8 COPEPODA 



parently have only two basal segments; but according to Hansen the first basal segment of the 

 natatory legs is probably fused with the complicated chitinous system of the ventral surface; if this 

 is right, the first basal segment of the authors is really the second, and the second the third. In the 

 description I have followed this nomenclature; the last basal segment is accordingly designated the 

 third one (corresponding to the second one of most authors in the antennae, mandibulae, maxillulae, 

 maxillipeds and natatory legs); the second basal segment in my description corresponds to the first 

 one of most authors in the maxillipeds and natatory legs; the second basal segment of the mandibu- 

 lae and the first one of the antennae are as show by Hansen poorly developed. 



About the different abbreviations used in this paper I refer to the following list. 



Plaucton nets used by the Ingolf. 



V signifies the big vertical plancton net. 

 V 1 — the smaller one. 



V 2 — net with different width of the meshes. 



P 1 Apstein's vertical net (Nr. 20). 



Apst. = A. The same net used in the surface. 



PI. — Surface plancton net. 



Cyl. — Cylindric net. 



Closing net is the net of von Petersen-Chun, 



modified by Hen sen. 

 Yt is the abbreviation of the youngfish trawl 



used by the Thor- 

 0. Exp. 1900 is the abbreviation of The Danish 



Expedition to East Greenland in the year 1900. 

 A. B. C. D. E. and F. are the different kinds of 



surface nets used by this expedition. 

 f°. = adult female, 

 fa* = fullgrown male. 



Y = a young specimen. 

 St. = the stage. 



St. I — VI signifies the postlarval development; 



St. I is the youngest first postlarval stage and 



St. VI is the adult male or female. 

 The abbreviations used in the description of the 



species are those used by Giesbrecht and 



following authors. 

 Basp. I — III = The first, second and third base- 



podite. 

 Ri = Ramus internus. > 

 Re = Ramus externus. 

 Ri I — III and Re I — III signifies the number of 



the segment of the endopodite or exopodite. 

 <n> signifies that two segments are fused e. g. 



Re II 02 III and segment 8 co 9 of the anten- 



nulae. 

 Si = an interior seta. 

 Se = an exterior seta. 

 Sp = a posterior seta. 

 Sa = an anterior seta. 

 Spr = a proximal seta (antenuulae). 

 Sd = a distal seta (antennulae). 

 St = a terminal seta (Re III pes I— V). 

 L, or Eob = lobe. 



Le or Li = Eobus externus or internus. 

 Sp = Spermatophores. Sp. within a bracket indi- 

 cates that specimens, bearing these structures, 



were secured. 

 Sin. and dext. means sinister and dexter. 



On the description of species. 



As I have personally examined all the samples from the three expeditions myself and have picked 

 out a fairly big number of specimens, generally more than a hundred, if so many were present, adult 

 as well as young ones, I think that we get a fairly good impression of the proportion between the 

 different stages; Paulsen has as far as Calanus finmarchicus is concerned picked out a hundred 

 specimens to get an impression of the proportional distribution of the stages. In the systematic part 

 I have given an almost complete description of the species, which were only imperfectly described; 

 in cases, in which good descriptions have been given by previous authors, I have only added features, 

 overlooked, or differing from existing description. Not only the males and females of the last stages 



