NATURAL HISTORY OF BRITISH FRESH-WATER LEECHES. 81
Distribution.—Britain:—Generally distributed. Near Clacton
(per Mr. Picton) ; Epping Forest ; Chigwell Row ; R. Stort
(H. W.) ; Finchley, Hampstead, Muswell Hill, Walthamstow,
Tottenham, Totteridge (W. Blair) ; near Norwich (Brightwell,
9) ; Eckington Canal (Evans, 15).
Ireland:—Common (Scharff, 39).
Foreign:—Occurs throughout the greater part of Europe,
and is found in Transcaucasia and Syria (Blanchard, 6).
Hirudo medicinalis, L. (=Sanguisuga officinalis, Sav.). The
Medicinal Leech. Plate VII., Figs. 11-13.
Description.—Body elongate and slightly flattened. The dorsal surface
has a well marked pattern with three pairs of longitudinal yellowish
bands. The lateral pair has an uninterrupted inner band of dark brown,
while each of the median and intermediate pairs has an interrupted band
of dark brown running down the middle. The ground colour of the dorsal
surface is usually a dark olive green, but may be slatey grey or reddish
brown. The ventral surface is dark brown with irregular grayish green
patches. Length 100-150 mm., and width 10-15 mm. Another
specimen when extended measured 250 mm. long and 30 mm. wide, (I
am indebted to Mr. Wm. N. Blair, jun., for two specimens taken in the
New Forest in 1911, from which the above description has been written-
Habits. (See pp. 70-74.)
Distribution.—Britain:—Near Norwich (Brightwell, 9) ;
Christchurch, Hants ; Weymouth (Johnston, 32); Loch Leven ;
L. Fleury near Blairnlone, near Comrie ; L. of Monteith ;
Gartincebar (Dalyell, 12) ; New Forest (W. N. Blair, 1911).
Ireland:—Lough Mask (Scharff, 39).
Foreign:—Germany (I. of Borkum and Thuringia, Johannson,
30) ; Italy (Blanchard, 7).
Herpobdella octoculata (=Nephelis octoculata, L.). Plate
VII., Fig. 9.
Description.—Body elongate, slightly flattened. Colour brown or
reddish brown on dorsal surface, lighter beneath. Colour generally
uniform. Length 20-50 mm., and width 2-5 mm. The clitellum is often
well marked. Genital openings separated by 4 rings (see Plate VII.,
Fig. 9). Somite V is triannulate. Eight eyes, 4 in the first ring and two
pairs in the 5th, as in H. atomaria.
Habits.—Lives in mud in stagnant ponds, on weeds and under
stones in running streams. This is a very common species
and has often been confounded with H. atomaria. It preys
upon the smaller aquatic worms and insect larvae. The cocoons
are elliptical in outline (4-6 mm. long and 2-4 mm. wide), are