The district in which these fossils were found is on the eastern frontier of the Cape Colony in South Africa, about 500 miles east of Cape Town. No granite has been observed here, and the lowest rocks are stratified, and in consequence of the dip, though variable, tending on the whole towards the interior of the country, the lower members of them are those nearest the coast. A red quartzose crystalline sandstone is described by the author as the fundamental rock, and as alternating with a talcose slate. This sandstone is assumed to be of the carboniferous period, vegetable impressions, apparently of a Lepidodendron, having been found in it, and it is traced by the author towards the west, parallel to the coast to within 50 miles of the Cape. Over this there occurs a rock, called by the author a claystone porphyry, containing fragments of the sandstone; next an argillaceous slate, alternating with sandstone and containing thin laminæ of limestone, and at a little distance is a stratum full of vegetable remains. Further to the north is a ferruginous sandstone with argillocalcareous nodules, in which nodules were found the, remains of reptiles characterised by the author as Bidental , and described by Professor Owen in the subsequent memoir.