312 ME. E. J. MIEES'S EEVISION OF THE HIPPIDEA. 



Eevision of the Hippidea. By Edwaed J. Miees, E.L.S., F.Z.S., 

 Assistant in the Zoological Department of the British 

 Museum. 



[Eead November 1, 1877.] 

 (Plate V.) 



Introductory Hemarhs. — The determination of the different spe- 

 cies of this small and peculiar group of Anomurous Crustacea, 

 and their identification with the brief descriptions of the earlier 

 authors, are often very difficult. Where the type specimens no 

 longer exist, it must of necessity remain uncertain what species 

 were known to Linnaeus and Pabricius. But three or four 

 species are mentioned by Lamarck and Latreille ; and only five 

 are described by M. Milne-Edwards in the second volume of the 

 ' Histoire Naturelle des Crustaces ' (1837). In the twenty years 

 following the publication of that work the number of species was 

 more than quadrupled, as we find that Stimpson, in 1858, in the 

 preliminary Eeport on the Crustacea collected by the United 

 States Expedition to the North Pacific, enumerates (but does not 

 describe) 23 species, contained in 6 genera ; and since the publi- 

 cation of his list several additional species have been described. 

 In the present revision of the group I have endeavoured, as far 

 as the state of our knowledge and the materials aff"orded by 

 the extensive collection of the British Museum will permit, to 

 determine the geograjjhical range and the extent of individual va - 

 riation in the several species, and to indicate reliable characters by 

 which they may be distinguished ; but as several species are either 

 desiderata or insufficiently represented in the national collection, 

 there yet remain several points requiring further elucidation. 



Three new species are described ; but as several of those pre- 

 viously recorded are reduced to the rank of synonyma, the total 

 number is only 22. 



It may be desirable to present a brief summary of the views 

 held by the diff'erent authors upon the classification and affinities 

 of the Hippidea, beginning with Latreille, who, by his researches, 

 may be considered to have laid the foundation of the natural 

 arrangement of the Crustacea. By this author (Cxen. Crust, et 

 Ins. i. p. 44, 1806) the genera RemipeSj Hippa, and Albunea were 

 arranged in the family Paguriens of the tribe Macroures ; but he 

 subsequently (Cuvier E. A. ed. 1, iii. p. 27, 1817) constituted a 

 distinct section, Anomaux, to contain these genera, together with 

 the Faguridcej Porcellanidce , and Galatheidce. Lamarck (Hist. 



