of the Galapagos Archipelago. 245 
to which I shall allude, is the gummy exudation for which the shrubby Sca- 
lesie are conspicuous, and which is equally a characteristic of some of the 
St. Helena Composite. The species in both instances are inhabitants of arid 
spots, fully exposed to the sun of the torrid zone, which together seem favour- 
able to the copious secretion of gums and gum-resins in various parts of the 
world. 
Lecuminosa.—This order is second only to the last in number of species, 
of which there are 24 contained in the various collections, but differs con- 
spicuously in its proportion of novelty, there being no peculiar genus, and 
only 7 species which are not found on the adjacent continent. Ofall the large 
natural orders of flowering plants, the Leguminosc contain by far the largest 
amount of universally diffused species, including very many of the littoral weeds 
of the tropics. Observation proves that this is in a great measure due to the 
transporting power of water, for neither do the seeds of the dispersed species 
bear winged appendages, nor are they of such a size as renders it probable 
that they are carried by aérial currents. The ubiquitous species possess, on 
the other hand, remarkable powers of resisting the effects of time and ex- 
posure, besides a vegetative power that enables them to overcome obstacles 
in the soil and climate of the locality they are transported to ; qualities which 
the Composite probably possess in a very limited degree, for we see their 
feathery pappus to have had little effect in spreading the majority of the 
individual species beyond any but very narrow limits. 
Of the Galapageian genera only Dalea and Galactia are exclusively Ame- 
rican, and all but the 7 species mentioned above are common tropical species, 
particularly in the West Indian islands. 
Evpsorsiace& form a very large proportion of the Galapageian Flora, 
consisting of 18 species, included in the tropical genera Acalypha, Croton, 
Euphorbia and Phyllanthus. They form jy of the Phenogamia, very much 
exceeding the proportion for the tropics of the new world, which is stated by 
Baron Humboldt as 35, or of Western Africa, which Mr. Brown gives as 3l. 
In amount of peculiar species this order here ranks next to Composite, & of 
the whole belonging to species very distinct from those of other countries ; 
the remainder are common West Indian or Southern United States plants. 
In the prevalence of peculiar Euphorbiacee and Rubiacee, this group has 
2x2 
