14(50 
THE VOYAGE OF H.M.S. CHALLENGER. 
Benthos ok the 1q polar areas, may be held to have produced a more rapid modification of species in 
C^A^^o^KAmc\ tropical waters than would take place in the colder waters towards the poles, so that 
AND OF THE I’oLAR mav bo urffod that these faunas on the east and west coasts of Africa, notwithstanding 
Heoion.*}. j a ' o 
their very distinct character, have not been separated from each other for so long a 
time as tlie polar faunas which more closely resemble each other. When we remember, 
however, tliat in the case of America the separation of the Atlantic and Pacific marine 
faunas is not so complete at the Isthmus of Panama as on either side of Africa, it 
may be assumed that the separation of marine faunas in the case of Africa is of much 
greater antiquity, possibly extending back to a time when there was a nearly universal 
climate all over the ocean. In the preceding extracts from Dr. Allman’s Eeport^ 
three different species of Grammaria are described from the Antarctic or Great 
Soutliern Ocean, each occurring in depths less than 100 fathoms in the same 
latitudes, but in widely different longitudes, viz., Grammaria insignis from Marion 
Island, Grammaria stentor from Kerguelen, Grammaria magellanica from Fuegia. 
A number of similar examples might be given from other widely separate points among 
Antarctic Islands and land-masses where a genus is represented by a different species 
in each area. This seems to show that these small land-masses in the Antarctic 
and Great Southern Ocean have been separated from each other for a sufficiently long 
time to have admitted of specific variations arising even in the cold Antarctic waters, 
and is consequently opposed to the view of a widely extended Antarctic continent, 
connecting all the other continents by their southern extremities, in recent geological 
times,^ for, with such a wide extension of land in the southern ocean, we would rather look 
for very many circumpolar species, as in the northern hemisphere, where continuous coast 
lines have probably existed for immense periods of time in arctic and boreal latitudes. 
CoNTiNENTAi, distribution of the great continental land-masses appears, from what has been 
I.*ANIvNf A<S8E^ AND 
THE DisTRiBunoN stutcd, and from other facts that might be adduced, to have a great influence on the 
OK Marine distribution of marine organisms, both in shallow water and in the deep sea. It is 
Organwms. . ° 
abundantly evident that the land of the continents has been most unstable, and can 
in no way be regarded as permanent, during the course of geological history. Not 
only ha.s the land been repeatedly torn down by denuding and disintegrating 
agencies, but the various strata have been repeatedly shoved above and depressed 
below the sea-level by those internal forces called into play chiefly by the 
contraction of the internal nucleus of the globe, from loss of internal heat through 
r.-uliation into space. We may assume that the materials of the original crust 
were somewhat homogeneous in composition. The destructive and reconstructive 
processes here indicated, together with the action of organisms, have brought about 
' S«e 1443 ante. 
* Tht ('hatham iHlandH ; their relation to n foriiu-r .Southern ('ontinent, by Henry 0. Forbes, Royal Geoynipldcal 
SiipjiGm'iilory Pti/iern, vol. iii., p. fi07, 189.3. 
