PREFACE. 



I have now the satisfaction of presenting to the scientific world the 2nd 

 Volume of my work on the Crustacea of Norway. 



The Isopoda have not yet been treated of as a whole by any of the 

 Scandinavian zoologists, although of solitary groups there have recently been 

 published several excellent monographs, especially by Danish zoologists. Thus 

 the Cymothoidce and jEgidce have been treated of by Prof. Liitken and Meinert, 

 the Cirolanidce by Dr. Hansen, and the extensive group Oniscoida by Mr. Budde- 

 Lund. Jn all these monographs, however, both indigenous and foreign forms 

 are combined, and the present Volume is accordingly the first faunistic work 

 on Scandinavian Isopoda. In as much as this is the case, I hope that it will 

 be of practical use to future zoologists, who may enter upon a study of the 

 indigenous Isopod-Fauna. 



The plan according to which the work has been carried out, is chiefly 

 that followed in the 1st Volume treating of the nearly-allied order Amphipoda. 

 Of course, in so doing, some limits have presented themselves, beyond which the 

 treating of the several forms could not pass, though in some instances, perhaps, 

 a more detailed account would havs been desirable. 



The difficulties connected with the elaboration of this work have been by 

 no means small. I have especially taken great pains in investigating and critically 

 determining the Epicarida, which undoubtedly is the most difficult of the Isopod 

 groups, being at the same time of very prominent interest in biological respects. 

 It is not improbable that some deficiencies and perhaps also errors may be found to 

 exist in my account of this or the other groups ; but considering the great difficulties 

 connected with this investigation, I hope that they will be excused, and that they 

 will soon be corrected by other zoologists. I may add, that the account especi- 

 ally of the Oniscoida and Epicarida would have been still much more defective, 

 if I had not been assisted in a most ready manner by the directors of the 



