500 MR. G. BENTHAM ON COMPOSITE. 
and many others are closely represented in both, indicating a 
common origin in one of the two; but whether the flora, or, indeed, 
any individual race, has travelled eastward or westward it would 
be diffieult to decide; the evidence is different as to different 
genera, and in almost any case may be explained both ways. 
Eupatorium, Solidago, and Aster (Euaster) are very large American 
genera, numerous in species throughout North America, diminish- 
ing, however, in numbers in the north-west, reduced to very few in 
East Asia, and dwindling down to a single one or two in West 
Europe. Most of the Anthemidee and Cichoriacez, numerous in 
the Mediterranean region and West Asia, as well as Tanacetum and 
Artemisia, whose chief seat is, perhaps, Central Asia, all diminish 
eastwards, and are reduced to very few in North America, chiefly at 
high latitudes or along mountain-ranges. The primá facie conclu- 
sion would be that the former, of American origin, had struggled to 
extend themselves westward with less and less of success as the 
distance from home increased, and the latter, of Old- World origin, 
had met with a similar fate in their progress eastwards. But, 
on the other hand, it might also be argued (perhaps, however, with 
less plausibility) that both had once ranged over the whole region 
in a small number of specific races, but that, the one set finding the 
west and the other the east more congenial, the circumstances 
more favourable to their preservation and development, they had 
in course of time multiplied in the one division not only in indi- 
viduals but in differentiated races, whilst in the other they had 
more or less succumbed to adverse influences and gradually 
become extinct, barring the few representatives still capable of 
accommodating themselves to the circumstances among which they 
are placed. Eight or ten, however, of the generic groups enume- 
rated have no such apparent continuity ; their widely disconnected 
areas seem to imply an ancient very wide range, early broken up 
through the greater part of its extent, leaving here and there a 
few isolated remnants which have lasted long enough to produce 
endemic races at the opposite extremes, the common parent races 
having become extinct in their typical forms. Adenostyles, with 
one species in California and two in Central Europe, Filaginez 
(Evax, Filago, and Micropus), with seven North-west-American 
and nineteen Mediterranean species, Bellis, with two in the 
southern states of North America, six in the Mediterranean 
region, Werneria, with one Abyssinian, one Himalayan, and about 
sixteen Andine species, Oentaurea, of a type unknown in Central 
