REGIONS AND AREAS OF DISTRIBUTION. 525 
We have here, again, as in the Mexican region, a large proportion 
of endemic monotypes or small genera; but the larger wide-spread 
American genera, especially Vernonia, Eupatorium, Mikania, and 
Baccharis, are so copiously represented, and some of the charac- 
teristie ones so rich in species, that the total average of the region 
is above seven to the genus, at least one more than in the Andine 
and two more than in the Mexican. Notwithstanding the large 
extent of the forest-plains above mentioned, almost as unfavourable 
for the development and preservation of Composite races as those 
of east tropieal Asia, the physical conditions of the hilly districts 
appear to be suited both for the preservation of expiring types in 
limited stations and for the luxurious development of others in 
the prime of life. 
The greater number of the monotypic or small endemic genera 
of the region belong to the southern portion, the campos and 
sierras of the Upper Rio San Francisco, and thence to Mattogrosso 
and Chiquitos, separating the great valleys or plains of the Amazon 
and the Parana. Itis there also that are to be found the most re- 
markable forms, unrepresented in any other part of America, the 
Lychnophoree, Schlechtendahlia, Wunderlichia, &c., the two latter 
having no very near connexions anywhere. A few,such as Pacou- 
rina, Sparganophorus, Riencourtia, Trichospira, &c., belong more 
specially to the northern or intermediate portion, but extend more 
or less into Brazil proper, and some of them have crossed over into 
tropical Africa; others, again, like St¿ftia, belong to both north 
and south divisions, with endemic species of limited areas in each. 
As characteristic tribes of the region, Vernoniacex undoubtedly 
take the first rank in the number of species, both in relation to 
the total Composite of the region (nearly one third) and in 
relation to the total number of the tribe in America (more than 
three fourths, including eighteen endemic genera). Helianthoidex, 
mostly of the subtribe Verbesineze, are also dominant, Eupatoriacee 
rather more numerous than in the Andine region, and Mutisiaceze 
about the same, several of the latter having their chief seat or 
being quite endemie in Brazil. Senecionidez, especially the genus 
Senecio, and Helenioidee are fewer than in any other American 
continental region; so also Asteroides, with the exception of 
Baccharis and the Gnaphalioid Inuloidez. The Old-World orders 
have but very few species or are quite unrepresented. 
Additions to the Composite flora of the region are chiefly to be 
expected from Mattogrosso and other western districts, and per- 
