264 TOILERS IN THE SEA. 



tion downward was from 30 feet to 36 feet. Ehren- 

 berg concluded that in the Red Sea living coral did 

 not occur below 36 feet. Stutchbury, after a visit to 

 the coral groups of the Paumotas and Tahiti, fixed 

 the depth at from 96 feet to 100 feet. Darwin writes 

 that, "Although the limit of depth, at which each 

 particular kind of coral ceases to exist, is far from 

 being accurately known, yet, when we bear in mind 

 the manner in which the clumps of coral gradually 

 became infrequent at about the same depth, and 

 wholly disappeared at a greater depth than 120 feet, 

 on the slope round Keeling atoll, on the leeward side 

 of the Mauritius, and at rather less depth, both 

 without and within the atolls of the Maldive and 

 Chagos Archipelagos, and when we know that the 

 reefs round these islands do not differ from other 

 coral formations, in their form and structure, we may, 

 I , think conclude that in ordinary cases reef-building 

 polypifers do not flourish at greater depths than 

 between 120 feet and 180 feet." 1 Captain Moresby 

 reported to Darwin that he found only decayed 

 coral on Padua Bank, north of the Laccadives 

 which has an average depth of between 1 50 feet and 

 210 feet, but that on some other banks in the same 

 group, with only 60 feet to 72 feet of water on them, 

 the coral was living. Lieutenant Wellstead has also 



1 Darwin on " Coral Reefs," p. 86. 



