194 



MAMMALIA ORDER XI.MARSUP1ALIA. 



the heading of kangaroos proper, and larger and lesser wallabies. While 

 the great grey kangaroo (M. giganteus) has the stature of a man, some of the 

 smaller wallabies are no bigger than a rabbit. The great majority of the 



species are confined to Australia and Tas- 

 mania, but the agile wallaby (M. agilis) is 

 common to Australia and New Guinea, 

 while the Aru Island wallaby (M. brnnii) is 

 restricted to the Aru and Kei Islands, and 

 the sombre wallaby (M. browui) is common 

 to New Guinea and the New Britain group. 

 From the true kangaroos the larger wal- 

 labies differ by their more brilliant coloration, 

 and the presence of a longitudinal external 

 bridge connecting the anterior ledge of the 

 molars with the first of the two transverse 

 ridges, coupled with the absence of a median 

 longitudinal bridge between the same ledge 

 and ridge. The habits of kangaroos and 

 wallabies have been so often described as 

 to render a repetition unnecessary. 



From the preceding genus the six species 

 of rock -wallabies (Petrogale) are distin- 

 guished by the shortness of the large claw 

 of the hind-foot, which only slightly exceeds 

 the naked pads on the sole in length, and 

 by the long cylindrical tail being thinner, 

 more thickly haired, and tufted at the tip. 

 These wallabies are restricted to the Australian mainland, and differ from the 

 true wallabies by inhabiting rocky districts instead of open plains. Their 

 climbing and leaping powers are highly developed ; but the tail is employed 

 solely as a balancing organ, and never as a support to the body. The 

 presence of a horny spur or nail of unknown function at the tip of the long, 

 tapering, and short-haired tail is a sufficiently distinctive feature of the three 

 nail-tailed wallabies constituting the genus OnychogaU. In addition to this, 

 these animals have the nose hairy (with the exception in some cases of the 

 base of the partition between the two nostrils) ; while the large claw of 

 the hind-foot is long, narrow, compressed, and sharply pointed. There is 

 also a difference in the form of the upper incisor teeth. Like the rock- 

 wallabies, the members of this genus are restricted to continental Australia. 

 The same is the case with the three species of hare-wallabies (Lagorchestes), in 

 which the nose is entirely or partially covered with hair, the large claw of the 

 hind-foot is long, stout, and not concealed by hair, while the rather short tail 

 is evenly haired throughout its length. In some respects forming a con- 

 necting link between the genus Macropus and the under- mentioned tree- 

 kangaroos, the three species of dorca kangaroos (Dorcopsis) are confined to 

 New Guinea, and present the following distinctive features. The excess in 

 the length of the hind over the fore-limbs is much less strongly marked than 

 in the true kangaroo and wallabies ; there is a large and broad portion 

 of the nose completely naked ; the head is long and narrow, with small ears ; 

 the fur on the nape of the neck is entirely or partially reversed, so as to 

 be directed forwards towards the head. In both jaws the fourth pre-molar 

 is a compressed cutting tooth, greatly elongated, from before backwards, and 



Fig. 10 2. -BENNETT'S WALLABY 

 (Macropus ualabatus). 



