2. An unrolled agate from Om el a Beed, near Zeghen, on the south of the Black Mountains. The occurrence of fragments of basalt, in this same neighbourhood, renders it probable that basaltic rocks exist in Situ, near the Pass of Kenair. TERTIARY FORMATIONS. 3. Two species of cardium, in a state of delicate preservation, resembling that of the shells of Grignon, near Paris, and embedded in a loose white sand, which has the appearance and degree of adhesion of coarse white sugar, from a gravelly plain on the north of Bonjem. 4. Slightly crystalline limestone, of a dark yellow colour, and loaded with fragments of organic remains, amongst which the most distinct are referrible to the genus Ostrea and Pecton. It is found in a mountain of Tripoli, thirty miles south of Benioleed. This limestone appears to be nearly of the same era with the Calcaire Grossier of Paris, and is separated only by a large desert plain from the deposit of shells last mentioned at Bonjem. The probable connexion of these strata with the tertiary formations in other adjacent parts on the coast of the Mediterranean, has been already suggested. 5. Soft, highly calcareous marl stone, of a light mottled gray colour, resembling in appearance the chalk marl of England: it is said occasionally to be streaked with red, and to contain modules of flint. It occurs in the Mountains of Mejdool, in lat. 26. 6. Quartzose sand dispersed through a matrix of indurated green clay, and affording the materials of which the town of Traghan is built. It is probable that these two last specimens, 5 and 6, are from strata not more ancient than the chalk of England, and possibly connected with the tertiary formations, No. 3 and 4. NEW RED SAND STONE. 7. Sand collected fifty miles on the north of Sockna, during a gale of wind from the drift sand, which is blown about the desert. It is composed of extremely minute grains of red semi-transparent quartz; observed with a lens, these grains appear to be rounded fragments, and present no crystalline facets. They possess, in a strong degree, that peculiar tint of red, which has caused the name of red sand stone to be applied to certain extensive formations which it pervades in Europe. The frequent occurrence of salt springs, and of rock salt and gypsum in the deserts of Africa, goes far to identify the sand of this continent with the new red sand in the south of England, which is characterised by containing similar mineral substances. It is still farther allied to it in being accompanied by strata of calcareous breccia and beds of limestone; in all of which magnesia is a considerable ingredient.