170
BRITISH ANNELIDS.
In some cases it is slimy, but clear; sometimes it has a peculiar
smell, and frequently it is turbid. In one instance the mucus is so
thick and yellow that the medium has to be frequently changed if the
worms are to be well preserved. They are tolerably uniform in size,
the average length being about three inches. The setae are in four
couples, and the members of each couple are nearly close together.
The internal structure is interesting, and in the case of one new
species (A. cambrica, Friend, not, however, found in Essex as yet),
it is only by the study of the internal anatomy that we can be abso-
lutely certain which species is under examination. I shall, however,
adhere as much as possible to my rule to make the identification of
species possible by the enumeration of external characters alone.
The foregoing account may be compared with the brief diagnosis on
page 109.
SPECIFIC CHARACTERS.
1. Allolobophora chlorotica, Savigny. The best known
member of the whole group is the Green Worm. It is one of our
most ubiquitous species, and may be readily recognised by its unique
appearance and habit. It is found in gardens and fields, but most
frequently under stones in pastures, or by the side of watering places
frequented by cattle. Here, an inch or two under the soil, or
covered by the stones and other things, it will be found sluggishly
coiled up in a ring, and looking very like a dirty, repulsive caterpillar.
Unlike the bulk of his brethren, he ignores the truth that
"He who fights and runs away
May live to fight another day."
He neither fights nor runs. Perhaps he feels secure in his ugliness,
or knows that, like the cuttle-fish or skunk, he can play a dirty trick
if need be, and cover his foe with foetid mucus.
The worm, when extended, is seldom more than three inches
long, and the girdle appears to be in the centre of the body. This
is owing to the greater diameter of the front segments, which, though
only thirty in number, extend over as great a space as sixty behind
the girdle. Such variety exists in the colour, shape, size, and habit
of the worm that it will be necessary, when the details have been
more fully worked out, to create some new forms and varieties ; but
for the present we will put the whole of the forms under the aggregate
title. The colour ranges from sea-green, through a dirty green, to a
dull yellow or clay colour. Sometimes it is almost flesh-coloured,