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141
but, unlike what is the case in that genus, the mandibles are provided
with dis-
tinct, though rather small palps. The peculiar fornicate character of the posterior
division of the body has given rise both to the generic and specific names.
1
Aspidarachna clypeata ),
(PI. LXII.)
G. 0. Sars.
Ilyaraclma clypeata, G. 0. Sars, Nye Dybvandscrustaceer fra Lofoten. Chr. Vid. Selsk. Forlxll.
1869, p. 168.
tfjx'cific Characters. Body scarcely more than twice as long as it is broad,
and generally much curved. Cephalon very broad in proportion to its length, frontal
edge evenly concaved, lateral parts obliquely expanded. The first 4 segments of meso-
some short and distinctly excavated transversally, with the anterior edge considerably
elevated and perfectly smooth, lateral parts acutely produced. The 3 posterior seg-
ments of rnesosome very large and evenly convex above, forming together a shield-like
plate advancing in front over the adjoining part of the anterior division. Caudal seg-
ment triangular, scarcely as long as it is broad at the base, tip obtusely pointed.
Superior antenna; with the basal joint very large, inner corner considerably pro-
duced, and armed with 2 long spines ; nagellum in female short, 3-articulate, in
male very much elongated, and divided into numerous short articulations clothed
with delicate sensory filaments. Inferior antennae nearly twice as long as the
body, the 2 outer joints of the peduncle armed inside with slender spines, fla-
gellum about the length of the peduncle. The 4 anterior pairs of legs scarcely
different in their structure from those in the 2 preceding genera, except that the 3rd
and 4th pairs are very much shorter, not nearly attaining the length of the body,
and having the ischial joint the longest. Carpal joint of the 2 anterior pairs of
natatory legs strongly expanded, broadly cordiform in outline, and densely fringed
with plumose seta?, propodal joint much shorter and oblong fusiform. Last pair
of legs, as in the 2 preceding genera, much more slender than the 2 preceding
ones. Uropoda with the basal part oblong oval and densely fringed with plumose
setae, outer ranius very small, though well defined. Colour whitish. Length of
adult female 4 mm.
Remarks. This is the only as yet known species of the genus, and may
easily be recognized by the short and compact body, and the peculiar fornicate
character of the posterior segments of the mesosonie.
') The generic name Aspidonotus given in the plate has been changed in the above
manner, because that name has been previously used in Zoology.