588 REPORT—1905. 
tropical Africa a floral element predominates, which is peculiar to this part of the 
world. An accurate comparison shows that this element is more nearly related to 
that of tropical Asia than to that of tropical America, and that it is especially nearly 
connected with that of India and Madagascar. But besides the tropical African 
element of the flora, we find in tropical Africa members of other elements—of the 
Madagassian, of the Indian, the South African, the boreal, the Mediterranean, 
and even of the tropical American. But it is to be noticed that these elements 
are distributed in the various formations in a very diflerent way. 
The different halophilous beach formations do not belong to the same floral 
element. On the coasts of East Africa there predominate, besides some plants 
truly African, members of the Indian and the Monsoon elements ; whereas on the 
coasts of West Africa exists an element belonging to both tropical America and 
tropical Africa. 
Besides, the accurate investigations of recent times have shown that in the 
hydrophilous and hygrophilous megatherm formations of Western Africa some 
genera exist, the other species of which are to be found only in the corresponding 
formations of tropical America. And not only some genera, but even whole fami- 
lies and tribes, are developed only in tropical America and in either West Africa 
or in the whole of tropical Africa; for instance, in the hygrophilous formations, 
the Mayacacee, Rapateacee, Musacee-Sirelitzioidee, Balanophoracee-Lanys- 
dor fice, Moracee-Brosimee, Caricacee, Humiriacee, Winteranacee, Cactacce- 
Rhipsalidee, Gentianacee-Leiphaimee. Jn the subxerophilous and xerophilous 
furmations of the plain regions and the inferior mountains some families and tribes 
behave in a similar mauner, namely, the Velloziacee, Hydnoraceea, Tarneracce, 
Loasacee, Rafflesiacee-Apodanthee, and Cytinee. Besides these families there 
are io be mentioned some natural orders which have also members in the monsoon 
lands, but which are developed in rich numbers only in America and Africa ; for 
instance, the Pontederiacee, the Moracee-Dorstenee, the Rosacee-Chrysobala- 
noidee, the Simarubacee-Simarubee, the Burseracee, the Dichapetalacee, and the 
large genera Hermannia and Asclepias. 
In the hygrophilous megatberm formations, and in the mesotherm formations 
of East Africa, especially in the rain forests and in the forests of the higher moun- 
tains, the Indian and Madagascar elements are rather numerous in members, and 
even the same species are to be found in the mountains of East Africa, the Mada- 
gassian Islands, and in India, especially many ferns. 
The South African element, too, is not absent in these formations, but it is much 
more numerous in species in the shrub formations of Angola and Kast Africa. In 
the xerophilous formations the tropical African element is very nearly related to 
the Indian element, especially north of the equator. 
Besides, in the subxerophilous and xerophilous formations of North-east Africa, 
and more in Somaliland than in Abyssinia, the Mediterranean element is repre- 
sented by numerous genera; for instance, Burus, Pistacia, Farsetia, Diceratella, 
Malcolmia, Gypsophila, Micromeria, Lavandula, Carduncellus, Cistanche, Juni~ 
perus, Callitris. . 
Finally, besides the Mediterranean, the boreal element has many species in 
the microtherm formations of the high mountains of Africa. These are relatively 
poor in plants originating from African types, whereas the boreal and Mediter- 
ranean forms which have immigrated into the higher mountains of Africa have 
developed in their new area new species and varieties. 
At last it must be mentioned that, in spite of the narrow relations between the 
African mountain vegetation and the Mediterranean flora, there are wanting 
many genera and orders otherwise distributed over large areas; for instance, the 
Abietinee, Fagacee, Betulacee, Pirolacee, Ericacee-Rhododendroidee, Aceracee, 
Caprifoliacee (with exception of Sambucus ebulus), Rosacee-Spiraeoidee, Coriari- 
acee, Daphne, Aconitiim, Aquilegia, Draba, Euonymus, Geum, Ribes, Rhus-Sect. 
Trichocarpe, Hieracium, Gentiana, Iris, Lilium, Fritillaria, Orchis, Ophrys. 
The fact that of all these groups no members exist in the higher mountains of 
Africa proves that the boreal element has immigrated from the North and East 
into the Mediterranean regions, whereas, on the other hand, some types, now 
