IULUS, in zoology; a genus of insects of the or-
der aptera. The feet are very numerous, being
on each side twice as many as the segments of the
body: the antennæ are moniliform; there are two
articulated palpi; and the body is of a femicylindrical
form. 1. The terrestris is a small species, having on
each side 100 very short closely set feet. The body is
cylindrically round, consisting of fifty segments, each
of which gives rise to two pair of feet; by which
means the feet stand two and two by the side of each
other, so that between every two there is a little more
space. Its colour is blackish, and the animal is very
smooth. It is met with under stones, and in the
earth. 2. The fabulosus is of an ashen-colour, smooth,
and sometimes has two longitudinal bands of a dun-
colour upon its back. The body is composed of
about sixty segments, which appear double; one part
of the segment being quite smooth, the other charged
with longitudinal striæ very close-set together, which
causes the cylindric body of the insect to appear inter-
sected alternately with smooth and striated segments.
Each segment gives rise to two pair of feet, which
makes 240, or 120 feet on each side. These feet are
slender, short, and white. The antennæ are very short,
and consist of five rings. The insect, when touched,
rolls itself up into a spiral; so that its feet are inwards,
but yet turned towards the ground. It is found to-
gether with the preceding one, to which it bears a re-
semblance, though it is much larger. There are other
species.