PREFACE TO THE SECOND EDITION. 
In the preparation of this work fora second edition, a few 
emendations have been made, and new facts introduced from 
recent publications on the subject. Among the latter, an 
account is given of the arrangements by MM. Le Clere and De 
Benazé, on Tahiti, for marking, in the future, the rate of 
growth of the Dolphin Shoal or reef. 
The Preface to the first edition alludes to some points 
in which the author differs from Mr. Darwin. The reader 
will find some additional remarks on these differences in the 
American Journal of Science for October, 1874, called out 
by the discussion of the subject in the new edition of Mr, 
Darwin’s “ Coral Reefs.” 
NEw HAVEN, Conn., October 1, 1874. 
