VI 



Copenhagen Museum, who have kindly placed at my disposal the rich collections 

 of these groups procured during recent years by that Museum. 



As to the systematic arrangement here adopted, some objections may 

 perhaps be urged against its validity. I must, however, observe, that it is chiefly 

 out of regard to the merely practical side of the question, that I have been 

 induced to retain unaltered this arrangement, proposed by me several years ago, 

 and now sanctioned by several distinguished authors. 



In the Appendix to the Volume, some additions, chiefly as regards the 

 geographical distribution of the species, are given, as also descriptions and figures 

 of a few new species. 



The plates, as in the 1st Volume, have been prepared by the autographic 

 method, the appropriateness of which has been proved both by the plates of the 

 1st Volume, and by several other illustrations published by the present author. 

 I am sorry, however, that some of the last plates of the present Volume have 

 been less perfectly executed, owing to some want of care on the part of the 

 lithographer in the transfer of my drawings. Yet I hope that these plates too will 

 be found sufficiently distinct to allow of easily recognising the species illustrated. 



In concluding this short preface, I wish in the first place to express my 

 most hearty feeling of gratitude to my friend, the distinguished Danish zoologist, 

 Dr. Hansen, for the kindness with which he has at all times assisted me, both 

 by forwarding to me specimens from the Copenhagen Museum, and by giving 

 me much useful advice and information. I am likewise indebted to Mr. Budde- 

 Lund, the well-known author of the work on air-breathing Isopoda, for identifying 

 some difficult forms of Oniscoitla. There are also several other gentlemen to 

 whom my thanks are due, partly for having sent me specimens, partly for having 

 assisted me in other ways. 



Finally, I beg to offer my best thanks to the direction of the Bergen 

 Museum for the readiness with which it has undertaken the continued publication 

 of this great work. 



G. 0. Sar*. 



