134 CLASS MAMMALIA. 



bristling, with long and abundant hairs, which fill it. But 

 this is hot so when the labial muscles raise the opercula, 

 distend the interior folds, and partly open the nasal con- 

 duits. These edges, by the tension of the skin are turned 

 upwards, and with them, the long hairs with which they 

 are furnished. 



Nostrils, which are habitually closed, and which to com- 

 municate with surrounding bodies, require an act of volition 

 in the animal, and the consequent exercise of certain 

 muscles, are, doubtless, a characteristic which possesses in 

 itself no ordinary degree of interest to the observer of na- 

 ture. The nycteres derive no small advantage from it; 

 they are thus enabled to establish their dwelling in places 

 from which other animals are repulsed by powerful or pes- 

 tiferous exhalations. It is doubtful, however, whether this 

 singular and inverse disposition of the nasal conduits be 

 meant to preserve the animal from the inconveniences of 

 infectious odours alone. Like every thing else, of the 

 kind, it supposes some corresponding modification else- 

 where, and we shall find, on investigation, that to this ge- 

 neral law of nature, the nycteres form no exception. 



The faculty of flying, in the bats, very naturally led men 

 to the notion of comparing them with birds. The latter 

 were observed to possess much more ease and grace in this 

 style of locomotion, owing not only to the superior per- 

 fection of their direct organs of flight, but also to the power 

 they possess of inflating themselves with air, and thus di- 

 minishing their specific gravity. It did not appear likely 

 that a similar faculty would be discovered in the bats, 

 whose pulmonary functions are, in fact, so very different 

 from those of birds. 



It is, nevertheless, true, that aerial vesicles have been 

 found in the nycteres, similar to those in birds, but still 

 larger, and that the animal can fill them at what time and 



