MARSUPIALIA. 493 



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 



t - ; c ----- ; Am - ; m - - = 24. 

 i i ' o o' * i i 44 



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- 

 dida) 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 

 and the powerful hind-limbs the Kangaroos are enabled to 

 effect extraordinarily long and continuous leaps. In fact, leap- 

 ing is the ordinary mode of progression in the typical Kan- 

 garoos; and when walking upon all fours their locomotion 

 is slow and ungraceful. The anterior extremity of the body is 

 very diminutive as compared with the posterior, and the fore- 

 limbs are quite small, but have five well-developed toes armed 

 with strong nails. The head is small, with large ears, and the 

 dental formula is 



. 3 3 o o i i 4 4 



There are therefore six upper incisors, two lower incisors, 

 and no functional canines (though rudimentary upper canines 

 are present in the young of some of the Kangaroos, at any 

 rate). The stomach is complex, and sacculated. The Kan- 

 garoos are all herbivorous, and mostly live, either scattered or 

 gregariously, on the great grassy plains of Australia. The 

 " Tree-kangaroos," however (constituting the genus Dendro- 



