THE MARSUPIALS, OK POUCHED ANIMALS. 97 



and root-eating Marsupials are far more alike in 

 structure than are the Eutheria among one another. 

 The largest numbers of teeth fifty is found in 

 the opossum, Didelphys. The marsupial pouch 

 the characteristic feature of the class has, it is 

 true, become reduced to a few unimportant folds on 

 the abdominal skin. Still, because of the number 

 of their teeth, and because the earlier fossil Mam- 

 malia show most affinity to them, they must be 

 regarded as the least modified members of the 

 family. 



The Didelphida?, or Marsupial Eats, are now 

 confined to southern and central America. Neither 

 geology nor palaeontology gives us any clue as to 

 how this has happened: whether and when this 

 branch separated from the main group confined to 

 Australia : whether the agreement of the Didelphidas 

 with the other Marsupials is a matter of converg- 

 ence : or whether the Australian Marsupials are of 

 American origin. However, we shall have to return 

 to this latter supposition owing to an anatomical 

 peculiarity. The dentition of the Marsupial Eat 

 shows most resemblance to our Insectivora, and they 

 also agree with them in many ways as regards mode 

 of life and food. Even Cuvier discovered their fossil 

 remains in the Eocene strata of Paris. It was only 



