898 FOUR-FOOTED AMERICANS 



in the trees to Batville and see how its inhabitants live 

 and work. 



" First look at the specialization that enables the Bat 

 to fly with real wings, — fly, and not merely sail like 

 the Flying Squirrel," said the Doctor, holding the Bat's 

 wings open. " See the shoulder, elbow, and long fore- 

 arm. The fingers begin to divide at the wrist, so the 

 hand has no palm. There is a sort of hooked thumb, 

 and then the other fingers grow long and support the 

 skin that makes the wing, as the frame supports an 

 umbrella. The hind limbs, you see, are small and very 

 weak in contrast to the strong collar-bone and long 

 arms." 



" Oh, yes ! " cried Nat. " Rap said a Flying Squirrel's 

 coat was like a blanket fastened to the wrist and ankles, 

 and the Bat's wings ai'e all skin like a three-cornered 

 shawl, with its arms fastened in the top corners and the 

 point fastened to the tip of its tail." 



" Yes, and you remember how the bird's wing was 

 like an arm with only the beginning of two fingers and 

 thumb, that served as a frame to hold the fringe of 

 feathers. Though birds are not. Mammals, their branch 

 of the animal tree grows very close by.'' 



"Are all Bats made the same way. Uncle Roy? I 

 remember a picture of one in a book that I had. It was 

 called the Vampire Bat; it ate people and belonged to 

 some very far away country. It must take a very big 

 sort of Bat to kill people." 



" The wings of all Bats are made on the same plan, 

 though their bodies vary greatly in size ; but the forma- 

 tion of teeth, noses, ears, and so forth, varies according 

 to the needs of the different species. Thus the Fruit- 



