vi 
an intermediate group. They have creeping or erect stems ; 
their leaves are small/sessile, whorled, or imbricated, and their 
fructification, which is spiked or axillary, consists of bivalved 
cases, containing minute powdery spores. Of this order, 
but few representatives are known to inhabit South Africa. 
§ 12. In most true Ferns, but especially in the dorsiferous 
ones, the peculiar course, position, distribution, and rami- 
fication of the nerves and veins, placed at the back of their 
fronds, are highly important for the supply of superior generic 
characters , being, as they are, closely connected with the 
insertion of the organs of fructification. They, therefore, 
are very valuable also in the arrangement of fossile Ferns, 
which, as we learn from geology, abounded in great number 
and variety during the carboniferous epoch of the earth, and 
of which some hundred species, belonging to different genera, 
have been described. 
§ 13. Although Ferns exist in nearly all parts of the globe, 
yet countries situated within or somewhat beyond the tropics, 
seem to be most genial to their growth and development. 
They generally delight in warm, moist, shady localities, and 
thrive best in woody, mountainous regions. In the western 
districts of the colony of the Cape of Good Hope they are 
proportionally rare for that reason, but increase in species 
towards the east, and become frequent and distinct in the 
dense woods, mountain ravines, and near the cascades of 
Natal. The aboriginal forests of British Kafir aria, as yet 
unexplored, undoubtedly conceal strange forms, quite new to 
the scientific world. 
§ 14. If we estimate (by moderate calculation) the entire 
number of South African plants at about 12,000 species, out 
of which one thousand, at least, are cryptogamic or cellular, 
it then becomes apparent, that the Ferns are but poorly 
represented in this great and imposing assemblage, forming 
hardly one-sixtieth part of the whole Flora, and scarcely one- 
fifth part of the plants of the lower classes, known to exist 
in so wide and rich a tract of territory. 
