126 FAUNA AMERICANA. 



Inhabit North America, from Canada to the 

 thirtieth degree of north latitude ; on either side 

 of the Rocky Mountains. Siberia, and northern 

 and temperate Europe. 



Genus. 

 Osteopera, Nobis. 



CHAHACTEBS. 



r Incisor 2. 

 f superior 10. ^ Canine 0. 



Dental formula.— Teeth 20.- 



- 

 ,J C Molar 8. 



■j r Incisor 2. 



Onferior 10. < Canine 0. 



C Molar 8. 



Inferior incisors slender, laterally compressed, 

 nearly pointed, not approximate, convex anterior- 

 ly ; molars nearly similar to those of the beaver ; 

 head very broad and flat; snout rapidly attenuated; 

 eyes widely separated ; zygomatic arches exceed- 

 ingly large, descending beneath the inferior mo- 

 lars, scabrous and convex externally, forming 

 within large osseous pouches communicating with 

 the mouth, anterior to the molars; lower jaw 

 proportionably small and slender; the condyloid 

 extending above the coronoid process. 



Species. 



1. Osteopera platycephala. 



Char. Essent. Head flat, ventricose at the 

 sides ; snout obtuse ; eyes widely separated. 

 Dimensions of the cranium compared with that 



