Vi INTRODUCTION. 
I am glad to have this opportunity of expressing my hearty thanks to the 
various gentlemen who have given me facilities for my study and assistance during 
its progress. I may be permitted to mention the names of Professor Perrier and 
M. Bernard in Paris, Professors Mobius, von Martens, and Dr. Weltner in Berlin, 
Professors Haeckel and Kiikenthal in Jena, and Professor Doderlein and 
Dr. Ortmann in Strassburg, all of whom gave me every assistance in their power. 
To Dr. Weltner I am further indebted for much valuable information on the 
Berlin types which he has been kind enough to supply since I visited the 
collections. 
It was at the suggestion of Dr. Giinther that the present work was 
undertaken, and his constant interest in its progress and the readiness with 
which he has given me assistance and advice in critical points have been a source 
of great encouragement to me. I have also pleasure in acknowledging the 
assistance rendered by my friend Prof. Jeffrey Bell. 
As a result of the comparison of the various European Collections already 
referred to, I have considered it necessary to reduce the number of distinct species 
described by previous authors from 169 to 130. To this number must be added 
the new species described by myself—91 in all. Short descriptions of 62 of these 
have already appeared in the ‘Annals and Magazine of Natural History’ for 
December 1891 and 1892. The remainder are now described for the first time. 
Some are based on specimens in the Collection of the British Museum, whilst 
others are founded on specimens referred to previously described species by 
various authors. 
For some time the idea was entertained to include an account of the fossil 
species of Madrepora in the present volume. Very little is known as to the 
position and affinities of the fossil species, and a careful study of their relations to 
existing forms would be of special interest on account of the great importance of 
the various species as reef-builders. The subject is, however, a very difficult one ; 
the type specimens are scattered, imperfectly described, and rarely figured, added 
to which most of the specimens which have come under my notice are 
fragmentary. Satisfactory material is not readily obtained, but even if that 
