fig. 15. Canal-bones from the main canal of the head of Salmo. Fig. 16. Dorsal diagrammatic view of the sensory canal system of Conger and innervation of the same. The figures 1 to 6 indicate the saccular dilatations, r.op., Ramus opercularis. Other lettering as above. Fig. 17. Lateral diagrammatic view of the same. Figs. 18,19. Cartilages from the occipital commissure of the sensory canal system of Conger. 2. Remarks on some Cranial Characters of the Salmonoids. By G. A. BOULENGER, F.R.S. [Received March 27, 1895.] Various attempts have been made to split up the Salmonoids into families and subfamilies. In his classification of 1871\ Prof. Cope proposed to separate the Coregonidae from the Salmonidse owing to their having the parietal bones united in front of the supraoccipital, whilst they are separated by the latter bone in the Salmonidee proper. In a recent paper, Dr. T. Gill2 controverts Cope's statement, remarking that " on examination of a skull of Coregonus " he finds the same relation of the bones as in Sedmo, whilst the arrangement ascribed to Coregonus is character- 1 Trans. Amer. Philos. Soc. (2) xiv. 1871, p. 454. ? Proc. U.S. Nat, Mus. xvi. 1894, p. 117. |