28 



BULLETIlSr 15 8, UNITED STATES NATION" AL MUSEUM 



segments of second, third, and fourth exopods each with two spines 

 on the outer margin. Basal half of the outer margin of the end 

 segment of the fourth exopod ciliated in the female, dentate in the 

 male. Fifth legs symmetrical in female but quite asymmetrical in 

 male, the left exopod without setae, the endopod often rudimentary ; 

 inner margin of basipods naked. Caudal rami short, each with six 

 setae, the third inner one greatly elongated. One species. 



NEOCALANUS GRACILIS (Dana) 



Figure 13 



Calanus gracilis Dana, Proc. Amer. Acad. Arts and Sci., vol. 2, p. 18, 1849. 

 Megacalanus gracilis A. Scott, Sihoga-'Expeditie, 29a, Copepoda, pt. 1, p. 12, 1909. 

 Neocalanus gracilis Sars, Resultats de campagues scientifiques du Prince de 

 Monaco, fasc. 69, p. 7, 1925. 



Occurrence. — Fifteen males 

 and females from trawl wings, 

 Stations 2183, 2195, Albatross; 

 7 females in vertical net. Sta- 

 tion 10331, GraTTipus, Gulf of 

 Maine. 



Distribution. — Tropical A t- 

 lantic (Dana) ; Mediterranean, 

 tropical Atlantic, tropical Pa- 

 cific (Giesbrecht) ; Gulf of 

 Guinea (Lubbock) ; Messina 

 (Glaus) ; Philippines (Brady) ; 

 Canary Isles and Malta 

 (Thompson) ; Indian Ocean 

 (van Breemen). 

 Color. — Body as a whole color- 

 less, transparent, and very dif- 

 ficult to see in the water, but 

 the appendages are more or less 

 red or pinkish, and the over- 

 lapping margins of the four posterior thoracic segments form narrow 

 transverse lines of deep vermilion, most pronounced dorsally, grad- 

 ually fading out ventrally. Directly above the mouth and often at 

 the posterior end of the thoracic cavity there are internal blotches 

 of a blood-red color mixed with yellow. A few much smaller spots 

 of the same color are irregularly distributed along the sides and at 

 the ventral edges of the segments. The eye is bright vermilion. 



Female. — Head fused with first segment of thorax; fifth segment 

 with rounded posterior corners; second inner seta of left caudal 

 ramus much longer than the corresponding one on the right ramus. 

 First antennae at least half as long again as the entire body, with 

 one or more enlarged plumose setae near the distal end. Distal seg- 



FiGUEE 13. — Neocalanus gracilis, female : a. 

 Dorsal surface ; 6, eud spine of first exo- 

 pod ; c, fifth legs of male 



