TRISTAN DA CUNHA 
393 
St. Helena, Ascension island, the Cape Verd islands, the 
Canaries and Madeira, is a matter which, must be left to future 
observations. Certain faunistic features appear to be in 
favour of such a theory. 
Tristan da Cunha is almost as large as St. Helena. It 
lies considerably further south, being bleak and inhospitable 
in the extreme, owing to its proximity to the northern boun¬ 
dary of the antarctic ice-drift. The flora is quite different 
from that of St. Helena, as it possesses antarctic affinities. 
The genera Nertera, Uncinia and Acaena inhabiting antarctic 
America, New Zealand or Australia occur here also. It has 
Lomaria alpina, in common with South America, Kerguelen 
island, New Zealand and Australia, while Spartina arundi- 
nacia occurs in Tristan da Cunha and St. Paul, and is related 
to a South American species.* The most remarkable member 
of the fauna is the genus Tristania which, with its two species, 
is confined to the island. It is related to the snail Opeas which 
inhabits both Africa and South America. 
Almost three hundred miles further south there is still an¬ 
other volcanic island, of which scarcely anything was known 
until it was visited by Dr. Bruce, the leader of the Scottish 
National Antarctic Expedition. First called “ Diego 
Alvarez ” according to Dr. Brown,f its name was later on 
changed to “ Gough island.” The island differs from some 
of the other islands referred to, in being densely covered with 
vegetation, which is similar in character to that of Tristan 
da Cunha. While showing the same general affinities, Diego 
Alvarez seems to have a stronger American element than the 
islands forming the Tristan da Cunha group. The land birds 
comprising two species of bunting (Nesospiza) and a galli- 
nule (Porphyriornis) are peculiar to the island, but related 
to species living on Tristan da Cunha. 
To briefly review the results of our studies so far, it appears 
highly probable that Brazil was entirely separated from 
western South America in Mesozoic and part of Tertiary 
times, but was connected with the highland of Guiana across 
the mouth of what is now the Amazon river, which flowed 
* Engler, A., “ Entwicklungsgeschichte der Florengebiete,” II., p. 159. 
t Brown, R. N. R., “ Diego Afyarez,” pp. 9—10. 
