They were thickly covered with eucalypti and brush, and, though based upon sandstone, were themselves of a schistose formation. YASS PLAINS. Yharr or Yass Plains were discovered by Mr. Hovel, and Mr. Hume, the companion of my journey down the Macquarie, in 1828. They take their name from the little river that flows along their north and north-west boundaries. They are surrounded on every side by forests, and excepting to the W.N.W., as a central point, by hill. Undulating, but naked themselves, they have the appearance of open downs, and are most admirably adapted for sheep-walks, not only in point of vegetation, but also, because their inequalities prevent their becoming swampy during the rainy season. They are from nine to twelve miles in length, and from five to seven in breadth, and although large masses of sandstone are scattered over them, a blue secondary limestone composes the general bed of the river, that was darker in colour and more compact than I had remarked the same kind of rock, either at Wellington Valley, or in the Shoal Haven Gully. I have no doubt that Yass Plains will ere long be wholly taken up as sheep-walks, and that their value to the grazier will in a great measure counterbalance its distance from the coast, or, more properly speaking, from the capital. Sheep I should imagine would thrive uncommonly well upon these plains, and would suffer less from distempers incidental to locality and to climate, than in many parts of the colony over which they are now wandering in thousands. And if the plains themselves do not afford extensive arable tracts, there is, at least, sufficient good land near the river to supply the wants of a numerous body of settlers. HOSPITALITY OF MR. O'BRIEN. We left Mr. O'Brien's station on the morning of the 21st, and, agreeably to his advice, determined on gaining the Morumbidgee, by a circuit to the N.W., rather than endanger the safety of the drays by entering the mountain passes to the westward. Mr. O'Brien, however, would not permit us to depart from his dwelling without taking away with us some further proofs of his hospitality. The party had pushed forward before I, or Mr. M'Leay, had mounted our horses; but on overtaking it, we found that eight fine wethers had been added to our stock of animals. HILL OF POUNI; ASPECT OF THE COUNTRY.