352 U.S. NATIONAL MUSEUM BULLETIN 236 



The particulars of legs 2 to 4 appear in figures 139b-d and the follow- 

 ing setal formula : 



tndopodite exopodite 



leg 2 0.221 0.1.123 



leg 3 0.1.4 (modified) 1.223 



leg 4 0.221 1.223 



Legs 2 and 4 with 3-segmented exopodite and 2-segmented endopo- 

 dites, leg 3 with both rami 3-segmented. 



Leg 2 (fig. 1396). No seta at internal border of 1st endopodal 

 segments. 



Leg 3 (fig. 139c). No seta at internal surface of 1st endopodal 

 segment; segment 2 externally lengthened into strong, spiniform 

 projection, reaching beyond 3rd segment, which is small, apex cut off 

 obliquely, with 4 setae. 



Leg 4 (fig. lZ9d). No seta at internal border of 1st endopodal 

 segment. 



Leg 5 (fig. 139e) much smaller than in female; external lobe big, 

 with strong seta; baso-endopodite scarcely developed, with some spini- 

 form hairs. Exopodite 3 times as long as wide, with total of 5 setae 

 (2 external, 2 apical, 1 internal), development of which appears in 

 figure 139e. External margin haired. 



Remarks. — The material of Esola longicauda in the Ifaluk collection 

 falls into two groups, one of which is described above as E. longicauda 

 Edwards, while the other, represented by a single male, is described 

 below as an unnamed variety of this species. I would have been 

 inclined to separate these two forms specifically but for the fact that, 

 from the literature available, E. longicauda appears as a very variable 

 species, variable in the length of the antennules and the setation of 

 the endopodites. Although, in all specimens recorded above, the 

 antennules are short and, in the specimens dissected, the 1st endopodal 

 segments of legs 2 to 4 lack the internal setae, it appears from a scrutiny 

 of the literature that very different conditions of setation of the 

 endopodites have been recorded; also evident is variability in length 

 of the antennular segments. Though the possibility that several 

 closely allied species are present cannot be altogether avoided, I have 

 been forced, by the lack of material, to leave this question open, 

 with the result that the identification of the present Ifaluk specimens 

 is provisional. Bearing the above recorded variability in mind, I do 

 not feel justified in describing the aberrant male specimen as a new 

 species and I have, therefore, entered it here as an unnamed variety. 



The geographical distribution of E. longicauda has been discussed by 

 Sewell (1940, p. 326) and Lang (1948); its area of distribution includes 

 localities in the northern temperate Atlantic, the tropical Atlantic, the 

 Mediterranean, and the Suez Canal zone. The length of specimens 



