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outer. Colour of dorsal face light reddish brown, the segments
of mesosome
being bordered behind with darker brown, and having on each side of the median
line a group of lighter dots or stripes; antennae banded with white. Length of
adult female 9 mm.
Remarks. This form has more generally been recorded under the specific
name maculicornis proposed by Koch; but, as the name pruiiiosus is the older one,
it ought certainly to be retained. Some other synonyms are quoted above. It
is easily recognizable by the oblong, flattened body, the abruptly contracted meta-
some, and the long and slender antennae, in these points somewhat resembling
Philoscia muscorum, from which, however, it is at once distinguished by
articulate antennal flagellum.
the bi-
Occurrence. I have met with this form not infrequently in the immediate
vicinity of Christiania, especially in refuse-heaps, together with PorceUio scaber; and
it has also been found by conservator Storm in similar situations at Trondhjem.
It is a very agile animal, running about with great rapidity when disturbed;
and, as the integuments are very thin and soft, it is easily injured when
being captured, unless great
care be exercised.
Distribution. Greater part of Europe, North Africa, North and South
America, Sumatra, Madagascar, etc.
Gen. 6. CyliStleUS, Schnitzier, 1853.
Generic Characters. Body oblong, very convex, capable of being rolled up
into a perfect ball, integuments rather hard. Cephalon with the lateral lobes distinct,
median lobe very small or obsolete. Side-plates of [mesosome large, those of
1st segment the largest. Metasome not abruptly contracted, epimeral plates
of 3rd to 5th segments well developed, recurved ; last segment conically produced
behind. Eyes distinct, lateral. Antennulse with the last joint conically produced.
Antennae long and slender, with the flagellum biarticulate. Oral parts of a similar
structure to that in Porcellio. Legs of moderate size, successively increasing in
length behind. Opercular plates of all the pleopoda provided
with air-cavities.
Copulative appendages of male of a similar structure to that in J'urcrlfio. Uropoda
rather much produced, especially in male ; inner ramus very narrow, and issuing far
in front of the outer.
21 Crustacea.