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105
Remarks. By most authors, this form has been recorded under the spe-
cific name albifrons, proposed by Leach; but as there cannot be any doubt that
the Oniscus marinus of 0. Fabricius is this species, the latter specific name, as
the older one, ought to be preferred to that of Leach. Four more synonyms are
quoted above. The laera Nordmanni Rathke, of which I have had specimens for
examination from the Caspian Sea, is a very nearly-allied species, but is distinguished
pretty well by the dense and regular garniture of spiniform bristles, and by the
still more poorly developed uropoda, the rami of which look merely like small
setiferous noduli. It seems to me somewhat doubtful whether the form figured
by Sp. Bate and Westwood under this name, is the true Rathkian species, or
perhaps more properly
the male of /. marina.
Occurrence. This species occurs along the whole coast of Norway, from
the Christiania Fjord to Vadso, in quite shallow depths. At low water, it is often
found in great numbers beneath stones on the beach, and sometimes at a consider-
able height above the level of the sea, together with Ligia oceanica and other
terrestrial Isopoda. Its flat body makes it admirably well adapted to cling to
the stones of the beach, andto conceal itself in their crevices.
Distribution. -British Isles (Sp. Bate), Kattegat (Meinert), Dutch coast
(Hoek), coast of France (Bonnier), Greenland (Hansen),
America (Harger).
Fam. 3. Munnidae.
Atlantic coast of North
Characters. Body generally diort and stout, with the 3 posterior segments
of mesosome, as a rule, sharply marked off from the 4 anterior, and much smaller.
Caudal segment more or less vaulted above, sub-pyriform. Eyes, when present,
placed on the tips of lateral, peduncle-like projections of the head. Superior an-
tennae placed widely apart, and more or less developed, with the flagellum gene-
rally multiarticulate. Inferior antenna? issuing immediately beneath the superior,
and without any outer appendage. Oral parts normal. 1st pair of legs much
shorter than the others, prehensile; the succeeding pairs more or less rapidly in-
creasing in length, simple, ambulatory. Uropoda generally small, somewhat removed
from the tip of the caudal segment, being sometimes subdorsal. Male
much smaller than female.
14 Crustacea.