230 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
corners of the anal segment, as wide as long and somewhat divergent, 
each with four stout setae of equal length. 
First antennae reaching three segments beyond the tips of the caudal 
rami and sparsely setose. The exopod of the second antenna is con- 
siderably longer than the endopod and is armed with rather long 
setae. The exopod of the first leg is 2-segmented, of the other legs 
3-segmented; the basipod of the fourth leg has a row of 11 or 12 
acicular spines, very similar to the fourth leg of armiger. These 
spines are slightly curved, diminish in length from the outside in- 
wardly, and are crowded closely together as seen in figure 110. Total 
length 4.75 mm. Metasome 3.70 mm. long. 
Male.—Smaller than the female but showing the same proportions; 
the frontal horn is larger and stands out farther from the forehead 
(fig. 113). On the contrary, the spines at the posterior corners of the 
metasome are smaller and scarcely curved at all. The urosome is 
5-segmented but no longer than the 4-segmented urosome of the 
female. 
Neither of the first antennae is geniculate; the second pair, the 
mouth parts, and the first four pairs of legs are like those of the 
female, the exopod of the first leg 2-segmented. In young males the 
fifth legs have the form shown in figure 111, the rami of both legs 
1-segmented with the exopods showing signs of segmentation. The 
fifth legs of the adult males are shown in figure 112, the right leg a 
little longer than the left. The second basipod of this leg is con- 
siderably swollen and the endopod is more than half as long as the 
proximal segment of the expod, narrowed basally and enlarged dis- 
tally into a bilobed knob. The basal segment of the exopod is one-half 
longer than the second segment and twice as wide, with a knob on 
the inner margin at the distal end. The second segment also has a 
rounded knob at its distal end armed with a small spine; the end 
segment is a curved and acute spine. The left endopod is short and 
rodlike ; the exopod is 3-segmented, the segments diminishing distally, 
the end segment tipped with a slender spine. Total length 4.25 mm. 
Metasome 3.20 mm. long. 
Types.—U.S.N.M. No. 70736; station 4700, latitude 20°29’ S., longi- 
tude 103°26’ W., Easter to GalApagos Islands. 
Remarks.—This species resembles robustus but is little more than 
half as large, has a frontal spine, the first exopod is 2-segmented and 
the first antennae reach beyond the caudal rami. Unlike kruppti, 
the spines at the posterior corners of the metasome are turned outward 
and curved upward, and are considerably larger. The details of the 
fifth legs in the male also contribute to the specific distinction, espe- 
cially the endopod of the right leg. 
