The publication of the Annual Reports for 1898 and 1899 of the Cape Geological Commission, coupled with the recent account of the geology of the Transvaal Colony by Dr. Molengraaff, and of which a short abstract has appeared in this Magazine, adds considerably to the knowledge of South African geology. The succession of the rock formations at the Cape has been constantly used as a basis of classification for the rock systems south of the Zambesi. In his recent paper Dr. Molengraaff correlates the formations of the Transvaal Colony with those met with in the south-eastern provinces of Cape Colony, and emphasizes the fact that the three stages of the Pretoria, Dolomite, and Black Reef series of the Transvaal Colony may be compared with the Witteberg, Bokkeveld, and Table Mountain Sandstone series of the Cape. It may therefore be of service to show on what grounds this supposed correlation is based. To do this the succession at the Cape of the formations below the Beaufort Beds in the typical region of the south-eastern province will first be given.