388 



CLASSIFICATION OF VERTEBRATES. 



zle. Emballonnra, old-world tropics ; Nociilio and Molossits, tropical 

 America. PHYLLOSTOMID.E, tropical America; have three phalanges to 

 the middle finger, nose-leaf present, tragus well developed. Chilonycteris, 

 Vampyrus, Glossophaga. Desmodus includes the blood-sucking or true 

 vampire bats. 



SUB-ORDER 2. FRUGIVORA (MEGACHIROPTERA). 



Large bats with smooth-crowned quadrituberculate molars, index finger 

 with three phalanges, clawed ; sides of the ear connected below ; tail, when 

 present, below the interfemoral membrane ; fruit-eating. 



The only family is the PTEROPODID^E of the East Indies; the species 

 of which are generally known as flying-foxes. About 70 species, 40 being 

 included in Pteropus. 



ORDER IV. RODENTIA (GLIRES). 



Placental mammals, with the extremities bearing claws, or 

 more rarely hoof-like nails ; feet plantigrade or subplantigrade, 

 usually pentadactyl ; condyle of lower jaw moving in an elon- 

 gate glenoid fossa ; teeth diphyodont ; canines absent ; incisors 

 long, \ or f , with persistent pulps ; molars (including premolars) 

 varying from f to f ; placenta discoidal, deciduate. 



FIG. 362. Skull of muskrat, Fiber zibithecus. 



The rodents are as sharply marked off from the other 

 mammals as are the sirenians or whales ; no forms, living or 

 fossil, serving to connect them with the other orders, unless, 

 possibly, with the tillodontia. Especially characteristic of the 

 group are the gnawing incisors, in which the enamel is on the 

 anterior face, the resulting wear keeping these constantly with 



