The basipod is broad and has 3 lobes, which 

 have 2, 2, 3 spines, respectively. 



The basipod of the first leg (fig. 10) has a 

 single seta on the internal margin of the coxa. 

 The exopod is 3-segmented. Each of the first 

 and second segments has an internal seta and 

 an external spine. The third segment has 2 

 external spines, 4 internal setae, and a terminal 

 spine that is serrated along the outer margin. 

 The endopod is also 3-segmented. The first seg- 

 ment has a single internal seta, the second seg- 

 ment 2 internal setae, and the third segment 

 6 setae. 



The second and third pairs of legs (figs. 11 

 and 12) are similar. The basipod carries a 

 single internal seta on the coxa. The exopod 

 is 3-segmented. Each of the first and second 

 segments has an internal seta and a strong 

 external spine. The third segment has 3 exter- 

 nal spines, 5 internal setae, and a strong termi- 

 nal spine that is serrated along the external 

 margin. The endopod is 2-segmented. The first 

 segment has 3 internal setae and 1 external 

 seta. The second segment has 8 setae. 



The fourth pair of legs (fig. 13) is similar 

 to the third, but the basis has a seta on the 

 posterior surface and the second endopodal 

 segment has 7 setae instead of 8. 



The basipod of the fifth leg (fig. 14) has 

 a plumose seta on the posterior surface of the 

 basis. The exopod and endopod each consist 

 of a single .segment. The exopod has a forked 

 tip, a strong spine along the internal margin, 

 and 3 small spines along the external margin. 

 The endopod also has a forked tip; it is about 

 one-third the length of the exopod. 



Remarks 



In the shape of the urosome the present 

 specimen is not in full agreement with the 

 description given by Giesbrecht (1892). Ac- 

 cording to A. Fleminger (personal communica- 

 tion), however, it is not outside the usual vari- 

 ability shown by the species. 



PontelUna phimata (Dana, 1849) 

 (Plate 13, figs. 15-16) 



Occurrence 



Sta. 7. 1 adult female, 1.94 mm. 



Remarks 



A single female referable to the above species 

 was in the present collections. The specimen 

 agrees in every detail with the description and 

 figures given by Giesbrecht (1892) except for 

 the structure of the endopod of the fifth leg 

 (fig. 16). The sizes of the right and left en- 

 dopods are slightly unequal, and each is single- 

 pointed, not forked. 



FAMILY ACARTIIDAE 



Acartia danae Giesbrecht, 1889 



Occurrence 



Sta. 3. 1 adult female, 1.20 mm. 



Remarks 



The female can be recognized by the large 

 spine on the first segment of the antennule, the 

 pointed posterolateral corners of the metasome, 

 and the structure of the fifth pair of legs. 



Acartia negligens Dana, 1849 

 (Plate 13, figs. 17-18) 



Occurrence 



Sta. 3. 3 adult females, 1.23 to 1.30 mm. 

 Sta. 5. 5 adult females, 1.22 to 1.28 mm. ; 



1 adult male, 1.15 mm. 

 Sta. 7. 7 adult females, 1.25 to 1.28 mm. ; 



1 adult male, 1.18 mm. 



Remarks 



In the female, the fifth pair of legs is some- 

 what similar to that of A. danae, but the pos- 

 terolateral corners of the metasome are rounded 

 and have small spines. The shape of the uro- 

 some and the fifth pair of legs of the male can 

 best be described by reference to figures 17 

 and 18. 



ACKNOWLEDGMENTS 



This work was made possible by a fellowship 

 from the International Cooperation Adminis- 

 tration of the United States. Stillman Wright 

 arranged my program so as to make the study 

 possible. Everet C. Jones and George D. Grice 

 advised me during the work; Paul L. Illg, 

 Donald W. Strasburg, Everet C. Jones, Abra- 

 ham Fleminger, George D. Grice, and Kuni 

 Hulsemann I'eviewed the manuscript. 



CALANOID COPEPODS FROM NORTH PACIFIC 



569 



