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Gen. 3. PleurOgOIlium,
Syn: Pleuracantha, G. 0. Sars (olim).
G. 0. Sars.
Generic Characters. Body short, depressed, with the 4 anterior segments
of mesosome more or less strongly dilated, the 3 posterior ones much smaller,
and having the lateral parts obliquely recurved. Cephalon comparatively smnll,
deeply sunk within the 1st segment of mesosome, and without any frontal lobes
or ocular processes. Caudal segment narrowly cordate or pyriform, constricted
at the base, tip more or less produced. Eyes wholly absent. Antennae differing
but little in size, and of a structure similar to that in Paramunnn. Mandibles
without palps, cutting part narrowly produced, molar expansion slender, lappet-
shaped. 1st pair of legs short and strong, subcheliform ; the others slender, in-
creasing in length posteriorly. Female operculum lanceolate, male, of a simi-
lar structure to that in Paraminma. Uropoda very small, biramous, placed
somewhat dorsnlly, and at a considerable distance from the tip of the caudal
segment.
Remarks. This genus was established by the present author in the year
1863; but the name Plcuracantlia, proposed at that time, having been already
appropriated, he changed it subsequently to Pleurogonium. The genus is nearly allied
to Paramnnna, but differs very markedly in the shape of the cephalon and caudal seg-
ment, as also in the absolute want of eyes and of mandibular palps. In addition
to the 3 Norwegian species described below, Mr. Beddard lias recorded 3 other
species from the Challenger Expedition
1. Pleurogonium rubieundum,
(PI. XLVII, fig. 2.)
as P. allidum, serration and inmuhim.
G. 0. Sars.
Pleuracantlia rubicnnda, G. 0. Sars, Om en anomal Gruppe af Isopoder (Chr. Vid. Selsk. Forli.
18H3), p. Iti.
Specific Characters. Anterior division of body in female nearly circular
in outline, the breadth almost equalling the length. Cephalon sub-pentagonal in
form, with the front obtusely produced, and the sides obtusangular. Lateral parts
of the 4 anterior segments of mesosome subangular, and each carrying in the
middle a very conspicuous rod-like spine, all the spines pointing in different
directions, so as to exhibit a radiating arrangement. The 3 posterior segments
of mesosome very small, with the lateral parts extended obliquely behind, and
each terminating in a knob-like projection. Caudal segment rather narrow, con-
siderably constricted at the base, side-edges evenly curved, and fringed with short
15 Crustacea.