of the Galapagos Archipelago. 243 
LI 
ferent. The relative abundance of Cyperacee to Graminec is extremely fluc- 
tuating, though in a measure amenable to very conflicting causes, which we 
can only partially follow. Of the Galapageian Graminec the Pow and Panicec 
are nearly equal, which is very unusual within the tropics; one of the species 
belongs to Eutriana, a genus almost peculiar to Ameri ica, and particularly 
to the mountainous regions or cooler parts. Two new species belong: to 
Aristida, which is also represented by a Species in the sterile island of 
Ascension. | 
. The Cowrosrrz are in every respect the most remarkable family in the 
Galapagos, both as regards number of new species and new genera, and 
from their forming much of the wood of the islands. They also are the most 
instructive, as the species are very clearly defined: the peculiar genera have 
representatives in the different islets; and whilst the new species are almost 
wholly allied to plants from the Andes or extra-tropical parts of America, the 
old are almost universally the weeds of the low coast of the same continent. 
It is not therefore with tliis family as with some others, that the new species 
are, though permanently, only partially distinct from the continental ones, and 
possibly varieties due to climatic causes; but they are the representatives of 
species which are only found beyond the reach of direct migration, or are to 
a great extent entirely new genera. 
In respect of the peculiarity of their Composite, the Galapagos may be com- 
pared with some other tropical islands, as the Sandwich group and St. Helena; 
also with two extra-tropical islands, Juan Fernandez and New Zealand. All 
of these have a larger amount of peculiarity in their floras than any other tracts 
of land of the same size. It has been noticed that the four last-named islands 
or groups are remarkable for possessing a great proportion of arborescent 
Composite, and in this too the Galapagos share, though the comparison can 
be carried no further between any of them; for whilst the order is here repre- 
sented by Melampodinew and Helianthew, in Juan Fernandez it is by Senecionew 
and Cichoracee, in St. Helena chiefly by Asteroideæ, in the Sandwich group by 
Verbesinee and Bidentinee, and in New Zealand by Helichrysee and Asterec. 
In all these cases, the further the islands are from the mainland, the less evidence 
do the Composita they contain afford of the botanical province to which each 
may belong. "Thus the Galapagos contain, in the peculiar plants of this order 
VOL. XX. 2K 
