THE KANGAROOS AND THEIR ALLIES 



1409 



Malayan region. The channel separating L/ombok and Celebes from Java and Bor- 

 neo is, however, of much greater depth than those dividing the other islands, and it 

 may accordingly be inferred that any land connection which formerly existed be- 

 tween the two groups must have been remote. 



In the Tertiary period opossums were distributed over a large portion of 

 Europe, and recent discoveries indicate the existence during the same epoch of Mar- 

 supials allied to the Australian thylacine in South America. In the preceding Sec- 

 ondary period, as we shall show later on, Pouched Marsupials appear to have ranged 

 over the whole world, and were then, together with Egg-laying Mammals, the 

 chief, if not the sole representatives of the class. 



THE KANGAROOS AND THEIR ALLIES 

 Family MACROPODID^ 



We commence our survey of the Pouched Mammals with their most aberrant 

 and specialized representatives, or those commonly known as kangaroos, wallabies, 

 rat kangaroos, etc. And it may 

 be mentioned here, that whereas 

 kangaroos are very frequently 

 spoken of as typical Marsupials, 

 this is really very far from being 

 the case. It is true that they con- 

 form in all essential characteristics 

 to the Marsupial type of struc- 

 ture; but they have been specially 

 modified for a particular kind 

 of progression namely, leaping. 

 This has profoundly modified their 

 whole organization, and rendered 

 them some of the most specialized 

 of all Mammals; and they retain 

 accordingly but little resemblance 

 to what may be termed a typical, 

 or generalized Marsupial, such as 

 a bandicoot, or thylacine. 



The kangaroos belong to a 

 group or suborder of Marsupials 

 characterized by the adaptation of 

 their teeth to a vegetable diet. 

 Thus the front, or incisor teeth, 

 as shown in the figure on p. 1410, SKELETON OF KANGAROO. 



are never more than three in num- 

 ber on each side of the jaws, and are usually three in the upper and one in the 

 lower jaw; while in all cases the innermost pair in each jaw are of larger size, and 



