36 
R. NORRIS WOLFENDEN. 
XANTHOCALANUS ANTARCTICA. 
(Plate VII., figs. 10, 11.) 
? 2'5 mm. long (cepfialothorax 2'0 mm., abdomen 0‘5 mm. long). Abdomen, 
therefore, only one-fourth as long as the thorax. Head rounded and rather oval in 
front, with bifid rostrum, composed of two chitinous plates each with a long and rather 
thick filament. Head separate from first thoracic segment, last two segments separate, 
and distal segment on each side produced into lappets ending in rather pointed but 
rounded margins. Furcal segments half as long again as broad. In the middle, the 
thorax is broad, about half as broad as long. Abdominal segments with row of 
pectinations laterally, and over whole dorsum at the margin of the very short anal 
segment. Anterior antennae twenty-four segments, and short, only reaching to the 
end of the cephalothorax. 
Posterior antennae with Re a little longer than Ri. 
Mandibles, Ri and Re about equal; B 2 with three marginal bristles ; Re elongated 
and narrow, with seven bristles. Maxilla, B 2 and Ri elongated and narrow, imperfectly 
segmented; B 2 with four, Ri 1 with 1, Ri 2 and 3 with six bristles, Li 1 nearly 
twice as long as broad, with long, thin hook bristles. Anterior foot jaws with very 
convex B 2, the proximal margin of the basals much embayed. Strong toothed and 
curved hook on the last lobe ; a number of brush processes, with small heads, and two 
vermiform processes distally. 
Posterior foot jaws, having proportionately B 1 : B 2 : Ri = 40 : 30 : 20, the 
second basal about three and a half times as long as broad, and a brush process on the 
first basal. 
1st feet Ri — 1 segment. Re = 3 segments with three long, thin marginal spines. 
2nd feet Ri — 2 segments, Re — 3 segments. Ri 2 with a strong corona of 
spines. 
3rd feet with a few delicate spines on surface of Re 2. 
4th feet Ri — 2 segments, Re = 3 segments. Ri 2 with a few spines on the 
outer margin. The exopodites of the 3rd and 4th feet not spinulose. 
5th feet small. A common basal and each three segments ; the first segment 
rather longer and broader than the second, with convex inner margin, and several 
(about eight or nine) strong teeth on the margin ; the second segment with two or 
three shorter spines on the proximal part of the convex inner margin ; the third 
segment with two short apical, and one outer and one inner marginal spines—four in 
all—each articulating with the segment, and on the inner margin a bunch of small 
teeth. A cluster of five spines on the distal surface of the last segment, and two very 
small spines on the outer margin of the middle segment distally. No spines on the 
surface of the two proximal joints. 
