COPEPODA FROM IFALUK ATOLL 81 



11. 1st segment of endopodite leg 2 about 3 times as long as wide. 



H. tenellus G. O. Sars 

 1st segment of endopodite leg 2 about 2 ji times as long as wide or shorter. . 12 



12. Terminal segment of endopodite leg 1 with some spinules, one of which points 



upward H. nicaeensis Glaus 



Terminal segment of endopodite leg 1 with some fine spinules or hairs, none 

 of which points upward 13 



13. Terminal segment of exopodite of leg 1 with 6 appendages: 5 claws and 1 seta. 



H. uniremis Kr0yer 



Terminal exopodal segment of leg 1 with 5 appendages: 4 claws and 1 



seta 14 



14. 2nd segment of endopodite leg 2 produced into a long spiniform process, 



reaching beyond tip of exopodite 15 



Spiniform process of 2nd endopodal segment of leg 2 short, just reaching 

 tip of exopodite 16 



15. Exopodite leg 5 with 5 appendages: 4 spines and 1 seta . . H. gracilis Glaus 

 Exopodite of leg 5 with 6 appendages: 3 spines and 3 setae, gradually de- 

 creasing in length H. confusus, new species 



IG. Exopodite of leg 5 spatulate, strongly narrowed at apex. 



H. septentrionalis Klie 

 Exopodite of leg 5 not spatulate, only slightly narrowed at apex .... 17 



17. Internal border of coxa of maxillipede deeply incised to form a square 



notch H. littoralis G. O. Sars 



Internal border of coxa of maxillipede concave 18 



18. Exopodite of leg 5, 3 to 4 times as long as wide . . . . H. clausi A. Scott 

 Exopodite of leg 5, no more than twice as long as wide . H. islandicus Klie 



Harpacticus clausi A. Scott, 1909 



Figures 24-26 



Harpacticus clausi A. Scott, 1909, p. 201, pi. 59 (figs. 9-14a).— Sewell, 1940, 

 pp. 153, 353, 355, 363, 364, figs. 9, 10.— Lang, 1948, p. 335, fig. 153 (no. 

 2). — Krishnaswamy, 1953, p. 67. 



Material. — Loc. 425, 1 ad. d^, 0.48 mm. 



Description. — This male specimen shows such a great resemblance 

 to the male of Harpacticus clausi described by Sewell (1940) that it 

 has been brought to that species. The description is from this male 

 specimen, which has been dissected and mounted. 



Adult male, total length 0.48 mm.; greatest diameter 0.15 mm.; 

 greatest length of fm-cal seta 0.30 mm.; proportion of cephalothorax 

 and abdomen 11:5. 



Body fairly slender in dorsal aspect, greatest diameter at end of 

 cephalic somite, anteriorly narrowing and front broadly rounded, 

 with rounded protuberance between antennular bases, representing 

 rostral base. Posteriorly body tapers slightly, division between 

 cephalothorax and abdomen distinctly marked. 



Head and 1st thoracic somite completely fused to form cephalic 

 somite; this somite 1% times as long as combined lengths of thoracic 

 somites 2 to 4. Lateral borders of cephalic somites not produced, 



