specimens which, by reason of their smaller size and much more strongly granulated head and body, may be distinct from the common form, but whether for these the name O. fossor, Koch, should be adopted remains uncertain. In the second set the genus Porcellio is as usual represented by the large and very abundant P. scaber, Latreille, sent by the ladies of Lane End, and reported from Mr. Webb's series of localities, 'near Dropmore' being in this case substituted for Hedsor. This species is not quite so broad as Oniscus asellus, and its surface is strongly granular. It is most often of a uniformly blackish grey colour in a general view, though on closer inspection lighter markings can be perceived and the borders are more or less pellucid. Sometimes it is marbled with grey and yellow, and this variety has been distinguished as marmoratus by Brandt and Ratzeburg. In the ordinary form the flagellum of the second antennæ has the two joints nearly equal, or the first a little shorter than the second. In some rather small prettily-marbled specimens submitted by Mr. Webb the first joint is much shorter than the second, a character shared by P. ratzeburgii, Brandt, from which however in some other respects they differ. At Eton Mr. Webb has met with P. dilatatus, Brandt. This broad, moderately granular species has the two joints of the antennary flagellum short and equal. From the preceding species it is well distin- guished by the apical segment, which, instead of being acutely triangular and dorsally grooved, is flat above and drawn out narrowly tongue-like to a rounded tip. In addition to the above a very handsome species, not hitherto included in the British fauna, has been sent me by the Misses Johnson from Lane End and from Eton by Mr. Webb. This new acqui- sition is P. rathkei, Brandt. It is more or less marbled over all the back, but has also three well-marked longitudinal stripes of pale flecks, which are drawn closer together on the pleon than on the person. The surface is moderately granular, but the hind margins of the person segments are smooth, not distinctly tuberculate as in P. scaber. The flagellum of the second antennæ has the first joint somewhat shorter than the second. The apical segment of the body is flat above and subacutely pointed at the tip. This species, like P. ratzeburgii, belongs to a section of the genus in which all the pleopods have the opercular branch provided with trachea? (or pseudo-trachea?), modified that is to say for aerial respira- tion. In the other species above mentioned it is only the first two pairs of pleopods that are thus modified. In the male of P. rathkei the seventh pair of legs have the antepenultimate joint dilated near the base, a peculi- arity to which attention has been called by Professor G. O. Sars.[1] The cosmopolitan species, Metoponorthus pruinosus (Brandt), taken by Mr. Webb at Langley and Eton Wick, agrees much in general shape with Philoscia muscorum, but in other respects more with Porcellio. It has the first two pairs of pleopods tracheate ; the frontal margin is straight. The second joint of the antennary flagellum is much shorter than the first. The apical segment of the body is short, acutely triangular. The surface is finely granular and in colour brown. To the same family belongs the
- ↑ Crustacea of Norway, Isopoda," ii. 180.
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