36 THE NOTOG^IC REALM. [CHAP. 



Tasmania, one (M. agilis) is common to Australia and Queens- 

 land, and two others (M. bruijni and M. browni} are confined to 

 New Guinea or the adjacent islands. Of the six species of rock- 

 kangaroos (Petrogale), none are found out of continental Australia, 

 and the same is true with regard to the three representatives of 

 the nail-tailed wallabies (Onychogale), and likewise with the three 

 hare-wallabies (Lagorchestes}. On the other hand, the three kinds of 

 dorca kangaroo (Dorcopsis) are exclusively Papuan ; while of the 

 climbing tree-kangaroos (Dendrolagus), three are from Papua 

 and two from Queensland. The single species of banded wallaby 

 (Lagostrophus) is Australian ; as are also the whole of the rat- 

 kangaroos, forming the genera Potorous, Caloprymnus, Bettongia, 

 and sEpyprymnus, and likewise the peculiar musk-kangaroo 

 (Hypsiprymnodon), which serves to connect the other members of 

 the family with the phalangers. 



Several of the existing representatives of the above-mentioned 

 genera are found in a fossil state in the cavern-deposits of New 

 South Wales and the Plistocene formations of Queensland, in 

 addition to which there are likewise several extinct representatives 

 of the genus Macropus, some of which considerably exceed the 

 largest living forms in point of size. The same formations have 

 also yielded the remains of three extinct genera, namely Palor- 

 chestes, Procoptodon, and Sthenurus, all of which appear to have 

 been allied to the wallabies, although some of the species were 

 vastly larger than any existing kangaroo. Another, but very im- 

 perfectly known genus Triclis, seems to have connected the 

 musk-kangaroo so closely with the phalangers, that it is scarcely 

 possible to draw any distinction between these two families. 



In the family of the phalangers (Phalanger idcz], which 

 differs from the more typical representatives of the preceding 

 by the more generalised characters of the skull, teeth, and 

 limbs, there is an exclusively Australian form in the koala, 

 forming the sole representative of the genus of the same name. 

 Of the five species of cuscuses (Phalanger}, one is, however, 

 common to northern Australia, New Guinea, and the Austro- 

 Malayan Islands, while the other four are restricted to the two 

 latter areas. The two species of true phalanger (Trickosurus) are, 

 on the other hand, exclusively Australian ; while the ring-tailed 



