44 6 



ZOOLOGY. 



small invertebrates. The brain is small and smooth. The in- 

 cisors are small. Many burrow, and have special adaptations 

 for such a life; among these one of the most interesting is 

 the degeneration of the eyes. The moles, shrews and hedge- 

 hogs are the chief representatives. 



FIG. 239. 



FIG. 239. Flying Fox (Pteropus). U. S. Dept. Agriculture Year-book, 1898. 



Questions on the figure. What is the structure and arrangement of 

 the wings in such a form as this? To what order of mammals does this 

 type belong? 



Order 8. Cheiroptera (hand-winged; the bats). Mam- 

 mals in which flight is made possible by a web or fold of the 

 skin stretching between the much extended fingers of the anter- 

 ior appendages ; between the arm, body, and the hind legs ; and 

 thence even to the tail. The thumb and posterior digits are 

 clawed. The sternum has a keel as in birds. The mammae are 

 thoracic. The bats are the only mammals capable of active 

 flight. They feed on insects or fruits. One species is known 

 to suck blood. (Fig. 239.) 



