224 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
First antennae 24-segmented, considerably thickened at the base 
and extending four segments beyond the tips of the caudal rami. 
The proximal half is quite regularly and densely setose, but on the 
distal half the setae are scattered irregularly. The endopod of the 
second antenna is five-sevenths as long as the exopod, and the latter 
is armed with very long setae densely plumose at their tips. The 
chewing blade of the mandible has very blunt teeth; the exopod of the 
palp is 4-segmented, with very long setae, the endopod 2-segmented 
with much shorter setae (fig. 99). The second maxilla has five 
digitiform lobes each with two setae, both lobes and setae very long 
(fig. 104). The maxilliped is 7-segmented, the proximal segment 
with three setae at the center of the outer margin and a curved spine 
at the outer distal corner. The second segment has three setae on 
the inner margin, and the five short terminal segments have a dense 
armature of very long setae. The exopods of all four pairs of legs 
are 3-segmented, the endopods have 1, 2, 3, and 3 segments, respec- 
tively. The basipod of the fourth leg has a row of nine very long 
acicular spines. The terminal spines on the second, third, and fourth 
exopods are very long and slender, pectinate on the outer and plumose 
on the inner side. Total length 7 mm. Metasome 5.55 mm. long; 
1.90 mm. wide. 
Male.—Metasome similar to that of the female but narrowed more 
anteriorly and with a more pronounced frontal crest. The head and 
first segment are completely fused, with no dorsal groove of separa- 
tion; the posterior corners of the metasome are broadly rounded, and 
the posterior margin is very reentrant. The urosome is 5-segmented, 
the second segment the longest and the anal segment the shortest and 
all about the same width. 
The first antennae are shorter than in the female and reach only 
to the abdomen, and neither of them is geniculate. The second an- 
tennae, mouth parts, and first four pairs of legs show no sexual dif- 
ferences. The two fifth legs are about the same length and each is 
biramose ; the two basipods of the left leg are much the longer, while 
those of the right leg are more swollen. The left exopod is 2-seg- 
mented, the end segment a curved claw, the endopod is 1-segmented 
and rodlike and only three-fourths as long as the basal exopod seg- 
ment. The exopod of the right leg is 3-segmented, the basal segment 
with three angular projections on its inner margin; the right endopod 
is 1-segmented and curled at its tip. Total length 7mm. Metasome 
5.45 mm. long, 2 mm. wide. 
Pypes.—U.S.N.M. No. 67131; station 4681, latitude 18°47’ S., longi- 
tude 89°26’ W., Peru to Easter Island. 
Remarks.—The distinguishing characters of this species are the low 
frontal crest, the length of the first antennae in the female, and the 
