THE BAT. 



321 



being a model of grace, when with folded wings it crawls slowly 

 along on its projecting elbows. To fly upwards from the ground 

 is a still more difficult task, and in the large-winged species 

 is impossible. In this case the bat is obliged to crawl up 

 a wall or a tree, which it can easily do by means of its sharp 

 claws, and then dropping down it expands its wings in the air. 

 Its organization would surely have been very imperfect were it 

 always obliged to prepare for flight in this inconvenient and 



Skeleton of Pteropus. 



circuitous manner, but it is only by accident that it ever sets foot 

 on the ground, where many dangers would await it, and where 

 it has nothing to seek. Whenever it wishes to rest from flight 

 it can at all times hook itself with its thumb-nail to a tree, a 

 rock, or any other rough surface ; and during sleep it suspends 

 itself by its hinder-claws with the head downwards, under the 

 roofs of houses and churches, in caverns, ruined buildings, and 

 similar situations, so as to be able to spread out its wings im- 

 mediately, whenever it desires to do so. Its forearm is incapa- 

 ble of rotating like the human arm, in consequence of the union 

 of the bones of which it is composed, and this is another admira- 

 ble adaptation to its peculiar habits. Not only would the pro- 

 nation and supination of the hand be wholly useless to the bats, 



