Several other vegetable species grow on the table-lands of the Algerine Sahara, which are found elsewhere under similar conditions of soil and climate. They are thorny shrubs and underwood, almost wholly belonging to the family of Salsolaceæ, or littoral plants, which only thrive on ground impregnated with salt; there are also sub-frutescent plants, partly dried up by the sun. In some places the nakedness of the earth is concealed by the bloom of geraniums and heliotropes. Further, you may notice in the region of the table-lands, the _Melantha punctuata_, a member of the Colchicum tribe, which bears a bouquet of very white flowers grown upon the sand, and surrounded by a crown of ensheathed leaves. Not unworthy of rejoicing the eyes of the most fastidious connoisseurs, it lives and dies unknown in the solitudes of the Sahara. [Illustration: VEGETABLE LIFE IN THE DESERT. 1. Jujube Tree. 2. Lentiscus. 3. Tamarisk.] In the hollows, where the earth preserves some degree of humidity, a fine soft sward prevails, of the most delicious emerald green; two herbs, the Alfa (_stipa tenacissima_) and the White Wormwood (_artemisia alba_),[68] often cover extended areas; the jujube trees clothe themselves in profuse foliage; the coloquinta stretches over the ground its branches loaded with spherical fruit; and the tamarisk, developed into a tree, waves in the wind its tufts of snowy and rose-hued flowers. It is in these meadows that the Arab rears his tent and pastures his flocks under a winter sky. The industrious and sedentary tribes seek in the oases a more benignant nature,-- "The yellow down Bordered with palm, and many a winding vale And meadow;" and a soil which will repay their toil with liberal harvests. And it is there only, in truth, that vegetation presents a development, a continuity, and sometimes even a variety, which recalls the fortunate countries of the Mediterranean region. The old geographer, Ptolemæus, compared the Sahara to a panther's skin, sprinkled with black spots on a tawny ground. These spots which, by an effect of contrast, are set off in black on the yellowish tint of the desert, are the far-famed oases, which have furnished our poets and romancists with so many an appropriate image. Ptolemy's comparison is the more accurate because these islands of verdure scattered over the sandy ocean, "Like precious stones set in a silver sea," have, in general, a circular form. We must except, however, the grandest and most beautiful of all, Egypt. That immemorial land of mystery and power is enchased in the Desert region like any other oasis, and only differs in its greater extent and more elongated figure. It stretches along the Nile like a ribbon-- "And Egypt joys beneath the spreading wave."