ON BOAJtD H.U.S. 'FLYING FISH' 



quantity of food, and in consequence would thrive the best, 

 and I thought that some exceptional and unexpected flow 

 of the tides and currents must cause the languishing con- 

 dition of the projecting reefs of the Bohoi Promontory and 

 the prosperity of the reefs of its sides. 



Before I had been long at work, however, at TaHsse, I 

 came to the conclusion that what I had observed at Bohoi 

 was rather a rule than an exception, for I never found in 

 any single instance that the most vigorous coral growth 

 was to be found upon those points of the coast line which 

 project furthest into the sea. 



The vigorous growth of reef-corals seems to be de- 

 pendent upon a great many conditions, the absence of any 

 one of which causes very obvious modifications in the 

 number of specimens, the number of species, and the size 

 and vigour of corals found upon the reef. 



First, as is well known, reef -building corals will only 

 grow in the warm waters of the tropical seas ; secondly, 

 they wiU only grow in water which is less than twenty or 

 twenty-five fathoms deep ; and, thirdly, in flowing water 

 which is neither too swift nor too stagnant, and bears the 

 kind of food which is necessary for their proper nourish- 

 ment. 



Unfortunately we have at present but little information 

 upon the rapidity of the flow of water which is most favour- 

 able for the growth of corals and but few observations on 

 the character of the food which the coral polypes like 

 best. 



At Tanjong Aros, at the north of Talisse Island, I found 

 that, although a few Astraeas could be seen growing at a 

 depth of two or three fathoms, no true reef was formed. 

 At this point the tide race sometimes runs at six or seven 

 knots an hour. At a point upon the reefs of TaMsse oppo- 

 site the island of Kinabohutan, where the tides flow at 



