_Lanistes carinatus_,[72] scarcely distinguishable from the Nile form. The _Melania_ occurring in mass in the uppermost calcareous bed appears to be a new species[73] whose nearest relation must in any case be _M. Nysti_ of the Oligocene, not _M. muricata_ of the Eocene, amongst forms at present known. _Turritella angulata_, Sow. A marine form, occurring below the basalt and indubitably this species, as it is well preserved and easily determined[74]; _T. angulata_ ranges from the Middle Eocene to the Lower Oligocene of the East and occurs in the Upper Mokattam of Syria.” From Widan el Faras the series continues westwards, forming several escarpments, the uppermost that of Jebel el Qatrani, and maintaining the same general characters. The tripartite character of the series, already noticeable between Qasr el Sagha and Widan el Faras (see foregoing section) becomes still more marked. The lowest division is very largely composed of fluviatile sands and sandstones, frequently coarse-grained and usually markedly current-bedded, divided by clays and containing an abundance of silicified trees and quantities of vertebrate remains. These soft beds, some 60 metres in thickness, have as a rule an extensive outcrop, forming an undulating plain averaging two or three kilometres in width. They are overlaid by some 17 metres of harder dark red sandstones, which invariably form a well-marked escarpment capped by a very constant two or three metres band of hard white or pinkish calcareous grit. This grit varies in composition, frequently passing into a marl; and one of the characteristics of this and the underlying red beds is the abundance of nodular masses of calcite and gypsum. In some localities, as for instance 3 kilometres W.N.W. of Qasr el Sagha, numerous spherical nodules of beekitic chalcedony occur in the beds of this division, and some of these when broken are found to be geodes lined with beautiful crystals of quartz and calcite.