20 
James Small. 
inter-tropical connection. This applies equally to Vernonia (Fig. 
36) with 948 species and the bridging sections Hololepis and 
Lepidaploa, and to Elephantopus witli 24 species and the bridging 
species E. sealer. In both genera there is also an extension north 
into the U.S.A. region. A path of migration across the islands of 
the Pacific is indicated by the above-mentioned sections of 
Vernonia, by E. scaber and by V. cinerea (ll). 1 The stretch of 
ocean between Peru and the Marquesas is not an impassable 
barrier, given a pappose fruit and the south-east trade winds (cp. 
Chapter IX). The occurrence of V. Zeylanica in Ceylon and 
Madagascar is probably explicable in the same way by a pappose 
fruit and the monsoons, although this case requires further 
examination. An Atlantic path of migration is indicated by 
Sparganophorus Vaillantii, which connects east tropical America 
with east tropical Africa. 
Except for E. scaber and one other species in Senegambia the 
Lychnophorinae are confined to America, but there are a number 
of African genera in the Vernoniinae. 
Asterece. The distribution of the primitive genus, Solidago, is 
typical (Fig. 37). A concentration in the U.S.A region is clear, 
and the path of migration is that of Senecio. This point, how¬ 
ever, is much clearer and more distinct in the maps of Aster, 
Erigeron and Conyza, which are too complex for inclusion in the 
present account. The centres of the sub-tribes are indicated by 
letters. The Homochrominse extend south into the Mexican 
region to a marked degree. The Bellidinae are rather diffuse, 
occurring in all the regions of the world, as do also the Hetero- 
chrominae with achief centre in the U.S.A. and other concentrations 
in Mexico, South Africa, Australia and the Eur-Asiatic 
regions. The Conyzinae are markedly African and the Grangeinae 
occur chiefly in tropical Africa and Asia. The Baccharidinae are 
another diffuse group but are chiefly Andine. 
Eupatoriece. For the present purpose Mikania and Eupatorium 
have been united into the basal group which has been referred to 
previously. The distribution of this group (Fig. 38) shows the 
characteristics of the Eupatorieae very well. There is a concentra- 
1 A migration to the Sandwich Islands from the Australian and Malay¬ 
an regions as well as from America is proved by Campbell (12), and was 
previously suggested by Hooker (IV, 39), who gave only general evidence. 
Hutton’s idea of a continental bridge across the Pacific in Tertiary times 
(42) is modified by Macloskie (118) into an “ archipelagian ” bridge from 
New Guinea and New Zealand to Chili, very similar to but perhaps more 
developed than the existing Pacific archipelago. 
