Myrmecobius, a genus of marsupial animals, established by Waterhouse, of which the typical species is the M. 'fasciatus of southern and western Australia. The teeth are very numerous, being incisors -8/6, canines 1/1-1/1 premolars 3/3 - 3/3, molars 5/6-5/6 =52. The fore feet are five-toed, with sharp nails for climbing and digging; hind feet four-toed, all free; head elongated, and snout acute; body slender; tail moderate and bushy. Length 10 in., tail 7 in. additional. The general color of the fore part of the body is reddish, gradually shading into the black of the posterior half, which has seven to nine white transverse bands; fur coarse above and finer underneath, below fulvous white. They have no pouch, the young, five to eight in number, being protected by the long hairs of the under side of the body. They are gentle, active, and squirrel-like animals, feeding on insects, especially ants, which they obtain by their long and extensile tongue, and on sweet vegetable juices; they are seen generally on trees, in whose hollows they live.
The fossil amphitherium or thylacotherium, of the lower oolite of Stonesfield, England, resembled the myrmecobius, as also did the dro-matherium of the trias of North Carolina, and the microlestes of the trias of central Europe.