INTRODUCTION. 
Tux total number of species referred to the genus Madrepora s. s. up to 1890, 
when the present work was undertaken, appears to be 157, not including the 
nomina nuda of Valenciennes and other authors. To these must be added 
twelve or fourteen others recently published by Rehberg. In most cases the 
species recorded by the various authors have been identified from published 
descriptions, and I am not aware that any author has compared together the 
type specimens contained in continental museums. The American types have 
not been redescribed or refigured since the original publication. The synonymy, 
therefore, lapsed into a state of confusion, and the lists of species recorded as 
occurring in certain areas are quite unreliable. It has thus been necessary to 
make, as far as possible, a renewed study of the type specimens of the numerous 
species already described. It has not yet been possible for me to study the type 
specimens preserved at Washington and other places in the United States, and 
thus I have only been able to judge of the characters and positions of the species 
described by Dana, Horn, and Verrill from the more or less complete data 
supplied by these authors. ‘The types described by European authors are in the 
Museums of Paris, Berlin, London, Strassburg, and Jena, whilst Klunzinger’s 
types are, I believe, preserved in the Museum at Stuttgart, but a complete set is 
also to be found in the Berlin Collection. I have not yet had an opportunity of 
visiting the Stuttgart Museum, and my notes on Klunzinger’s Red Sea Collection 
are based on the study of the specimens identified by Klunzinger which are 
contained in the Berlin and London Collections. 
