.326 M. A. Boeck on the AmpJiipoda 



Recently this family has also been in other countries the 

 object of attention to naturalists. By this means not only has 

 the number of known species and genera been increased^ but 

 so much diversity of form has been met with, that the mode 

 of classification established by Milne-Edwards can no longer 

 be regarded as satisfactory. Dana, who has the merit of 

 having treated not only of the forms which he was able to 

 study attentively himself, but also of those which he found 

 described by other authors, has elaborated an entirely ncAv 

 systematic arrangement which evidences a clear conception 

 of the nature of these animals. He has raised Milne-Edwards's 

 families into higher groups (subtribes), and divides these into 

 families and suljfamilies. Spence Bate, who also elaborated a 

 new systen, in which, however, he only ti'eats of the English 

 species, has nevertheless, by calling attention to the relation 

 between differences of forai and differences in mode of life, 

 contributed to the recognition of those characters to which we 

 must have regard in their natural arrangement. A. Costa's 

 works upon the Amphipoda occurring in the Mediterranean 

 also contain material towards their systematic arrangement. 



It will, however, be easily seen that just as the augmented 

 material in conjunction with a greater knowledge of the struc- 

 ture and mode of life of the Amphipoda has enabled these new 

 systems to be brought forward, so may further investigations 

 modify them in turn. The division of the Amphipoda into 

 three primary sections (the Hyperidoe^ Gammaridce^ and Ca- 

 prelUdce) will probably always retain its value ; but the cha- 

 racters upon which the subdivisions are founded will hardly 

 remain of the same importance, so that the boundaries of the 

 groups will have to undergo alteration. Thus, for examj)le, 

 Dana and Spence Bate differ as to the limits of the various 

 families and subfamilies, so that the same genera are often 

 found in different subfamilies. They do not entirely agree in 

 the characters upon Avhich they depend for their principle of 

 division. To this must also be added that these observers did 

 not know the northern species of Amphipoda from their own 

 investigation ; possibly, also, the languages in Avhich these 

 are in part described ])revented the characters adduced being 

 completely understood, so that a few errors have crept in. 

 For the present, therefore, we can hardly arrange our Amphi- 

 poda in a system consistently carried out, or in all parts fol- 

 loAv one already established. I will therefore, like Bruzelius, 

 in the following preliminary contribution to the natural history 

 of the Norwegian Amphipoda, merely cite the genera one 

 after the other imder families, in the manner in which I think 

 they ought to ])c placed side by side in accordance with their 



