90 THE BRITISH WOODLICE.
Oniscus asellus is one of the largest of our woodlice and it is
also probably the commonest, though Porcellio scaber is in many
places quite as abundant. The body of Oniscus is broad and
expanded and the colour is usually a slate grey with yellowish
markings more or less regularly arranged.
From the genus Porcellio the species with which we are-
concerned is at once distinguished by the three
jointed flagellum. Porcellio has but two joints
and has besides a prominent lobe projecting
from the middle of the head, which is not seen
in Oniscus. Philoscia, although it has three joints
to the flagellum, has a narrow abdomen and
lacks entirely the lateral lobes which are a
feature of the other genera of Oniscidae
Oniscus fossor of Koch (34) was recognized by
Kinahan and by Bate and Westwood as a
species. Dr. Scharff submitted specimens to
Professor Budde-Lund who found no differences
between them and Oniscus asellus. The former
(63) mentions, however, that the characteristics
of the supposed species are those of young
examples of Oniscus asellus, and Professor Sars
(59, p. 173) seems to be of the same opinion.
Many young examples of Oniscus asellus that we have examined
have a curious whitish transverse band owing to the light colour
of the dorsal plates of the first abdominal segments. The
flagellum also does not seem to shew in young animals a distinct
division into three joints.
BRITISH LOCALITIES :—
England : High Beach, Epping, including an albino; Maldon;
Brightlingsea; Iver; Hanwell; Eton; Kew; Pamber Forest;
Kingston-on-Soar ; Bluebell Hill, Maidstone ; (W. M. W.) :
Lynmouth ; (W.M.W. from J.T.C.).
Scotland : (Scharff, 63). Dinnet, Aberdeenshire; (W.M.W.
from Madame Christen
Ireland : (Scharff, 63). Yellow form with black spots, Donegal
(R.W.)
FOREIGN DISTRIBUTION :—
Europe: Almost throughout; (12). France; (25): Spain; (12): Sweden;
Norway; Denmark : Germany ; Holland ; Italy ; Iceland ; (59) : Faroe Islands ;
Thornsham ; (R.F.S.)
Africa : Azores; (24).
America : Greenland ; (59) : North America ; (Budde-Lund).