Page:The Zoologist, 4th series, vol 1 (1897).djvu/226

198 noticed. The aboriginal hunter puts a dead fish in the water outside the hole of the "Djinnjokma," and waits with a light spear all day for the animal to come out and feed; but very often he waits in vain, at least, that is my experience.

Only once on the Daly, in the month of August, an aborigine brought me a living adult female specimen with three young ones, and a few juvenile specimens were received later. The Hydromys is strong, of a very savage temper, bites hard, and when irritated gives vent to a grunting squeak.

The common Black Rat, Mus rattus, was observed in Arnhem Land, and frequently found in the dwellings of colonists. Except in these houses and their immediate surroundings, I did not observe it; but I am unwilling to lay any stress on the circumstance that no specimens of this species came to my notice during my travels in the forests. It may easily have escaped my attention, and the animal may, but certainly not to any great extent, inhabit the woods of the north. The species is undoubtedly introduced either by European ships or Malay trepang-fishers, the latter for centuries having every year visited the northern coasts of Australia.

Arnhem Land was inhabited not only by Mus rattus, but by a number of small species of the genus Mus, the specific determination of which has proved impossible, chiefly owing to the small series of specimens collected. These forms are undoubtedly indigenous to the country, and belong to the original fauna of Australia. They are so numerous and so widely distributed, even to the remotest parts of Arnhem Land, that they can scarcely be considered as introduced. In places where the white man had seldom, if ever before, trod, they seemed to occur in the greatest numbers.

These mice and rats, the size of which generally averages about that of the common Cricetus frumentarius of Europe, play a quite important part in the economy of nature. In order that the soil, even in its pristine condition, shall retain its power of nourishing vegetable life, a constant turning and renewal is necessary. Subsoil must in one way or another be conveyed to the surface, and replace that which has become deficient in nourishing