William Town, the seaport town of Australia Felix, named after his Majesty King William IV., stands on a very low piece of land forming the southern shore of Hobson's Bay, called Point Gellibrand, after a gentleman from Hobart, one of the first who brought stock to Port Phillip. He was lost in the bush in a very mysterious manner in 1834. No trace of him or his horse was found till 1842, when some of the natives showed where his mouldering bones lay. The point that bears his name scarcely projects sufficiently to afford large ships shelter from south winds in Hobson's Bay. In the North-West corner of the latter is the mouth of the Yarra-yarra river; but although only one mile and a half from the general anchorage, it is very difficult to be made out. The following anecdote will illustrate the difficulty of detecting the mouths of rivers in Australia. Soon after we anchored in Hobson's Bay, a small schooner passed, going to Melbourne. Several of the officers were at the time standing on the poop, and each selected a spot at which the schooner was to enter the river; and although, as I have before stated, we were only one mile and a half from it, none of us was right. A single tall bushy-topped tree, about a mile inland, rose over the schooner as she left the waters of Hobson's Bay. William Town consisted, at that time, of only a few houses. One disadvantage under which this place labours is badness of water, while the country around it is a dead level, with clumps of very open woodland. The formation is whinstone, but the soil's fertile quality shows an absence of sandstone. RIVER YARRA-YARRA. Proceeding up the Yarra-yarra, we found that about two miles from the mouth, the river divides, one branch continuing in a northerly direction, and the other, a narrow sluggish stream, turning suddenly off to the eastward. The banks are so densely wooded, that it is seldom if ever that its surface is ruffled by a breeze. MELBOURNE.