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178
wards, frontal lobe less prominent, and broadly rounded. Side-plates
of meso-
some well developed, with the posterior corners acuminate. Metasome scarcely
attaining
1
/4, of
the length of the body, epimeral plates of 3rd to 5th segments
prominent, recurved; last segment considerably produced, being almost as long
as it is broad at the base, terminal part acute and slightly grooved above. An-
tenna? rather slender, nearly half as long as the body, 2nd and 3rd joints of
the peduncle carinated outside, the carina being in each of the joints produced
at the end to a dentiform projection; flagellum not attaining the length of the
last peduncular joint, and having its proximal articulation nearly twice as long
as the distal one. Last pair of legs in male more strongly built than in female,
with the carpal joint considerably dilated. Opercular plates
pairs of pleopoda with very distinct air-cavities. Uropoda
rather broad, and considerably larger
of the 2 anterior
with the outer ramus
in male than in female. Colour of dorsal
face yellowish grey, variegated with dark brown patches, which are generally ar-
ranged in 5 longitudinal series on the mesosome, cephalon and middle part of
metasome uniformly blackish. In fresh specimens, moreover, a double row of
very conspicuous light yellow patches occurs along the middle of the mesosome,
caused by some opaque matter lying beneath the skin (renal excretions). Length
of adult female reaching to 14 mm.
Remarks. The present species may be easily recognized by the compa-
ratively greatly depressed body, the broadly rounded frontal lobe, the slender
antennae, and the peculiar colouring of the dorsal face. In fresh specimens, the
above-mentioned opaque patches along the dorsal face of the mesosome are very
conspicuous, and may at once suffice for distinguishing this species from its allies.
The extent of the dark patches is, on the other hand, rather variable ; but in all
the specimens the cephalon and the middle part of the metasome exhibit a
uniformly dark colour, and this has, indeed, given rise to the specific name, me-
hmocephalus, proposed by Koch for this species.
Occurrence. In the vicinity of Christiania this form is by no means un-
common, occurring in some places rather abundantly beneath stones and pieces
of wood, and I have also received specimens collected by conservator Storm at
Trondhjem. It is not uncommonly found in rather dry situations, where no other
Oniscoid seems to thrive. It is very agile, running about with great rapidity
when disturbed, and is thus only to be got hold of with difficulty.
Distribution. Sweden, Denmark, Germany, Britain, France, Hungary,
Russia, North America.