POPULAR SCIENCE REVIEW. 
266 
strength of the ordinarily horn young in the more highly organ- 
ized or placental Mammalia. But one existing genus of these 
Marsupials is known elsewhere in the world — the opossums, 
viz., of America ( Didelphis , Linn.). Our knowledge of the 
various modifications of the Didelphs of Linnaeus has been 
derived exclusively from the remnant of that vast Melanesian 
continent of which Australia, Tasmania, New Gruinea, and a few 
outlying insular fragments now remain. The carnivorous kinds 
are represented by the Tasmanian Thylacine, of the size of the 
wolf, by the somewhat smaller Sarcophile or Devil of the Tas- 
manian colonists, and by still smaller Dasyures or native cats 
and weasels of Australia. The insectivorous kinds are repre- 
sented by the bandicoots (Perameles, Myrmecobius, Cheer opus) ; 
the frugivorous species by the arboreal phalangers, koalas, and 
petaurists ; the root-eaters by the burrowing wombats ; the 
grazers and browsers by the numerous and varied family of the 
saltatory potoroos and kangaroos. The largest existing marsupial 
in Australia is the Boomer kangaroo ( Macropus major). The 
skull of the biggest kangaroo which has come under my obser- 
vation does not exceed eight inches in length. Such a kangaroo 
will outweigh by one-half the biggest thylacine. 
John Grould, in his beautifully illustrated work on “ The 
Mammals of Australia,” gives the length of 2 ft. 2 in. to the 
wombat of Tasmania ( Phascolomys ursinus) ; the bones of the 
Phascolomys latifrons of the Australian continent indicate a 
somewhat larger animal, but the skull scarcely exceeds 7 in. in 
length. The skull of the largest of the extinct wombats is 
more than a foot in length. 
Between this and the largest existing wombat were two other 
species of intermediate dimensions ; there were also wombats 
distinct in kind, but resembling in size, the two or three 
existing species ; finally, there existed a smaller species in 
Australia. All these have passed away. Admitting the specific 
distinction of the two kinds of wombat now living in Australia, 
and that of the sole existing Tasmanian species, fossil remains 
have made known the former existence of seven kinds which 
have become extinct. These wombats ranged from the size of 
a marmot to that of the European bear ( Ursus arctos), and the 
distinctive characters of the largest kind are of generic value. 
The fossil evidences of kangaroos are more abundant and 
varied than those of the wombats. I shall limit myself to a 
brief notice of the larger extinct kinds. 
I have referred to the dimensions of the skull of the biggest 
known existing kangaroo. 
The first extinct species represented by the fossils obtained 
by Sir Thomas Mitchell, from the caves of Wellington Valley, 
had a skull of 10 in. in length. I called it Macropus Titan, 
