364 VERTEBRATE ZOOLOGY 



role of birds while the latter are asleep. " Blind as a bat" is a fa- 

 miliar aphorism that has its basis in the fact that the bats' eyes are 

 so sensitive to lights of low intensity that they are blinded by the 

 broad daylight. At night they skim rapidly and dexterously through 

 the air catching insects on the wing with remarkable expertness. In 

 the daytime they spend their time sleeping in caves or other dark 

 sheltered places, hanging up-side-down by means of the claws of 

 their hind legs. They are decidedly gregarious, living in colonies of 

 thousands within the narrow confines of certain small caves. A com- 

 mon American species is the Brown Bat (Eptesicus fuscus) ; another 

 common species of the eastern parts of North America is the Little 

 Brown Bat (Myotis lucifugus), which is less than three and a half 

 inches in length. The Vampire (Desmodus rotundus) is a bat of rather 

 large size, native to South America. True to its reputation it lives 

 the life of a blood-sucker, attacking horses and cattle and occasionally 

 men. Its mode of attack is to fasten its razor-edged front teeth 

 (Fig. 188, E) in the throat and to sever a vein or an artery, after which 

 it proceeds to gorge itself with blood. One curious family of bats, 

 the Molossidce, are of interest because they have become secondarily 

 terrestrial, appearing to be more at home on their feet than one would 

 expect of a bat; for they run about almost like mice. This is quite 

 in contrast to the usual situation among bats, which move about on 

 the land with extreme awkwardness. When the typical bat crawls 

 it hooks the thumb-nail in front and pushes with its feet behind, a 

 pitiably helpless mode of locomotion. 



ORDER 4. CARNIVORA (FLESH-EATING MAMMALS). This is an im- 

 mense order, characterized by large average size, predatory habits, and 

 dominant position in the economy of nature. The largest carnivores, 

 lions, tigers, and bears r.ank as kings among beasts. The cheek teeth 

 are generally provided with sharp cutting edges, and the canines are 

 characteristically large and curved. The brain is relatively large and 

 complex; a fact that accords well with their high grade of intelligence. 

 The clavicle is vestigial or absent, giving them a narrow-chested ap- 

 pearance. Digits are never less than four and are armed with curved 

 claws. It is difficult to enter into a more detailed account of the 

 order as a whole, because the two sub-orders, Fissipedia and Pinni- 

 pedia, are unlike in so many particulars. 



Sub-Order 1. Fissipedia (Terrestrial Carnivores). The dentition 

 (Fig. 169) is probably the best diagnostic character of this group; 



