112 
DEPTH AT WHICH 
Ch. IV. 
7 or 8 fathoms depth, the bottom is formed, as fcould 
be seen through the clear water, of great living 
masses of coral, which at about 10 fathoms generally 
stand some way apart from each other, with patches of 
white sand between them, and at a little greater depth 
these patches become united into a smooth steep slope 
without any coral. Captain Moresby, also, informs me 
in support of the above statement, that he only found 
decayed coral on the Padua Bank (northern part of the 
Laccadive group), which has an average depth of 25 
to 35 fathoms ; but that on some other banks in the 
same group, with a depth of only 10 or 12 fathoms 
(for instance, the Tillacapeni bank) the coral was 
living. 
Professor Dana likewise states that during the various 
and extensive surveys in the Pacific Ocean, made during 
the United States exploring expedition, no evidence 
was found of corals growing beyond the depth of 20 
fathoms. 1 I may here add that Sir E. Belcher, though 
he does not state to what depth living corals extended, 
says that many soundings were taken off Bow atoll, at 
depths ranging from 50 to 960 fathoms, and that the 
bottom always consisted of coral sand. 2 
With regard to the coral-reefs in the Bed Sea, 
Ehrenberg has the following passage. ‘ The living 
corals do not descend there into great depths. On the 
edges of islets and near reefs, where the depth was 
small, very many lived ; hut we found no more even at 
1 Corals and Coral Islands, 1872, p. 116. 
2 Voyage Round the World, 1843, p. 379, vol. i. 
