28 
The Ferns of South Africa. 
has done this in a most satisfactory manner.* The leading idea 
in his arrangement is, that from the east coast to the Drakensberg 
and Stormberg mountains, the tropical flora extends south, till cut 
off by the Karroo ; which, crossing from the Atlantic to the Indian 
ocean, has a flora peculiar to itself, and that the mountains and 
slopes south of the Karroo have quite a distinct flora. The 
upper Karroo forms his composite region, and his Kalihari region 
includes the remainder. 
The distribution of ferns, apart from cosmopolitan species, will 
most probably be found to follow in a general way the same lines, 
though the presence or absence, of almost half of our ferns, seems 
to be controlled more by the humidity of the atmosphere in any given 
spot, than by its geographical position, and it has been found more 
convenient here to adopt well known geographical areas, as under, 
but in which the main idea of Mr. Bolus’ arrangement is main- 
tained. 
1. West, or south-west, including : — 
a. The coast slopes from the mouth of the Olifant’s River 
on the west coast, to the mouth of the Groote River 
on the east coast. 
b. The Karroo, Upper Karroo, and Namaqualand. 
2. East, from the Groote River to the Fish River, and up to 
the Winterberg and Sneemberg Mountains. 
3. Kaffraria, from the Fish River to the Natal Border. 
4. Natal. 
5. Orange Free State. 
6. Transvaal. 
7. Bechuanaland. 
The east district is, in part Karroo, modified as it approaches 
the coast, and the west and east districts together, comprise the 
Karroo and all south of it, while the others form natural divisions 
of the district north of the Karroo. 
The following list shows how the ferns are distributed through 
these, and it also shows what species grow in South Africa and no- 
Sketch of the Flora of South Africa , Cape Town, 1886. 
