Stewart—Botanical Conditions on the Galapagos Islamds. 283 
The lower slopes of the mountain are more heavily covered 
with vegetation than is the plain just mentioned, but even here 
there are often areas of a considerable size which have scarcely 
any vegetation on them. The species which occur on the plain 
also occur on the side of the mountain in greater number, and 
many of them that were stunted on the lower part, reach their 
normal size around an elevation of 1,000 ft. The increase in the 
humidity 1 of the atmosphere is shown at this elevation, and 
above, by the large amount of Usnea longissima, and other lichens, 
which cover the vegetation to such an extent as to give it a gray¬ 
ish appearance. A number of mesophytic plants were first seen 
around 1,300 ft. elevation, the most noticeable of which were: 
Pisonia floribnda, Psidium galapageium, and Scalesia micro- 
cephala, the last of which forms a zone on this side of the moun¬ 
tain to an elevation of 1,650 ft. There are also a great many 
Bursera trees at an elevation of 1,200 ft. and above. Below this 
they were few in number. Ferns begin to appear at a slightly 
higher elevation. 
There is an abrupt change in the appearance of the vegetation 
at an elevation of 2,000 ft. The character of the soil also 
changes here from pumice to disintegrated lava mixed with vege¬ 
table mold, so that the change in the vegetation is due more to an 
increase in the number and size of plants than to a sudden 
change of forms. There are heavy forests here made up of 
trees of Bursera graveolens, Pisonia floribunda, Psidium gala¬ 
pageium, and Zanthoxylum Fagara as well as many species of 
bushes the most of which were found at a lower elevation al¬ 
though usually smaller in size. The trees are often covered with 
vines/of Cissampelos Pareira, and fruticose lichens continue to be 
abundant. Ferns are also abundant, the common species being 
Adianaum concinnum, Doryopteris pedata, Polypodium pectina- 
tum, and Trachypteris pinnata. Small specimens of Opuntia 
myriacantha were seen at this elevation and they continue to 
within a few hundred feet of the top of the mountain according 
to Mr. R. H. Beck, who visited this region. 
The sides of this mountain were not explored botanically above 
an elevation of 2,100 ft. From the top of a tree at this elevation, 
the whole of the country beyond could be seen. The character 
of the vegetation did not seem to change until the steep slope, 
below the rim of the crater is reached. Just below the rim, in 
several places, there were light green areas which, according to 
