SUMMARY. 



The Challenger collection contains 161 species, or well-marked varieties, of Anomura, 

 referable to 52 different genera, and of these 86 species and 7 genera are described as new 

 to science. 



The large proportion of new species is scarcely to be wondered at when the nature of 

 the Challenger dredgings is borne in mind. Prior to 1873 scarcely any deep-water 

 investigations had been made in the seas visited by the Expedition, and the abysses of 

 the ocean practically remained a sealed book to naturalists ; hence it is not surprising 

 that slightly more than three-fourths of the total number of new species were taken 

 beyond the one hundred fathom line. 



In some respects the collection is disappointing, a few of the shallow-water groups 

 being but poorly represented, while many well-known and widely distributed species are 

 conspicuous by their absence. The interest and value of the collection is, however, by no 

 means confined to the deep-water forms, for the careful manner in which the locality and 

 conditions of existence were noted at the time of capture has disclosed many important 

 facts, and added materially to our knowledge of the distribution qf shallow-water species. 

 The main interest, however, centres in the Paguridea and the Galatheidea — two great 

 grouj)S which extend to abyssal depths. 



The more highly specialised Anomura, i.e., the Dromidea, Raninidea, and Hippidea, 

 are less fully represented in the collection than the Macruran forms, and, like the 

 Brachyura, they appear to be almost confined to shallow water. With the exception of 

 Homologenus, founded by Alphonse Milne-Edwards for the reception of a West Indian 

 species, to which a young Homolid taken by the Challenger is doubtfully referred, none 

 of the Dromidea are known to occur beyond the five hundred fathom line, though several 

 genera are found in comparatively deep water. So far as is known the Raninidea are 

 even more completely restricted to shallow water, and few of the species in all probability 

 occur at greater depths than 200 fathoms. The deepest water in which any Raninid has 

 been found is 210 fathoms, at which depth specimens of the rare Japanese Lyrcidus 

 tridentatits, De Haan, were taken off the Fiji Islands. The Hippidea are represented 

 by only four species, all of which have been previously described, though two belong to 

 rare and little known forms. There is every reason to believe that the members of this 



