148 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



Diagnostic characters: Urosome female 4-segmented, male 5- 

 segmented; the two middle caudal setae jointed basally. Antennules, 

 female and left male, 26-segmented; segments 13-22 with partial rows 

 of spinules. Right antennule male 23-segmented, with three segments 

 beyond gcniculation ; segment preceding geniculation with distal longi- 

 tudinal comblike row of spinules. Maxilla with six lobes, two on basal 

 division. Total number setae, endopod 3, legs 1-4: 6, 8, 8, 7. Leg 1, 

 inner apical spine of exopod 3 subequal to segments 2 + 3. Leg 5 

 female, inner apical spine of exopod 3 longer than outer spine, about as 

 long as segment. Leg 5 male, right exopod 2, first outer spine about 

 twice the length of second spine; left exopod 3-segmented, outer spine 

 of segment 2 reaching beyond segment 3; left endopod with movable 

 basal process as long as the endopod. 



Female 



Length, dorsal midline, 0.83-0.90 mm.; the greater number of 

 specimens 0.86-0.87 mm. 



Body slender and of distinct calanoid shape. (In a few specimens, 

 the fore part is curved downwards so that the body does not have the 

 usual erect appearance shown in fig. 2. Although the normal flexibility 

 of the body segments or effect of the preservative might account for 

 some of this, there is a real though small difference in the amount of 

 the curvature of the fore part of the body in individual specimens.) 

 Metasome 2.7-3 times the length of the urosome, with its greatest 

 width at beginning of second segment; 6-segmented, the division be- 

 tween the cephalic segment and that of leg 1 not so distinct as those 

 of the other segments. Cephalic segment, in dorsal view, rounded 

 anteriorly and tapered sharply outwards so that beyond the middle 

 the segment is nearly as wide as the second segment; its length, in 

 midline, a little greater than that of the other segments combined. 

 Length of segment 2 a little less than that of segments 3 and 4 together 

 (relative lengths, segments 2-4 : 35:20:20). Segments 2-5 with lateral, 

 apically acute, hyaline flanges. Last segment not expanded laterally, 

 in dorsal view the "wings" narrowed and slightly pointed; in lateral 

 view, the wings show on the inner edge, three notches bearing minute 

 hairs, the notch nearest the outer edge the largest and easily visible, 

 the others seen only at high magnification (fig. 3). 



Urosome (fig. 1) 4-segmented, the genital segment the longest; the 

 fourth segment very short, reduced to the width of the caudal rami, 

 with which it is more or less fused medially, but clearly distinct 

 outwardly. Relative lengths of the segments and rami (dorsal) : 



1 2 3 4 CR 



28 13 10 4 16 



