IN Petermann's Geographische Mittheilungen, 1884, Heft iv., is an article on the island of São Thomé, accompanied by maps both of that island and of the neighbouring island of Rolas, by Prof. R. Greeff in Marburg. The contribution is the result of several months' residence on those islands in the course of a scientific tour through the islands of the Gulf of Guinea in 1879 and 1880. The map of the two islands in question is the united product of Prof. Greeff and of the proprietor of Rolas, Francisco José de Araujo: a map based partly on immediate exploration and observation, partly on careful information derived from natives. It both corrects and supplements in considerable measure the only two previous maps of St. Thomas known to the authors—that of 1829 by the English commander, T. Boteler, and that of 1844 by the Portuguese, Lopez de Lima. In the present map are entered for the first time the districts into which St. Thomas is divided, its “villas,” its connecting highways, its more important plantations, and also the demarcation between the comparatively small cultivated part and the large wooded wilderness of the south and the interior. The map of Rolas is the first that has yet appeared of this island, which is intersected by the Equator. The history of St. Thomas is sketched from the year 1470, when it was discovered, without a single human inhabitant and almost wholly overgrown with forest, by the Portuguese sailors, João de Santarem and Pero de Escobar. Prof. Greeff calculates the dimensions of the island, which stretches ovally from 0° 2′ to 0° 30′ N. lat. and from 6° 34′ to 6° 54′ E. long., at about 52 kilometres by 34 kilometres, or altogether about 920 square kilometres.