78 Proceedings of the Royal Physical Society. 
Habitat—Under stones, old wood, dead leaves, etc., almost 
everywhere. This is a variable species; the colour varies 
from a uniform dark slaty-grey to reddish and light cream 
colour, and it is always frequently ornamented with dark or 
light coloured blotches. The anterior antennz of Porcellio 
are seven-jointed. In “Sessile-eyed Crustacea,” Porcellio 
dilatatus, Brandt and Ratzeburg, is first included under P. 
scaber, Latreille, as a synonym or a variety, and then at p. 478 
it is described as a distinct species. The form described as 
P. dilatatus is, as the name implies, proportionally broader 
than P. scaber, and this appears to be its chief characteristic, 
I am inclined to regard it as a variety of P. scaber. Several 
varieties of P. scaber occur in our district. A rufous or 
brownish-coloured variety, smaller than the typical form, is 
found under stones at the foot of Salisbury Crags; this I have 
named for the sake of reference var. rufa. A large variety 
of a light cream colour, speckled with black, was obtained at 
Largo, on the shore,-a little above high-water mark. A 
common variety is one of a uniform dark slaty-grey colour, 
which seems to be the P. dubius of Koch. The more typical 
colour is dark slaty-grey, with splatches of yellowish or 
whitish scattered over it in a somewhat regular biserial 
manner—the yellowish or whitish colour appears as if 
dusted on. 
Porcellio pictus, Brandt and Ratzeburg. 
Porcellio pictus, Brandt and Ratzeburg, Arzne-Thiere, ii., pl. 12, 
fig. 5. 
1868. iY ,, Bate and Westwood, loc. cit., ii,, p. 480. 
Habitat.—— About old walls and under stones, appearing to 
prefer dry rather than damp places. This species is easily 
distinguished by the peculiarly pretty markings, and by the 
grooved and acutely-pointed telson. The vividness of the 
coloration varies much; hence several species have been 
described by authors from their placing a greater value on 
the variation in colour than it deserved. Colour is always a 
more or less doubtful character in the definition of a species. 
I obtained P. pictus near Seafield, at the foot of a wall 
