MARSUPIALIA. 251 



American Marsupials extends also to the fossil forms 

 found in these regions, for the earliest marsupial remains 

 which have been detected in both countries are distinctly 

 allied to the existing Fauna. 



"In none of the orders of the higher mammalia do we 

 find such wide limits as to the size of the body, for the 

 order includes kangaroos as tall as a man, and little 

 mouse-like creatures of dwarf proportions. The fur is 

 in most cases long and soft, its coloring rarely very 

 marked, and often very sober. In the structure of the 

 skeleton the Marsupials are rather allied to the higher 

 mammals than to the Monotremes. The lower jaw is 

 always characterized by the inflection of the angle, a 

 peculiarity which has assisted in the recognition of the 

 marsupial character of the earliest fossil mammalian 

 remains, which almost invariably consist of lower jaws. 

 The number of bones in the vertebral column is remark- 

 ably constant, except in the caudal region, the tail being 

 more or less rudimentary in the Wombat and Koala, but 

 w^ell developed in the Kangaroos and Phalangers, serv- 

 ing the former species as a sort of fifth leg, and being 

 used by the latter in climbing. 



"The relative length of the fore and hind limbs is 

 very different in the different groups, the difference being 

 especially striking in the kangaroos, where the fore limbs 

 are particularly short. The bones of the fore arm are 

 distinct, and allow of a rotary motion, the one around 

 the other; the same is true of the bones of the hind legs 

 in the climbing forms, but in the leaping forms such 

 rotation is not possible. Of the toes of the hind feet, 

 the inner one is sometimes opposable after the fashion 

 of a thumb. This inner toe may be absent, or the second 

 and third next it may also disappear or be much reduced. 



"The brain of the marsupials is small, and consequently 

 the cavity of the skull is relatively small as compared 

 with the bones of the face. The surface of the brain is 

 almost destitute of convolutions, and the two halves of 

 the brain are less intimately joined by the corpus callo- 

 sum than is the case in the higher animals. 



In the number and arrangement of their teeth the 

 different families of Marsupials differ from one another 

 more than those of the higher orders. The vegetable 



