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 Avhich has been mostly removed. 



A few lierbaceous 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^^'^-' 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 



