1410 



THE POUCHED MAMMALS, OR MARSUPIALS 



SKUI.IV OF I,ESUEUR'S RAT KANGAROO. 



c. tusk, or canine tooth. 



adapted for cutting. As a rule their upper canine teeth, or tusks, are small, or 

 wanting, and this invariably holds good for those of the lower jaw. As regards 

 their molar teeth, these are invariably characterized by having broad, flattened 

 crowns, surmounted either by tubercles or transverse ridges, and adapted for the 

 trituration of vegetable substances. 



The members of the Kangaroo family vary greatly in size, and in the relative 

 length of the hind-limbs, but they are collectively characterized as follows. In the 

 upper jaw there are three pairs of incisor teeth, with sharp and cutting edges; while 

 the lower jaw is furnished with a large single pair inclining forward, and sometimes 



biting against one another with a scis- 

 sor-like action. The upper canine, or 

 tusk, if present at all, is of small size, 

 as in the accompanying figure; while 

 there is no corresponding lower tooth. 

 In the adult the cheek-teeth are five 

 in number on each side, of which the 

 first is a premolar; this condition ob- 

 taining in the figured skull. In young 

 animals there are, however, two milk- 

 molars in place of this premolar; the 

 number of cheek-teeth then being six 

 on each side. The molar teeth them- 

 selves may carry either a pair of transverse ridges, or four blunt tubercles. A char- 

 acteristic feature of the family is to be found in the lower jaw, which has a deep 

 pocket in the outer side of the hinder portion, communicating at its base by a large 

 perforation with the canal on the inner side. The pocket is shown in the accom- 

 panying figure, but the communicating aperture is concealed by its outer wall. In 

 all the members of the family the fore-limbs are short and feebly developed, with 

 five complete digits. The hind-limbs, on the contrary, are very powerful, and more 

 or less elongated. Usually they have but four toes, of which the one corresponding- 

 to the fourth in the typical series of five is much larger than either of the others, 

 and terminates in a huge claw. The outermost toe is considerably smaller, but still 

 stout. The two toes on the inner side of the large one, corresponding to the second 

 and third of the typical series, are, however, reduced to small slender rods, lying 

 parallel to one another, and inclosed in a common skin. These rudimental digits 

 are of course useless in progression, and their aborted condition is technically known 

 as syndactylism. The head, especially in the larger forms, is small in proportion 

 to the body, and tapers toward the muzzle. Generally the tail is long, cylindrical, 

 and tapering; while it frequently aids in supporting the body, and may be prehensile. 

 The female is provided with a large pouch, of which the aperture looks forward. 



All the members of the Kangaroo family are purely vegetable feeders, and are 

 mainly confined to Australia and Tasmania, where, before the introduction of sheep 

 and cattle, they took the place of the Ruminants of other regions. They are di- 

 vided into numerous genera, of which the first includes the true kangaroos and wal- 

 labies. 



