410 



GENERAL ZOOLOGY 



surrounding islands. The mammals comprising it are of vari- 

 ous external form, but the females of nearly all species have 

 an abdominal fold of skin forming a pouch into which the 

 almost helpless young are placed by the mother when born ; 

 they are then carried about with her until they are able to 

 take care of themselves. The kangaroos vary from the size 

 of a rabbit to that of a sheep. The hind legs are developed 

 for jumping. The Virginian opossum (Didel'pJiys Virginia 'na, 



FIG. 210. Photograph of Opossum 



Fig. 216) of our southern and middle Atlantic states is the 

 most northern member of the opossum group, many species of 

 which are found in South and Central America. It has the 

 habit of feigning death when in danger 'of capture, hence the 

 expression, " playing 'possum." 



Fossils from the rocks of the latter part of the Age of Rep- 

 tiles show that marsupials were widely distributed over the 

 earth at that time. Then came the separation of the Austra- 

 lian continent from the land to the north, isolating the mar- 

 supial fauna from the larger and more diversified land areas. 



