354 U.S. NATIONAL MUSEUM BULLETIN 236 



from these areas is: 9 0.6-0.8 mm.; cf 0.42-0.5 mm. Additional 

 records from the Pacific area have since become available: Nancowry 

 Harbour in the Nicobar Islands; Addu Atoll in the Maldive Archipel- 

 ago (Sewell, 1940: in weed washings, 9 0.62 mm.); Port Denison in 

 Western Australia (Nicholls, 1945: cT 0.46 mm.). Noodt (1955) 

 records a female specimen of 0.79 mm. from the Sea of Marmara off 

 Turkey. 



In the Ifaluk collection, specimens of E. longicauda occur exclusively 

 in sand samples, taken 80-340 feet from the reef margin at Falarik 

 in the Ifaluk AtoU. 



Esola longicauda Edwards, 1891, variety 



Figures 1366, 137c, 140 



Material. — Loc. 592, 1 ad. cf , 0.42 mm. 



Description. — The following is based on the above-mentioned 

 male specimen, which has been dissected and mounted. 



Adult male, total length 0.42 mm.; greatest diameter 0.12 mm.; 

 length of longest furcal setae 0.45 mm. 



The general shape of the body is the same as in the typical Esola 

 longicauda except for the following points: 



1. Demarcation between cephalothorax and abdomen less distinct 

 than in typical species since narrowing in diameter is more gradual 

 and cephalic somite more lengthened (fig. 1366). 



2. Cephalic somite, near insertion of antennules, with lateral in- 

 cision, with the result that very distinct pair of lateral, forwardly 

 directed horns present. Rostrum with broad base, separated from 

 cephalic somite by distinct groove. The cup-shaped depressions 

 at the antennular bases, which are scarcely visible in the male of 

 the typical species, are very prominent here. Sides of cephalic somite 

 greatly produced to shield oral parts completely (fig. 137c). 



3. Antennules (fig. 140/) greatly lengthened compared with typical 

 species; all segments, but particularly 1st, 2nd, and 4th, are longer. 

 1st segment with two lateral spines; distal, at least on right side, 

 bifid. 4th segment, as it is lengthened, appears less swollen. Conical 

 process long, and longitudinal groove bordered with stiff hairs. 



4. No difference in structure of abdomen, antenna and oral 

 appendages. Legs (figs. I40a-d) are nearly identical but have dif- 

 ferent setal formula: 



Leg 5 (fig. 140e) almost as in typical species, but 5 exopodal setae 

 have slightly different distribution, as appears in comparison between 



