350 



CASSELL'S POPULAR NATURAL HISTORY. 



Another genus,* of wliicli the Virginian opos.su m is an example, is restricted to America. It 

 contains about twenty species. 



The upper incisors are ten, of which the two middle are longer than the rest ; the lower incisors 

 are eight; the canines as usual ; the molars above, seven, the first three, false, triangular, ronipivs.--.i'd ; 

 the molars below, seven, the first three false; the true molars, both above and below, crowned with 

 sharp tubercles. Of all terrestrial mammalia, the Myrniecobius excepted, these animals have the 

 greatest number of teeth, amounting to fifty. 



ASTRAGALUS OF 

 THYI.ACIXl.-S. 



TEETH OF TIlTl.ACINl'S. 



The limbs are short ; the feet plantigrade ; the toes, five on each foot, armed with sharp, strong, 

 curved claws, except the "inner toe on the hinder feet, which is opposable, and without a nail. A 

 naked skin, which is extremely sensible, covers the soles. The tail is scaly and naked, except at its 

 base ; it forms an organ of prehension, but varying in power in different species. The head is long and 



SKELETON OK THYI.AI IMS. 



pointed ; the profile straight ; the eyes small, dark, and prominent, having no eyelids, but provided 

 with a nictitating membrane. The ears are large, thin, naked, and rounded ; the tongue is rough, 

 with horny papillte ; the snout is long ; the muzzle pointed, naked, and moist ; the nostrils are lateral ; 

 the mouth very wide; and the expression of the face unpleasant. In one division, the females have a 

 pouch for their young ; in another, the pouch consists only ot a slight fold of skin. 



The opossums are the only marsupial animals that exist beyond the pale of New^Holland, and the 



DUU-lphi?. 



