262 POUCHED MAMMALS OR MARSUPIALS. 



Opossums lead solitary lives, except in the pairing 

 season when they occupy nests of dried grass, in the 

 hollows or roots of trees, which are shared by the young 

 as soon as they are able to leave the pouch. 



"The opossum brings forth a litter corresponding 

 more or less nearly to the number of her teats. These 

 are thirteen, disposed in a circle, six on each side and one 

 in the middle. 



"The developmental changes which take place within 

 the body of the mother occupy from twenty-four to 

 twenty-eight days. The young are then born in a per- 

 fectly helpless condition, and only about half an inch 

 in length. They are immediately placed in the pouch by 

 the mother, one being attached to each of the long teats. 

 The mouth at this stage is well formed, and the fore 

 limbs are sufficiently advanced for the claws to assist 

 the young to cling to the teats, but the hind limbs are 

 developed afterwards. After attachment, the corners of 

 the mouth grow up around the teat, insuring a more per- 

 fect channel for the flow of the milk ; this is further aided 

 by a well-marked groove on the upper surface of the 

 tongue. In five or six weeks the young opossums have 

 attained the size of little mice, and in about two months 

 have developed sufficiently to leave the pouch. 



In the species of Opossums that are characterized by 

 the absence of the pouch, the young are born practically 

 in the same condition, but they are carried on the back of 

 the mother after they are old enough to leave the teats, 

 being securely held there by means of their prehensile 

 tails, which are twined around the tail of the mother. 



The color variation in Opossums is largely due to age, 

 the half grown animals looking blackish at a little dis- 

 tance while the old ones have a whitish appearance. The 

 skins are worked up either in their natural color, or dyed 

 and sold as Black Marten or skunk opossum. 



