446 ONisciDj:. 



The terminal segment of the tail is longer, but nar- 

 rower than the preceding. Its posterior margin is regu- 

 larly rounded, wliilst on each side the lateral posterior 

 angle is produced into a strong tooth. The branchial 

 apparatus consists of the five anterior pairs of the deli- 

 cate membranous plates on the underside of the tail, 

 through the centre of which a large artery passes to 

 about two-thirds its length, sending off numerous 

 branches that break up into a minute vascular network 

 that spreads itself out over the entire surface. Of these 

 plates the first pair is furnished, in the male, with a pair 

 of minute linear styles at the inner angles. The second 

 pair in the same sex is armed at its inner extremity with 

 two long and nearly straight appendages, extending to 

 the middle of the fifth pair. The terminal pair of these 

 organs is formed into elongated appendages at the ex- 

 tremity of the body, of which the basal portion or 

 peduncle is longitudinally elevated in the centre, but 

 laterally depressed, oblong, with the posterior extremity 

 narrowing. It articulates in a distinct notch of the pos- 

 terior margin of the segment. The extremity of this basal 

 portion is truncate, with the outer angle acute, and with 

 the lateral lobe obsolete. It bears two filiform cylin- 

 drical appendages, which under a strong lens are seen to 

 be furnished with minute regularly distant hairs. The 

 inner is rather longer than the outer, and furnished at its 

 extremity with a minute but strong hair. 



The eggs and young are borne by the female beneath 

 the body ; the latter have only six segments of the body, 

 and six pairs of legs, the seventh segment being rudi- 

 mental, when they first quit the ovary. 



The general colour is dull light green in the young 

 male, with white spots. 



The male is much larger tlian the female, and is gene- 

 rally of a paler and less varied colour. 



