▼i 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. 1 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 aflBnities 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 



