94 THE BRITISH WOODLICE.
Genus—PORCELLIO Latreille, 1804 (37), p. 45.
Flagellum, with two joints; abdomen, broad; frontal lobe projecting.
Porcellio is easily separated from the previous genera—Oniscus,
Philoscia, and Platyarthrus—by its two-jointed flagellum. The
fact that the abdomen is not abruptly narrowed separates it
from Metoponorthus, which also lacks the prominent frontal lobe
so characteristic of Porcellio, The species of this genera might
be confused with Cyclisticus which has two joints to the flagellum
and a broad abdomen, but the latter genus has the power of
rolling itself into a ball, while its frontal lobe is very small, and
the first segment of its thorax is comparatively larger than in any
species of Porcellio.
Porcellio scaber Latreille. Plate XIII.
1804 Porcellio scaber Latreille (37), p. 45.
1818 Oniscus granulatus Lamark (36), p. 261.
1818 Porcellio nigra Say (62), p. 432.
1840 Porcellio brandlii Milne-Edwardes (46), p. 168.
1840 Porcellio dubius Koch (34), part 34, pl, VIII.
1847 Porcellio asper Koch (35), p. 207, pl. VIII., fig. 98.
1857 Porcellio montezumae Saussure (60), p. 207.
1865 Porcellio paulensis Heller (31), p. 136, p. XII., fig. 5.
1868 Porcellio scaber Bate and Westwood (1), p.
1876 Porcellio graniger Miers (44), p. 223.
1885 Porcellio graniger Budde-Lund (8), p. 149.
1898 Porcellio scaber Sars (59), p. 176, pl. LXXVII.
The body of Porcellio scaber is densely covered with tubercles.
Its colour is usually of a very dark grey, but at times it is quite
red or variegated with yellow. Albino speci-
mens have been recorded. The two joints
of the flagellum are of the same length and
together equal that of the last joint of the
peduncle. Air-tubes are present in the outer
plates of the first two abdominal appendages.
BRITISH LOCALITIES :—
England : High Beach, Epping ; Warley;
Brightlingsea ; (W.M.W.): Maldon; (W.M.W.
from R.M.): Langley ; Kew ; Skirmett; Pamber
Forest; (W.M.W.): Liphook; (C.S.) : Stoke-
on-Trent; Kingston-on-Soar; (W.M.W.)
Scotland : Dinnet (W.M.W. from Madame
Christen.
Ireland : Common everywhere ; (Scharff, 63.)
FOREIGN DISTRIBUTION :—
Europe : Throughout; (59): France; (28) : Spain ; (15):
Iceland; (59) : Faroe Isles—Thorsharn and Naalsoe—
(R.F.S. and B.M., N. Annadale).