CRUSTACEANS first and second joints are small. It should also be observed that the con- tinuity of the body's outline is maintained between the last segment of the peraeon and the third of the pleon, the first two pleon segments being hemmed in between these, and narrower than either of them. Philoscia muscorum (Scopoli), which was taken in woods on the borders of Herefordshire between Ludlow and Richards Castle, is a smooth, shining species, with pretty symmetrical markings. It is smaller and more nimble than the Oniscus. In the flagellum of the second antennae the second and third joints are subequal, together little or not at all longer than the first joint. Platyarthrus hoffmannseggii, Brandt, was found at Berrington in its accustomed habitat, an ants' nest. The flagellum of the second antennae is really two-jointed, but the first joint from its smallness is difficult to observe. The species is easily captured, as it is blind and perhaps in consequence slow to apprehend danger. Its creamy colour and small size give it a vague resemblance to the pupal ants. For the same reasons it is something like the recently extruded young of some larger species. PorcelHo scaber, Latreille, found at Ludford, competes with Oniscus asellus in abundance, approaches it in size, excels it in the roughness of its tubercular ornamentation. The standard colour of this species may be described as a uniform dark grey, amounting almost to black. But there are several variations which seem rather prevalent on the borders of Hereford- shire and Shropshire, comprising a uniform brown and an irregular blotching of yellow and brown. It is easy to fancy on a cursory inspection that two or three different species have been captured, but a more careful survey dispels the illusion. Metoponorthus pruinosus (Brandt) is a narrow, slightly rugose species. The head is small, with the lateral lobes, so conspicuous in P. scaber, here little developed. In the second antennae the first joint of the flagellum is much longer than the second. Undamaged specimens, according to Mr. W. M. Webb, ' are of a beautiful bluish-grey colour, owing to a " bloom " which is easily brushed off, revealing a dark reddish-brown tint beneath it.' " It is described as very common by Bate and Westwood, and as cosmopolitan by Budde-Lund, who no doubt rightly attributes its wide distribution to the agency of human navigation. Yet it is not always easy to find. Nor is this experience confined to Great Britain. In 1 847, Adam White named a species PorcelHo zealandicus, as coming from New Zealand. This was described and figured by E.J. Miers in 1876, and in 1885 Budde-Lund suggested that it might be identical with our M. pruinosus. But it was not till March, 1905, that Professor Charles Chilton was able absolutely to confirm this suggestion. He had for many years been on the look out for this species among the Isopoda of New Zealand, but without success till the date mentioned. He notes, too, that while M. pruinosus remains rare ; on the other hand PorcelHo scaber, Latr., another introduced species, is extremely common all over New Zealand, and in addition to being found near inhabited places, has penetrated to some extent into the bush far from houses." The caprice of distribution is further illustrated by Armadillidium vulgare (Latreille), 'which is common,' '« Webb and Sillem, The British Woodlice, p. 37 (1906). " Tram. New Zealand Inst, xxxviii, 64 (1905). 119
