INTRODUCTION. ' 



THE CLASSIFICATION OF THE ANOMURA. 



In the following account I propose to discuss briefly the more important schemes of 

 Classification which have been adopted for the group. 



In the first volume of his classical Histoire Naturelle des Crustacea, published in 

 1834, Professor H. Milne-Edwards separated from the Brachyura and Macrura of older 

 writers, under the designation of "Anomoures," those forms in which the thoracic sterna are 

 linear, the penultimate abdominal segment is provided with appendages, the female genital 

 openings are placed on the basal joints of the legs, and the abdomen is either loosely 

 applied to the under surface of the thorax or semi-extended. In the earlier part of the 

 century Latreille, who occupied a very prominent place among the older carcinologists, 

 divided the Decapod Crustacea into its two branches, Brachyures and Macroures, the latter 

 including a section Anomaux, in which many of the forms we now term Anomura were 

 placed, the remainder being referred to the Brachyura. 



In the second volume of his great work, Milne-Edwards subdivided the Anomoures 

 into two families, termed respectively the " Apterures " and the " Pterygures," which were 

 characterised by the absence or presence of terminal abdominal appendages. In the first 

 of these families he included such forms as Dromia, Homola, Lithodes, and Ranina, 

 while Hippa, Pagurus, and Porcellana were included in the second. The Galatheidaj 

 were referred by the same naturalist to the Macroures, and the aberrant genus Latreillia 

 was placed in the Brachyures. 



De Haan, in his fine work on the Crustacea of Japan,^ divides the Decapoda into five 

 great sections, as follows : — (1) Brachygnatha, including the Dromiacea ; (2) Oxystomata ; 

 (3) Astacina ; (4) Carides ; and (5) Anomala. As regards the Anomala he has followed 

 Latreille, and he further subdivides the group into the following families: — (l) Gala- 

 theidea ; (2) Porcellanidea ; (3) Hippidea ; (4) Paguroidea ; (5) Lithodeacea. De Haan's 

 classification is to a large extent founded on the structure of the mouth organs, and it 

 has till quite recently scarcely received from carcinologists that attention which it 

 deserves ; at the same time there can be little doubt that it is in many respects, as 



' Crustacea in v. Siebold, Fauna Japonica, 1835—19. 



