The _States of Northern Africa_ have a thoroughly Mediterranean fauna, whose facies on the whole shows rather more affinity to Spain than to Sicily. The Helices of Morocco and Algeria belong to the same groups as those of southern Spain. Many are of a dead white colour, the better to resist the scorching effect of the sun. _Ferussacia_ is abundant, _Geomalacus_ and _Parmacella_ are represented by a single species each, and there is one _Clausilia_. According to Kobelt,[366] the original land connexion between southern Spain and Morocco must have been much more extensive than is usually assumed, and probably reached at least to the meridian of Oran and Cartagena. The Mollusca of Oran and Cartagena are, according to him, much more closely related than those of Oran and Tangier, or those of Cartagena and Gibraltar, but at Cartagena some species, which are characteristic of the Mediterranean coasts from Syria westward, disappear, are absent from the rest of Spain and from Morocco, but reappear on the south-western coasts of France. These species may possibly have pushed along that arm of the sea which, when the Straits of Gibraltar were closed as far as the latitude of Oran and Cartagena, united in comparatively recent times the Bay of Biscay with the Gulf of Lions. The following genera, which do not occur in Spain, have probably spread into northern Africa as far as Algeria, _via_ Sicily and Tunis, namely, _Glandina_ (1 sp.), _Daudebardia_ (1 sp.), _Pomatias_ (2 sp.). Tunis shows strong traces of Sicilian influence, and Kobelt found a colony of snails, of Sicilian affinities, as far west as Tetuan. _The Sahara._--The Algerian Sahara contains, in many places, a sub-fossil Molluscan fauna which appears to show that the district has, in quite recent times, undergone a gradual desiccation. The species are mainly fresh-water, including _Melania_, _Melanopsis_, and _Corbicula_, with here and there valves of _Cardium edule_, and indicate, on the whole, an affinity with recent Egyptian, rather than North African species. It is probable that a vast series of _étangs_, or brackish-water lakes, once stretched along this region, and were ultimately connected with the sea somewhere between Tunis and Egypt. [Illustration: FIG. 195.--Characteristic shells of S. France: =A=, _Helix_ (_Macularia_) _niciensis_ Fér.; =B=, _Leucochroa candidissima_ Drap.] (ii) _Southern France._--The southern portion of France bordering on the Mediterranean contains many species, especially of _Helix_, which do not occur in the centre and north. Amongst these are--