80 



CHAPTER IV. 



ON THE GROWTH OF CORAL-REEFS. 



In this chapter I will give all the facts, which I have 

 collected, relating to the distribution of coral-reefs, — 

 to the conditions favourable to their increase, — to the 

 rate of their growth, — and to the depth at which they 

 are formed. 



These subjects have an important bearing on the 

 theory of the origin of the different classes of coral- 

 reefs. 



Section I. 



On the Distribution of Coral-Beefs, and on the Conditions favourable to 

 their Increase. 



With regard to the limits of latitude over which coral- 

 reefs extend, I have nothing new to add. The Ber- 

 muda Islands in 32° 15" N., is the point furthest re- 

 moved from the equator in which they appear to exist; 

 and their extension here so far northward no doubt is 

 due to the warmth of the Grulf stream. In the Pacific, 

 the Loo Choo islands, in lat. 27° N., have reefs on their 

 shores, and there is an atoll in. 28° 30', situated N.W. 



