110 FAUNA AMERICANA. 



animals are hunted for their oil, their skin and 

 tusks, the ivory of which is more homogeneous 

 than that of the elephant, and does not tarnish 

 by time. 



Family MARSUPIALIA. 



Char. Growth of the young premature ; fre- 

 quently a pouch formed by a fold of the skin in 

 the female, enclosing the mammae, and destined 

 to receive the young foetusses at birth ; in some 

 instances lateral folds exist as rudiments of this 

 pouch. The Marsupial bones are peculiar to 

 both sexes. 



Scrotum and testicles, situate anterior to the 

 penis, the glans of which is usually bifurcated ; 

 uterus communicating with the vagina by two 

 narrow canals; thumb of the hind foot sometimes 

 wanting, at others very distinct, without nail and 

 opposable to the other toes ; dental system very 

 different in the various genera; canine^ some- 

 times wanting in one or both jaws ; incisors vary- 

 ing from two to six or ten in number, in most in- 

 stances the number varies in each jaw. 



First division. — Long canines and small inci- 

 sors in both jaws ; abdominal pouch in the fe- 

 male sometimes wanting. 



Genus. 

 Didelphis, Linn. Erxl. Bodd. Cuv. Geoff. Illig. 



