FISHES. 347 



It has been observed that this inflation occurs usually in those fishes 

 in which the nerve is not swelled at its base ; and in which, conse- 

 quently, there is no supernumerary pair of tubercles in front of the 

 anterior lobes of the brain. 



Nevertheless, it is swelled very evidently in the rays, although these 

 tubercles are wanting. 



The filaments of the olfactory nerve penetrate regularly into all the 

 folds of the pituitary membrane, and terminate at their edges. 



We do not perceive, in osseous fishes at least, that the covering of 

 the nostrils enjoys any mobility, or that the orifices are furnished with 

 muscles to open or shut them. 



It is certain that fishes enjoy the faculty of smelling ; that odours 

 attract or repel them ; and there is no reason to doubt that the seat of 

 this faculty is the organ now described. 



However, it is by no means impossible, that this delicate membrane 

 may also be used in recognizing substances mixed with or dissolved 

 in water, and which of themselves would possess no odour, thus 

 directing the fish in the selection of the waters which would be more 

 or less suited for it. 



It may be safely conjectured, that the degree of the faculties with 

 which this membrane is endowed, depends on the developement 

 given to it by the number and extent of its folds. 



Organs of Taste. 



Fishes, with few exceptions, swallow their food I'apidly, and without 

 chewing ; even those whose jaws are armed in such a manner, as to 

 bruise and cut their aliments, cannot keep them long in the mouth, 

 on account of the position and action of their respiratory organs ; 

 there being no salivary glands to moisten them, they could taste them 

 but feebly, even supposing they had received organs enabling them to 

 discern keenly the differences of the flavour; but it appears that the 

 organs of taste themselves are rather feeble. 



There are some fishes, in which the floor of the mouth, has no pro- 

 minence meriting the name of a tongue : in most, the tongue is 

 short, and but slightly detached ; it is never supplied with particular 

 muscles for giving a motion of prolongation, or flexion, which it has 

 in quadrupeds ; but even when it is most distinct, and most fleshy in 

 appearance, it merely consists of a cellular or ligamentous substance, 

 applied to the front of the lingual bones ; lastly, its surface is often 

 armed with toeth, sometimes densely packed together, like paving 

 stones, and which must necessarily deprive it of whatever little sensi- 

 bility it might have had, without them. 



Its nervous supply is very scanty, and comes from the glossophar- 

 yngeal, after it has expended almost its entire substance on the first 

 branchia. 



It might be supposed that some portions of the palate, or pharynx, 

 supply the place of the tongue for this kind of sensation, and especi 

 ally as we find in the genus of cyprins, at the entrance of the throat* 

 the vault of the palate furnished with a fleshy, soft, thick substance, 



