411 
REVIEWS. 
COPAL EEEFS * 
A LTHOUGH Mr. Dana, a most distinguished American observer and 
^ student of coral reefs, opposes some of Mr. Darwin’s conclusions, that 
fact is rather to be rejoiced at than otherwise, since it has doubtless led to 
the publication of a new edition of a book which first made its appearance 
thirty-two years since ; and we may congratulate the author when we find 
that he has not in any material way altered his opinions, but has gone into 
the subject at greater length than ever, and has found an ample suppty of 
facts to bear out his original views. It is to be regretted that we have not 
space to go fully into his various arguments, but at all events the following 
extract from the preface will tolerably explain the differences which exist 
between Professor Dana and Mr. Darwin. “ In this work,” says Mr. Darwin, 
referring to Dana’s book published in 1871, “he justly says that I have not 
laid sufficent weight on the mean temperature of the sea in determining 
the distribution of coral reefs ; but neither a low temperature, nor the 
presence of mud-banks, accounts, as it appears to me, for the absence of 
coral reefs throughout certain areas ; and we must look to some more re- 
condite cause. Professor Dana also insists that volcanic action prevents the 
growth of coral reefs much more effectually than I had supposed ; but how 
the heat or poisonous exhalations from a volcano can affect the whole cir- 
cumferance of a large island is not clear. Nor does this fact, if fully 
established, falsify my generalization that volcanoes in a state of action 
are not found within the areas of subsidence, whilst they are often present 
within those of elevation , for I have not been influenced in my judgment 
by the absence or presence of coral reefs round active volcanoes ; I have 
judged only by finding upraised massive remains within the areas of eleva- 
tion, and by the vicinity of atolls and barrier-reefs. With reference to the 
areas of subsidence, Professor Dana apparently supposes that I look at 
fringing-reefs as a proof of the elevation of the land ; but I have expressly 
stated that such reefs, as a general rule, indicate that the land has either 
long remained at the same level, or has been recently elevated. Neverthe- 
less, from upraised recent remains having been found in a large number of 
cases on coasts which are fringed by coral reefs, it appears that of these two 
alternatives recent elevation has been much more frequent than a stationary 
* “ The Structure and Distribution of Coral Beefs.” By Charles Darwin, 
M.A., F.K.S., F.G.S. Second edition, revised. London : Smith & Elder, 
1874. 
