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or less elongated, basal part not produced inside, rami narrow, styliform, sub-
equal, each with a single apical spine.
Remarks. This genus was established by Fabricius as early as in the
year 1798, to include the Onisctis oceanicus of Linne. It is chietiy characterised
by the form of the metasome, and the structure of the antennula3 and uropoda.
Mr. Btidde-Lund enumerates no less than 17 different species, 12 of which have
been examined by himself. Of these only a single species belongs
European fauna;
it will be described below.
Ligia oceaniea, (Lin.).
(PI. LXX.)
Oniscus oceanicus, Linne, S3 -
st. nat. ed. 12, 1.
2, p. 10(il.
: Syn Ct/ntothoa oceaniea, Fabr.
Ligia scopulorum, Leach,
belgica, Bosc.
to the North
Specific Characters. Body oval in form, scarcely more than twice as long
as it is broad, dorsal face moderately convex and slightly granulated. Cephalon,
when seen from above, semi-oval, with the front evenly rounded, and with a slight
transversal depression dorsally. Lateral parts of niesosorne lamellarly expanded,
and denned from the corresponding segments by a slight groove, posterior cor-
ners obtusely acuminate. Metasome exceeding y4 f the length of the body, and
rounded in form, with the epimeral plates of the 2 anterior segments concealed;
those of the 3 succeeding segments well developed, recurved. Last segment
rather broad, seniilunar, evenly arched at the tip, lateral parts forming a similar
recurved expansion to those of the preceding segments. Eyes large and convex,
consisting of numerous densely crowded visual elements. Antennulse extremely
small, scarcely projecting in front, the first 2 joints of about equal length, last-
one exceedingly minute, nodiform. Antenna rather strongly built and exceeding
half the length of the body, flagellum about the length of the peduncle, and
composed of about 12 short articulations. Legs moderately strong, spinous.
Opercular plates of pleopoda exhibiting a very delicate, branchial structure. Uro-
poda about the length of the metasome, basal part somewhat flattened, and slightly
produced at the end outside, rami twice the length of the basal part, and narrow
styliform, each terminating in a slender spine. Colour of dorsal face grey, with
;i bluish or greenish tinge, and more or less distinctly variegated with irregular
lighter patches, legs minutely spotted. Length of adult female 20 mm. ?
up to 28 mm.
of male