34 R. NORRIS WOLFENDEN. 



than Hi ; fifth feet of three segments, last much smaller than proximal two, only basal 

 with marginal teeth, end segment with three short outer and one long inner spine. 



$ a pair of fifth feet, the right very rudimentary and short, of three segments. 

 (Polar Sea. Norway.) 



5. X. CRISTATUS. 

 X. cristatus, Wolfenden, Jour. Mar. Biol. Assoc., 1904, p. 111). 



Size 5 'Omm.; head triangular and with prominent crest, anterior antennae 

 reaching to end of furca ; fifth feet of three segments, all densely spinulose, with two 

 short apical spines. $ not known. (West of Ireland.) 



6. X. SUBCRISTATUS. 

 X. subcristatus, Wolfenden, Plankton Studies, Part II. (190G), p. 31. 



Size 7"0 mm. ; head with crest, abdomen very hirsute, furcal segments very short, 

 anterior antennae reaching end of genital segment ; fifth feet three segments, the distal 

 long and tapering, with two short apical spines ; all these segments densely spinulose. 

 $ not known. (South Polar Sea.) 



7. X. MAGNUS. 

 X. magnns, Wolfenden, op. tit., p. 32. 



Size 8 '8 mm. ; head rounded, not clearly separated from next segment; furcal 

 segments very short, anterior antennae reaching the genital segment ; abdominal 

 segments very hirsute ; fifth feet of three segments, very small ; all segments very 

 spinulose, with two apical and two lateral spines on the last segment. <? not known. 

 (South Polar Sea.) 



8. X. SIMPLEX. 

 A', simplex, Wolfenden, op. cit., p. 30. 



Size T45 mm. ; whole surface of thoracic segments covered with fine prickles, 

 anterior antennae very short, posterior antennae with Re nearly twice as long as Ri ; 

 anterior foot jaws with only vermiform processes, posterior foot jaws with long, thin 

 BZ without bristles ; fifth feet very small, of common basal and two segments, the 

 distal one very small, with two apical spines on the left and only one on the right foot. 

 c5 unknown. (West of Ireland.) 



9. X. CALAMINUS. 

 X. calaminm, Wolfenden, op. cit., p. 34. 



Size 5'5 mm. ; furcal segments as broad as long, posterior antennae with rami of 

 equal length ; anterior foot jaw with powerful toothed hook on fourth lobe, and two 

 slenderer hooks on fifth lobe ; brush and vermiform processes ; posterior foot jaw short 

 and stout, the bristles of the eudopodite very peculiar and like quills, with broad 

 chitin expansion with serrated edge ; fifth feet very small, of three segments ; distal 

 segment with short apical and two short marginal spines. (Bay of Biscay.) 



