FAMILY DIDELPHID^E ; OPOSSUMS. 



343 



the genus Didelphis, or Opossum, of which about twenty species 

 are known, some of them very small. The teeth are more nume- 

 rous than in any other known terrestrial Mammal except the 

 MyrmecoUus,* the increase being in the number of the incisors, 

 which are ten above and eight below, the canines being (as usual) 

 one on each side of either jaw, and the molars seven, the four 

 last, or true molars, being crowned with sharp tubercles. The 

 limbs are short ; the feet plantigrade (or having the sole applied 

 to the ground) ; and the toes, which are five on each foot, armed 

 with sharp, strong, curved claws, except the inner toe or thumb 



Fro. 169. VIRGINIAN OPOSSUM. 



on the hinder feet, which is opposable and destitute of a nail. 

 The tail is scaly and naked, except at its base; and is usually 

 more or less prehensile. In some species the pouch is almost 



* A small shrew-like Marsupial, whose place seems to be between the two suc- 

 ceeding families. 



