50 BRITISH COPEPODA. 



shorter, setae, the longer one being geniculated in the 

 middle, and bearing on the distal half a pectinately 

 arranged series of minute cilia; the outer branch has 

 all its joints armed with strong apical spines, between 

 which the external margins are closely ciliated. The 

 second and third pairs of feet have both branches 3- 

 jointed, the inner branches shorter than the outer (fig. 

 10) ; inner branch of the fourth foot (fig. 11) short, 

 2-jointed; basal joint of the fifth pair (fig. 15) broad, 

 the inner segment scarcely at all elongated, but bearing 

 five, stout, shortly -plumose setae ; second joint ovate, 

 narrow, provided with one long apical and three mar- 

 ginal setae, all of which are plumose, the inner margin 

 has also two much shorter setae. Tail-segments (fig. 

 17) not much longer than broad, bearing two apical 

 setae, the innermost of which is at least three times 

 longer than the outer, and is minutely aculeate along 

 the margins; anal operculum (fig. 17 a) denticulated. 

 Length -^nd of an inch (1*1 mm.). 



Male. Anterior antenna (fig. 3) constricted so as 

 to form a hinge between the fifth and sixth joints ; 

 thickly beset with short marginal hairs. The second 

 and third joints of the inner branch of the second foot 

 are incompletely separated (fig. 12), and the apical 

 setae are much reduced in size ; in the third foot the 

 inner margin of the second joint is produced into a 

 long, downward-pointing, spinous process (fig. 13), 

 while the third joint has only a single small apical seta, 

 all the other setae of the branch being wanting ; the 

 joints of the fourth foot present the same characters 

 as in the female, except that the marginal setae of the 



