122 fauna americana. 



Section i. 



Gnawers with clavicles. 



Char. Clavicles complete, often very strong. 



Genus. 

 Castor, Linn. Briss. Schreb. Cuv. Geoff. Illig- 



CHABACTSBS. 



r Incisor 2. 

 'superior 10. < Canine 0. 



Dental formula.— Teeth 20.^ rfJcisor 2* 



l^inferior 10. < Canine 0. 



.( 



^ Molar 8. 



Incisors very strong ; anterior faces, even and 

 flat ; posterior faces angular ; molars compound, 

 their crowns nearly plane, presenting circum- 

 volutions of enamel and grooves on their sides, 

 viz. three external and one internal on the mo- 

 lars of the upper jaw ; one external and three in- 

 ternal on those of the lower jaw ; eyes small ; ears 

 short and round ; five toes to each foot, the ante- 

 rior short and not separate ; the posterior longer 

 and united by a membrane ; tail broad, depressed, 

 oval, naked, and scaly. Two pouches containing 

 an unctious and odoriferous matter, situate on 

 each side of the male organs of generation. The 

 salivary glands very large. 



Species. 

 1. Castor fiber, Linn. Erxleb. Schreb. tab. 175- 



