The geological constitution of the country is as yet very imperfectly known, especially in the interior. The low region of the seaboard has a very uniform character. It consists of sandstones or clay rocks and loose beds of reddish soil containing marine shells. At certain points, such as Cape Verd and Cane Roxo, the sandstones crop out; it is the red colour of the sandstone in fact which has given Cape Roxo or Cap Rouge its name. Clay slates also occur, and at intervals these sedimentary strata are interrupted by basaltic amygdaloid and volcanic rocks. For instance, the island of Gorée is basaltic; the Bissagos (Bissão) Islands are composed of scoriae and other volcanic products; and a great part of the coast to the north of Rio Nuñez consists of basaltic and amygdaloid rocks. The base of the mountains is formed in certain places of clay slate, but more generally of granite, porphyry, syenite, or trachyte. In those districts mica schists and iron ores occur. Iron and gold are found in the mountains and the alluvial deposits. The streams also carry down gold dust. Many of the valleys are covered with fertile soils and there is generally a fertile belt along the river sides; but the rest of the country is rather arid and sterile.

The climate is far from being so unhealthy as is frequently asserted. Except when yellow fever is raging, Europeans may live there as satisfactorily as at home. There are two seasons, the dry season and the rainy season or winter, the latter contemporaneous with our summer. Along the seaboard the dry season is cool and agreeable; in the interior it is mild only for the three months which correspond to our winter, and then it becomes a time of intolerable heat. The annual temperature increases as we advance south and more rapidly as we advance east into the interior, except, of course, where an ascent is made to higher altitudes. To the south of Cape Verd the changes of temperature become less and less marked; Bissão has a more equable climate than Gorée. Eastwards the monthly range of the thermometer becomes more extensive. The maximum readings, which are exceptional at St Louis, become almost the rule at Bakel on the upper Senegal and at MacCarthy on the Gambia. In the north, on the banks of the Senegal, the north-east trade-winds blow for eight months of the year, the daily land and sea breezes which cool the atmosphere along the seaboard not being felt far inland. During the other four months there prevails a gentle south-west monsoon accompanied with frequent calms, storms, tornadoes, and rains. Southwards along the coast the trade-winds gradually decrease in both strength and duration, while the south-west monsoon becomes more powerful and persistent. The rainy season begins at Gorée between 27th June and 13th July, on the Gambia about 20th June, on the Casamance about the end of May, at the Bissagos Archipelago about the middle of May, and on the Rio Nuñez at the end of April. During this season Senegambia, drenched by heavy rains brought from the ocean, has everywhere one uniform appearance. The mean temperature is throughout very close on 81° Fahr. and the range of the thermometer is extremely limited. The rivers overflow and flood the lowlands. Storms are frequent. Vegetation displays its fullest energy. The fever exhalations are unfortunately also at their worst. At St Louis, Gorée, Dagana, and all along the Senegal there are 35 days of rain, a slight increase being apparent in the upper course of the river. At St Mary’s, Bathurst, there are 48 days, at Sedhiu 84, at Bissão 111, at Boké 137,—a steady increase as we approach the equator. The number of storms follows almost the same ratio of increase, and showers which last two or three hours at St Louis give place to whole days of rain on the Casamance and the Rio Nuflez.

The king of the Senegambian trees is the baobab (Adansonia digitata), which sometimes at the height of 24 feet has a diameter of 34 feet and a circumference of 104. Acacias are very numerous, one species, A. Adansonia, being indeed the commonest of all Senegambian trees and valuable for its ship-timber. Among the palm-trees the ronier deserves to be mentioned, as the wood resists moisture and the attacks of insects; in some places, as in Cayor, it forms magnificent forests. The wood of the cailcedra (Khaya senegalensis), a tall tree, is used in joiner’s work and inlaying, and its bark furnishes a bitter tonic. The mampatas grows sometimes 100 feet high, its branches beginning only at a height of about 25 feet The tree producing the famous kola-nut grows on the banks observances. Every canton, every village in independent Senegambia is governed either by a chief (“king ”) or by an “almamy” elected by a group of villagers.

Senegambia is divided into French Senegambia (with the territories placed under French protection), English Senegambia, Portuguese Senegambia, and independent Senegambia, comprising the native states not under the protection of a European power. French Senegambia is called the colony of Senegal (q.v. ). English Senegambia comprises the establishments of the Gambia (q.v. ) and the islands of Los. Portuguese Senegambia consisted till quite recently of Bissagos Archipelago and the “factories” of Zighinchor on the Casamance, Cacheo and Farim on the Rio Cacheo, and Geba on the Geba. By an arrangement effected in 1886 Portugal ceded Zighinchor to France in exchange for Massabé on the Loango coast. Germany, which seemed at one time disposed to place various territories of Dubreka, Koba, and Kabitai under its protection, has formally abandoned the plan. The independent states are not very numerous, but for the most part they are more extensive than the protected countries. They were quite recently—Jolof, lying between the Senegal and the Gambia in one direction and between the Falemé and the ocean in the other; Buré in the Mandingo region, a territory abounding in gold; Guidimakha in Gangara, on the right bank of the Senegal. There still remain among the more important Kaarta, the country of Segu, and Futa-Jallon.

Several lines of English, French, and German packets call at the Senegambian ports, and small steamers ascend the navigable portions of the rivers. A railway unites St Louis and Dakar, and another line is being constructed from Kayes to Bafulabé (on the upper Senegal), with a projected extension to Bammako. There is telegraphic communication between Dakar and St Louis, and a second line puts all the ports of the upper Niger and the left bank of the Senegal into connexion with St Louis, which has touch of Europe by means of a submarine cable passing by way of the Canary Islands to Cadiz. The foreign trade of Senegambia consists in the exportation of gums, ground-nuts, sesame, oil, india-rubber, birds’ feathers, hides, wax, and ivory, coffee from the Rio Nunez, and rice from the Casamance, and the importation of iron, alcoholic liquors, firearms, ammunition, coral, beads, tobacco, preserved foods, and blue calico (guinée). (D. K*.)