Page:Natural History, Fishes.djvu/223

Rh, are doubtless delicate organs of touch; and, being principally conferred on such species as habitually grovel on the bottom, they may be intended to compensate for the lack of light in such situations, as an aid for the discovery and trial of substances proper for food. The tongue, in most fishes, appears not to be an organ of taste; when it projects at all into the mouth, it is commonly covered with integuments, which are callous and void of sensitive papillæ, or else these are hardened and sharpened into bony teeth, studding its surface, and denying the power of sensation. "The integuments of the palate, however, not unfrequently present that degree of vascularity, and supply of nerves, which indicate some selective sense, analogous to taste. In the Carps, the palate is cushioned with a thick, soft vascular substance, exuding mucus by numerous minute pores, but more remarkable for its irritable, erectile, or contractile property; if you prick any part of this in a live Carp, the part, rises immediately into a cone, which slowly subsides; this peculiar tissue is richly supplied by branches of the glosso-pharyngeal nerves; it may assist in the requisite movements of the vegetable food, as well as add to it an animalizing and solvent mucus, whilst it is undergoing mastication by the pharyngeal teeth."

These teeth themselves are interesting from their position and nature. The lower pharyngeal