COPEPODS OF THE WOODS HOLE REGION 



25 



in the plankton, and have been described by Damas, 1905, and by 

 Lebour, 1916. 



CALANUS HELGOLANDICUS (Claus) 

 FlGUBE 11 



CetocMlus helgolandicus Claus, Die frei lebenden Copepoden, p. 171, pi. 26, figs. 



2-9, 1863. 

 Calanus helgolandicus Sabs, Crustacea of Norway, vol. 4, p. 11, pi. 4, 1901. 



Occurrence. — Ten males and females from trawl wings. Stations 

 951, 986, 993, Fish Hawk; 2 females in vertical net. Station 10245, 

 Grampv^. 



DistHhution. — British Isles (Brady) ; coast of France (Canu) ; 

 Mediterranean (Giesbrecht) ; Black Sea (Karawajew) ; Norwegian 

 coast (Sars) ; Australian coast 

 (Brady) ; Chesapeake Bay (Wil- 

 son). 



Color. — Those from Station 951 

 showed blotches of reddish along 

 the ventral edges of the segments 

 and at the posterior end of the body ; 

 lines of vermilion also sometimes ap- 

 peared between the segments, but 

 were more often wanting. In the 

 lot obtained at Station 993 the entire 

 body was of a bright pink by lamp- 

 light. (Rathbun.) 



Female. — Head separated from the 

 first segment; fifth segment with 

 rounded posterior corners; first an- 

 tennae reaching about 2 segments be- 

 yond the tips of the caudal rami; 

 caudal rami scarcely longer than the 

 anal segment; inner margin of first 



basipod of fifth legs concave and armed with coarse teeth 

 length, 2.75-3.25 mm. 



Male. — Smaller than the female; first antennae relatively a little 

 longer, extending three or four segments beyond the caudal rami. 

 Fifth legs quite asymmetrical, both left basipods and the two proxi- 

 mal exopod segments elongated, the distal exopod segment only half 

 the length of the second segment, the left endopod reaching but 

 little beyond the first segment of the exopod. Right leg much 

 shorter than the left, its endopod reaching well beyond the base of 

 the end segment of the exopod. Total length, 2.5-2.8 mm. 



Remarks. — Most recent authors regard this species as a synonym 

 of pmnarchicus, but Sars gave sufficient reasons for restoring it as a 



Figure 11. — Calanus helgolandicus: a. 

 Female, dorsal surface ; i, male, 

 left fifth leg 



Total 



