4: THREE CRUISES OF THE "BLAKE." 



Mexico. Less than fifty years ago there were not more than 

 twenty known species of Crustacea from the West Indian region. 

 The " Blake " has added no less than forty new genera and 

 150 new species to those thus far described. Ten of the genera 

 and nearly forty of the species belong to the well-known Bra- 

 chyura, in spite of the fact that Stimpson and Milne-Edwards 

 had, before the explorations made by the " Blake/' apparently 

 very fully worked out the species of this group from the dredg- 

 ings of the " Hassler " and " Bibb " ; sixteen genera and over 

 sixty species belong to the less known Anomura ; and there are 

 fourteen genera and about fifty species of Macrura. 



Among the mollusks the total number of littoral species re- 

 corded by Adams and D'Orbigny is 580, as compared with 461 

 collected by the " Blake." This number also includes 210 lit- 

 toral species, while 251 are abyssal. The number of genera rep- 

 resented by the former is about 110, while some 98 genera are 

 found in the "Blake " collection. These numbers are of course 

 approximate. 



The immense collections of echinoderms are peculiarly inter- 

 esting. Of the deep - sea echinoderms the most striking are 

 the Elasipoda, a new order of holothurians, established by Dr. 

 Theel for the reception of these extraordinary and aberrant 

 types, of which no less than fifty-two species were discovered by 

 the " Challenger " expedition. Previous to that time three spe- 

 cies of the group were known, one from the Kara Sea, and 

 two subsequently found in the northern parts of the Atlantic 

 by the Norwegian North Atlantic expedition. The " Blake " 

 dredged about nine species of this remarkable order, three of 

 which were unknown before. 



There are now described eighty-three species of sea-urchins 

 from the Caribbean fauna. Of these, eleven were added by the 

 dredgings of Count Pourtales in the "Bibb" and "Hassler," 

 nineteen were discovered by the " Blake," and thirteen species 

 previously known from other districts were obtained for the first 

 time in the Caribbean arid adjoining seas by the Coast Survey 

 expeditions, so that the list of species has been more than 

 doubled by the dredgings made since 1876. 



The "Blake" dredged fifty -four species of starfishes, of 



