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THE MAMMALS 



Order— Marsupialia 



The marsupials are advanced over the monotremes in some respects, 

 but are primitive in a number of their characteristics when compared 

 with the other mammals. There is no cloaca in the adult — openings of 



I 





Photo by Carl R. Moore 



Fig. 28.4. Young opossums in the pouch of their mother. These baby "possums" are 

 less than a half inch long and each one's mouth has fused onto a nipple of the mam- 

 mary glands. They were "born" three days before this picture was taken. 



the anus and the urogenital tubes are separate. The mammary glands 

 have well developed nipples, and there are special muscles to pump the 

 milk down the throats of the nearly helpless young. The eggs are 

 large and, in most species of marsupials, contain all the food which 



