18. The same, of a greyish-brown colour; cells elliptic, and partly filled with carbonate of lime. “ Black mountains near Sockna.” 19. Greenish and yellowish grey, fine-grained crumbling sandstone. Found with the gypsum of the hills to the northward of Om-el-Abeed.” 20. The same, brownish-yellow ; “ occurring in beds near Om-el-Abeed.” 2 1. The same, reddish and yellowish, fine-grained, rather friable. . Wady Kawan. 22. Similar, reddish-brown variety of sandstone, but more friable than the preceding. Tadrart ridge. 23. The same, of a colour between grass and leek-green, fine-grained, very crumbling. “ Traghen, under a gypsum crust ; often in beds of from tèn to twelve feet. I t has the appearance of some of the soft sandstone in the mountain range near Tripoli.” 24. Yellowish-white friable sandstone, and fine sand, strongly impregnated with salt. “ Under a calcareous crust, Fezzan.” 25. Similar sand of a very fine rounded grain. “ From thé Wady, in which is the Trona lake.” 26. Yellowish clayey sandstone, filled with small rounded quartz grains and minute white particles of small univalve shells, (Paludina?) “ Gaaf.” j 27- Tine and close-grained yellowish-white sandstone, of a thin stratified structure, which is distinctly seen at the disintegrated parts of the fragment. “ Wady Katefa, under the basalt ; forming fine precipitous walls in the middle of the range.” 28. Brownish-red friable sandstone ; the rounded grains of various sizes, loosely united by clay. “ Sandstone of the hills of Wady Ghrarbi. There is a finer and tender species, and also a stratiform one ; but my specimens are lost.” 29. The same, of a similar colour, intermixed with yellowish, less crumbling, and containing pebbles. “ From the hills to the westward of Hamera, on which the town is built.” 30. Sandstone of yellowish colour and fine-grained, faintly variegated with purple. Aghadem; 31. The same, fine-grained, white, with linear purplish streaks, being the edges of horizontal filmy depositions of iron ochre of that colour. Wady Kawan. 32. A similar variety, exhibiting purplish-yellow and red variegations, thoroughly impregnated with salt, which is also seen efflorescent on the surface. “ Hills of Wady Ghrarbi.” S3. Similarly coloured sandstone, in laminar fragments, passing, by decomposition, into soft clay variegated with the same colours. Wady Kawar. 34. Tabular fragment of very close-grained nearly compact variegated sandstone ; colours, purplish and two shades of yellow, in irregular stripes. “ Sebha district.” 35. Purplish-brown slaty sandstone, micaceous on the planes of separation, passing into cream yellow and white clay-stone of the same structure. “ Aluminous slate (sic) in different states, forming a considerable part of the mountain range, Tadrart, Tuarick country.” 36. A tabular fragment, like the preceding; micaceous on the rifts, of reddish brown colour, being thoroughly penetrated by oxide of iron. Aghadem. 37- Yellowish sandstone, composed of round grains of quartz, with white clayey cement, which, towards the surface of the rolled piece, becomes quartzy. From ditto. 38. A similar large-grained variety, of reddish-yellow colour with brown streaks, in which the cementing clay, become quartzy, is scarcely distinguishable from the grains. “ Forming the eastern boundary of the hills near Traghen.” 39. A large fragment of the same quartzy sandstone, of yellow Colour, with red streaks and brown nucleus, nearly compact, so as to exhibit on its conchoidal fractural surfaces the traces only of a granular structure. “ Strewed over the plain between Ghudwa and Mourzuk.” 40. The same, brownish-red, in the shape of a rolled amorphous fragment, having acquired a uniform glossy surface like red jasper. From ditto. 41. Yellowish variety of the same, the granular passing into compact structure. “ Thick exposed beds from Om el Abeed to Sebha.” 42. Yellowish-grey variety of the same, as perfectly Compact tabular fragments, having their surfaces studded with small polymorphous bodies imitating the appearance of parts of secondary fossils. From ditto. 43. The same as the preceding, having its surface marked by small bivalve shells, converted into the mass of the sandstone. From ditto. 44. Sharp-edged fragments, of a variety like No. 39., of a deep chocolate- brown colour and flat conchoidal fracture. “ Between Sebha and Timinhint; rocks about 250 feet high.” II
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