Vor. I] STEWART—BOTANY OF THE GALAPAGOS ISLANDS 211 
the same islands. In the first instance it seems likely that the 
size of the island and the degree of slope are involved. On 
large islands, like Albemarle and Indefatigable, the southern 
sides slope very gradually, and the transition and moist regions 
extend down much lower than on Abingdon and James, which 
are smaller and have steeper sides. A notable exception 
occurs, however, at Iguana Cove on the southwest side of Albe- 
marle Island, where the conditions are very peculiar indeed. 
This is the only place on the islands, outside of a few isolated 
spots near brackish springs, where there is sufficient moisture 
at sea level to support a mesophytic vegetation. But the extent 
of the moist region at this place is very limited, for at Christo- 
pher Point, only five miles north, and at Essex Point, four 
miles south, the vegetation at sea level is again very xero- 
phytic. The great difference in elevation of the different 
regions on the leeward and windward sides of the islands, is 
due to the fact that the fog in passing over the tops of the 
mountains rolls down but a short distance on the leeward sides, 
and leaves the islands at a much higher level than it struck 
them on the windward sides. The lower limits of the moist 
regions are usually as well marked, by the difference in the 
color of the vegetation, on the leeward as on the windward 
slopes of the islands. 
GENERAL FEATURES OF THE FLORA 
PTERIDOPHYTA 
Filices are the family that contains the largest number of 
species, but at the same time the smallest number of endemic 
forms in proportion to the number of species represented, of 
any family of vascular plants found on the islands. Ferns 
occur mostly in the transition and moist regions, where they 
sometimes grow in great profusion. They are not confined to 
these regions, however, as there are instances of their occur- 
rence under decidedly xerophytic conditions in the dry region. 
The species which occur thus are Ceropteris tartarea, Cheilan- 
thes microphylla, Notholaena sulphurea, Polypodium squam- 
atum, and Trachypteris pinnata. Hydrophytic ferns are few 
in number, and are confined to a few rather restricted areas, 
in the moist regions on several islands, where the amount of 
