CHAPTEB IV. 
ON THE GROWTH OF CORAL-REEFS. 
In this chapter I will give all the facts, which I havo 
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 tho 
theory of the origin of the different classes of coral- 
reefs. 
Section I. 
On the Distribution of Coral-Reefs, 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 Gulf 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. 
