642 



MAMMALIA. 



Mammifer, is the existence of two peculiar bones attached to the 

 anterior margin of the pubis, which in the living animal are im- 

 bedded in the muscular walls of the abdomen, and thus support the 

 pouch of the female. The marsupial bones, however, exist in the 

 male likewise ; and even in the MONOTREMATA, that are evidently 

 nearly allied to the proper MARSUPIALS, although no pouch is 

 met with even in the female sex, the bones alluded to are found 

 connected with the pubis. 



This great section of the Vertebrate creation, which, perhaps, 

 ought rather to be regarded as a class by itself, is composed of 

 numerous families, of diverse forms and very opposite habits. The 

 Opossums (Didelphis) of the American continent live in trees, and 

 devour birds, insects, or even fruits : in these, the thumb of the 

 hind foot is opposable to the other fingers, and adapted for grasp- 

 ing the boughs, whence they are called Pedimanes; their tail is like- 

 wise prehensile. Others are terrestrial in their habits, wanting the 

 prehensile thumb. 



Fig. 298. 



The Kangaroo Rat, or Potoroo (Hypsiprymnus), of whose ske- 

 leton we have given a drawing (fg. 298), is remarkable for the dis- 

 proportionate size of its hind legs: these, moreover, have no thumb, 

 and the two innermost toes are joined together as far as the nails; 

 so that there appear to be but three toes, the inner one being fur- 

 nished with two claws. Such legs are well adapted to make strong 



