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179
3. Porcellio dilatatus, Brandt.
(PL LXXVIII, fig. 2.)
Pwcellio dilatatus, Brandt & Ratzeburg, Medicin. Zoologie, Vol. II, p. 78, PL 12, fig. 6.
Syn: Porcellio scaber, M.-Edw. (not Latr.).
Specific Characters. Body broadly oval, not nearly twice as long
as it
is broad, dorsal face moderately convex, and rough owing to rounded elevated tu-
bercles, especially densely crowded in the middle of the segments. Cephalon with
the lateral lobes large, obtusely truncated at the tip, frontal lobe distinctly pro-
jecting, obtusely triangular. Side-plates of mesosome rather large, with the
posterior corners obtusely acuminate. Metasome nearly twice as broad as it is
long, and scarcely attaining ]
/4 of the length of the body, epimeral plates of 3rd
to 5th segments greatly prominent, semilimar; last segment nearly as long as it
is broad at the base, outer part considerably produced and plane above, tip ob-
tusely rounded. Antennae rather strongly built, 2nd joint of the peduncle much
dilated, flagellum shorter than the last peduncular joint, and having
its articula-
tions subequal in length. Legs comparatively short and thick. Opercular plates
of the 2 anterior pairs of pleopoda with air-cavities. Uropoda
with the outer
ramus rather broad, inner ramus scarcely extending beyond the last caudal seg-
ment. Colour of dorsal face dark slaty grey, the segments of mesosome ex-
hibiting on each side of the median line an assemblage of irregular, somewhat
lighter patches. Length
of adult female 14 mm.
Remarks. Though rather nearly allied to P. scaber,
with which it was
confounded by M. -Edwards, this form may be easily recognized by its unusually
broad body, and by the shape of the last segment of the metasome.
Occurrence. A well-marked adult specimen of this form,
the one here
delineated, was sent to me from conservator Storm, who found it in a garden
hot-house in Trondhjem. I have myself taken 2 not yet fully grown specimens
in the Botanical Garden in Christiania, likewise from a hot-house. It is slower,
in its motions than most other species.
Distribution. Denmark, Germany, Poland, Holland, Britain, France,
Triest, New Guinea, Australia.