auc. 1899] AZARINE INVERTEBRATES OF SINGAPORE 131 
means common as arule. In the dredge are obtained, according to 
the depth of water, nature of the substratum, strength of currents, 
etc., different forms of invertebrates which, as a rule, recall at once 
some English genus, the most noticeable being perhaps the Sponges, 
Hydroids, Gorgonians, Polyzoa, Ascidians, and the five groups of 
Echinoderms. The littoral fauna is not at first sight strikingly unusual 
except in those places where the reef-building corals flourish; here 
undoubtedly a surprise awaits any zoologist who sees them for the first 
time. Often as he may have seen the beautiful photographs in Saville- 
Kent’s well-known work on the Australian Barrier-reef or collections 
of coral such as are exhibited at the Natural History Museum at 
South Kensington, or often as he may have read the accounts of 
Darwin, Dana, Murray, Semper, and others on the formation of coral 
reefs, he will hardly, until he is brought face to face with the reality, 
have been able to form a mental picture which at all adequately 
represents the actual charm and beauty of the living coral, reposing 
calmly “like a flower garden” (as I think Moseley described it) 
beneath the seemingly unnatural transparency of a tropical sea. 
In these shallower waters, which rarely exceed a depth of 30 
fathoms, the reefs differ considerably from those usually described, and 
a short account of them may not be out of place. 
The reef-building corals form a fringe which is by no means always 
continuous round the islets or on the margin of the coast; on the 
latter especially there are extensive tracts covered with sand or mud, 
and with occasional mangrove swamp, but totally devoid of reefs, coral 
being represented by small clumps distributed very sparsely at 
intervals of often several yards. In places where the reef is present, 
its distance from the shore varies from a few yards to half a mile or 
more, and in many cases no part of the reef proper is dry at low spring- 
tides; the actual width of the reef itself is also very variable, but 
rarely exceeds about ten yards; on its outward edge it slopes somewhat 
abruptly to about five or six fathoms, and then more gradually seawards. 
Between the reef and the shore there is nearly always a flat covered 
with mud, and very often with an abundant growth of brown sea-weed 
which harbours a large fauna. This mud flat is very nearly level, and 
at lowest spring-tides there is left about a foot of water in the deepest 
parts, the highest portions of the “ flat” being just dry. The mud some- 
times extends nearly up to high-water mark, but as a rule it is separated 
from the land by a belt of sandy or rocky ground, or occasionally by 
projecting volcanic rocks excavated by the sea into hollows, which on 
the retreat of the water form tide-pools, and contain numerous nooks 
and crannies in which molluscs, crabs, and other animals find a hiding- 
place. Here at any rate at first sight the naturalist will readily admit 
that he might be on English ground. As he looked more closely he 
would probably see large fleshy Alcyonarians abounding on the mud- 
flat, and to some extent replacing our anemones, the latter being only 
