A HISTORY OF KENT jointed. It is a smooth and shining, rapidly running species, common at Tunbridge Wells, and probably all over England. Oniscus asellus, Linn., agrees with it in the number of joints to the flagellum and in being found at Tunbridge Wells and indiscriminately elsewhere, but it is very much larger, slow-moving, and though glossy by no means absolutely smooth. In all our remaining species the flagellum is two-jointed, still in Platyarthrus hoffmannseggii, Brandt, the first of the two joints is characteristic by its minuteness. This species has been taken at Tunbridge Wells in an ants' nest, the habitat which it appears invariably to occupy. Porcellio scaber, Latreille, is common at Tunbridge Wells, but not a rarity anywhere. Of the same genus P. pictus, Brandt and Ratzeburg, and P. laevis, Latreille, are also assigned to this county.' Between the first and third no confusion is possible, because P. scaber, as the name intimates, is rough all over with tubercles, while the very broad P. laevis is named from the smoothness of its surface. The painted Porcellio is recorded from Chislehurst and has also been taken at Tunbridge Wells. It comes near to P. scaber, but it differs from it in having the first joint of the flagellum longer than the second. Also the head is very dull in contrast to the variegated colouring in the rest of the dorsal surface. Metoponorthus pruinosus, Brandt, is recorded from Chislehurst. It differs from the species of Porcellio, which have the front strongly trilobed, by a reduction of the lateral lobes giving it comparatively a ' straight front ' in accord with its generic name. Cylisticus convexus (de Geer) is re- ported by Mr. W. M. Webb from Bluebell Hill, Maidstone. It is Hke Porcellio, but capable of globation.^ AnnadilUdiitni vulgare (Latreille) and A. nasatum, Budde-Lund, have both been taken at Tunbridge Wells, and the latter also at Riverhill, near Sevenoaks. From all the preced- ing terrestrial isopods, except Cylisticus, they are marked off by the power they possess of rolling up into a ball. In the common species the front is simple, but in A. nasatum its middle part is turned back dorsally with something of a nasiform projection. Though twelve out of the twenty-four English species may be thought a fair proportion for a single county to possess, no doubt Kent will eventually be found to have several in addition to those here enumerated. The Amphipoda, which agree with the Isopoda in having sessile eyes and a peraeon or middle body of seven articulated segments, differ from them very essentially by the position of the breathing organs. These in the genuine isopods are confined to the pleon, but in all the amphipods are attached to limbs of the peraeon. Of this latter order the species are extremely numerous, and it is reasonable to suppose that the few recorded from Kentish waters are an inconsiderable percentage of the number really present. The fresh-water species, Gammarus pulex (Linn.), is plentiful here as elsewhere, found in ponds, rivulets, and occasionally in wells. But of more interest are the 'well shrimps' ' British sessile-eyed Crustacea, ii. 482, 484. ' Loc. cit. ii 488. 3 The British Woodlice, p. 39, pi. 21. 250
