S ince my paper on Mesozoic Australian Geology was written, a lady, who had for some time resided in New South Wales, whilst on a visit in Bath, requested me to look at some minerals she had brought with her from Australia; and these consisted chiefly of auriferous quartz, variegated sandstones, and other specimens most likely to attract a lady collector. Amongst them, however, was a block, a few inches square, of what was supposed to be coal, which at first view looked very much like the Tertiary brown coal of Germany, and which Dr. von Hochstetter, in his account of the Geology of New Zealand, has shown to occur extensively in that colony. Its examination led me to observe that it was not bituminous, and that it was only a piece of chocolate-coloured, micaceous, laminated marl. Thinking it possible that it might contain Microzoa, the request that I might have it for examination was readily assented to. A memorandum on the block of marl indicated that the bed from which it came was ten feet thick, and that it was met with in sinking a shaft for gold, at a depth of from 100 to 110 feet, on the banks of the Rocky River, Sydney Flats. In the New-South-Wales Catalogue of the International Exhibition, T. Dalton, Esq., remarks, on the Rocky-River district, that vegetable remains were found in a silicified state amongst the lowest strata of sand, resting upon the granites, beneath the basalt on all parts of this gold-field.