Number 22. Phascogale leucogaster, Gray. Head and shoulders grey, behind rather browner, with scattered longer black-tipped hairs; chin and beneath pure white; feet brownish grey. Body and head, 4; tail, 2 1/2 inches. Inhabits Western Australia, banks of the Canning River, April 1839, Mr. Gould. More specimens and further observations may prove these to be only local varieties of one species; but the specimens we have from the same localities are similar in character, which is not the case with the different specimens of Hepoona. Number 26. Perameles fasciata, Gray. Grey brown, rump with three black bands; tail white, with a black streak along the upper side. Inhabits Liverpool Plains and South Australia; smaller than P. gunnii. Number 28. Perameles fusciventer, Gray. Brown, yellow grizelled; tail above blackish, beneath grey; head short, conical; belly grey brown, with broad rufous channelled hairs. This species is like P. obesula in colour, but the head is shorter, and the belly of that species is white, with white bristles. Number 37. Dromicia nana. The dentition and the peculiar form and character of the tail of this species at once point out that it should constitute a distinct genus from the other Phalangers, from which it differs in many of its habits. Number 38. Hepoona cookii. Specimens from the same locality differ from one another in the extent of the white on the tail, in the darkness of the colour of the fur, and in the limbs and sides of the body being of the colour of the back, or more or less rufous. There are either five or six species, or only one. Number 39. I have retained the name of Petaurista for the flying Phalangers with hairy ears, as Dr. Shaw's Didelphis petaurus is evidently the same as P. flaviventer, and has naked ears, like the other species, and his name Petaurus should be used rather than Mr. Waterhouse's Belideus for this genus. Number 40. Petaurista leucogaster, may only be a variety of P. taguanoides. Number 42. Petaurus macrourus. This species is only known from the figures of Dr. Shaw. They have a specimen of a young Petaurista taguanoides, under this name, in the Paris Museum. Number 43. Petaurus breviceps. This is probably the species called P. peronii in Mr. G. Bennett's catalogue of the Australian Museum. It may also be M. Desmarest's; if this is so, the latter name will have to be adopted, and the one first used erased from the list. Number 47. The Macropi with hairy muffles are found in grassy places, while the Halmaturi are confined to the scrubs; and the Petrogalae, or Rock-Kangaroos, to the rocky districts; the latter, like Bettongia, sit with their tail between the legs. Mr. Gould informs me the animals of the latter genus also use their tails for the purpose of carrying the grass to their nests. The tree Kangaroos of New Guinea have a tail somewhat like a squirrel. These differences of habit show the propriety of dividing this group of animals into genera.