FLORA AND FAUNA. 13 



forests except on the Malabar coast, in Ceylon, and around the Caribbean seaboard, 

 whereas in North Africa the dum palm {liypliœne thehakci), and the deleb (borasstis 

 flabelliformis), as well as the date {jihœnix dactijlifera) cover extensive tracts in the 

 oases of the northern Sahara. Compared with the number of its species, the 

 Nigretian flora possesses many trees with an abnormal development of stem, leaf, 

 and fruits. The baobab is noted for the enormous size of its trunk, while the 

 kigelia and some other bignoniaceae have fruits two feet long, and the ensete, a 

 variety of the musaceae, displays the largest foliage in the entire vegetable 

 kingdom. 



The Kalahari flora, south of the tropical domain, resembles that of the Sahara, 

 except that it forms no oases, nor are the few watered tracts anywhere shaded by 

 palms. This flora is distinguished by its thorny acacias and mimosas, and, like 

 that of Northern Nigretia, it abounds in graminaceous species. On its northern 

 margin some almost rainless districts grow the welwitschia, a remarkable plant, so 

 flush with the ground as often to escape the notice of travellers. Burrowing 

 downwards in the form of a reversed cone, it displays above ground nothing but a 

 rough surface over a yard long, throwing o£E right and left two cotyledons of a 

 leathery appearance, and occasionally exceeding 16 feet in length after a growth 

 of one hundred years. 



On the east coast of Africa, the transition between the vegetable zones is more 

 gradual than on the opposite side, where the tropical domain is abruptly limited by 

 the Kalahari desert. Along the Indian Ocean the change takes place imper- 

 ceptibly from north to south through the Limpopo basin and Natal. On this 

 seaboard, which is skirted by the warm Mozambique stream, the southern limit of 

 the palm lies 16 degrees lower down than on the Atlantic coast. But on the 

 whole the vegetation south of the Orange River is clearly distinguished from that 

 of the rest of the continent. Although the rainfall is limited and the geological 

 formations far from varied, the Cape flora, consisting chiefly of grasses, shrubs, 

 and bushes, is altogether unique for the multitude of its intermingled species. In 

 this respect it is unrivalled even by the richest European countries. Nowhere 

 else do the mountain slopes present more vegetable forms disposed in belts sharply 

 separated from each other by the several zones of altitude. It may be asked 

 whether this Cape flora is not a survival from far more extensive lands engulfed in 

 the sea, most of whose vegetation has found a refuge in the relatively limited tract 

 bounded northwards by the basin of the Orange River. In the same way the 

 island of Madagascar appears to have preserved a great part of the flora of the 

 vanished " Lemurian " continent. It still possesses over forty vegetable families 

 peculiar to itself. 



The appearance of Europeans and Semites has been accompanied by the 

 introduction of many new species, which in several districts have displaced and 

 even exterminated the indigenous forms. Elsewhere the range of certain plants 

 appears to have been modified even without the intervention of man. Thus the 

 papyrus, which three thousand years ago was characteristic of the Egyptian Nile, 

 is now, according to Schweinfurth, found only on the Upper Nile near the equator. 



