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shorter than the inner. Male not passing beyond the last larval stage, and undistin-
guishable from the female larva, except by the presence of the male generative
organs, which form 2 small hags within the last segment
of mesosome. Ovaries
of female sometimes fully developed even in the last larval stage. Parasitic on
Crustacea of very different orders, more generally occurring within the marsupial
cavity
of their hosts.
ItC'marlcs. Under this head T combine the four families, Cyproniscidoe,
Cabiropsidce, Podasconidce and Cryptoniseidce of MM. Giard and Bonnier. The
chief motive which has led the above mentioned authors to the establishment of
these four families, seems to have been the occurrence of the parasites, each
family containing only forms which are stated to infest one group
of Crusta-
cea. In my opinion, however, this circumstance cannot be regarded as a suffi-
cient criterion for the distinction of separate families, unless there are also found
very essential differences in the structural relations. This, indeed, seems, not to
be the case, and the last larval stage in particular, as also the male, in all these
forms is of a very uniform appearance, and easily distinguishable from that of the
2 above-described Bopyroid families.
The earliest known genus, from which the family has derived its name,
is Cryptoniscus, established by Fritz Miiller for a peculiar parasite found on a
Peltogaster infesting a Brasilian Pagurid, and having in its adult state a perplex-
ing resemblance to a Plauar'ia, hence the specific name planar'iohles. Subse-
quently several other genera have been established, amounting to about 12 in
all. Of these. 5 will be described below, of which 4 at least are stated to
be represented in the fauna of Norway.
Gen. 1. CyprOniSCUS,
Kossman. 1884.
ic Characters. Body of adult female forming an inert curved sac
wholly filled with ova or embryos, and affixed to the host by
the aid of a thin
flexible chord; dorsal face convex and exhibiting distinct traces of segmentation,
ventral face flattened, lateral parts expanded, anterior extremity broadly produced,
posterior obtusely rounded and incurved. Body of immature female stib-pyri-
t'orm, bluntly truncated in front, hind extremity narrowly exserted, lateral parts
not distinctly defined. Body of young female, imediately after the trans-
formation, subfusiform, very faintly segmented, front part still enveloped by the