94 CLASS MAMMALIA. 



it easily resumes the only position which is completely 

 suitable to its nature. 



It is in the air alone that the bats really enjoy themselves. 

 It is there alone that they feel possessed of perfect liberty ; 

 can avail themselves of their resources ; and experience the 

 most boundless confidence. Sometimes, indeed, this confi- 

 dence carries so far as to make them brave real dangers. 



But these aerial courses cannot be perpetual : repose 

 must follow. For this critical moment the bats reserve all 

 their prudence. The perception of the dangers to which 

 they are then exposed leads them to seek the most profound 

 and inaccessible retreats, and to take the precaution of sus- 

 pending themselves to the vaulted roof of caverns, with the 

 head hanging downwards. Simply fastened in this manner, 

 by the nails of their hinder feet, they have only to let go 

 their hold to escape by flight every unforeseen attack. 



We may now see the reasons for this inverse position, to 

 which it is remarkable that none but the bats are restrained. 

 From no other situation could they so conveniently resume 

 the modes of operation to which they are familiar — from 

 no other could they derive so many facilities of escape from 

 their enemies, and of losing themselves in the vast 

 immensity of air. When the bats are ready to shoot forth 

 and have to unfold the embarrassing mantle formed by the 

 membrane of their wings, it is necessary that they should 

 have a space at its sides proportioned to the amplitude of 

 its extent. That they should fall, therefore, from an 

 elevated position, is obviously necessary to the complete 

 fulfilment of their intended flight. 



The hinder feet of the bats, which are intended to affix 

 these animals to the ceilings of their retreats, must have a 

 form appropriated to this destination. It is easy, on this 

 principle, to account for the parallelism and equality of 

 their toes, as also for the curved form and steely point of 

 their talons. That system, which gives to the different parts 



