Mammalia. 



265 



supported by the arm and the excessively elongated fingers ; 

 the fold in our bats extends to and includes the tail. The 

 thumb is free from the wing mem- 

 brane and has a hooked claw by 

 which the bat can hang, but usually 

 when at rest it hangs head down- 

 ward by the hooked claws of the 

 hind limbs. Every one is familiar 

 with the flight of our bats as they 

 zigzag after insects. Bats are chiefly 

 nocturnal. There is much super- 

 stition concerning them. There are 

 in the tropics some blood- 

 sucking bats, but ours ^ 

 are not only harmless P 

 but beneficial. Our bats <& 

 hibernate in caves, hoi- ^ 

 low trees, etc. The large 

 bats of the East Indies, > 

 known as flying foxes, 

 are fruit eaters. 



The Whales. Though living con- 

 tinually in water, whales are true 

 mammals ; they bring forth their 

 young alive and nourish them by 

 means of milk. The fore limbs are 

 developed into flippers. The tail is 

 horizontally flattened, and its two 

 lobes are called flukes. Whales are 

 devoid of hair. The whalebone whale 

 has in its mouth a long series of 

 fringed baleen plates (whalebone), which serve as strainers. 

 The whale ingulfs whole schools of crustaceans, jelly- 



