12 ORGANS OP SENSE OF FISHES. 



531. The nature of the integuments of Fish necessarily 

 renders their sense of feeling very imperfect ; and deprived as 

 they are of prolonged members, and particularly of flexible 

 fingers adapted to take hold of objects, it is only by means of 

 their lips that they can exercise the sense of touch. The fila- 

 ments which are often seen around the mouth, appear to inform 

 them of the contact of bodies. The sense of taste must also be 

 very nearly absent ; for their tongue is scarcely moveable, and 

 is not fleshy ; it receives very few nerves, and the food never 

 remains long in the mouth. The apparatus for smelling is of a 

 much more complicated structure ; but is not arranged so as to 

 allow either air, or the water serving for respiration, to pass 

 through it. The nasal fossa only consists of two cavities, closed 

 at the back ; each generally opens outwards by two nostrils, 

 and is furnished by a pituitary membrane folded in a very 

 remarkable manner. The ear is nearly always placed completely 

 within the cavity of the skull, upon the sides of the brain ; and 

 simply consists of a vestibule surmounted by three semicircular 

 canals, at which the sonorous undulations can only arrive after 

 having put into vibration the common integuments and the bones 

 of the cranium. In general we see nothing that can be compared 

 to the external ear, to the membrana tympani, or to the drum. 

 Lastly, the eyes are very large and nearly immoveable ; they 

 have no true eyelids, nor lachrymal apparatus. The skin is 

 continued over the eye, and is thin enough to be traversed by 

 the light. The cornea is almost flat ; the pupil very large, and 



but little or not at all contractile; 

 and the crystalline lens is sphe- 

 rical. These organs generally 

 do not usually present any pe- 

 culiarity as to their position ; 

 but amongst some fish there is 

 a remarkable anomaly. Thus, 

 amongst the Soles, Plaices, 

 Turbots, and other flat-fish, 



they are not placed as usual on both sides of the head, but 

 are both situated on the same side ; and this kind of mon- 



