DISTRIBUTION OF SPHAGNUM AND CAREX 341 



The South American and African Connection. — Before leaving 

 the subject of South America reference may be made to another 

 point of similarity between Sphagnum and Carex, which concerns 

 the scanty connection with Africa in the sense below defined. With 

 both genera the two continents hold but a single species in common, 

 namely, Sphagnum pulchricoma and Carex cederi. The first named, 

 which is characteristic of the Southern United States and of tropical 

 South America, has only been recorded from one locality outside the 

 New World, namely, in the Lake District of Central Africa. The 

 second is a typical North American and Eurasian species of Carex 

 that has extended south as far as Tasmania and New Zealand and 

 South Africa in one hemisphere, and as far as Patagonia in the other, 

 being represented in all three regions by the same peculiar variety. 

 For reasons to be now given it is held that this variety originated 

 independently in South America and New Zealand, but was supplied 

 from Patagonia to South Africa. Concerning the parent species 

 there is no necessity to appeal to any transference across the Southern 

 Ocean between extra-tropical South America and the Australian 

 and New Zealand region, since the two regions could have derived 

 it from northern latitudes on their own sides of the globe, the species 

 being widely distributed in North America and in Northern and 

 Central Asia. As regards its occurrence in South Africa, however, 

 the indications are that this region received the variety across the 

 ocean from Patagonia, as it is not recorded from any part of the 

 African continent except from the high mountains of Basutoland, a 

 matter dealt with in a later page. Reference will also be made 

 below to the significance of the existence of the New World species 

 of Sphagnum (S. pulchricoma) in Central Africa. 



The African Peat-mosses and Carices. — This brings us to the 

 discussion of the representation of the Peat-mosses and Carices in 

 the African continent ; and here again the behaviour of the two genera, 

 offers a striking parallel, since they illustrate in a similar way that 

 remarkable isolation which Africa so often exhibits in its flora as 

 well as in its fauna. By Africa, we mean Africa with the Mediter- 

 ranean Littoral excluded. This Mediterranean province of the 

 European region receives from Europe species of Sphagnum and 

 Carex that as a rule have failed to penetrate farther south. Thus 

 species of Sphagnum, like S. rufescens and S. turgidulum, which are 

 widely distributed over Europe, cross the Mediterranean only to 

 reach Tunis and Algeria. However, although the great majority 

 of the European Carices have been compelled to halt in North Africa 

 after crossing the Mediterranean, a few have penetrated to the south 

 of the continent. 



The Check to the Southward Advance of the Carices into 

 Africa. — Just as in the New World the Carices from the north have 

 been ever pressing south, so in the Old World the northern Carices 

 have been ever endeavouring to reach the interior of Africa; but 

 they have in nearly all cases been rolled back by the obstacles 

 presented by the Atlas ranges and the sandy wastes of the Sahara 

 and of Libya. Not more than 13 per cent, of the European species 

 of Carex that have established themselves in the southern region 



