446 ONISCID A. 
The terminal segment of the tail is longer, but nar- 
rower than the preceding. Its posterior margin is regu- 
larly rounded, whilst 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 than the female, and is gene- 
rally of a paler and less varied colour. 
ie obey 
