REGIONS AND AREAS OF DISTRIBUTION. 545 
cannot be said to be rich in Composite, especially in species, very 
much less so than tropical America, but the forms are more varied. 
All the tribes are represented in it, although the three in which its 
neighbour the Mediterranean region is so rich (the Cynaroidex, 
Cichoriacez, and Anthemides) have but very few species, and 
those few chiefly in the Abyssinian mountains, which have some 
connexion northwards. The southern Mutisiacex and Arctotides 
are also as scantily represented; the Calendulacee, an African 
tribe both northern and southern, have, as far as known, only a 
single species within the tropics. All these, however, are chiefly 
extratropical tribes. Those which exhibit in tropical Africa the 
greatest numbers are among those which elsewhere have a more 
tropical character :—Vernoniacez, of which the genus Vernonia 
alone numbers seventy species, including the considerable endemic 
section Stengelia ; Inuloidee, chiefly Plucheinez and Gnaphaliez, 
also, however, with- several of the more specially African subtribes 
Euinulez and Buphthalmee ; and Helianthoidex, chiefly American 
types. The American Eupatoriacez, notwithstanding their semi- 
tropical character, as well as the Helenioidex, are represented each 
only by a single endemie species, and the Eupatoriaceous one is 
probably a modification of an Asiatic rather than of an American 
Eupatorium ; the three other tropical-African Eupatoriacez which 
figure in the preceding Table are amphigeous species enumerated 
in Table 4, the origin of whose dispersion is uncertain, but which 
might be supposed to be of ancient introduction from America. 
The numbers, however, of all the above tribes are small; the 
only large genera are Vernonia and Helichrysum; all the others, 
except Gaaphalium and Conyza, have less than ten species ; and the 
general average, including Vernonia, is under four to a genus, 
lower than in any region except limited insular ones. The total 
number of species is also much smaller than in any except the 
tropical-Asiatic region ; whilst the genera are more numerous and 
more diversified than in the tropical-Asiatic, the Australian, or 
the Europso-Asiatie regions. About twenty of them are endemic: 
the majority of these, as well as of the endemic species of other 
genera, appear to be limited to the eastern portion of the region ; 
it is there chiefly that several South-African and American genera 
are represented by single or very few species, and there also that 
some of the Mediterranean genera extend a few representatives. 
East tropical Africa seems, indeed, to be the principal area of pre- 
servation of the most ancient tropical flora of the Old World. The 
2Q2 
