78 VERTEBRATA. 



vertebrated animals, those which have the least ap- 

 parent signs of sensibility. Having no elastic air at 

 their disposal, they remain mute or nearly so, and 

 all those sensations awakened or sustained hy the 

 voice remain unknown to them. Their eyes almost 

 immoveable, their bony and rigid countenance, their 

 limbs deprived of the power of inflexion, and every 

 part moving at the same time, deprive them of the 

 faculty of varying their physiognomy, or expressing 

 their emotions. Their ear, enclosed on every side 

 by the bones of the skull, without external conch or 

 internal labyrinth, and composed only of a sac and 

 membranous canals, scarcely allows them to distin- 

 guish the most striking sounds : and, in fact, an 

 exquisite sense of hearing would be of very little 

 use to those destined to live in the empire of silence, 

 and around whom all are mute. Their sight, in the 

 depths of their abode, would be little exercised, if 

 the greater number of the species had not, by the 

 size of their eyes, been enabled to supply the defi- 

 ciency of light; but even in these species, the eye 

 scarcely changes its direction ; still less can it change 

 its dimensions, and accommodate itself to the distance 

 of objects ; its iris neither dilates nor contracts, and 

 its pupil remains the same in every degree of light. 

 No tear bathes this eye, no eyelid soothes or pro- 

 tects it ; and in this Class it must be regarded as 

 only a feeble representation of that beautiful, bril- 

 liant, and animated organ of the higher Classes of 

 animals. Procuring food by swimming after a prey 

 which itself swims with greater or less rapidity, 



