The outer divisions of the tail appendages are considerably longer than broad, and are more or less paddle-shaped. It will be noticed that the slope from thorax to telson is more gentle than in the common species, _Armadillidium vulgare_, and the first thoracic segment is not so greatly developed. Consequently the species which we are considering does not produce a perfect sphere, and the antennæ are not hidden when it rolls up. It is interesting to compare this species with _Cylisticus convexus_. The surface of the body is smooth, and its colour is a delicate brownish grey with more or less distinct rows of darker markings. _BRITISH LOCALITIES:--_ _England_: Maldon; (W.M.W. from R.M.): Bluebell Hill, Maidstone (W.M.W.); Clifton, banks of the Avon; (W.M.W. from J.T.C. 1900): Leigh Woods, Clifton; Tunbridge Wells; South Devon; (Stebbing in 49); Cheddar Cliffs, Somerset; (Norman, 49). _FOREIGN DISTRIBUTION:--_ _Europe_: France; (28): Spain; (12): Italy; (23). =Armadillidium vulgare= Latreille. PLATE XXIII. 1804 _Armadillo vulgaris_ Latreille (37), p. 48. 1804 _Armadillo variegatus_ Latreille (37). 1853 _Armadillo ater_ Schnitzler (65), p. 48. 1816 _Armadillo maculatus_ Risso (56), p. 158. 1818 _Armadillo pillularis_ Say (62), p. 432. 1825 _Armadillo pustulosus_ Dermarest (11), p. 323, pl. XLIX. 1830-4 _Armadillidium commutatum_ Brandt and Ratzeburg (4), p. 81, pl. XIII., fig. 123. 1833 _Armadillidium zenckeri_ Brandt (3), p. 185. 1839 _Armadillo trivialis_ Koch (34), part 28, pl. XIV. 1898 _Armadillidium vulgare_ Sars (59), p. 189, pl. LXXXII. The common pill woodlouse is _Armadillidium vulgare_. Its frontal lobe is not large, though it is broad, while its margin where it joins the head is rounded and slightly recurved. The proximal joint of the flagellum is somewhat the shorter and the two together, as in _Armadillidium nasatum_, are of about the same length as the last joint of the peduncle. The telson has the form of a triangle with the angles truncated and is about as long as it is broad at the base. The outer divisions of the tail appendages are considerably broader than they are long. The species can roll itself up into a very perfect sphere, and when it assumes this form its antennæ are hidden beneath the much expanded lateral plates of the first thoracic segment. [Illustration: FIG. 57.--FLAGELLUM AND LAST PEDUNCULAR JOINT OF THE ANTENNA OF _Armadillidium vulgare_.] The body is smooth, shiny, and strongly arched. Its colour varies very considerably, generally it is of a slaty-grey, but yellow markings are often present to a greater or less extent. In a specimen before us (from Bluebell Hill, Maidstone) the head is of a uniform dark grey, the sides of the thorax are yellow, while the back is mottled with the same colour. The abdomen, including the telson, is also yellow with the exception only of the tail appendages, which are dark grey.