INTKODUCTION. Xxi 



The Report on the Hydroids was written by Prof. George J. 

 Allman ; on the Crinoids, by Dr. P. H. Carpenter ; on the Hy- 

 droids of the first expedition, by Prof. S. F. Clarke ; on the 

 Crustacea, by Prof. Alphonse Milne-Edwards ; on the Annelids, 

 by Prof. Ehlers ; on the Myzostomidse, by Prof, L. von Graff ; on 

 the Isopods, by Mr. Harger ; on the Ophiurans, by Mr. Lyman ; 

 on the Starfishes, by Prof. Perrier ; on the Corals, by Pourtales ; 

 on the Sponges, by Prof. Oscar Schmidt ; on the Bryozoa, by 

 Prof. Smitt ; on the Holothurians, by Dr. H. Theel ; on the An- 

 thozoa, by Prof. Verrill ; and on the Pygnogouidae, by Prof. E. 

 B. Wilson. Mr. Garman, who accompanied me as assistant dur- 

 ing the first cruises of the " Blake," was indefatigable in caring 

 for the collections brought together, and he also wrote the 

 Report on the Selachians. 



In addition to the preparation of the special Reports in their 

 departments, I am also indebted to Prof. Goode and Dr. Bean, 

 for additional notes on the Fishes ; to Mr. Dall, for the greater 

 part of the account of the MoUusks ; to Mr. Lyman, for that of 

 the Ophiurans ; to Mr. Fewkes, for that of the Acale^^hs ; and 

 to Prof. S. I. Smith, for that of the Crustacea. To Mr. John 

 Murray I owe special thanks for his suggestions and assistance 

 in writing the chapter on Submarine Deposits. Commander 

 Sigsbee was kind enough to look over the chapter relating to 

 the equipment of the " Blake." Commander Bartlett of the 

 Hydrographic Office has read the chapters on the Gulf Stream 

 and on the hydrography of the Caribbean region ; he has also 

 supervised for this volume the drawing of several of the accom- 

 panying maps. 



I have myself prepared the Reports on the Coral Reefs, the 

 Surface Fauna of the Gulf Stream, the Sea-Urchins, and a few 

 minor papers relating to the cruises of the " Blake." 



To the U. S. Coast Survey Office I am of course under the 

 greatest obligation for cojjies of the many reports, maps, and 

 sections contained in that office to illustrate the hydrography of 

 the West Indian region and of the Gulf of Mexico, and that 

 of the Atlantic coast of the United States. Prof. James D. 

 Dana has kindly read some of the cha23ters relating to the geo- 

 logical problems discussed, and to Mr. Winsor I am indebted 



