Sahār is the name commonly used to particularise that description of Desert which is of sand alone, forming a plane surface, without either stones, rocks, water, or any sustenance capable of supporting animal or vegetable life, with a smooth horizon and without beaten paths. Ghrood are those species of sand hills which I mentioned having once or twice passed in Fezzan: they are of an indefinite height, some being so steep as to be entirely impassable: others, and indeed all of this particular name, are traversed with difficulty. In some instances, palms grow on these hills; which are generally situated on the borders of stony plains, where the wind has collected and formed them. Sereer is the appellation of gravelly plains, from which the sand has been swept by the force of the winds; and it is on this kind of Desert alone that sand hills are found. The gravel is generally of a small size: in some instances, rounded as pebbles on a sea beach; in others, sharp and pointed, as if recently broken; and a third kind is not unfrequently seen, covering spaces of many miles in extent, of stones which have a shining exterior, as if highly polished. Warr is a rough plain, covered with large detached stones lying in confusion, and very difficult to pass over. The tops of mountains, particularly the Soudah, are distinguished by this name: it is, in fact, applied to such tracts of country as are only travelled with the greatest fatigue and difficulty, on account of the many obstacles thrown in the way by stones, small hillocks, &c. Hatïa implies a spot which possesses, in a slight degree, the power of fertility, and produces a few small stinted shrubs, scattered at intervals, on which camels may make a scanty meal, or travellers a fire. Wishek: sand hills or plains, which afford only wild, unproductive, or uncultivated date bushes, are called by this name. All Wishek bear the appearance of having been formerly what are called Ghrāba, which is a term always used to distinguish parts which produce cultivated or fruit-bearing palms, but having no town near them; the owners of the dates only coming in the season to collect them. Zezeera is a term also used in common with Ghrāba, but I believe only by Fezzanners. Soobker is the designation of salt-plains, which are marshy in winter, and in summer become broken and rough by the influence of the sun; or of that particular species found in Fezzan, where the salt and earth or sand are so closely combined, as to form a substance resembling stone, and equally hard to cut or break. One of these plains, between Trāghan and Māfen, is about three or four miles in the broadest part, and above twenty-five in length.