HYDEACAKINA I THE GENUS OXUS KRAMER. 31 



at the distal end, and one not so long placed a little way down 

 on the outside edge at distal end. The third segment has also 

 two long spines placed near the middle of the extensor margin. 

 The fourth segment is the longest, and has two or three fine 

 hairs on the extensor margin. 



The genital area is placed in a shallow bay formed on the 

 posterior margin of the epimeral plate. The anterior edge of 

 the genital plates nearly touches the bottom of the bay, but at 

 the posterior end of the bay the sides are wide apart ; the depth 

 of the bay is about three-fourths the length of the genital plates. 

 The genital area is composed of two movable plates which 

 expose or partly cover three acetabula on each side of the genital 

 fissure. Another characteristic of this species is the shape of 

 these genital discs^ which are fusiform or spindle-shaped. PL 1, 

 fig. 7 is one drawn to show how it appears at the side of the 

 fissure. In other species of this genus the acetabula are rounded 

 at each end, not spindle-shaped. 



The legs are very like those found in Frontipoda and Gnaphis- 

 cus, and require no special description, but all are figured on 

 PI. 1, figs. 9-12. 



Male. — The male, which does not appear to have been found 

 by either Sig Thor or Halbert, is very like the female. Not 

 much description is necessary; it is as usual a little smaller 

 than the female, being about 1-0 mm. in length. The genital 

 area is smaller, not so wide, and placed closer to the posterior 

 margin (PI. 1, fig. 6). The discs or acetabula are of the same 

 shape as in the female. The male genital organs can be seen 

 through the chitin of the epimera in mounted specimens, but not 

 sufiicient detail can be made out for the purpose of making 

 a satisfactory drawing. The two strong spines at the apex of 

 the first pair of epimera are similar to those found in the female. 



Nymph. — The nymph is about 0-55 mm. long and has the same 

 outline as the adult. It is also of the same orange colour, 

 but less brilliant. The provisional genital area is formed of 

 four acetabula protected on each side by a chitinous ridge 

 PI. 1, fig. 8). The legs have fewer hairs. Only one nymph has 

 been found, which is probably the nymph of the male. It will 

 no doubt be found that the nymphs of the male and female 

 are quite distinct, as was the case in the genus Frontipoda. 



The larvae and life-history are unknown. 



