Introduction
Jebel Marra is a volcanic massif situated in the west of Sudan (24ยฐ 16' E, 12ยฐ 38' N) -45 miles long and 30 miles at its greatest width . It is about 575 miles away from Khartoum . The massif embraces several peaks, some of which exceeding 10,000 ft. Although GOOD (1924) suggests that its volcano is extinct, HAMMERTON (1966) managed to observe hot springs and fumaroles ; a finding which may indicate volcanic activity .
The plateau and the massif are built mainly of basement complex, Jebel Marra volcanic complex and superficial deposits . The soils which prevail in this district are chiefly of alluvial and colluvial types derived from the basement complex as well as from the volcanic materials (ANDREw, 1948 and HUNTING, 1958) .
It is certain that there are not yet any algal studies related to this region of the Sudan and the present work represents an initial investigation for such studies . In December 1965, a study-tour was made to Jebel Marra and several algal collections were carried out in the hope that algal composition of this part of the world would be manifested and consequently available for comparison with similar areas either under the same or different climatic conditions .
Several valleys dissect this massif and since this paper is the first of its kind on this area, every effort was made to collect from as many