107
BRITISH ANNELIDS.
WITH ESPECIAL REFERENCE TO THE EARTHWORMS OF ESSEX
By REV. HILDERIC FRIEND, F.L.S.
(Continued from page 65.)
THE genus of earthworms which now remains to be examined is
represented in England by no fewer than fifteen species, so
far as our present knowledge will allow us to judge. So large a
group is certain to present a considerable variety of forms, and by
a systematic study of each species it is possible to separate the genus
into three or four well marked sections, thus enabling the student
the more readily to identify the various forms. Before we proceed
to this sub-division, however, it will be desirable to obtain a clear
idea of the genus as a whole. As I have already indicated, Eisen
split up the old genus Lumbricus in 1873, and made two new genera.
His nomenclature was of the most intelligible character. Selecting
the old Lumbricus terrestris, L. as his type, with its head perfectly
mortised and tenoned into the first ring, he called all the worms
which had a differently formed lobe Allolobophora or "Different-lobe-
bearers." There was one worm, however, which, while it had a
different lobe from that of the typical Lumbricus, and so was nearly
allied to the new genus Allolobophora, yet had its male pore on segment
13 instead of segment 15. To distinguish this genus from the other,
Eisen turned to its posterior extremity and found it to be sharply
angular. He therefore called it Allurus, or "Different-tail worm";
and hence we have the true Lumbricus as the type, with two genera
differing either in the shape of the head or of the tail.
Thus, while the genus Allolobophora agrees with Allurus in the
shape of the lobe or prostomium, it differs from that genus in the
position of the male pore. Again, while some of the species belong-
ing to the genus Allolobophora closely resemble the true Lumbrici,
they may always (with one exception, which is at present anomalous) be
distinguished by the shape of the prostomium. Having, in my last
paper, given a few of the principal characters of the genus Lumbricus,
I may here supply a similar account of the genus Allolobophora.
GENERIC CHARACTERS OF THE ALLOLOBOPHORAE.
Lip, or prostomium, only partially bisecting the first ring or peris-
tomium.
Setae eight in each segment, either in couples or forming separate rows.