2,50 



laminae in the state of separation which the water 

 produces. But it is not all aquatic animals that 

 are thus furnished with an apparatus hy which 

 the air contained in the water is subservient to 

 life : cetaceous animals, as those of the whale kind, 

 respire, like men and quadrupeds, by means of 

 lungs ; and, of course, they are obliged at cer- 

 tain intervals to come to the surface, in order to 

 throw out their former air, and to take in a fresh 

 supply. Some fishes, also, as the lamprey and 

 myxine, possess, instead of gills, several small 

 vesicles on each side of their gullet over which 

 the water, entering from the mouth, is again ex- 

 pelled, generally by small apertures on each side 

 of the body. 



With respect to the senses of fishes, there can 

 be no doubt that they enjoy the sense of smell, 

 and that they are acutely sensible of odorous 

 bodies ; so much so, indeed, that the very per- 

 fection of this function is often fatal to them ; for 

 some kinds are so strongly allured by aromas, 

 that by smearing the hand over with them, and 

 immersing it in water, they will often flock to- 

 wards the fingers and may be easily taken. In 

 all fishes, external openings or nostrils are very 

 apparent. They generally constitute, it is true, 

 only blind sacs ; but their inner surface is of 

 considerable extent, and upon their lining mem- 

 brane, a pair of large nerves, analogous in their 

 function to the olfactory nerves of man, are dis- 

 tributed. 



Fishes have in general no eyelids, but in place 



