HABITS AND LIFE-HISTORIES OF WOODLICE. 111
pusillus; as the grasses grow, however, they seek the shade and
moisture of their roots. It is at all times somewhat difficult to
detect this species, owing to its dark colour resembling the soil
and to its habit of remaining perfectly still when uncovered,
unlike the other species which immediately scurry away to
shelter. They seem to favour sweeter soil than does T. pusillus,
and their diet consists of the living roots of mosses and grasses
rather than decaying vegetation. They tend to live in small
areas in large numbers, and isolated specimens are rare. Found
almost all the year round. Sexes are easily distinguishable by
their colouration, the females being pale yellow or occasionally
pink, with brown or reddish markings, whilst the males are light
brown with darker brown markings. The males are slightly
larger than the females. R. S. Bagnall (1913) distinguished three
colour varieties of P. muscorum :—
var. obscura. Very dark, almost uniform colouration,
var. flava. Bright yellow or light lemon yellow, dark
markings,
var. rosea. Deep rose-pink colour.
The var. obscura I have not seen, unless, as I suspect, they are
the males of the so-called var. flava. Bagnall adds that the
northern examples are darker than specimens from the south of
England.
Armadillidium vulgare. Common on chalk lands, on heaths
and on slopes covered with low scrub, such as are found in railway
cuttings, road sides, etc. They also occur in the neighbourhood
of houses and builders' yards, where there is loose cement or lime
—in fact, in most places where chalk is present. I have found
them in woodland, but never in large numbers. On light soils
they are difficult to detect, owing to their very close resemblance,
when rolled up, to chalk pebbles. Unlike the other species they
favour open, well-drained areas, and can survive even on dry
stones warmed by the heat of the sun. The males are distinctly
darker and more uniformly coloured than the females, and lack
the light yellow markings found along the dorsal surface of the
latter. The males are larger in size, thus rendering the sexes
easily distinguishable. Found from mid-April to November,
and occasionally during mild weather in winter.