23 
illustrated by the South African Flora . 
in the same category, e. g. Cliffortia (about 40 species, mostly south-western 
Cape Colony), allied to Bencoma (a genus with 2 species in Madeira and 
the Canary Islands).’ 
The distribution of the Thymelaeales and Cliffortia , &c., would surely 
favour a northern origin, and would therefore tell against Schonland’s 
postulate of land connexions in the southern hemisphere. 
We shall now deal with some of the families belonging to the Tubiflorae, 
since these illustrate present-day tendencies extremely well. 
Acanthaceae. 
Thimbergia atriplicifolia is a variable veld species widely distributed 
over the whole eastern side. Three other species (in addition to a whole 
series of varieties), viz. T. aspera , T. xanthotricha , T. Bachmanni , only differ 
slightly from T. atriplicifolia. T. aspera is distinctly more tropical, Natal 
coast-belt and northern Transvaal; T. xanthotricha , Transvaal, near Bar- 
berton only ; T. Bachmanni , Transvaal, Orange Free State, and Pondoland. 
The discontinuous distribution of T. aspera between the coast-belt and 
the northern Transvaal is paralleled in many other cases in various families. 
Good examples exactly similar to this may be found in the genera 
Dyschoriste, Belpharis , Crabbea , Barleria, Justicia. Blepharis mollugim- 
folia extends from India through tropical Africa to Mossel Bay, being very 
common all over the eastern side of South Africa. B. setosa, which differs 
only in the scabrous leaves and setose bracteoles, is recorded only for 
the Natal coast-belt and tropical Transvaal. Similarly B. boerhaaviaefolia , 
which has the same distribution as B. molluginifolia , has given rise to 
several allied but apparently rare species in the tropics. Crabbea nana and 
C. hirsuta are very closely related and are both widely distributed grass- 
veld species, an example of splitting or of A giving rise to B. C. robusta 
differs in being larger and having larger leaves and flowers. It is of 
a distinctly higher ecological type, and is more mesophytic ; only recorded 
for Swaziland. C. angustifolia differs from C. hirsuta in minor characters. 
Distribution: Transvaal and Bechuanaland, endemic. C. peduncidata is 
nearly related to C. nana , and is endemic in Natal and rare. The whole 
family is very rich in examples like the above. The genus Chaetacanthus 
has four species, all endemic and all closely related. Two of them are 
widely distributed, two rare, an obvious example of the breaking up of an 
ancestral form. The Acanthaceae are a tropical family which have invaded 
South Africa, chiefly along the eastern side. They are peculiarly charac- 
teristic of the moist marginal belt in Natal coast-belt scrub and forest. 
The grass-veld species and more xerophytic species generally are, however, 
more widespread in South Africa. 
Since we have already sufficiently indicated how numerous the examples 
are in practically all families of the application of our general principles to 
species and varieties, we shall now make use of some members of the 
