274 Wisconsin Academy of Sciences, Arts, and Letters. 
occur on the old lava around an elevation of 500 ft., all of which 
have probably been inactive for a very long time. The lava on 
the south side has been thrown into ridges and folds in places, 
and there are also occasional lava tunnels the tops of which have 
fallen in. One of these is located near the shore and is filled 
with sea water. The south side of the island slopes up gradu¬ 
ally to an elevation of about 500 ft., above which the slope is 
steeper. 
The top of the mountain was envelloped in fog at the time it 
was visited so that a survey of the surrounding region could not 
be made. There seemed to be no central crater present, however, 
and the highest part may be the remains of a portion of the rim. 
There is a range of hills, about two miles west of the summit, 
which runs parallel with the coast line, and have an elevation of 
about 1,200 ft. These hills rise abruptly from a broad, flat 
plain just east of them, which has an average elevation of 900 ft. 
It is possible that this plain may be the floor of an old crater, the 
rim of which has been mostly removed. 
A few herbaceous halophytes grow on the sand beaches near 
where we anchored. There was also a low thicket of bushes of 
Laguncularia racemosa bushes growing here. Other than these 
no halophytes were found. 
All of the vegetation of the south and southeast sides of the 
island below an elevation of 450 ft. consists of species w^h are 
usually found on the lower and dryer parts of these islands. 
They are smaller and fewer in number, however, than is usually 
the case, a condition that may be due to the very scanty soil on 
these parts. The lava on this part of the island is bare in most 
places, and the only soil to be found is in the lava crevices. In 
consequence of this condition, a large part of the surface is not 
suitable at present for the support of higher plants. The trees 
of Bursera graveolens are small, seldom exceeding a height of 8 
ft. Usually they are mere bushes. Besides the small Bursera 
trees, Opuntia galapageia is the only other species which reaches 
the size of a tree in these lower regions. It occurs here abund¬ 
antly, and has weak spines and closely arranged branches. Eu¬ 
phorbia viminea forma castellana is the most common bush in 
this region. It is about the only one that occurs in mass, all 
other bushes being scattered. This species seems to be better 
adapted to maintain an existence under the sterile conditions 
than most of the other species found here. Other bushes found 
