SENSES OF FISHES. 11 



Even carp however likes animal food, and will de- 

 vour small eels, frog-spawn, and the roe or the young 

 of fishes, including its own species, as well as water 

 insects, which are the staple food of every sort of fish 

 from the minnow to the salmon, every thing that lives 

 and moves being swallowed without, so far as we can 

 find, any discrimination of species or much nicety of 

 selection. 



Smell in Fishes. 



Smelling in land animals is immediately connected 

 with breathing, and we cannot easily conceive how 

 smell is produced except by a current of air, in which 

 odoriferous particles are diffused, passing through a 

 moistened channel, as was first so admirably described 

 by Schneider two hundred years ago ; but in fishes 

 which do not breathe, smell cannot be thus produced, 

 though there can be no doubt of their being endpwed 

 with this sense. Water, indeed, is as good a medium 

 for diffusing odours as air, and there is the less necessity 

 for a current of this being produced through the 

 nostrils, as fish move about so constantly through the 

 water. Their nostrils, therefore, are in general large, 

 but imperforate backwards ; that is, they do not com- 

 municate with the throat, but in some fishes, such as 

 the rays and the sharks, the nostril opens by a con- 

 siderable chink into the mouth, and through this a 

 current of water may probably run. M. Dumeril and 

 the Rev. W. B. Daniell think, that, from the structure 

 of the nostril, and the want of an aerial medium for 

 odours, fishes cannot smell at all, and that their 



