478 MR. G. BENTHAM ON COMPOSIT X. 
comprising amongst them only eleven species, connected in some 
measure both with Crepis and Lactuca (viz. Zacintha, Acanthoce- 
phalus, Heteracia, Rhagadiolus, and Kelpinia), are also limited to 
the Mediterranean region. 
Leontodon, about forty species, is another of the Mediterranean 
genera which has a few species widely spread over Europe and 
extratropical Asia, and two or three are now to be met with in 
various distant regions, but probably as colonists only, except in 
North America, where Torrey and Gray’s monotypic genus Apar- 
gidium may be considered as an endemic species of Leontodon, 
nearly related to one of the European mountain species. The 
genus has been broken up into ten or twelve sections or genera; 
but they are either monotypie or have no special area, and all 
belong to the same general Mediterranean region. 
Taraxacum, nearly allied to Leontodon, and variously estimated 
at from four or five to above forty species, has a very wide distribu- 
tion, accommodating itself to every variety of station (thus account- 
ing for the intricate variability of its forms) and readily colonizing. 
The extratropical regions of the northern hemisphere comprise 
its chief centre; and it may be more universal in the Old World 
than in North America ; but it appears to be also a true denizen 
of the far south, both in America and Australia, and is to be met 
with even in warmer regions. 
The genera Troximon, sixteen species, Pyrrhopappus, three or four 
species, Calycoseris, two species, and the monotypic Glyptopleura are 
all American and almost exclusively north-western, with their chief 
centre in the Mexican region (including California). Troximon 
reappears in one or two species in extratropical South America, 
and Pyrrhopappus extends somewhat eastward in North America. 
These genera are quite absent from the Old World; but they may 
in some measure be considered as West-American representatives 
of Leontodon and Taraxacum. 
Hypocheris, about thirty species, allied to Leontodon in habit 
and structure, has a wider general distribution, and a rather more 
American character. Common to both the New and the Old 
World, with two species so generally distributed and so readily 
colonizing as to make it difficult to say where they are most at 
home, Hypocheris bas perhaps most species in the mountain and 
temperate regions of America, especially South America, but the 
most diversified forms in the Mediterranean region of the Old 
World. Minute differences in the pappus have induced its general 
