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. 



<J 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. 119. 



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. <J not known. (West of Ireland.) 



6. X. SUBCRISTATDS. 

 X. subcristatus, Wolfenden, Plankton Studies, Part II. (1906), p. 81. 



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. 

 (J not known. (South Polar Sea.) 



7. X. MAGNUS. 



- * 

 X. magnus, Wolfenden, op. cit., 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. <J not known. 

 (South Polar Sea.) 



8. X. SIMPLEX. 

 X. simplex, Wolfenden, op. cit., p. 30. 



Size 1'45 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 

 B 2 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. 

 <J unknown. (West of Ireland.) 



9. X. CALAMINUS. 

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



Size 5 '5 mm. ; furcal segments as broad as long, posterior antennae with rarni 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 endopodite 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.) 



