76 BRITISH C0PEP0DA. 



denticulated plates on their inner margins. The 

 number of joints is reduced by coalescence to twenty- 

 one. The main branch of the posterior antenna (fig. 

 5) is triarticulate ; the secondary branch composed of 

 five joints, of which all except the second are very 

 small. The branchial appendages of the maxillae (fig. 

 13, Plate X) are well developed, and the setae of the 

 prehensile lobes are strong and plumose. The ante- 

 rior foot-jaws (fig. 14, Plate X) are large and armed 

 with stout, curved, plumose setae. Lower foot-jaws 

 (fig. PI. XI), 7-jointed, the basal joint very large, and 

 bearing five long, curved, plumose setae ; the remain- 

 ing joints slender. First pair of swimming feet small, 

 both branches three-jointed. Second, third, and 

 fourth pairs large, but having the inner branch two- 

 jointed, and the terminal spines (fig. 7) long and 

 slender, sword- shaped, finely serrated on the inner 

 and setose on the outer margin. Fifth pair of feet in 

 the female (figs 9, 10) two-branched ; the inner branch 

 rudimentary, consisting of one small joint with a 

 cloven apex ; outer branch long, two-jointed ; the first 

 joint long, bearing two small spines on the outer side, 

 and one long one at the inner apical angle; second 

 joint small, having three terminal spines, the inner- 

 most of which is longer than the other two, and is 

 roughened with a series of wart-like prominences on 

 the outer edge. Fifth foot of the male (fig. 8) com- 

 posed of one branch, four -jointed, the last two joints 

 forming a sort of grasping hand. The last thoracic 

 segment of the male is produced only on the right side 

 into a projecting spine. The inferior (ventral) angle 



