I n Australia, until the year 1860, no deposits of Secondary age had been demonstrated, although Sir T. L. Mitchell, in 1846, during his exploration of tropical Australia, had collected Belemnites and a few other fossils, which are now known to belong to a Lower Secondary formation, such as occurs on the Maranoa River, in Queensland. During my own explorations in 1851–3, I had received a portion of an Ammonite found in the Clarence River District, in New South Wales; and in 1859, Mr. Selwyn* obtained two supposed Cretaceous fossils from the drift-gravel in Victoria. But these were all the data that had been accumulated in Eastern Australia up to 1861, when my paper “On the position of certain plants in the Coal-bearing beds of Australia” was read before the Geological Society†. But of Oolitic fossils no species had been found in New South Wales in 1860, nor to my knowledge in any part of Australia, as stated in my book on the Gold-fields; for I was then unaware even that Mr. Gregory had discovered any Secondary fossils in Western Australia, which fact I first became acquainted with in an editorial note appended to the paper cited. In Mr. Gregory's paper‡, afterwards published, he mentions Cretaceous, but not Jurassic fossils. Shortly after this, my friend Mr. W. P. Gordon, who then lived at Wollumbilla, north of the Condamine River, was requested by me to examine his neighbourhood, and to send me any fossils he might discover, as I was led to