MAMMALS 



203 



Fig. 370. — Vampire {P/iyllostoma spectrum) of South America. X £. 



the fold of the skin extend to the hind legs ? The tail ? 

 Are the finger bones or the palm bones more prolonged 

 to form the wing skeleton ? 



The skin of the wing is rich in blood vessels and nerves, 

 and serves, by its sensitiveness to the slightest current of 

 air, to guide the bat in the thickest darkness. Would you 

 judge that the bat has sharp sight? Acute hearing? 



The moles do not hibernate ; the bats do. Give the 

 reason for the difference. If bats are aroused out of a 

 trance-like condition in winter, they may die of starvation. 

 Why ? The mother bat carries the young about with her, 

 since, unlike birds, she has no nest. How are the young 

 nourished ? Order Why ? (Key, p. 193.) 



The Gnawing Mammals. — These animals form the most 

 numerous order of mammals. They lack canine teeth. In- 

 ference ? The incisors are four in number in all species 



