392 
COMPENDIUM OF GEOGRAPHY AND TRAVEL 
because the island is evidently the centre from which 
most of the animals of the surrounding islands and many 
of those of North Australia have been derived. 
Mammalia are very scarce. The largest and almost 
the only placental mammal is the wild pig, of a peculiar 
species ; and there are also a few peculiar mice. All the 
rest are marsupials, the most remarkable being the small 
tree kangaroos forming the genus Dendrolagus , while some 
of those which are terrestrial are yet more allied to the 
sfiny ant-eater ( Proechidna ). 
last than to the Australian kangaroos. Seven other 
genera of marsupials belonging to the families Dasyuridce , 
Peramelidce , and Phalangistidce inhabit New Guinea, and 
of these, four do not inhabit Australia and one more is 
only found in the adjacent northern territory. The 
Monotremata are represented by spiny ant-eaters 
(. Proechidna ) of two species, allied to the echidna of 
Australia. 
In birds the richness is as conspicuous as is the 
poverty in mammals. Already more than 400 species 
