332 
APPENDIX II. 
late date are on record, 1 and if those geologists are right who 
consider the Sclilern dolomites as being to a great extent 
due to reef-building corals, we have in the Triassic deposits 
of the Italian Tyrol reefs thick enough to satisfy the most 
exacting requirements. 
It is then, I think, premature to regard the theory 
which was advanced by Mr. Darwin, and has received the 
approval of an observer of such an exceptional experience 
as Professor Dana, as conclusively disproved by the results 
of the more recent investigations. That this theory may 
have been expressed in terms a little too comprehensive, 
that there may be a larger number of exceptional cases 
than was at first supposed, is quite possible. This, however, 
is the almost inevitable lot of every great generalisation. Its 
author concentrates, and rightly concentrates, his atten- 
tion on the salient features, as one who gazes first at a 
mountain group fixes his eyes upon the principal peaks 
and for a time pays little attention to, perhaps even 
under-estimates the importance of, the subordinate ranges ; 
nevertheless his conception of the physical structure of the 
region, though modified, is not overthrown by the work of 
subsequent travellers. This may prove to be the case in 
regard to the present controversy. It may very possibly 
be found that, as remarked by Mr. Bourne, the history cf 
coral reefs is more varied and complicated than was at first 
supposed, but it seems to me that, as the evidence at 
present stands, it is insufficient to justify a decision adverse 
to Mr. Darwin’s theory as a general explanation. 
1 See pp. 309, 322 of this work 
