24 
R. NORRIS WOLFENDEN. 
First feet Ri= 1, lie =3 ; no Se on Re 1, and very short Se on Re 2. 
Second feet Ri = 2, Re — 3. 
Third and fourth feet Ri and Re — 3. 
Fifth, each of three segments, two basal, each short and comparatively thick, 
terminal segment longer and thinner, prolonged, with a stout curved hook with short 
bristles on the upper margin and an external marginal thin and short bristle. 
The male is rather smaller than the female, the abdomen has five segments, the 
mouth organs are as in the female, but the fifth feet are transformed into clasping 
organs, that of the right side of four segments, the left of five. The second and 
third segments of the left are elongated, the distal segment short and broadened 
out, the distal extremity ending in a spine, and at the opposite side a short knob 
process, apparently without marginal hairs. 
The right foot with short broad second basal, and two distal very elongated and 
thin segments, with a long thin sickle-shaped process at the end, which appears to be 
a continuation only of the joint above it, and though forming an elbow, does not 
articulate. 
In the general structure this small Copepod bears great resemblance to the 
species Stephus antarcticum, which, however, is twice as large; the fifth feet in the 
female as well as the male are different, and the two species are therefore quite distinct. 
Stephus antarcticum. 
(Plate V., figs. 4, 5, 6, 7, 8.) 
? l’85-2'0 mm. long, cephalothorax about three times as long as abdomen, and 
in its broadest part distal of the middle line one-third as broad as long. Head evenly 
rounded, a little produced in front, but without trace of rostrum, a weak line indicating 
its division from the first thoracic segment. Last two segments of the thorax im¬ 
perfectly divided, and last segment a little unsymmetrical ; on the right side a little 
longer than on the left, produced into a round-ended margin, on the left side more 
acutely pointed, which is most marked in lateral view. Abdomen of four segments 
respectively proportioned: genital segment, 2:3 and anal as 20:13:8:8; furcal 
segments as long as the anal, and as broad as long. Genital segment laterally swollen 
in the upper part (genital protuberances) and again slightly swollen laterally in its lower 
part, with on each side a bunch of rather long spines, none dorsally. Furca with four 
tail setae on each side, outer margins haired and with, on each side, a short lateral 
spine instead of the usual bristle, and on the ventral side a very short accessory 
bristle. Of the tail bristles, the two middle ones are much the longest and thickest, 
and those of the right side more so than those of the left. 
Anterior an ten use reach in both sexes to about the end of the second abdominal 
segment, having twenty-four segments, the eighth and ninth coalesced. In the posterior 
antennae the exopodite is longer than the endopodite. The mandibles with branches 
