270 U.S. NATIONAL MUSEUM BULLETIN 2 36 



Exopodite of leg 5 twice as long as broad, ovate; external wall 

 straight and spinulose, internal wall convex. 6 marginal setae, 

 distribution of which appears from figure 106^. Baso-endopodite short, 

 reaching ji length of exopodite, with 4 setae. 



Leg 6 (armatiu'e of genital plates) composed of 2 setae. 



Color as in female. Lenticular spots at base of rostrum less dis- 

 tinctly developed. 



Remarks. — The specimens described above agree in aU essential 

 details with Gurney's description; they also have the same setal 

 formula, which is different from all other Nitocra species. The trans- 

 formation of the internal spine on the basis of leg 1 in the Ifaluk 

 specimens (and apparently also in Gurney's specimens since this 

 character is not mentioned in his description) is less than in the speci- 

 men recorded by Petkovski (1954) and Roe (1958). Petkovski, 

 moreover, has described a variety as Nitocra affinis f. rijekana, which 

 is very little different from the typical form (the differences are the 

 shape of the above-mentioned spine of leg 1, the development of the 

 internal setae on the 3rd exopodal segment of leg 4, and the length of 

 the setae on leg 5). It is not impossible that several closely allied 

 forms have been lumped together under the heading Nitocra affinis 

 Gurney, which are all linked together by the same aberrant setal 

 formulae but are different in several other characters. 



The species has been described by Gurney (1927) from Port Taufiq 

 and Ismailia in the Suez Canal zone (9 0.61 mm., cf" 0.48 mm.). 

 Willey (1930) subsequently mentioned specimens from Mangrove 

 Bay on Somerset Island, Bermuda (9 0.51-0.63 mm., cT 0.425 mm.). 

 Additional records are from the Dalkey area of County Dublin, 

 Ireland (Roe, 1958); Castro Marina (probably Castellammarre), 

 southern Italy (Chappuis, 1938); and near Dubrovnik, Yugoslavia, on 

 the Adriatic (Petkovski, 1954). Petkovski's form rijekana was found 

 near Rijeka, Yugoslavia, in the northern Adi'iatic (9 0.6 mm., cT 0.5 

 mm,). In the majority of the above-mentioned localities the species 

 was found in sand, living in the interstitial water of sandy beaches, 

 etc. In the Ifaluk collection also the species occurs exclusively in 

 sand samples: it was found in nearly the whole of transect B, which 

 was made at about the middle of Falarik in the Ifaluk Atoll, from the 

 reef margin inward, at distances varying from 60 to 340 feet from the 

 reef margin. The species appears to be a characteristic component 

 of the interstitial water masses of the sandy beaches of Ifaluk. 



Genus Leptomesochra G. O. Sars, 1911 



Since Lang's revision (1948, p. 838) of this genus (type species 

 Normanella attenuata A. Scott, 1896), many new species have been 



