CLASS MAMMALIA 



647 



burrow in the bank, the entrance of which is under water. In 

 this chamber one or two eggs are laid and the young reared. 



Order Marsupialia. — Marsupials or Pouched Mammals. — 

 The Marsupials occur mainly in Australia and neighboring 

 islands, but a few are natives of America. Their method of 

 reproduction is peculiar. The eggs,- which are without shells, 

 absorb food from the uterus; they are not laid, as in the mono- 

 tremes, but hatch within 

 the mother's body and the 

 young are born in an im- 

 mature condition. The 

 mother transfers them 

 with her lips to a pouch 

 on the abdomen, where 

 they are fed, by means of 

 teats, upon milk from the 

 mammary glands. 



The opossums (Didel- 

 PHUDiE) and kangaroos 

 and wallabies (Macro- 

 p.odid^e) are well-known 

 groups. The opossums 

 are confined to America. 

 There are four genera and 

 about twenty- five species; . 

 only one of these is com- 

 mon in the United States, 

 the Virginia opossum, 

 Didelphis virginiana (Fig. 514). The opossum occurs in the 

 Southern and Middle states. It sleeps during the day, usually 

 in a hollow tree or stump, but is active at night, seeking insects, 

 eggs, young birds and mammals, berries, nuts, etc., which con- 

 stitute its food. When disturbed the opossum frequently feigns 

 death, or " plays possum." Two or three litters of from six to 

 fourteen young each are produced per year. The young remain 



Fig. 514. 

 giniana. 



— The opossum, Didelphis vir- 

 (Photographed by the author.) 



