During the four months from July to October inclusive, when the "hivernage" or rainy season is at its height, the prevailing winds are weak and variable, the mean temperature (80° F.) is very constant, and the air saturated with moisture. Rains and thunderstorms are frequent, the river overflows, the swampy tracts are flooded. Although the same conditions prevail everywhere, the rains begin somewhat earlier in the interior than on the coast, and the season lasts considerably longer at Goree than at Saint-Louis. The humidity is on the whole considerably less than in most other tropical regions, and Saint-Louis has on an average scarcely more than thirty rainy days with an annual rainfall of less than 20 inches. In the interior lying farther south, and at Goree, the proportion appears to be somewhat higher, and at Kita there was a rainfall of over 50 inches in 1882. Hail, almost unknown elsewhere in the tropics, is not rare in Kaarta, where "hard water," as it is called, is regarded as a valuable medicine.
Flora.
Lying on the frontier of the Saharian and Sudanese zones, French Senegambia resembles both these regions in its flora. The northern vegetation is allied to that of the neighbouring Saharian steppes, while the southern assumes a more tropical aspect, the variety of forms increasing in the direction of the equator. Although some species are peculiar to Senegambia, this region is far from presenting the same diversity as other tropical lands. During five years of exploration, Leprieur and Perrottet collected only sixteen hundred species, a very small number compared with the exuberance of the Indian, Australian, and South American floras. Some extensive tracts are occupied by a few graminaceae to the exclusion of all other forms. These are fired by the herdsmen in the dry season, and the conflagrations caused by them prevent the development of large forest growths.
As in the corresponding Nubian regions, where grassy savannahs also prevail, there are numerous gummiferous plants, such as the acacias, which cover whole districts north of the Senegal. Even in the south the most widespread tree is the goniaké, or Adansonia acacia, whose hard, close-grained wood yields an excellent material for ship-building. On the coast the characteristic plants are the arborescent malvacea), the gigantic baobab, and the bombax. In Senegal the baobab was first studied by Adanson, whence its botanical name of Adansonia digitata. But so early as the beginning of the sixteenth century Cadamosto already spoke with amazement of these stupendous growths, which yield the so-called "monkey-bread," eaten also by man. Still larger and of more symmetrical form than the weird-like headless baobab is the bombax, whose enormous aerial roots form large recesses, in which travellers take refuge for the night and where "palavers" are sometimes held. Although usually regarded as the fetish tree in a pre-eminent sense, some of the natives convert the stem into canoes of 18 or 20 tons burden. The down of its fruit, too short and fragile for weaving purposes, supplies a substitute for touchwood.
The cocoa-nut, now abundant in Lower Senegal, is of comparatively recent
