In a hasty sketch of the geological structure of the island of Cape Breton, which appeared in the second number of the ‘Quarterly Journal of the Geological Society,’ I stated that excellent sections of the Sydney coal-measures were exhibited in the sea-cliffs extending from Miray Bay to Gape Dauphin. I have recently examined one of the most interesting sections within those limits, viz. that afforded by the cliffs on the N.W. shore of Sydney Harbour, which runs directly at right angles to the strike of the strata, exposing almost every individual bed from the old red sandstone, through the overlying carboniferous limestone, millstone grit and coal-measures. The total thickness of the coal-measures, calculated from the highest bed of the millstone grit to their abrupt termination on the sea-coast, is 1843 feet, their dip being N.E. at an angle of 8°. In this section erect fossil trees are found at various levels, but they are more particularly abundant in a stratum of arenaceous shale lying almost immediately under the main coal, where within a space of eighty feet, measured along the base of the cliff, eight erect trunks are seen with roots and rootlets attached to them. Fig. 1 is a section of the strata under the main coal, showing the relative positions of the trees at right angles to the planes of stratification~ as they appear in the face of the cliff, the upper part of which overhangs and prevents us from observing how far the stems continue upwards. In