, has produced in the end very similar
results in both cases. Still, when we come to examine the more intimate
underlying structure of the two animals, a profound fundamental
difference at once exhibits itself. The one is distinctly a true
squirrel, a rodent of the rodents, externally adapted to an arboreal
existence; the other is equally a true phalanger, a marsupial of the
marsupials, which has independently undergone on his own account very
much the same adaptation, for very much the same reasons. Just so a
dolphin looks externally very like a fish, in head and tail and form and
movement; its flippers closely resemble fins; and nothing about it
seems to differ very markedly from the outer aspect of a shark or a
codfish. But in reality it has no gills and no swim-bladder; it lays no
eggs; it does not own one truly fish-like organ. It breathes air, it
possesses lungs, it has warm blood, it suckles its young; in heart and
brain and nerves and organisation it is a thorough-going mammal, with an
acquired resemblance to the fishy form, due entirely to mere similarity
in place of residence.

Running hastily through the chief marsupial developments, one may say
that the wombats are pouched animals who take the place of rabbits or
marmots in Europe, and resemble them both in burrowing habits and more
or less in shape, which closely approaches the familiar and ungraceful
guinea-pig outline. The vulpine phalanger does duty for a fox; the fat
and sleepy little dormouse phalanger takes the place of a European
dormouse. Both are so ridiculously like the analogous animals of the
larger continents that the colonists always call them, in perfect good
faith, by the familiar names of the old-country creatures. The koala
poses as a small bear; the cuscus answers to the racoons of America. The
pouched badgers explain themselves at once by their very name, like the
Plyants, the Pinchwifes, the Brainsicks, and the Carelesses of the
Restoration comedy. The 'native rabbit' of Swan River is a rabbit-like
bandicoot; the pouched ant-eater similarly takes the place of the true
ant-eaters of other continents. By way of carnivores, the Tasmanian
devil is a fierce and savage marsupial analogue of the American
wolverine; a smaller species of the same type usurps the name and place
of the marten; and the dog-headed Thylacinus is in form and figure
precisely like a wolf or a jackal. The pouched weasels are very
weasel-like; the kangaroo rats and kanga