202 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
equaling in length the median lobe. Free fourth segment with 
strongly convex sides and as wide as the posterior end of the median 
carapace lobe. Genital segment barrel-shaped and nearly as wide as 
the fourth segment, with no trace of leg rudiments. Abdomen 2- 
segmented, the segments the same width but the anal segment longer 
than the basal. Caudal rami suborbicular, inserted in the reentrant 
corners of the anal segment and scarcely projecting behind it. 
First antenna rather stout, with short setae; basipod of the second 
antenna with a stout posterior spine acute at its tip, the terminal 
claw bent abruptly near its center. First maxilla simple, its inner 
margin an S-curve; second segment of second maxilla longer than the 
basal segment, with a small spine distal to the center of its inner 
margin, the inner terminal seta twice as long as the outer. Maxilliped 
with the basal segment much swollen and armed on its inner surface 
with a stout spine and a corrugated ridge against which the powerful 
and strongly curved terminal claw shuts. Furca® H-shaped, the 
lateral arms enlarged at their bases, the central crossbar quite slender. 
The four pairs of legs are biramose, each ramus 2-segmented with 
spines and setate as shown in figures 57 to 60. Attention is called to 
the abnormal seta on the inner margin of the basal segment of the 
second leg. Total length 3.82 mm. Carapace 2 mm. long, 1.85 mm. 
wide. 
Lype.—U.S.N.M. No. 70752; station H3789, Cape Martin, Nukuhiva 
Island, N. 30° E., distance 614 miles. 
Remarks.—The distinctive characters of this species appear in 
every one of the appendages but especially in the arrangement of the 
spines and setae on the four pairs of legs. 
Genus ECTINOSOMA Boeck, 1864 
ECTINOSOMA CURTICORNIS Boeck 
Betinosoma curticornis Borck, Forh. Vid. Selsk., Christiania, vol. 14, p. 45, 1872. 
Station 4663. Two females of this small harpactid were found in 
a surface tow at this station off the Peruvian coast. It is not in- 
cluded in any of the other plankton lists. 
Genus EUAETIDEUS Sars, 1925 
EUAETIDEUS BRADYI (A. Scott) 
PLATE 7, Figures 70, 71 
Aetideus bradyi A. Scorr, Copepoda of the Siboga-Expedition, monogr. 29a, pt. 1, 
p. 38, pl. 5, figs. 1-12, 1909. 
*The name furca is used to designate this appendage of parasitic copepods and hence 
cannot be rightly applied to the caudal rami of pelagic forms. 
