MAMMALIA 369 



bird, the Archceopterix." The bones of this order are slender 

 and hght. The skull and teeth present many extraordinary 

 variations. The radius is long and curved, the ulna is rudiment- 

 ary, and the knee is directed backward. The sternum is keeled 

 for the attachment of the pectoral muscles, the chief muscles of 

 flight. The ribs are flat and sometimes ankylosed together by 

 their margins. The fibula is rarely fully developed. The hind 

 limbs are small and serve as a means of hanging the body head 

 downward in rest or sleep, but are almost useless for walking. 

 The skull is almost as large as the chest. The ears are sometimes 

 much longer than the head. The nostrils are wide and are often 

 surrounded by highh' complicated sensitive membranes, which 

 sometimes give the face a comical or even hideous expression. 

 These are often more strongly developed in the male. The cheek 

 teeth of the insectivorous bats terminate in sharp points, and 

 are designed for cutting to pieces the hard parts of hard-shelled 

 insects. The fruit-eating bats have molars with rather smooth 

 crowns, while the vampires (Fig. 296, p. 371) have molars 

 with scissor-edges and large canine teeth with sharp, cutting 

 edges. The eyes are minute except in the fox Ijats. The wing 

 membranes are sensitive, containing intricate network of blood- 

 vessels, nerves, and " end organs," and thus, by the aid of their 

 sensitive wings and sensitive membranes on the face, bats are 

 enabled to fly without touching bodies in their way, though they 

 be in utter darkness or when their eyes are so minute and fur- 

 buried that they could not detect the intruding object. The 

 cerebral hemispheres are smooth and do not extend over the cere- 

 bellum. Bats are small and nocturnal and generally insectiv- 

 orous, generally feeding on the wing, thus they are beneficial. 

 Some are fruit-eating, and others, as the vampires of South 

 America, are blood-sucking, attacking warm-blooded animals, 

 and will even withdraw a quantity of blood from a sleeping man. 

 There is nothing whatever to fear from the ba+s of the United 

 States, for their claws and teeth are weak. The fur is usually 

 brown or gray, " but a few Oriental species are mottled or varie- 

 gated with orange, bright yellow and black," as is shown by 

 the " painted " ])at of Ceylon. This bat hides by day in the 

 folded leaf of a plantain, and when disturbed, looks more like a 

 butterfly than a bat. Mr. Swinhoe, a naturalist long residing 



