46 THE BOOK OF NATURE STUDY 



and in such retreats they have sometimes been discovered in 

 incredible numbers. 



They feed, as might be supposed, only when on the wing, 

 their prey being beetles and small flies, such as commonly swarm 

 in the air during the summer and early autumn months. 



Among those who delight to watch the singularly silent flight, 

 with its amazingly rapid twists and turns, there appear to be 

 few who can hear the curiously shrill screech of delight which 

 these animals from time to time give forth. The sound is a short, 

 sharp, creaking note, and must be listened for expectantly. 



While most animals leave their young in places of safety 

 while they roam abroad in search of food, the young of the bat 

 clings to its mother's body from the moment it is born till it has 

 acquired strength enough to fly, grasping her by means of the 

 claws of the hind-feet and the claw on the thumb. 



Bats are creatures by no means easily captured, but they 

 may be found by careful search in suitable localities, and will 

 prove most valuable object lessons. They should, however, be 

 held captive only for a day or two, for they can never be kept 

 alive very long, owing to their voracious appetites. During this 

 period of durance vile, however, they should be fed on a liberal 

 supply of raw meat, minced fine, and it should be remembered 

 that a bat will consume its own weight in food during twenty-four 

 hours. 



The peculiarities of the bat will become the more apparent 

 by passing from one extreme to another from the bat to the 

 mole, for example. 



If the bat is the child of the air, the mole is no less the child 

 of the earth, for most of its life is passed underground. In 

 acquiring the power to live in such an environment, changes of 

 structure as profound as those which characterise the bats have 

 been made. Thus the body has assumed the form of a pointed 

 cylinder, while the fore-limbs have become, so shortened that 

 only the hands are visible externally. The" hind-limbs are 

 relatively small and weak. 



Into the nature of the various peculiarities of the skeleton 

 of the mole it will obviously be unnecessary to enter here. But 

 attention should certainly be drawn to the enormous size of the 



