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and to a 'great extent encompassed by the 1st segment of mesosome, subcordate in
form, with the frontal margin thickened and deeply insinuated in the middle. Segments
of mesosome only visible dorsally, very narrow, band-like, lateral parts well defined
on the shorter side, and each projecting into a small, knob-like prominence, those on
the other side inconspicuous; coxal plates only present on the former side, very
small and imperfectly defined from the lateral parts. Metasome more or less
projecting behind, abruptly contracted and slightly tapering distally, segments well
defined, the last one narrow conical in form, and minutely incised on the tip.
Oral area wholly concealed below. Incubatory plates
on the shorter side of the
body rather small and densely crowded together, each divided by a transversal fold
into 2 segments; those of the other side very large, especially the 2nd, which
alone forms the greater part of the boundary of the marsupium ; 5th plate on
this side apparently wanting. Legs more or less twisted and extended dorsally,
those of the larger side all obliterated except the 1st one, though slight rudiments
of the 3 posterior ones may always be found as 3 extremely
small bifurcate
appendages just in the angle between the mesosome and nietasome. Outer la-
mellae of pleopoda foliaceous, rounded oval, successively diminishing in size from
before backwards, those on one side much larger than on the other. Body of
young female, with the incubatory plates not yet fully developed, subclavate in
form, anterior division, as in fully grown specimens, very asymmetrical, but having
all the legs distinctly developed; those of the larger side however, being, rather
irregularly arranged and partly folded in beneath the ventral face. Body of
still younger female oblong oval in form, somewhat irregularly twisted, but having
all the segments very sharply defined. Cephalon freely projecting in front, and
rather broad. Segments of mesosome strongly vaulted above, and having the
lateral parts on both sides considerably produced and deflexed. Metasome not
abruptly contracted. Legs regular on both sides, being
all folded in beneath
the ventral face. Inner lamellae of pleopoda larger than the outer. Body of
immature female (in the 1st postlarval stage) very slender, vermiform, nearly
symmetrical throughout, with the cephalon semicircular, and the lateral parts of
the segments obtusely produced; outer lamellae of pleopoda wanting. Adult
male oblong, linear, with the segments of mesosome very sharply marked off
from each other, metasome forming an undivided piece, broad at the base and
conically tapered distally. Colour of fully grown female
~
dark brownish violet.
Length of female attaining 11 mm., that of male 3 mm.
Item i irk *. This form was first described by Kr0yer in the year 1840
as Bojii/rtt* uhiloinrn-dlis. ;nxl it was 3 years later that H. Rathke published his
description of P/ir//.r//x hipj>oli/tt'*. That these two forms are identical is