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VERTEBRATE ANIMALS. 



Order II. Marsupialia. 



The name of Marsupials is derived from the fact that the females 

 of this order are furnished with an abdominal pouch or marsupium 

 (sometimes very imperfect), within which the nipples are situated. 

 When born, the young are placed by the mother within this pouch, 

 where they adhere to the teats, and can be carried about without 

 injury. Even when further advanced, the young often betake them- 

 selves to the shelter of the marsupium. No placenta is present, and 

 the young when born are therefore in a very imperfectly developed 

 state. The so-called "' marsupial bones " (fig. 228) are present, and 

 as they spring from the front of the 

 pelvis they no doubt serve to support 

 the pouch ; but this cannot be their 

 sole use, as they exist in the males, and 

 also in the Montremes, in whom there is 

 no pouch. All Marsupials possess teeth, 

 and the pectoral arch has now the same 

 form as in the higher Mammals, the 

 coracoid bones being now amalgamated 

 with the shoulder-blade. The cranial 

 bones are distinct. The intestine does 

 not terminate in a cloaca. 



Though the Jlarstipialia form an ex- 

 tremely natural order, sharply separated 

 from the other Mammals, they include a 

 large number of varied forms. In fact, 

 this order, from its being the almost ex- 

 clusive possessor of a continent so large 

 as Australia, has to discharge, in the 

 general economy of nature, functions 

 which are elsewhere performed by sev- 

 eral orders. As regards their geograph- 

 ical distribution, with the single excep- 

 tion of the family Didelphidts (the true Opossums), the whole order 

 of the Marsupials is exclusively confined to Australia, Van Diemen's 

 Land, New Guinea, and the adjacent islands. 



The Marsupials may be primarily divided into the vegetable-eating 

 and the rapacious or carnivorous forms — the former characterised by 

 the absence or rudimentary condition of the canine teeth, the molars 

 having broad, grinding crowns ; whilst in the latter there are well- 

 developed canines, and the molars are not adapted for grinding. Of 

 the vegetable-eating forms, the best known are the Kangaroos (J/oc- 



Fig. 228. — One side of the pelvis 

 of a Kiingaroo, showing; the 

 " marsupial bones " (m) — after 

 Owen. 



