JANIRA. 335 
ISOPODA., ASELLIDA. 
NORMAL/4. 
Genus—JANIRA. (Leach.) 
ONISCODA. (Latreille.) 
Generic character. Pereion serrated along the lateral margins; 
pleon having all the segments coalesced into a single plate; 
covered, in the female, beneath with a large, flat membranous 
plate concealing the branchial feet ; and furnished at the tip with 
a pair of elongated bifid uropoda. Outer antenne as long as 
the animal. Dactyla biunguiculate. 
Tuts genus has hitherto been known only by Leach’s 
short and insufficient characters, which have been repro- 
duced by subsequent authors ; it is closely allied to Jera in 
its general character, but is at once distinguished by the 
pair of elongated styles at the extremity of the tail, 
each of which is terminated by a pair of narrow, slender 
plates, as in the genus Asellus. 
These styles are liable to be detached at a very slight 
touch, and hence many specimens of the animal are 
found destitute of them. They arise in a terminal 
emargination of the segment, but smaller than in 
Jera, and having its postero-lateral margin finely ser- 
rated. In the males, the large terminal segment is 
furnished at its base, on the underside, with the male 
organ, which is narrow, flattened, nearly. reaching to the 
extremity of the segment, and with its tip quadriden- 
tate. In the female, this terminal segment is entirely 
covered with a very thin membranous operculum, con- 
cealing the branchial apparatus. The outer antenne, 
