BRITISH ANNELIDS.
61
debted, moreover, to an unknown friend, through Mr. George Day,
F.R.M.S., for some specimens taken at Epping Forest.
The species are as follows :—
1. Lumbricus terrestris, Linn. Hab., Epping Forest; East Ham ;
Canning Town : Plaistow Marshes.
2. Lumbricus rubellus, Hoffm. Same localities.
3. Lumbricus purpureus, Eisen. Same localities.
1. Let us first examine the common earthworm. It is generally
thought that every one knows this species when he sees it; but it is
a curious fact that almost up till the present day this worm has been
confused with half a dozen others, and scarcely any one has been
able to give us an absolutely reliable diagnosis. Now, thanks to the
labours of Rosa, Eisen, and others, we have arrived at a clear under-
standing respecting the true specific and generic characters of Euro-
pean worms, and can identify any species that may be alighted on
with certainty.
The earthworm (L. terrestris) differs from the other two, both in
size, and in the position of the girdle. Unlike them, it also has pro-
tuberances on the sides of the fifteenth segment. In other respects,
the three species can scarcely be said to have any distinguishing
feature either externally or internally. These, however, are ample,
as we shall presently see.
In point of size L. terrestris is one of our largest worms. It is con-
stantly associated with different species of Allolobophora, which it
closely resembles when only casually examined, though the differ-
ences are very marked to a trained investigator. It is usually from
four to six inches in length, with a thick round head (applying the
term vaguely to the front portion of the body), a well-marked girdle
when adult, and a flattened tail. In colour it is a warm or dark
brown, with a beautiful play of iridescent colour along the anterior
half of the body. The girdle and undersurface are a little lighter
than the tail, but there is a fair margin in all species of worms with
reference to the shade of colour they may assume. If the head is
examined carefully with a pocket lens it will be found that the small
rounded lip or prostomium in front is fitted into the first ring of the
body by a perfect "mortise and tenon" arrangement. This is one
of the distinguishing features of the genus, and applies to each of the
species.