_a_, Basisphenoid; _b_, Occipital; _c_, Supraoccipital; _d_, Exoccipital; _e_, Paroccipital; _f_, Alisphenoid; _g_, Neural arch of first vertebra; _h_, _i_, _k_, second, third, and fourth vertebra; _h_’, _i_’, Parapophyses of second and third vertebra; _i_", process of the third vertebra for the attachment of the air-bladder; _k_, _l_, _m_, Chain of ossicles; _n_, Air-bladder; _o_, vestibulum; _p_, _p_, Ampullæ; _q_, _q_, Canales semicirculares; _r_, Sinus impar.] The connection is effected by means of a chain of ossicles in _Siluridæ_, _Characinidæ_, _Cyprinidæ_ and _Gymnotidæ_. A canal issues from the communication between vestibule and its sac, and meeting that from the other side forms with it a common _sinus impar_ (Fig. 52, _r_), lodged in the substance of the basi-occipital; this communicates on each side by a small orifice with two subspherical atria, on the body of the atlas, close to the foramen magnum. Each atrium is supported externally by a small bone (_m_); a third larger bone (_k_) completes the communication with the anterior part of the air-bladder. From the sinus impar a bifid canal penetrates into the alisphenoids, in which it terminates. In _Cobitis_ and several Loach-like Siluroids the small air-bladder consists of two globular portions placed side by side, and wholly included within two bullæ, formed by the modified parapophyses of the second and third vertebræ. The three ossicles on each side are present, but concealed by the fore part of the osseous bulla. * * * * * _Organ of Taste._--Some fishes, especially vegetable feeders, or those provided with broad molar-like teeth, masticate their food; and it may be observed in Carps and other Cyprinoid fish, that this process of mastication frequently takes some time. But the majority of fish swallow their food rapidly, and without mastication, and therefore we may conclude that the sense of taste cannot be acute. The tongue is often entirely absent, and even when it exists in its most distinct state, it consists merely of ligamentous or cellular substance, and is never furnished with muscles capable of producing the movements of extension or retraction as in most higher Vertebrates. A peculiar organ on the roof of the palate of Cyprinoids, is perhaps an organ adapted for perception of this sense; in these fishes the palate between and below the upper pharyngeal bones is cushioned with a thick, soft contractile substance, richly supplied with nerves from the Nervi vagus and glossopharyngeus.