NOTICE. 



The two Memoirs which form this volume will be widely separate from one 

 another in the final collation. 



A considerable part of Mr Moseley's Report on the special groups of 

 Corals and coral-building polypys, to which he had mainly devoted his 

 attention, was prepared during the voyage of the Challenger, and, from the 

 great interest which appeared to me to attach to his investigations on the 

 Helioporiclge and on the structure of Millepora, and of other Hydroid forms, I 

 was glad to have it in my power to sanction the publication of two papers on 

 these subjects in the Philosophical Transactions for the years 1876 and 1877, 

 in anticipation of the Official Report of the Expedition. In 1878 Mr Moseley 

 was selected by the Council of the Royal Society to deliver the Croonian 

 Lecture, and at his request I made a special application to the Treasury, in 

 accordance with which he was permitted to make a further contribution of his 

 results, and was also most liberally allowed the use of the plates, which were 

 prepared at Government expense for the Report. The papers from the 

 Philosophical Transactions have since been recast, with some additions and 

 alterations, by the author. The third part of Mr Moseley's Report, the 

 description of the Deep-Sea Madreporaria, procured during the voyage, with 

 most of its accompanying illustrations, appears now for the first time. 1 

 have not thought it necessary to give either lists or descriptions of reef- 

 building Corals, or of those from shallow water. Our opportunities of collect- 

 ing systematically were not nearly so great as those of many other expeditions, 

 as, for example, the American Expedition under Captain Wilkes, where the 

 Corals were so admirably described by Professor Dana. Much attention was, 

 however, paid to the general structure of Coral Reefs, and any important points 

 in connection with littoral species will be mentioned when treating of these. 



Only a comparatively small number of Birds were procured by the 

 Challenger Expedition. As the object of the Expedition was almost 



