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Gen. 2. ROClnela, Leach, 1815.
Syn : Acherusia, Lucas.
Generic Characters. Form of body resembling that of ^Ega, though being
somewhat less compact, and more depressed. Metasome generally less broad, with
the terminal segment rounded off at the end, and finely ciliated. Eyes well
developed, with very large and conspicuous cornese. Antennae slender, the supe-
rior ones much shorter than the inferior, and with the basal joints not expanded.
Epistomal plate very small and narrow. "Mandibles considerably produced, with
the cutting edge expanded inside to a linguiform lamella (molar expansion ?) ; pal})
well developed, with the basal joint much elongated. Maxillse nearly as in ^Ega.
Maxillipeds with the palp composed of only 2 joints, the terminal one armed with
strong recurved teeth. The 3 anterior pairs of legs having the propodos more or
less expanded and armed inside with strong spines, dactylus forming a very large
and evenly curved hook; the 4 posterior pairs slender, resembling
those in ^Ega. Pleopoda and uropoda normal.
in structure
Remarks. This genus, established by Leach, is nearly allied to JEga,
though exhibiting
some well-marked differences both in the structure of the oral
parts, and in that of the anterior pairs of legs. The genus Achemsia of Lucas
is undoubtedly identical with that of Leach. Nine species of the genus are re-
corded in the work of Schodte & Meinert, from different parts of the Oceans.
Of these, only a single species is represented in the fauna of Norway.
Rocinela danmoniensis, Leach.
(PI. XXVII.)
Rocinela danmoniensis, Leach, Diet. sc. nat. XII, p. 349.
Syn: Achemsia rotundicanda, Lilljeb.
Specific Characters. Body somewhat varying in form, being, in sexually
developed specimens of both sexes, comparatively broader and more compact than
in younger, though equally large specimens, in which the 4 posterior segments
of mesosome are particularly large, and defined by rather broad, thin-skinned
interspaces. Cephalon subtriangular in form, being produced
in front to an obtuse
point. Coxal plates acutely produced, with the outer face smooth. Metasome
defined from the mesosome by a conspicuous constriction, and of inferior breadth,
1st segment in adult specimens nearly concealed, epimera acutely produced; ter-
minal segment semi-oval, or broadly linguiform, evenly rounded at the end, dorsal
face plain, outer part of edge finely ciliated, and armed with minute adpressed
9 Crustacea.