Ch. VI. DISTRIBUTION OF CORAL-REEFS. 
187 
Sea, in tlie sea between the barriers of Australia and 
New Caledonia, in the Caroline, Marshall, Gilbert, and 
Low Archipelagoes, — is a very striking fact. So is the 
presence of active volcanic vents and chains on or near 
many of the shores coloured red on our map, and which 
are fringed with reefs ; for, as we have just seen, these 
fringed coasts have been recently upheaved in a large 
number of cases. Active volcanos likewise coincide 
with proofs of recent elevation on or near several 
other long lines of coast within the limits of our map, 
where there are no reefs of living corals, and which 
consequently are not coloured red. It must be here 
remarked, with regard to the proofs of both subsidence 
and elevation, that I do not judge by the absence or pre- 
sence or nature of the coral-reefs round the volcanos 
themselves ; for, as Dana repeatedly insists, the corals 
may have been there destroyed or injured by the heat 
or exhalations. Nor have I taken into account the 
presence of upraised organic remains on the flanks of 
the volcanos themselves. I judge from the position of 
the active volcanic vents in relation to neighbouring 
islands and coasts, situated at too great a distance for 
any corals growing there to be injured by the eruptions ; 
and where, from the presence of atoll-formed or barrier- 
reefs, or of upraised marine remains, we have reason 
to believe that either subsidence or elevation has 
occurred within a recent period. 
The following cases offer a few partial exceptions to 
the rule that active volcanos are situated at a distance 
from the areps of subsidence. The Great Comoro 
