CRUSTACEA. 655 
To this division also belongs Oniscus viridis of SLABBER, Natuurk. Ver- 
lust. Pl. 12, figs. 4, 5, which, according to Minne Epwarps, forms a 
distinct genus. 
Arcturus Latr. Feet of first pair short, palpiform. Feet of 
second, third and fourth pair furnished with long hairs, with last 
joint plane, elongate. External antennze of the length of body. 
Sp. Arcturus Bafini Wustw., Idotea Baffinti SABInE, M1nNE Epwarps Hist. 
nat. des Crust. Pl. 31, fig. 1;—Arcturus longicornis Wrstw., GUERIN 
Iconogr., Crust. Pl. 31, fig. 2; in this species the first four pairs of feet 
stand very remote from the last three. 
Orver VIII. <Amphipoda. 
Hyes sessile. Four antenne, the two middle inserted above the 
lateral. Mandibles mostly furnished with palps. Two pairs of 
maxille and one pair of foot-jaws. Trunk mostly divided into 
seven distinct segments, bearing seven pairs of feet not cloven into 
two oars. Membranous vesicles for respiration adhering to the base 
of some of the feet. 
We unite here, after the idea of Kroryrr, the Lemodipoda of 
LATREILLE with the order of the Amphipods ; see Kroryer Tids- 
skrift, tv. 1843, pp. 490—495. 
Section I. Lemodipoda. Posterior part of abdomen or tail 
short. First segment of trunk conjoined with head, an oblique 
furrow alone on each side indicating the separation; feet of this 
segment inserted forwards, beneath the head. Two or three pairs 
of branchial vesicles in the anterior part of trunk. 
Lemodipoda from amos and dirous; these animals were thus 
named because they have two feet under the head, as though at the 
throat. They do not swim, but creep on marine plants and animals 
in search of food. The posterior part of the body is little developed. 
In most the feet are wanting in those rings that carry gill-vesicles, 
and conversely the gill-vesicles are wanting on those rings that have 
feet. 
Family XXI. Lemodipoda. (Characters of the section). 
Phalanx I. Cyamea. Body oval, mostly much depressed, with 
transverse segments. Antenne with four joints, the last slender; 
