220 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
fal 
Stations 3712; 4680 ; 4757; 4758; 5120; 5185 ; 5227; 5232; 5233; 5246; 
5263 ; 5287; 5296. Established by With upon female and young male 
specimens from the North Atlantic and reported by Sars from 28 
Monaco stations all in the Atlantic and all the specimens females. 
It is not included in any of the other plankton lists. The Albatross 
secured the first adult males to be obtained. This is also the first 
record from the Pacific. 
Female.—Metasome elongate elliptical, two and a half times as long 
as wide, and only slightly narrowed at either end. Head with a 
prominent crest in the form of a helmet at the top of the forehead in 
side view; posterior corners of the last segment rounded. Urosome 
less than a fourth as long as the metasome; genital segment asym- 
metrical, swollen on the right side. First antennae reaching the center 
of the genital segment. Proximal segment of the fourth basipod with 
a plumose seta and a single spine on the inner margin near the distal 
end. Total length 6.10 to 6.70 mm. 
Male.—Metasome considerably narrower than in the female; head 
with a prominent frontal crest but not galeate as in the female; fifth 
segment with rounded posterior corners. Urosome one-fifth as wide 
and two-fifths as long as the metasome and 5-segmented, the anal 
segment very short. Caudal rami longer than wide, the setae nearly 
as long as the entire abdomen. 
First antennae reaching the middle of the genital segment, the basal 
segments stout, the remainder quite slender, neither antenna genicu- 
late. The exopod of the second antenna about one-third longer than 
the endopod; the mouth parts and first four pairs of legs like those of 
the female. In the fourth legs the first segment of the basipod has a 
plumose seta on the inner margin; the second basipod is unarmed. 
The first segment of the exopod has a tripartite spine at its outer distal 
corner and the first segment of the endopod has two short spines on 
the outer margin. The fifth legs are shown in figure 334. The two 
basipods of the right leg are considerably thickened and elongated, 
and the second one is invaginate at the distal end for the reception of 
the exopod. The latter is 2-segmented; the first segment is widened 
at its base where it is inserted in the basipod and has two knobs on its 
inner margin. The end segment is curved a little and its inner surface 
is cut transversely into a series of flattened ridges (fig. 335). The 
endopod is more strongly curved and also has two knobs on its inner 
surface, a larger one near the base and a smaller one near the tip. 
The left leg is uniramose, 4-segmented, and tipped with a small 
curved spine. Total length 5.9 to6.10mm. Metasome 4.25 mm. long. 
Allotype male—U.S.N.M. No. 74117; station 5227, latitude 
12°53’45’" N., longitude 121°52’30’ E., east of Mindoro, Philippine 
Islands. 
