MARSUPIALIA. 49 1 



as in the Ornithorhynchus, but the two mandibles are greatly 

 elongated, and are enclosed in a continuous skin till close 

 upon their extremities, where there is a small aperture for the 

 protrusion of a very long and flexible tongue. The jaws are 

 wholly devoid of teeth or anything in the place of teeth; and 

 the nostrils are placed at the extremity of the cylindrical snout 

 The feet have five toes each, furnished with strong curved 

 digging-claws, but the toes are not webbed. The Echidna 

 measures from fifteen to eighteen inches in length, and is a 

 nocturnal animal. It lives in burrows, and feeds upon insects, 

 which it catches by protruding its long and sticky tongue. 



ORDER II. MARSUPIALIA. The order Marsupialia consti- 

 tutes by itself the sub-class Didelphia, and forms with the 

 Monotremata the division of the Non-placental Mammals. 

 With the single exception of the genus Didelphys, which is 

 American, all the Marsupialia belong to the Melanesian pro- 

 vince ; that is to say, they all belong to Australia, Van Diemen's 

 Land, New Guinea, and some of the neighbouring islands. 



The following are the characters which distinguish the 

 order : 



The skull is composed of distinct cranial bones united by 

 sutures, and they all possess true teeth ; whilst the angle of 

 the lower jaw is almost always inflected. The pectoral arch 

 has the same form as in the higher Mammals, and the cora- 

 coid no longer reaches the anterior end of the sternum. All 

 possess the so-called " marsupial bones," attached to the brim 

 of the pelvis. The corpus callosum is very small, and has 

 been asserted to be absent. The young Marsupials are born 

 in a very imperfect condition, of very small size, and at a 

 stage when their development has proceeded to a very limited 

 degree only. It is believed that there is no placenta or vas- 

 cular communication between the mother and foetus, parturition 

 taking place before any necessity arises for such an arrange- 

 ment. As the young are born in such an imperfect state of 

 development, special arrangements are required to secure their 

 existence. When born, they are therefore, in the great ma- 

 jority of cases, transferred by the mother to a peculiar pouch 

 formed by a folding of the integument of the abdomen. This 

 pouch is known as the " marsupium," and gives the name to 

 the order. Within the marsupium are contained the nipples, 

 which are of great length. Being for some time after their 

 birth extremely feeble, and unable to perform the act of suc- 

 tion, the young within the pouch are nourished involuntarily, 

 the mammary glands being provided with special muscles 

 which force the milk into the mouths of the young. At a 



