16 
TOPULAR SCIENCE REVIEW. 
to be found in the residue. St. Paul’s Rocks are detached mi- 
niature islands about 1° N. of the equator, and having a longi- 
tude of 29° 15' W., and are 500 miles from the nearest point 
of South America, lying about midway between that and the 
African coast. The rock approaches serpentine in structure. 
Not a trace of land vegetation, not even a lichen, is to be found 
here. 44 It is a remarkable fact,” says Darwin, 4fc that all 
the many small islands, lying far from any continent, in the 
Pacific, Indian, and Atlantic oceans, with the exception of the 
Seychelles and this little point of rock, are, I believe, composed 
either of coral or of erupted matter.”* 
On Aug. 22, St. Vincent’s Island was left by the Challenger 
for Bahia, to make her fourth section across the Atlantic. Bahia 
was reached on Sept. 15, after a successful but stormy voyage. 
Fernando de Noronha was stopped at, en route for Bahia, Sept. 
1st and 2nd being spent here. The entire length of the whole 
chain of islands is about seven geographical miles, the group 
being situated in 3° 50' S. lat., and being distant from Cape St. 
Roque, the nearest point in South America, more than 200 
miles. On the main island there is a remarkable column of 
44 phonolite,” or clinkstone, more than 1,000 feet high, called 
“ The Peak.” The island is volcanic. The Cape gooseberry 
and the castor-oil plant grow wild here. The plant mentioned 
by Darwin as covered with fine pink flowers, but without a single 
leaf, is a euphorbiaceous plant — J atropha gossypifolia , Linn. 
44 Its bare stem,” remarks Mr. Moseley, 44 and branches render it 
a striking object amongst the green of the creepers when the 
forest is viewed from the sea.” The flora is not very rich in 
species, and the same plants occur everywhere. There are neither 
ferns nor mosses, nor liverworts, though moist and shady places 
are not wanting, and lichens are very scarce. Mr. Darwin ob- 
serves that the volcanic island of Fernando de Noronha, placed 
in many respects under nearly similar conditions, is the only 
other country where he has seen a vegetation at all like that of 
the Galapagos islands.f 
After a stay of a little more than a week at Bahia the Chal- 
lenger left for the Cape of Good Hope, touching at Tristan 
d’Acunha on the way thither. This group of islands has an 
area of about sixteen square miles, although stated by Grisebach 
( Vegetation der Erde) to be only two square miles in extent. A 
plant resembling a chrysanthemum— -Chenopodium tomentosum 
— with strong-scented leaves, is used by the inhabitants, a de- 
coction of it, under the name of 44 tea,” being drunk with milk 
and sugar. It grows abundantly on Inaccessible Island, which 
is distant about 23 miles from Tristan. Inaccessible Island is 
* Darwin’s " Naturalist's Voyage.” 
t Ibid. 
