THE BRITISH WOODLICE.
83
Genus—LIGIDIUM Brandt, 1833 (3), p. 173
Zia, Koch (34).
Abdomen narrow; habitat, wet moss.
In Ligidium there are numerous joints to the flagellum, lateral
lobes are absent from the head, and the tail appendages are com-
pletely to be seen. All the segments of the abdomen are
distinctly narrower than those of the thorax and in this it agrees
with Trichoniscus, Trichoniscoides, Philoscia, and Metoponorthus.
In these, however, the flagellum has never more than seven
joints, the tail appendages (as in all genera but Ligia and
Ligidium) are partially hidden by the last segment, and in all the
four but Philoscia there are lobes to the head.
Ligidium hypnorum, Cuvier. Plate II.
1792 Oniscus hypnorum Cuvier (9), pl. XXVI., figs. 3—5.
1793 Oniscus agilis Persoon, quoted by Koch in Panzer (51), part 5, pl. XXIV.
1830 Ligia hypnorum Bosc (2). p. 179.
1833 Ligidium persoonii J. F. Brandt (3), p. 174, pl. IV., figs. 6—7.
1840 Zia agilis Koch (34). part 34, pls. XXII. and XXIII.
1844 Ligidium personii Zaddach (77), p. 17.
1853 Ligidium personii Lereboullet (39), p. 14, pl. I., fig. 1, pl. II.. figs. 20—31.
1857 Ligidium personii Kinahan (32), p. 275, pl. XXI., fig. 14, pl. XXII., rig. 9.
1873 Zia saundersii Stebbing (70), p. 286.
1873 Ligidium agile Norman (48), p. 419.
1885 Ligidium hypnorum Budde-Lund (8), p. 254.
1898 Ligidium hypnorum G. O. Sars (59), p. 158 pl. LXXI.
This species, which like the last, is the only British
representative of its genus, was added to our
fauna in 1873 by the Rev. Thomas R. R.
Stebbing (70) who found specimens in the
neighbourhood of Copthorne Common, Surrey.
Up to the present time, when we are pleased
to announce that we discovered it in the
spring of 1902 at Warley in Essex, Ligidium
hypnorum has not been recorded from any other
place in the British Islands.
As the name of the species implies, it lives
in wet situations and in its turn connects Ligia
with the forms which inhabit drier places.
Ligidium hypnorum might be mistaken for
Philoscia muscorum, but as already pointed out in
the generic description, the latter has but a few
(three) joints to the flagellum, instead of from
ten to thirteen. From Ligia, the species under
consideration is distinguished by its small size, narrow abdomen,
and habitat.