in prehistoric times by rivers that ran through the present dry sand-channels which the Arabs call Bahr-et-Abied, or rivers without water. The fact that river-shells were discovered in these beds during the French expedition to Egypt lends some support to this view. M. Delamotte has devoted some twenty years to the examination of the subject, and, while he does not undertake to determine when the rivers were dried up, he has reached a conclusion as to the manner in which it was done. He believes that the whole plateau of Khartoum was in prehistoric times a grand lake whence the Nile issued as it now issues from the Victoria and Albert Nyanzas. The cataracts were, however, higher than they are now, and the river, instead of precipitating the whole mass of its waters over the rocks, was divided into streams which found their way through the channels marked by the present Bahr-et-Abiad, and carried the water into the parts of the country which are now desert. The granite and porphyry of the cataract were gradually worn away in the course of ages, their level was lowered, and the Nile, instead of being forced into branch-channels, fell over them and concentrated its waters into its present single stream. M. Delamotte is examining the region of the Upper Nile again, for the purpose of verifying his theory, and of determining if it is possible, by constructing a system of dams and sluices, to raise the level of the cataracts, and cause the waters to flow again through the channels they have deserted.
Sports in the Colors of Squirrels.—A correspondent of "Forest and Stream" relates an interesting instance of the development of varieties of colors in squirrels, which took place in South Carolina several years ago. A Mr. K——, who owned a considerable plantation in the county of Marlborough, had presented to him a pair of milk-white squirrels. His woods were much frequented by gray squirrels, and fox and black squirrels were numerous in the pines and cypress-swamps at some distance from the plantation. The white squirrels bred, producing two young ones, also milk white. The animals were very prolific, under the protection of the owner, who prohibited the intrusion of hunters, and, in course of time, spread to the adjoining plantations, and many of them took to the immense swamps "bordering on the Big Peedee River. They also began to sport and change their color, and, from being pure white, became marked with every possible variation of black and white. The correspondent who relates these facts has killed, at various times, at least a dozen thus marked. One of them was of a deep, sparkling black color, except as to the ears and the large, bushy tail, which were snow-white, save a small commingling of the black and white at the root of the tail, and the lower part of the belly and the inner edge of the flanks, which were of a clear ash-gray. The varieties seem to have almost disappeared since the war. In the last individual that the correspondent has noticed, the markings were less pretty and the colors less distinct; the white was turning to ash and the black to brown, the consequence, he supposes, of wild breeding.
A New African Tribe.—Dr. Emil Halub recently addressed the London Geographical Society respecting a hitherto undescribed African tribe called the Marutse. They inhabit the country formerly ruled by the Makololo, described by Dr. Livingstone, who have ceased to exist. Dr. Halub said that when he crossed the Zambesi, and entered into their country, it seemed that he had left Africa, for the tribes were entirely different from the others in South Africa. They belong to thefamily, but differ from the other members of this family in their appearance, customs, and workmanship. They have their own civilization, independent of influence from white men; and, while the other tribes have nothing which could be called a religion, they believe in a Supreme Being and in a life after death. They call the Supreme Being N'yambe, but have so great a reverence for him that they do not like to pronounce his name. Whenever a serious event happens, as when a man is killed by a buffalo, a crocodile, or an elephant, the common expression is "N'yambe has ordered it, and it is no use resisting." When a member of the royal family was ill, he was taken to the grave of one of his ancestors, when the king knelt on the grave, and prayed to the deceased, "You, my