61
SOME NOTES ON THE NATURAL HISTORY
OF BRITISH FRESH-WATER LEECHES :
WITH RECORDS OF THEIR OCCURRENCE IN
ESSEX.
With Plates VI and VII.
By HENRY WHITEHEAD, B.Sc.
[Read 28th October 1911.]
IN 1911 a very important paper, entitled "A Revision
of the British Leeches," by Mr. W. A. Harding, was pub-
lished in Parasitology. Previous to the appearance of this paper,
the most recent work dealing with British leeches was John-
ston's Catalogue of the British Non-parasitical Worms in the
Collection of the British Museum, published in 1865.1
Mr. Harding's paper gives full descriptions of all the known
British species with lists of synonyms. It contains an extensive
bibliography and is well illustrated by coloured plates and
figures. With such an admirable work in existence, some
explanation seems necessary for the appearance of this paper.
Few members of the Club have an opportunity of consulting
the work mentioned,2 and therefore the writer proposes to give
a brief description of each species, emphasizing only those
features by which specimens may be recognized. A number
of observations on the life-histories and habits of these animals
are scattered through the scientific periodicals of this and other
countries, but these observations do not appear to have been
brought together. An attempt is being made in this paper to
do so and to add to this material a few notes made by the writer
whilst collecting and studying Leeches during the past two
years.
Folk-lore and early references to Leeches.—Leeches are
referred to in very early writings, but unfortunately the species
were hopelessly confused, and therefore the observations are of
little scientific value.
Probably the earliest reference to Leeches is in Proverbs
xxx., 15. "The horseleach hath two daughters, crying, Give !
Give !" The word translated as horseleech in this passage
has been the subject of much discussion. The original Hebrew
word was Aluka (Halucah or Gnaluka) and this was translated by
1 An account of the Irish fresh-water leeches by Dr. R. F.Scharff is given in the Irish
Naturalist, vol. vii., (1898) pp. 188-194.
2 A copy has been kindly presented to the Library of the Club by Mr. Harding—Ed