86 U.S. NATIONAL MUSEUM BULLETIN 236 



Remarks. — This male specimen agrees perfectly with Sewell's 

 description of the male of H. clausi A. Scott. The only point in which 

 there is a difference is the armature of the 2nd endopodal segment of 

 leg 3; Sewell figures no spines on the anterior aspect, whereas three 

 distinct spines are present on that segment in the present specimen 

 (and on the corresponding segment of leg 4 in Sewell's and my own 

 specimen). The agreement in the shape and armature of leg 5 is 

 very striking. Because of the occurrence of spines on the endopodal 

 segments of legs 3 and 4 the species might be confused with H. 

 ohscurus, a species found so far only in the North Atlantic. In 

 H. ohscurus, short, coarse spinules are present on both 1st and 2nd 

 endopodal segments of legs 3 and 4 (in H. clausi there are fine, slender 

 spinules on endopodal segment 2 of legs 3 and 4 and apparently only 

 in the male). The difference in the shape of the exopodite of leg 5 

 is very striking: club-shaped in H. ohscurus and almost cylindrical 

 and much longer in H. clausi. 



A single female specimen of this form was described by A. Scott from 

 material collected by the Siboga Expedition at the surface near the 

 Paternoster Islands (9 0.67 mm. long); this specimen, the holotype, 

 apparently is lost. Additional female and male specimens afterwards 

 were recorded from Nancowry Harbour in the Nicobar Islands by 

 Sewell (1940) and shortly were described and figured. The female 

 and the males measured 0.6 mm.; they were obtained in weed wash- 

 ings. The present male specimen was obtained from the reef edge 

 south of Elangelap in the Ifaluk Atoll, where it occurred in 3 to 4 feet 

 of water. 



Harpacticus confusus, new species 



Figures 27-30 



Material.— Loc. 425, 3 ad. 99, 0.37-0.39 (0.38) mm.; 1 ad. d', 

 0.35 mm. 



Description. — The following is based on a 0.39 mm. long female 

 (holotype), which has been dissected and mounted; the male allotype 

 also has been described, dissected, and mounted. The two remaining 

 specimens of the type lot are tubed as paratypes. 



Adult female, total length 0.39 mm.; greatest diameter 0.11 mm.; 

 length of longest furcal seta 0.23 mm. 



General shape of body in dorsal aspect fairly slender, greatest 

 diameter at 2nd thoracic somite, anteriorly slightly tapering and 

 rounded ; posteriorly very gradually tapering, division between cephalo- 

 thorax and abdomen marked by distinct constriction (fig. 276). 

 Head and 1st thoracic somite fused to form cephaUc somite, which is 

 much longer (4:3) than combined lengths of thoracic somites 2 to 4; 

 in dorsal aspect, anteriorly rounded, rostral base visible as smaU 



