18 NATURAL HISTORY OF 



panied by a negro lad, who had received instructions where 

 Lo conduct me. I was provided with a small tin vasculum, 

 which I had brought on shore on speculation, and in this I 

 stowed away my specimens as I met with them. I well 

 remember the curious and novel sensations which, while 

 riding over the desert plains, covered with a strangely unfa- 

 miliar tropical vegetation, composed principally of succulent 

 plants, salt and bitter to the taste, and brightly-coloured 

 Labiatae, characteristic of such barren situations, I experi- 

 enced. On the sandy flats, not far from the sea, a thorny 

 species of Acacia, and another plant, which in its general 

 growth, made me think of Tamarisk, were abundant, together 

 with a species of gourd, which covered the sandy soil with its 

 trailing stems, and exhibited flowers and fruit in various stages 

 of maturity. After ascending a little way, the prostrate stems, 

 brilliant yellow flowers, and prickly fruits, of a species of Tri- 

 hulus became conspicuous, together with a variety of grasses, 

 among which were representatives of the genera Cynodon and 

 Digitaria, and also a millet-like grass, which my companion, 

 with whom I carried on as much conversation as the limited 

 acquaintance which we possessed of each other's languages 

 would permit of, informed me was " much good for bullock." 

 Still higher up I observed various succulent Crassulacece, and 

 Mesemhryacece, a yellow-flowered composite plant with a woody 

 stem ; a Convolvulus, with beautifully-veined leaves and large 

 pinkish-white flowers, exquisitely pencilled with purple ; a 

 yellow-flowered leguminous plant like a Lotus ; a wild fig ; a 

 shrubby Datura; and the Euphorbia previously mentioned, un- 

 mistakable from its stiff artificial-looking manner of growth, 

 and abounding in milky acrid juice. Numbers of Egyptian 

 vultures {NeopJiron percnopterus) were soaring about in the air 

 in all directions, and perching on the crags ; the old birds in 



