466 ONISCID”®. 
ISOPODA. ONISCID. 
NORMALI4. 
Genus—ONISCUS. (Linneus.) 
Generic character. Ovate, sub-depressed. Cephalon with 
large lateral lobes extending outwards beneath the eyes. Outer 
antenne eight-jointed ; second joint dilated at the base; seventh 
and eighth joints sub-confluent. Coxe of the first, second, and 
sixth segments of pleon obsolete; third to the fifth, broad and 
curved, acute at tips. Terminal uropoda posteriorly exserted ; 
apical portion ovate, pointed at tip. Inner lobe linear, short, 
extending slightly beyond the telson, which is convex. 
THE species of this genus are typical of the family, 
commonly called wood-lice, and are distinguished from 
the other equally common species by having the ter- 
minal portion of the outer antennz composed of three 
joints, of which, however, the articulation between the 
last and preceding joint is less distinct than the pre- 
ceding. 
The Philoscie, which have also eight-jointed setose 
antennz, are distinguished at once from the Onisci by 
the narrowness of the segments of the tail and the length 
of its exserted terminal appendages. 
“The external angles of the superior margin of the 
third ring of the head are produced into a broad lobe, 
which covers over the origin of the external antenne ; 
it is then continued across, projecting slightly over the 
frontal line of the cephalic segment; the transverse 
suture is well marked; the second ring very narrow, 
almost obsolete. The lateral lobes are continued back- 
wards, and are separated by a suture from the external 
