. The Cambridge natural history. Zoology. XIV SENSE-ORGANS 389. outer surfaces of the fibrous membranes which close a pair of vacuities in the outer bony walls of the periotic capsules, the inner surfaces being bathed by the perilymph surrounding the auditory organs. This method is characteristic of certain Serranidae, Berycidae, Sparidae, Gadidae, and Notopteridae/ and probably in the Hyodontidae. In the second method, of which several Clupeidae { Herring, Pilchard, etc.) furnish examples, the periotic vacuities are open in- stead of closed, and the sac-like ends of the tubular extensions
. The Cambridge natural history. Zoology. XIV SENSE-ORGANS 389. outer surfaces of the fibrous membranes which close a pair of vacuities in the outer bony walls of the periotic capsules, the inner surfaces being bathed by the perilymph surrounding the auditory organs. This method is characteristic of certain Serranidae, Berycidae, Sparidae, Gadidae, and Notopteridae/ and probably in the Hyodontidae. In the second method, of which several Clupeidae { Herring, Pilchard, etc.) furnish examples, the periotic vacuities are open in- stead of closed, and the sac-like ends of the tubular extensions from the air-bladder are in actual contact with protruding outgrowths from the utriculus.^ The third method, by far the most elaborate, is by the intervention of a series of movably connected " Weber- ian" ossicles, of which the most posterior on each side (the tripus) is inserted into the dorsal wall of Fi«- of the air-Madder of a Siluroid (Macrones nemnrus) ex- the air-bladder (Fig. 223), while the anterior one (scaphium) forms the outer wall of a median back- ward prolongation (sinus impar) of the perilymph-containing spaces surrounding the two auditory organs. This in turn encloses a similar median prolongation (sinus endolymphaticus) from the two sub-cerebrally united endo- lymphatic ducts (Fig. 223).' This complex mechanism is present in the Cyprinidae, Siluridae, Characinidae, and Gymnotidae; and hence the term " Ostariophysi " * as a collective name for these families.* ^ Bridge, Journ. Linn. Soc. xxvii. 1900, p. 503. ^ Ridewood, Journ. Anat. and Phys. xxvi. 1892, p. 26. ^ E. H. Weber, De aure et auditu Hominis et Animalium. Pars i. De aure Animalium Aquatilium, Leipzig, 1820 ; Bridge and Haddon, Fhil. Trans. 184, 1893, p. 65. " Sagemehl, Mmyh. Jahrh. x. 1885, p. 22. ^ The Weberian ossicles are modified components of certain of the anterior vertebrae. The scaphium represents the neural arch of the first vertebra ; the inter- calari
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