Introduction. 



My studies on the Plancton-Copepods, brought home by the Danish Ingolf Expedition, which 

 were commenced about 1904, have been delayed for several reasons, of which the three principal ones 

 are: in the first place that I for several years was occupied with other topics, in the second place that the 

 rich collections of The Thor Expedition from the waters around Iceland as well as those of the Danish 

 Expedition to East Greenland 1900 have greatly added to the work to be done; the third reason is, 

 that it was my intention to give so full an account of each species as possible, not only of the adult 

 males and females but also of the different stages of Copepodites. 



On the Material. 



The principal source of material was that of the "Ingolf" 1894 and 1895; the investigation of 

 this expedition "extended over the eastern part of the seas along the west coast of Greenland from a 

 point a little north of the polar circle to about 58 L. N., two degrees south of Cape Farewell, from 

 there in a north-easterly direction towards Iceland, the waters round this island and between Iceland 

 and the Faeroes, lastly eastwards to a line drawn almost due north from the Faeroes to Jan Mayen". 

 The above quotation is from Hansen's Crustacea Malacostraca I of the Ingolf-Expedition vol. Ill 2 

 1908, to the introductory remarks of which paper I partly refer. The southern limitation in the 

 Atlantic was about 6o° L. N. 



Comparatively few specimens were taken with the trawl; a good many of the samples were 

 gathered with ordinary vertical nets (P and V) in a depth lying between 50 — 300 fathoms and the sur- 

 face and a few ones with a closing net in considerable depth; numerous samples were taken at the 

 surface with net marked PI, Apst and Cyl during the voyage. The Ingolf collections give a very 

 good picture of the plankton copepods, the big as well as the small species, but only down to a depth 

 of 300 fathoms; the deeper layers of these regions are, as shown by the Thor, populated by numerous 

 species, which were not taken by the Ingolf, at least as far as the Atlantic South and west of Iceland 

 is concerned. It is a pity that no deep hauls were made on the West Coast of Greenland; an Atlantic 

 fauna, identical with that mentioned, should certainly be found here. It is rather interesting that in one 

 of the few samples, taken with a closing net at a considerable depth near Jan Mayen St. 118 a new 

 species Euchtzte Bradyi was found and in another a single specimen of so scarce a species as Scapho- 

 calanus brevicornis G. O. Sars was secured. 



The Ingolf's material from the Atlantic, rich in specimens, of the bigger as well as the smaller 

 species, which inhabit the intermediate as well as the upper layers, is in a useful way supplemented 



The Ingolf-IIxpedition. III. 4. . j 



