W. A. Harding 
173 
variable pattern based generally upon three pairs of reddish brown or 
yellowish, more or less distinct, longitudinal stripes often interrupted 
by black ocelli or spots occurring on the last ring of each somite. 
Ventral surface usually yellowish green, more or less spotted with 
black, with a pair of black marginal stripes. 
103 rings. Rings 6 and 7 are fused ventrally to form the posterior 
margin of the anterior sucker. Rings 8 and 9 are also united on the 
ventral side. Somites I, II, III and XXVII uniannulate ; IV, XXV and 
XXVI biannulate, V, VI, VII and XXIV triannulate; the 16 somites 
VIII—XXIII are complete with five rings. 
The male genital orifice lies between rings 31 and 32, that is, 
between the second and third rings of somite XI; the female orifice is 
five rings behind the male, between the second and third rings of 
somite XII. 
The anus opens in ring 102 or between this and the preceding ring. 
Length, in extreme extension, 100—125 mm. ; in extreme contrac¬ 
tion, 30—35 mm. Width, in extreme extension, 8—10 mm.; in extreme 
contraction, 15—18 mm. 
Distribution. Hiruclo medicincilis occurs in sluggish and stagnant 
waters in Europe and the adjacent parts of Asia. In Europe, where it 
was formerly abundant, it is now chiefly confined to the South and 
East. In Germany it is still found in the Island of Borkum, near 
Marksuhl, in Thuringia and perhaps also near Mieselstein, in Allgau 
(Johansson, 1909, p. 78). 
It was at one time a common British species but was becoming less 
frequent as early as 1816. “Formerly,” says Johnson (1816, p. 41), 
“ this species was very abundant in our island ; but from their present 
scarcity, owing to their being more in request among medical men, and 
to the rapid improvements which have of late years taken place in agri¬ 
culture, particularly in the draining and cultivation of waste-lands, we 
are obliged to receive a supply from the Continent.” In 1842, according 
to Brightwell (p. 13), it was found occasionally in the neighbourhood of 
Norwich, but was by no means common, and Johnston (1865, p. 49) 
states that the only British examples he had seen were the two in the 
British Museum Collection which he refers in his Catalogue to the 
variety chlorogastra. 
In Scotland Dalyell (1853, p. 29) notes that medicinal leeches “ of 
late years...had become scarce at the places previously affording them,” 
and Thompson (1856, p. 427) states that, although becoming scarce, they 
