OF THE CLASS MAMMALIA. 235 



In some the young are born with the eyes open, and are 

 ready at once to seek their nourishment ; but a great number 

 are born with the eyes closed, and in a state of great feeble- 

 ness, so that they can scarcely move ; and some being born as 

 it were before their term, could not live, were they not to 

 attach themselves to the tit of the mother, to which they 

 remain as it were suspended. In such animals generally, 

 thus imperfectly developed at birth, the integuments of the 

 lower part of the belly form a pouch in front of the mammae, 

 in which the young are lodged for a time. This structure 



Tig. 194. The Opossum. 



characterizes the opossums of the New World, and the kan- 

 garoo and other marsupial animals of Australia. The young, 

 placed in this pouch by the mother, attach themselves each 

 to a nipple, and remain suspended there until sufficiently 

 strong to leave the pouch, to which, however, they return 

 as to a place of safety, until sufficiently grown to act for 

 themselves. 



