The purpose of this paper is to discuss certain aspects of pre-Karroo (unfossiliferous) stratigraphy of Tanganyika and to make certain proposals, which are considered desirable in order to further geological research in East Africa and to aid in regional and detailed mapping. A summary of the unfossiliferous rocks, together with these proposals, changing the names of certain systems, is systematized in Table I. The suggestions embodied in this scheme are as follows:

The Portencorkrie igneous complex, a trapezoidal area of plutonic rocks intrusive into Silurian sediments, is situated in the Rhinns district of Wigtownshire some sixteen miles south of Stranraer and about four miles north-west of the Mull of Galloway. It appears on the Geological Survey (Scotland) 1-inch Sheet 1, and lies within the Ordnance Survey 6-inch quarter-sheets Wigtownshire 33 S.W. and 37 N.W. To the north and south the igneous margin can be followed with fair accuracy, while to the east the boundary is obscured by drift. Westwards, the rocks pass beneath the Irish Sea.