Examples of the Australian echidna have on several occasions been "in residence" at the Zoo; while the Hon. Walter Rothschild has been fortunate in keeping living specimens of both this and the very rare three-toed New Guinea variety in his admirably appointed menagerie at Tring.
Photo by W. Saville-Kent, F.Z.S.] [Milford-on-Sea.
COMMON OR VIRGINIAN OPOSSUM.
The only marsupial animal found north of Mexico.
The Platypus.
The egg-laying mammal known as the Duck-billed Platypus differs very essentially from the echidna both in aspect and habits. It is adapted especially for an amphibious life, and for feeding on molluscs, worms, and insects, which it abstracts from the muddy bed or banks of the rivers that it frequents. The somewhat depressed ovate body is covered with short dense fur much resembling in colour and texture that of an otter. The tail is short and flattened like that of a beaver, but in place of being naked and scaly, as in that animal, is covered, on the upper surface more particularly, with long, coarse, bristle-like hairs that intercross one another in all directions. Neither is this tail used, as with the beaver, as a mason's trowel, it being simply subservient as a steer-oar. The feet are all four distinctly webbed, the membranes of the front feet in particular projecting to some distance beyond the extremities of the claws, and so communicating to these members a singular resemblance to the feet of a duck. The head of the platypus tapers off from the body without any conspicuous neck, and terminates in a most remarkable duck-like beak, having at its base a supplementary membranous ferrule-like structure which would seem to serve the purpose of limiting the distance into which the beak of the animal is thrust into the mud during the quest for its accustomed food, and at the same time protecting the creature's eyes. The mouth of the adult platypus contains no teeth, simply a few horny plates; but, singularly to relate, rudimentary teeth exist temporarily in the young animals. These provisional teeth, moreover, correspond in a marked manner with those of some ancient types of mammals which occur as fossils in the tertiary deposits of North America. The platypus, with relation to the obliteration of its teeth in the adult state, is regarded as a very exceptionally modified form and not as the immediate prototype of the ordinary mammals.
The platypus is found in Tasmania and in the south and eastern districts of Australia only, being altogether unknown in the west and north. Being especially shy and retiring, and to a large extent nocturnal in its habits, it is not frequently seen even in districts where it may be rather abundant. The animal excavates burrows of so great a length as from thirty to fifty feet in the river-banks that it frequents, and at the extreme end of these burrows it constructs a loose nest of weeds and root-fibres, which it uses as its retreat, and also for the production of its eggs and young. There are invariably two entrances to these burrows, the one being under water, and the other usually opening into a tangle of brushwood at some little distance from the water's edge. As many as from one to four eggs and young may be produced at a time, but two is the more general number. From the first it would appear that the eggs and young are deposited and nursed in the nest, not being retained or carried about in a pouch, as observed of the echidna.
Photo by D. Le Souef] [Melbourne.