Crustacea Malacostraca. HI. 



By 



H. J. Hansen. 



V. The Order Isopoda. 

 I ntrod uction. 



Before entering on the subject of the present paper I may refer to the "Introductory Remarks" in 

 "Crustacea Malacostraca I" published in 1908, because they contain various statements that need 

 not be repeated here. In that chapter I explained the limits of the area investigated by the "Ingolf" 

 and other Danish expeditions to our northern dependencies; the principal sources (apart from the "Ingolf) 

 for the material examined were enumerated, and the principles followed as to "occurrence" and 

 "distribution" were laid down. Zoologists wishing to get some information on these and allied topics 

 may find them in the paper mentioned. 



Our earlier knowledge of the Isopoda living at the coast of Greenland in depths down to 

 nearly a hundred fathoms was rather good, but as to the fauna of the deeper tracts of the adjacent 

 seas it was extremely poor. In 1913 K. Stephensen enumerated 37 valid species of marine Isopoda, 

 the deep-sea forms included, belonging to the fauna of Greenland. Of the Isopoda from Iceland and 

 the Fseroes and the deep sea around these islands our knowledge was very poor; in various papers I 

 have found a number of species also occurring at Greenland, and, besides, in all 9 species recorded 

 which were unknown from the seas of the last-named country. The result is that according to the 

 literature 46 valid species are known from the seas around our northern dependencies. In the present 

 paper 164 species are enumerated, and all, excepting 3 species not seen by me, have been secured by 

 Danish expeditions. The "Jngolf" has gathered 121 of these species, and no less than 74 have been 

 taken only by that expedition; 61 of its species are established as new to science. The "Thor" (Dr. 

 Joh. Schmidt) has secured no less than 46 species, 9 of which have been taken exclusively by this 

 ship, and 4 among these are new. The Ryder-Expedition and the two Amdrup-Expeditions to East 

 Greenland gathered several species, and 3 among them are new ; many species, 2 amoug them new, 

 are due to many other collectors in earlier or in more recent times. 



A comparison with the faunas of Norway and Great Britain may be of some interest, as the 

 Malacostraca in the seas at these countries have been more thoroughly investigated than in any other 

 area of our globe. In his "Account" Vol. II (1896 — 1899) G. O. Sars described 84 valid species of marine 

 Isopoda from Norway (the forms included in his work, but in reality belonging to the Danish fauna 

 and not taken near Norway, I have omitted in this enumeration); of these 84 species, 33 (among them 



The Ingolf-Expedition. III. 5. I 



