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different order. Furthermore, on the very same species of Spirontocaris (Hippo-
lyte), S. securifrons, and at about the same place, below the anterior part of the
tail, may be found sometimes a Bopyrid (Phryxus), sometimes a rhizocephalic Cirriped
(Sylon), and the same species is very often found to be infested by another Bopyrid
(Bopyroides). A similar case is also shown in our common hermit crab, Eupagurus
bernhardus. It may be found infested by a Pseudione under its carapace,
or it
may carry on the dorsal face of its tail a very different Bopyrid, Atlielges, and
the place of the latter is not infrequently occupied by a rhizocephalic Cirriped Pelto-
gaster, to which again sometimes a Liriopsis is found attached. There is nothing
that forbids the assumption, that the Amphipoda may also be infested by para-
sites of very different nature, and indeed Dr. Hansen has shown that they not
infrequently contain in their marsupium Choniostomatidce belonging
to 2 different
genera, Stenothochtres and Sphwronella. As to the Cryptoniscid in question,
there is a circumstance, which makes it rather improbable
that it should be
transformed to a Podascon. One of the specimens, the one here figured, was
found, on a closer examination, to be provided with very fully developed ovaries
in the form of 2 dark-coloured bags extending through the greater part
of the
mesosome, and containing a restricted number of comparatively large ovarial
eggs. In no other instance have I found the ovaries in this stage developed to
such a degree, and this seems to indicate that the metamorphosis of the present
form might be far less complete than in other Epicarids. Perhaps we even have
here an instance of the female retaining its larval characters also in the adult
state. In this connexion it is worthy of note that the present form is of
considerably larger size than any other larval stage of Epicarida with which I
am acquainted.
Occurrence. The specimen examined by the Rev. Th. Stebbing was found
among the ova in the marsupical pouch of an Onesimus plautus Kroyer, taken
in the Barents Sea. I have myself found it under altogether similar circumstances,
and on the very same host at Bodo, and have also occasionally taken it off the
Nordland coast free in the sea by the aid of the tow-net. The same form also
occurred in some Plankton-proofs taken during Nansen's Polar Expedition in the
glacial sea, north of Siberia.
From the above mentioned finding-places, it seems to be a true
arctic form.