LECTURE VIII. 47 



others with the stomach^ Some Fishes are totally 

 destitute of the air-bladder, and such Fishes are 

 observed to remain always at the bottom ; as the 

 whole tribe of what are termed fiat-Fish. If in 

 such Fishes as are provided with an air-bladder, 

 that organ be punctured, so as to let out its con- 

 tained gas or particular aerial fluid, the Fish is 

 unable to rise afterwards, but is obliged to remain 

 continually at the bottom*. 



The teeth in Fish are extremely various in the 

 different tribes, in some very large and strong, 

 in others very small ; in some sharp, in others 

 obtuse ; in some very numerous, and in others 

 very few. Sometimes they are placed in the jaws, 

 sometimes in the palate or the tongue, or even at 

 the entrance of the stomach. The eyes are in 

 general large, and very much flattened, or far 

 less convex than in quadrupeds and birds ; this 

 structure being better calculated for giving them 

 an easy passage through the water they inhabit : 

 in return, the central part of the eye, or what is 



* It is observed by Cuvier, that some Fishes having remained 

 for a considerable time near the surface of the water, under a 

 hot Sun, have had their air-bladder so dilated by the heat com- 

 municated to its contained gas, as to be unable suddenly to com- 

 press it sufficiently to permit themselves ta descend. 



