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lished by MM. Giarcl and Bonnier as Day us m-ijrfus, but this is only a nominal
species, and undoubtedly identical with that originally recorded by Kr0yer.
Dajus mysidis, Kr0yer.
(PI. XCIII, CIV).
tni/sidis, Kroyer, in Gaimard's Voyage, PL XXVIII, fig.
1.
Si/n. : Bopyrus mysidum, Packard
Leptophryxus mysidis, Buchholz
Dajus mixtus, Giard and Bonnier.
Specific Character*. Body of fully grown female oval quadrangular in
outline, broadest in front and slightly narrowed behind, Cephalon imperfectly
defined, and curved downwards, frontal margin straight. Lateral parts of meso-
some greatly swollen, and projecting anteriorly in the form of bluntly rounded
protuberances extending beyond the limits of the cephalon, median part sub-
depressed and exhibiting 5 or 6 distinct transversal sutures defining the seg-
ments. Metasome rather short and but slightly projecting, being conically
tapered, its 1st segment much larger than the others. Oral area placed wholly
in front, comparatively broad, semicircular. Antennulse very short, 3-articulate ;
antennae much more slender and extended laterally, being composed of 8 or 9
articulations successively diminishing in size distally. First pair of incubatory
plates larger than the next succeeding ones, and divided by a transversal fold
into 2 segments ; last pair, extending behind the oral area, rather broadly over-
lapping each other in the middle. Body of young
female narrower, subclavate.
with the mesosome more distinctly segmented, and the metasome more produced ;
that of still younger female oblong, attenuated behind, with the cephalon freely
projecting in front, and the coxal plates occupying the side-edges of the meso-
some. Body of immature female, immediately after the metamorphosis,
still nar-
rower, somewhat resembling the male in shape, but having only 5 pairs of legs,
and the metasome distinctly segmented. Adult male linear, subcompressed, with
the 6 posterior segments of mesosome very sharply marked off from each other.
metasome forming a thickish, undivided piece of oval or elliptical form, carrying
at the tip 2 extremely small appendages (rudiments of uropoda). Colour of
female along the middle of the dorsal face reddish brown, lateral parts whitish.
Length of fully grown female 4 mm.,
that of male 1 mm.
Remarks. As above stated, this form was first recorded by Kroyer, and
figured by him in Gaimard's work from a not yet fully developed specimen. The
same form was subsequently described under two different names, viz., by Packard