They consist of long, square, circular, or oval enclosures—dolmens similar to those of Western Europe,—and almost always surrounded by circles of upright stones. The silence of historians respecting them need not make us doubt their extreme antiquity, for did it not take a very long time to induce the scientific men of our day to turn their attention to Algeria at all? The exploration of Tunisia has enabled us to study the Stone age in that district, and a few years ago it was announced that nearly three thousand objects of different types had been found in thirteen different localities.38 My son found near Gabes an immense number of small worked flints not unlike a human nail, the origin and use of which no one has been able to determine. The association of weapons and implements roughly finished off, with chips and stones still in the natural state, bears witness to the existence at one time of workshops of some importance. The recent discoveries of Collignon correspond with those in Algeria, and complete our knowledge of the basin of the Mediterranean. In the Cave of Hercules, in Morocco, which Pomponius Mela spoke of as of great antiquity in his day, have been found a great many worked flints, such as knives and arrow-heads. We shall refer later to the important monument of Mzora and the menhirs surrounding it, the builders of which certainly belonged to a race that lived much nearer our own day than did the inhabitants of the Cave of Hercules. The south of Africa is not so well known as the north, and the difficulty of making explorations is a great obstacle to progress. For some centuries, however, polished stone hatchets from the extreme south of the continent have been preserved in the museums of Leyden and Copenhagen, under the name of _thunderstones_, or _stones of God_. A great many are found in British South Africa, especially at Graham’s Town and Table Bay.39 Gooch, after describing the physical configuration of the Cape, says that stone implements are found in all the terraces at whatever level of the Quaternary deposits. With these stone objects were found a good many fragments of coarse hand-made pottery, that had been merely baked in the sun, and was strengthened with good-sized pieces of quartz. Similar peculiarities are noticed in ancient European pottery. We shall have to refer again to these singular analogies, one of the chief aims of this book being to bring them into notice.