12 K 



Canadian Arctic Expedition, 1918-18 



terminal set of the natatory legs in the original description are cultriform, 

 dilated in the middle. Owing to the state of preservation of the specimen at 

 my disposal, I can say nothing on this point. 



The length was 1-52 mm., the anterior antennae were broken. Relative 

 lengths of anal .segment and caudal furca: anal segment 9, furcal length 15, 



Fig. 3. Eurytemora gracilis 9 . Urosome from above. 

 Fig. 4. Same. Part of fifth leg. 



width of caudal ramus 2; surface of caudal rami smooth (Fig. 3). In the last 

 pair of legs (p. 5), the distal joint was lost; the unguiform process of the proximal 

 joint of the Ramus (Re 1) projects nearly, horizontally inwards, abruptly 

 narrowing to a distal acuminate portion which is ciliated on the inner edge 

 (Fig. 4). Genital segment with lateral convexities separated by a constriction 

 (Fig. 3). 



10. Eurytemora herdinani I. C. Thompson and A. Scott, 1898. 



This is one of the most typical and abundant Copepods of the gulf of St. 

 Lawrence. It was first obtained in 1897 by Prof. W. A. Herdman, who collected 

 surface plankton through the ship's pump continuously day and night whilst 

 the steamer was going at full speed across the Atlantic. Though not previously 

 observed on the Pacific coast, it was taken at a number of stations by the Can- 

 adian Arctic Expedition: Tables I, II, VI, VII, IX, station 42p (under 

 Pseudocalanus) , and the following. 



Station 17 a,b,c: 60 9' N., 167 38' W., three surface hauls, with net number 

 3, fifteen minutes each, preserved in one vial, July 6, 1913. Numerous small 

 copepods, mostly adult <? , some young forms, but not one female. 



TABLE XI (STA. 17o, 6, c.) 



Eurytemora herdmani cT 45 



Acartia d" 45 



Tortanus discaudatus <? 10 



100 



Probably both Acartia longiremis and A. clausi are present in subequal 

 numbers, but as the metathoracic thorns of longiremis may be lost or worn down, 

 it is not safe to differentiate these species by male characters. Another vial 

 of the same date, labelled Sta. 17e, surface 30 minutes, same locality and net, 

 contained a scanty gathering which included some Euphausiid eggs, one male 

 Eurytemora herdmani, and a number of Acartia longiremis, both male and female. 

 To begin to understand these relations it would be necessary to know approxi- 

 mately the time of day and the light conditions. In any case the assembling 

 of males, as displayed in the table above, is not too commonly observed. 

 Station 19: See under Acartia longiremis. 



