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fully grown, the parasite causes a very large and conspicuous
rounded tuber-
osity on the carapace of its host, occurring sometimes on the left, sometimes on
the right side (see fig. 24). The walls of this tuberosity fit exactly around the
sides of the parasite, and the very capacious marsupial pouch is thereby
completely closed, the incubatory plates extending only for some distance up the
sides of the cavity. As is the case with most other Epicaricla, the parasite in-
variably turns its head backwards in relation to its host,
and the dorsal face
towards the body of the latter. Such a position is in this instance of essential
significance for the aeration of the marsupial cavity, the water washing the
branchial cavity of the host from behind forwards being thus easily introduced
into the marsupium of the parasite from between the 1st pair of incubatory
plates. The number of ova contained in the marsupium is immense, and may
amount to several thousand in all. I have observed the embryo in its last stage
of development, immediately proceeding the 1st free larval stage, and have found
it to agree exactly with that of Phnjxus abdominalis, as represented
in PI. 91.
The male is found clinging to the ventral face of the metasome of the female,
just behind the last pair of incubatory plates, being generally placed trans-
versally
(Sp. Bate).
to the axis of the female.
Distribution. Greenland (Kroyer), Barents Sea (Hoek), British Isles
Gen. 3. PseudlOne, Kossman, 1881.
Syn. : Palcegyge, Giard & Bonn (part).
Pliry.nis, Sp. Bate & Westw. (part).
Generic Characters. Body of female oval or pyriform in outline, more
or less asmymetrical, with the segments both of mesosome and metasome very
sharply defined. Cephalon distinctly marginate in front. Segments of mesosome
with the lateral parts elevated and divided by a transverse groove into 2 lobes;
coxal plates well
defined, though rather small, discontiguous. Epimeral plates
of metasome more or less
projecting, lamellar; last segment very small. Antennae
and oral parts as in Bopyroides. 1st pair of incubatory plates with the distal
segment produced to a narrow linguiform lobe, as in Bopyrus; the succeeding
pairs large, arching over the ventral face. Legs more or less projecting later-
ally, and of usual structure. Pleopoda well developed, biramous, rami lanceolate,