COPEPODA FEOM IFALUK ATOLL 59 



with a fine seta at apex. Internal surfaces of 1st and 2nd endopodal 

 segments haired, 3rd endopodal segment of leg 4 small; setae, 

 especially the internal, greatly lengthened. 



The vai'ious particulars of the legs follow from figures 16a-<i and 

 the setal formula: 



endopodite exopodite 



leg 1 1.1.5 0.0.6. 2 



leg 2 1.2.120 0.0.013 



leg 3 1.2.020 0.0.113 



leg 4 1.1.020 0.0.013 



Leg 5 (fig. 156) apparently 1-segmented, but basal segment fused 

 to 5th thoracic somite, which bears fine, external seta near insertion 

 of free segment. "Shoulder" set with fine, scale-shaped teeth. Free 

 segment flattened, 3 times as long as broad, slightly reniform, external 

 margin shortly haired, at about % length from apex with fine seta. 

 Apex set with 3 setae of unequal length, median seta greatly length- 

 ened. Internal (concave) margin of free segment nude. 



Color deep yellowish-brown. 



Remarks. — In spite of certain differences in setation, I have 

 identified the Ifaluk specimen with a Bomolochus described from 

 Japan and taken from a species of fish, Leptoscarus japonicus (Cuvier 

 and Valencienne), which apparently does not occur in the region of 

 the Marshall Islands. I have based this apparently curious conclusion 

 on the follo\ving considerations. 



Bomolochus leptoscari Yamaguti, as appears at once from Yamaguti's 

 figiu-e (1953, pi. 1, fig. 9), with regard to the general pattern of the body, 

 occupies a more or less isolated position in the genus. The cephalo- 

 thorax is very large and formed by the head and somites 1 to 3, which 

 all have about the same width; the abdomen is notably short. There 

 is complete conformity in the structure and setation of antennules, 

 antennae, and oral parts. The very characteristic structure of leg 1 

 is identical in both forms. The differences in setation are restricted 

 to the following points: 



Leg 2. 2 internal setae occur on the 2nd endopodal segment in 

 the Ifaluk specunen that are not figured by Yamaguti (pi. 2, fig. 15), 

 but in his drawing of that leg there is one additional internal seta on 

 the 3rd exopodal segment. 



Leg 3. There are 2 setae at the internal margin of the 2nd endopodal 

 segment in the Ifaluk specimen, none on that segment in Yamaguti's 

 specimen (pi. 2, fig. 16). 



Leg 4. There is a fine seta on the internal aspect of the 1st and 2nd 

 endopodal segments of the Ifaluk specimen; these setae appear to be 

 absent on the corresponding segments of Yamaguti's specimen (pi. 

 2, fig. 17). 



