BRITISH ANNELIDS.
63
sible to secure not only the red worm, but the new species as well,
which it most nearly resembles.
The red worm has no swellings on the 15th segment where the
male pores are situated. The girdle covers segments 27 to 32, and
the band (tubercula pubertatis) extends over 28, 29, 30, 31. The
tail often spreads out into a spoon shape (spathulate), a property of
great value when it lies with the head exposed, as it can grasp its
burrow very firmly thereby. The bristles are arranged as in the earth-
worm, while the head is exactly similar in shape. This worm is pro-
bably more common and widely distributed than the last, though it has
generally been supposed that the common earthworm was ubiquitous.
3. The purple worm (L. purpureus) is the smallest of the set. It
usually attains larger dimensions in Essex and the south of England
than it does further north, and I have sometimes found it impossible
to determine to which species a given specimen must be referred till
I had counted the segments preceding the girdle. A good deal yet
remains to be done before we can decide what influences affect the
size, colour, shape and structure of the different species of worm ; and
it is, therefore, of the highest importance that collectors should note
carefully every detail likely to assist in the solution of these questions.
The purple worm is usually two to three inches long. It resembles
the red worm in colour, shape, and general appearance. Some-
times it is of a pretty chestnut colour, which will account for one of
its synonyms (L, castaneus, Hoffmeister). The tail is sometimes
more square or angular than that of L. rubellus, and it frequently
mimics the Square-tail in this respect, as well as by going rapidly
backwards. The girdle covers six segments as usual, viz.: 28 to 33,
and the band extends over 29, 30, 31, 32. The bristles are in four
pairs, and on the under side of segment 10 there is usually a tumid
growth. The male pore is not raised on papillae. In this, as in the
other species, a series of openings may be observed along the back :
and it is sometimes important to observe the number of the segments
between which the first of these dorsal pores is found. The numbers
are given below.
We may now summarise the characters of the genus in order that
it may be possible to distinguish it from Allolobophora.
GENERIC CHARACTERS OF LUMBRICUS.
Prostomium forming with the peristomium a perfect "mortise and
tenon.''