OPOSSUMS. 



277 



Stirling, by whom the marsupial mole was first made known to science, states that 

 most of the specimens he obtained were "captured by the aboriginals, who, with their 

 phenomenal powers of tracking, follow up their traces until they are caught. For 

 this reason they can only be found with certainty after rain, which sets the surface 

 of the sand and enables it to retain 

 tracks that would lie immediately 

 obliterated where it is dry and loose. 

 Nor are they found except during 

 warm weather, so that the short period 

 of semitropical summer rains appears 

 to be the favourable time for their 

 capture." Perpetual burrowing seems 

 to be the characteristic trait of this 

 animal. On "emerging from the sand, 

 it travels on the surface for a few 

 feet, at a slowish pace, with a peculiar 

 sinuous motion, the belly much flat- 

 tened against the ground, while it 

 rests on the outsides of its fore-paws, 

 which are thus doubled in under it. 

 It leaves behind it a peculiar sinuous SKULL f 1 and -) ^ D skeleton of the hind (3) and 



. . , i,i , • • FORE (4) FEET OF THE POUCHED-MOLE (about 3 Hat. 



triple track, the outer impressions, size ).-After Stirling. 



more or less interrupted, being caused 



by the feet, and the central continuous line by the tail, which seems to be pressed 



down in the rear. It enters the sand obliquely, and travels underground either for 



a few feet or for many yards, not apparently reaching a depth of more than 



two or three inches, for whilst underground its progress can often be detected by 



a slight cracking or moving of the surface over its position.'' 



The Opossums. 



Family DlDELPHYIDsE. 



The last family of the existing Marsupials is constituted by the well-known 

 opossums, which are now confined to America, although during the early portion 

 of the Tertiary period they also ranged over Europe. Closely allied to the 

 Australian Dasyuridce, the opossums are mainly distinguished by the hind-foot 

 having a well-developed inner toe, which, although nailless, is capable of being 

 opposed to the other digits. They are further distinguished by the number of their 

 incisor teeth, of which there are five pairs in the upper and three in the lower jaw. 

 The tail is generally of considerable length, partially naked and prehensile at the 

 extremity; and the feet are likewise devoid of any hairy covering. Although com- 

 plete in a few of the species, the pouch is generally either wanting altogether, or 

 represented merely by a couple of longitudinal folds in the skin of the abdomen, which 

 partially conceal the numerous teats. As a rule, opossums may be compared in 

 general outward appearance to rats, although they have longer snouts terminating 



