There is but a single species of _Cylisticus_ found in this country, so that it is not necessary for us to go into much further detail with regard to it. _Cylisticus convexus_ has the two joints of the flagellum about equal, and they together in turn closely approximate in length to the last joint of the peduncle. Mr. Stebbing says, in a letter, that British examples do not appear to have the "white tail-piece" seen in Continental ones. It is not noticeable in the preserved specimens which we have seen from Berkhamsted and Leixlip, but it is very evident in the living ones found at Hanwell and Maidstone. The abdominal appendages 1 to 5 are provided with air-tubes. [Illustration: FIG. 55.--FLAGELLUM AND LAST PEDUNCULAR JOINT OF THE ANTENNA OF _Cylisticus convexus_.] _BRITISH LOCALITIES:--_ _England_: Maldon; (W.M.W. from R.M.): Hanwell; Bluebell Hill, Maidstone; Eton; (W.M.W.): Berkhamsted; Portland; (Norman, 49). _Scotland_: Salisbury Crags; Edinburgh; Lanarkshire; Rothesay; (Scott, 68): Killwinning; (John Smith _fide_ Robertson, 57): Highgate; (Bate and Westwood, 1). _Ireland_: Leixlip, Co. Dublin; Tempo, Co. Fermanagh; Goresbridge, Co. Kilkenny; (R.F.S.) _FOREIGN DISTRIBUTION:--_ _Europe_: France; (25): Sweden; Norway; Denmark; Germany; Bohemia; Holland; Belgium; Turkey; Caucasus; (59). _North America_; (59). _Family_--ARMADILLIDIIDÆ. =Tail appendages not projecting when the animal is walking.= _Genus_--=ARMADILLIDIUM= Brandt, 1833 (3), p. 184. _Flagellum, with two joints; outer division of the tail appendages expanded and broader at the hinder end._ The members of the genus _Armadillidium_ are more likely to be confounded, by the uninitiated, with the "Pill-millipedes" than with other Woodlice. Excepting _Cylisticus_ (which has long pointed tail appendages) no other British forms have the power of rolling themselves up into a complete ball. The very arched body is characteristic of _Armadillidium_, and so is the groove into which the basal joints of the antennæ fit when the creatures curl up. The first two abdominal appendages only are provided with air-tubes. =Armadillidium nasatum= Budde-Lund. PLATE XXII. 1885 _Armadillidium nasatum_ Budde-Lund (8), p. 51. 1892 _Armadillidium nasatum_ Dollfus (14), p. 10, fig. 12. 1899 _Armadillidium nasatum_ Norman (misprinted _Porcellidium_) (49), p. 57. pl. VI., figs. 5-8. _Armadillidium nasatum_ has a narrow but very prominent frontal lobe, which is almost square and curves somewhat upwards and backwards. The joints of the flagellum are approximately equal, and are together of the same length as the last peduncular joint. The telson is as long as it is broad at the base, and tapers to a roundish point, while its sides are slightly incurved. [Illustration: FIG. 56.--FLAGELLUM AND LAST PEDUNCULAR JOINT OF THE ANTENNA OF _Armadillidium nasatum_.]