36 R. NOREIS WOLFENDEN. 



Xanthocalanus antakcticus. 



(Plate VII., figs. 10, 11.) 



? 2"5 mm. long {cephalothorax 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'i with four, Ril with 1, Ri2 and 3 with six bristles, Li I 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 brusli processes, with small heads, and two 

 vermiform processes distally. 



Posterior foot jaws, having proportionately B 1 : B 2 : Ri = iQ : dO : 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 = Z segments with three long, thin marginal spines. 

 2nd feet Ri — 2 segments, i?e = 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 = S 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. 



