In _Ligidium_ there are numerous joints to the flagellum, lateral lobes are absent from the head, and the tail appendages are completely 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., fig. 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. [Illustration: FIG. 36.--FLAGELLUM AND LAST PEDUNCULAR JOINT OF THE ANTENNA OF _Ligidium hypnorum_.] 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. _BRITISH LOCALITIES:--_ _England_: Warley, Essex; (W.M.W.): Copthorne Common, Surrey; (Stebbing, 70). _FOREIGN DISTRIBUTION:--_ _Europe_: France; (25): Sweden; Denmark; Germany; (59): Turkey; (8). _Family_--TRICHONISCIDÆ. =Flagellum with less than ten joints; head with lateral lobes; tail appendages partly hidden.= _Genus_--=TRICHONISCUS= Brandt, 1833 (3), p. 174. _Abdomen narrow; eyes compound; flagellum, usually with more than three joints._