May 5.--Proceeded down the river, ascended the eminence mentioned yesterday, and from the top of a cypress tree a very distant view of the whole country was obtained: the opening through which the river apparently runs bore S. 75 1/2 W.; the country to the south and south-west extremely low. A range of hills, lying nearly east and west, bounded the level tract on the other side of the river; these hills and two or three detached hammocks excepted, there was nothing to break the uniformity of the scene. The country was in general poor, with partial tracts of better ground; the hills were slaty, and covered as well as the levels with small eucalypti, cypresses, and casuarinas. About a mile from this place we fell in with a small tribe of natives, consisting of eight men; their women we did not see. They did not appear any way alarmed at the sight of us, but came boldly up: they were covered with cloaks made of opossum skins; their faces daubed with a red and yellow pigment, with neatly worked nets bound round their hair: the front tooth in the upper row was wanting in them all: they were unarmed, having nothing with them but their stone hatchets. It appeared from their conduct that they had either seen or heard of white people before, and were anxious to depart, accompanying the motion of going with a wave of their hand. About three miles from our last night's halting-place we had to cross a small creek, the banks of which were so steep that we were obliged to unload the horses. I rode up the creek about three quarters of a mile, and came upon those extensive plains before-mentioned; the soil of this level appears a good loamy clay, but in some places very wet: it was far too extensive to permit us to traverse much of it; we saw sufficient to judge that the whole surface was similar to that we examined; it was covered with a great variety of new plants, and its margin encircled by a new species of acacia, which received the specific name of PENDULA, from its resembling in habit the weeping willow. Low hills to the north bounded this plain, whilst a slip of barren land, covered with small trees and shrubs, lay between it and the river. It appeared to me that the whole of these flats are occasionally overflowed by the river, the water of which is forced up the creek before-mentioned, and which again acts as a drain on the fall of the water.