81
THE BRITISH WOODLICE.
By WILFRED MARK WEBB, F.L.S., and CHARLES SILLEM.
(With Plates I.—.XXV., and numerous other Illustrations.)
[Continued from page 56.]
In 1857 Kinahan read a paper before the British Association
(32) in which he described fourteen species of woodlice from the
British Islands, and eleven years later when Bate and Westwood
published their book (1), the number had risen to seventeen.
One of the species (Oniscus fossor), however, was doubtful, and
although Dr. Scharff in 1894 (63) rejected it, his list contained
also seventeen species, for in the meantime the Rev. T. R. R.
Stebbing had found Ligidium hypnorum in Surrey (70).
Since then the Rev. Canon Norman, Dr. Scharff, the Rev.
T. R. R. Stebbing, and one of the present writers, have added
other species, as will be seen from the following pages, in which
all those found, up to the present time in the British Islands
are described and figured.
We shall now consider in detail the British genera and
species of woodlice and give their synonymy and distribution.
Order—ISOPODA.
Tribe—ONISCOIDA.
Section—LIGIAE.
THE TWO DIVISIONS OF THE TAIL APPENDAGES ALIKE IN SHAPE.
Family—LIGIIDAE.
Flagellum with ten or more joints; tail appendages
wholly visible ; head without lateral lobes.
Genus—LIGIA Fabricius, 1798 (27), p. 301.
Abdomen broad; body large; habitat, the seashore.
The genus Ligia agrees with Ligidium alone, in that the
flagellum of the larger antennae has more than ten joints. In
both genera, there are no lateral lobes to the head, and the tail
appendages are wholly visible from the upper surface of the
body. The latter in Ligia is, however, very many times bigger
than in Ligidium and shows no abrupt decrease in the width of
its segments when the abdomen is reached.
G