166 Mr. HOLROYD'S Journewy to Kordofan. [ 1837 stratum is sandstone, and continues to be such till within an hour of reaching Abil Samud, wherc we came upon grey granite, furrowe(l by veins of primitisTe quartz. The gravel, both to the AIr and S. of Abu Samufl, contains quartz pebl)les in great aloundance; and I noticed also portions of siliceous fossil trees, similar to those observed at Haagbarlak. At Abu Samud, the wells of Bay-I'ldah, and in short as far as E1 Hajir, sandstone occurs with only one exception, where a vein of re(l granite crossed from W. to E. between these two latter places. I observed occasionally stones of a yellowish grey colour, spotted with black points, reseml)ling those which are thrown up by Vesusius during its eruptions. I also found abllndance of fragmexlts of hard san(lstone, containing quartzose pebbles, wllich were in patches, and.at no great (listance from each other. The patches of stones of a grey cc)lour, which appeare(l volcanic, were at least 40 or 50 miles from the hills; and though they appeared to have been deposited after some volcanic convulsion, we were unable to discover any extinct volcano; the sand dves not drift much in this desert. I also occasionally found hard black cinders. It is, however, renarkable that these isolated patches are found at so great a distance from the mountains. At 8 hours S. of Ambukol we came upon patches where water had collected during the periodical rains; and upon looking at the map I observed that Mr. Arrowsmith had laid down their northern limits very correctly.

The desert of Bayudah abounds in herbaceous plants, and one or two varieties of the mimosa. It also possesses many objects of great interest in the zoological kingdom, especially the leopard, orys, and gazelle. Its few inhabitants belong to the tribe of Kab'abish Aralas.* In 2 hours and 40 minutes we halted for the night at Jagjoke. Feb. 1. We travelled E3 hours and 40 minutes to Kerreri. On the following day, in 4 hours, we arrived at the northern point of the White Nile (Nil el Abyad), on which we embarked, an(l in less than an hour arrived at Khartum.

The direction from Ambukol to E1 Hajir was from N.W. to S.E., and the distance occupied us 52 hours' march, nvhich, at 22 miles per hour, would gi+7e us 130 miles; from E1 Hajir to Khartum, from N. to S., folloving the course of the river, 16 hours 20 minutes, or about 42 miles. The position of the junction of the Bahr el Abyad, or White River, with the Bahr el-Azrak, or Blue Ri;rer, in the observations given me by M. Linant, is 15? 34' 40tt N., and Si? 11' 25t' E. of Gr. These oleservations do not agree with those already ma(le by the same gentleman, and published in a memoir on the Eaht e1 Abyad, in the second solume of the London Geographical * Plural of Kabbash, " a shepherd."-F.S.