REPORT ON THE ANOMURA. 1&7 



THE CHIEF GEOGRAPHICAL AREAS WITH THE SPECIES OF 

 ANOMURA OBTAINED IN EACH. 



In order to- facilitate the distributional study of the species collected during the 

 Expedition, I have thought it advisable to group them according to the special areas in 

 which they were found. In doing so I have followed the arrangement adopted by Mr. 

 E. J. Miers in his Report on the Challenger Brachyura, which is in part founded on 

 that originally proposed by Professor Dana. As regards the distribution of the littoral 

 and shallow-water forms of higher Crustacea, he believes that four great regions can be 

 recognised, viz.: — (l) The Arctic or Boreal Circumpolar Region; (2) the Antarctic or 

 Austral Circumpolar Region ; '(3) the Atlantic Region ; and (4) the Indo-Pacific or 

 Oriental Region. 



Of the Circumpolar Regions much remains to be learnt, but so far as is known 

 their Crustacean fauna is a scanty one when compared with that of the other two 

 divisions ; in some respects they appear to gradually merge with the latter, for it has 

 been shown that certain characteristic genera, e.g., Lithodes, extend almost to the tropics, 

 but are then found only in deep water where the temperature conditions are favourable. 

 No part of the Arctic Region was visited by the Challenger, but I have followed Mr. 

 Miers by including in the Antarctic Region all those species taken to the south of 40° S. 

 latitude, an arrangement which has at least the merit of being convenient. 



The Atlantic and Indo-Pacific Regions stand clearly apart from one another, each 

 containing many species with a wide range of distribution, though if the deep-water 

 forms be excluded a comparatively small number are common to both. Each of these 

 great regions may be subdivided into a number of provinces, all of which are character- 

 ised by the presence of distinct species, and in most cases also of distinct genera. The 

 following arrangement will be found on the whole consistent with the distribution of 

 other groups of marine animals, and the nomenclature is in many respects similar to 

 that adopted by Mr. Hoyle in his Report on the Challenger Cephalopoda : — 



Atlantic Provinces. 



1. Scandinavian. - 



2. New England. 



3. West Indian. 



5. Mediterranean. 



6. West African. 



7. South African. 



4. Lusitanian. 



1 The provinces printed in italics were not visited by the Cliallenger. 



