I have not made any special study of stone implements, nor have I been able to pay any considerable attention to their collection during my journeys, having usually found my time very fully taken up with other matters. I have, however, been much struck by the wide distribution of stone implements in the desert. I have found them, for instance, not only in Siwa Oasis and near the wells of Abu Mungar and Sheb, but also on the plateau between Baharia and Farafra, on the open desert between Terfawi and Owenat, and to the south-west of Owenat near the Anglo- French boundary. This wide range of occurrence, coupled with the finds of Schweinfurth and others on the plateaux nearer the Nile, inclines me to think that there is scarcely any part of the Libyan Desert in which stone implements might not be found by an expedition which would make the collection and study of them one of its main objects. The likeliest places in which to search (besides the neighbourhood of old wells and springs) would appear to be the shores of the various lakes and around the feet of hills affording shelter from wind and sun; for it is in such localities that I have most usually come across implements and pottery. Grinding-stones, often with a sort of stone rolling-pin, unpolished celts, knives, and arrow-heads are the principal forms of implement I have met with. Many of the grinding-stones must have been carried for a considerable distance, for they are made out of rocks which do not naturally occur in the localities in which they are found. Whether this wide distribution of stone implements would justify the view of Blanckhenhorn[59] that primitive man lived on the desert plateaux rather than in the Nile Valley must, I think, be settled by the further collection of specimens and by a careful comparison of the forms to be found in the two situations. In this connection I may remark that the grinding-stones I have seen in the desert seemed to me to be very similar to those used by the Nubians of the Nile Valley to-day for grinding corn. APPENDIX SOME RECENTLY DETERMINED POSITIONS IN THE LIBYAN DESERT