XX11 BOTANY OF SOCOTRA. 



anchorage to be obtained around the island, but no one of them is safe at all 

 seasons of the year. On all sides the hills rise with considerable abruptness 

 over a wide area, forming bold perpendicular cliffs of several hundred feet in 

 height, whose base is washed by the waters of the Indian Ocean ; but at other 

 places they leave plains varying in breadth up to as much as five miles between 

 their base and the shore. On the south side of the island is the largest of these 

 shore plains — Nogad, — which, extending nearly the whole length of the island, 

 is for miles covered with dunes of blown sand. On the north, plains occur 

 chiefly at the mouths of the streams, and are the sites of the only places which 

 can be called villages. 



The internal hilly part of the island may be roughly and shortly described 

 as a wide undulating and intersected limestone plateau of an altitude averaging 

 1000 feet, which flanks on the west, south, and east a nucleus of granite peaks 

 over 4000 feet high. The whole of this hilly region is deeply cut into by 

 ravines and valleys. These in the rainy season are occupied by roaring torrents, 

 but the majority of them remain empty during the dry season. There are, 

 however, many perennial streams on the island, especially in the central 

 granitic region, where amongst the hills the most charming bubbling burns 

 dashing over boulders in a series of cascades, or purling gently over a pebbly 

 shingle, make it hard to believe that one is in such proximity to the desert 

 region of Arabia. Most of the perennial streams are, in the dry season, fiumaras. 

 The eastern end of the island is most destitute of water; there in the dry 

 season are no streams, and, springs being rare, it is the most arid region. 



In its climate Socotra contrasts favourably with the adjacent shores of 

 Arabia and Africa. During the N.E. monsoon, from October to April, it is 

 cool. January and February are the most pleasant months. Hain falls twice 

 in the year, at the changes of the monsoons, at which time the stream-courses 

 are filled with mighty torrents. The temperature, of course, varies much with 

 the altitude, and one may pass in the course of a few hours from the tropical 

 heat of the shore-plains to the cool temperate air of the mountain-ranges. 

 The average temperature on the plains in Jannary is said to be about 70°, but 

 in the hotter months is as much as 86°. On the plateaux the temperature 

 often goes down at night to 52°. The higher peaks are, at least in the 

 cold season, frequently enshrouded in mists, and at night heavy dews fall. 

 The hills are healthy ; but on the plains, especially at the changes of monsoons, 

 fever is prevalent. 



The fundamental rocks of Socotra are gneisses, both hornblendic and 

 granitoid, belonging, like those of north-west Scotland and of north-east 

 America, to the earliest archsean age. These crop out on the hill slopes and in 

 the valleys, but do not as a rule form the exposed higher parts of the island. 

 Through this fundamental mass cut felspathic granites of varying texture and 



