MARSUPIALIA. 559 



turned inside out. Though they form an extremely natural 

 order, sharply separated from all the rest of the Mammals, 

 the Marsupials form a large and varied group. In fact, this 

 order, from being the almost exclusive possessor of a conti- 

 nent as large as Australia, has to discharge in the economy 

 of nature functions which are elsewhere discharged by several 

 orders. 



The Marsupialia are divided by Owen into the following 

 sections : 



a. Rhizophaga. In this section is the well-known Australian 

 animal, the Wombat (Phascolomys fossor), often called by the 

 colonists the " badger." The Wombat is a stout, heavy 

 animal, which attains a length of from two to three feet. The 

 legs are very short and stout, and the animal burrows with 

 ease by means of strong curved digging-claws, with which the 

 fore-feet are furnished. The tail in the Wombat is quite 

 rudimentary, and the whole body is clothed with a brown 

 woolly hair. In its dentition the Wombat presents a curious 

 resemblance to the herbivorous Rodents. There are two 

 incisors in each jaw, and these are long and rootless, growing 

 from permanent pulps. There are no canines, so that the 

 incisors and praemolars are separated by a considerable space. 

 The dental formula is 



i i o o i i 4 4 



i - c ; pm : m - - - = 24. 

 i 1> o o' * i i' 4 4 



The praemolars and molars agree with the incisors in growing 

 from permanent pulps, in which respect the Wombat differs 

 from all the other Marsupials, and agrees with the herbivorous 

 Rodents, with those Edentata which have teeth, and with the 

 extinct Toxodon (Owen). 



The Wombat is a nocturnal animal, and feeds chiefly upon 

 roots and grass. 



b. Poephaga. In this section are the Kangaroos (Macropo- 

 didce) and the Kangaroo-rats or Potoroos (Hypsiprymnus), all 

 strictly phytophagous. The Kangaroos are distinguished by 

 the disproportionate length of the hind-limbs and dispropor- 

 tionate development of the posterior portion of the body as 

 compared with the fore-limbs and fore part of the body. The 

 hind-legs are exceedingly long and strong, and the feet are 

 much elongated the whole sole being applied to the ground. 

 The hind-feet have four toes each, of which the central one 

 is by far the largest, and the two inner toes are very small, 

 and are united by a common integument. The tail is also 

 extremely long and strong, and by the assistance of this organ 



