20 THE RIVER-SIDE NATURALIST. 



All our bats are nocturnal in their habits, although one 

 or two of them often appear in the gloaming, and at times 

 even at midday, but as a rule the day is passed in sleep 

 in the darkest places they can find, in hollows of trees, 

 old ruins, towers of churches, dark barns, and the like. 

 They are all insectivorous and fly with remarkable rapidity. 

 The ease with which they turn and twist about in their 

 flight and in pursuing their prey is extremely interesting to 

 watch on a calm summer's eve. The skin of the wing is so 

 sensitive that it was found by Spallanzani that if bats are 

 deprived of their sight and hearing, they were able to fly 

 about with absolute certainty, and avoid objects purposely 

 placed in their way. The ears of bats, forming so im- 

 portant a part in their economy, are therefore much larger 

 than would appear necessary for the size of the animal. 





HEAD OF THE GREAT BAT. 



