COPEPODS GATHERED BY ALBATROSS—WILSON 349 
Male.—On the first basipod of the left fifth foot the row of denti- 
cles along the inner margin runs off onto the posterior surface just 
beyond the center of the segment, leaving the distal part of the margin 
smooth. The endopod is attached to the center of the inner margin 
of the second basipod and is bilobed at its tip. The base of the ter- 
minal chela of the exopod is enlarged to twice the diameter of the 
segment to which it is attached and then abruptly narrowed at the 
origin of the arms. The inner arm is widened at the base and the 
tip and narrowed between the two and the swelling at the tip is trilo- 
bate. The inner tooth on the outer arm is about one-fourth of the 
length of the arm from its base, often still nearer to the base. 
Remarks.—These are the details that help to characterize the 
species and that are to be compared with those given below for U. 
darwinii, in order that the two species may be completely separated. 
UNDINULA DARWINII (Lubbock) 
PLATE 19, FicurES 256-259 
Undina darwinii Lussock, Trans. Linn. Soc. London, vol. 23, p. 179, pl. 29, figs. 4, 
5, 1860. 
Stations 4; 8; 9; 13; 19; 23; 27; 31; 63-68; 70; 71; 75-78; 80; 82; 
236 ; 8681 ; 3782 ; 3829 ; 3878 ; 3912; 3980 ; 4011; 4037 ; 4588; 4613; 4635; 
4638; 4644; 4648; 4671; 4681; 4700; 4705; 4707; 4708; 4713-4716; 
4722; 4730; 4734; 4742; 5134; 5155; 5185; 5190; 5199; 5233; 5320; 
5386; 5387; 5507. Reported in the Challenger, Carnegie, and Siboga 
plankton lists. The following characters distinguish this from the 
preceding species and will identify it: 
Female.—Head narrowed scarcely at all, with a somewhat pointed 
forehead ; the posterior corners of the metasome symmetrical, each ex- 
tending just beyond the center of the genital segment and angular at 
the tip. In the urosome the genital segment is considerably wider 
anteriorly than the abdomen, but tapers to the same width posteriorly. 
It is not so thick as it is long, and it has a sharp spine on the posterior 
margin at the center of the dorsal surface. The short setae on each 
caudal ramus are more than half as long as the longest one and the two 
longest ones are curved like parenthesis marks. 
Male.—On the first basipod of the left fifth foot the row of denticles 
along the margin does not run off on to the dorsal surface but keeps 
along the margin. The endopod is attached to the inner distal corner 
of the second basipod and is not bilobed at its tip. The base of the 
terminal chela of the exopod is enlarged to almost twice the diameter 
* of the segment to which it is attached, but it is not narrowed at the base 
of the arms and keeps the same width throughout its length. The 
inner arm is much widened at its base and tapers distally to an appar- 
