INTRODUCTION. 



The Preliminary Reports on the Echini of the Blake Expeditions for 

 1877-78, for 1878-79, and for the summer of 1880, were published in Vol. 

 V., No. 9, Bull. M. C. /.. and Vol. VIII.. No. 2, Bull. M. ('. X. In the former 

 Report will be found all the Stations occupied in the Gidf of Mexico and 

 Straits of Florida : in the latter, the Stations explored along the West India 

 Islands and the Atlantic coast of the United States. I give in this Report, 

 therefore, only principal localities in sufficient number to indicate the geo- 

 graphical range and bathymetrical distribution of each species as determined 

 by the dredgings of the '-Blake." In the Eteporl on the Echini of the 

 Challenger Expedition 1 have given a list of the bathymetrical and geo- 

 graphical distribution of all the species of Echini then known, including the 

 species collected by the Blake Expeditions. The Preliminary Reports on the 

 Deep-sea Echini, collected by Mr. Pourtales off the Florida Reefs, were 

 published in the Bull. M. C. X., Vol. I., No. 9. The final Report was incor- 

 porated in Part II. of the Revision of the Echini under the name of " East 

 Coast Echini," UL Cat. M. C. Z., No. VII. Mem. M.C.Z., Vol. III.. 1872-74. 



The importance of the collection of the Echini brought together during 

 the cruises of the " Blake" is well shown by a comparative statement of our 

 knowledge of the Caribbean Echinid Fauna before and alter the explorations 

 undertaken under the auspices of the I'nited States Coast Survey. 



There are now known eighty-three species of Sea-urchins from the Carib- 

 bean Fauna. Of these, eleven were added by the dredgings of Count 

 Pourtales in the "Bibb" and •• Sassier," nineteen were discovered by the 

 "Blake," and thirteen species previously known from other districts were 

 dredged for the first time in the Caribbean and adjoining seas by the Coast 



