118 CLASS MAMMALIA. 



under ground. Deprived of the faculty of rendering them- 

 selves deaf at pleasure, they fly to retreats where the noise 

 and cries of diurnal animals cannot reach them. 



In compensation for this simplicity of form in the ear, 

 the organ of smell, as we before observed, is singularly com- 

 plicated. We find the entrance of the nasal cavities as 

 favourably disposed in the Rhinolphi for the conveyance of 

 odours as the ears are for that of sounds. They are formed 

 by a sort of conch, as if the odorous emanations, in a mode 

 analogous to the communication of sounds, were collected 

 and directed into the olfactory chambers. 



We cannot consider this peculiar organization, common 

 to the Rhinolphi, the Phyllostomata, and the Megadermes, 

 as accidental. An arrangement so scrupulously accurate in 

 all its details, must involve a fixed design, and mark a very 

 distinct type. 



The nasal chambers do not extend in the Rhinolphi beyond 

 the first molars. But they are inflated and globulous, and 

 the entrance to the nostrils is both in front and underneath. 

 It is a large opening, terminated by the intermaxillary bone, 

 which is reduced to a simple lamina, and is obedient to the 

 motion of the lips. 



These last, which are elevated by their swelling almost to 

 the height of the forehead, leave a vacuum between them- 

 selves and the nasal chambers, at the bottom of which, and 

 as it were in a tunnel, are the two openings of the nostrils. 

 A fold of skin protects and furnishes the circuit of this 

 tunnel, and thus forms the conch of which we have spoken. 

 This fold is extended in front of the nostrils like a horse- 

 shoe (from which one species derives its name), and it is 

 detached and elevated behind, like a leaf, differing in form 

 according to the species. 



The thickness of the lips results from an aggregate of 

 muscular fibres, which are glued, as it were, one over the 

 other, and opposite in their direction. The occasional con- 



