150 
The British Leeches 
Houghton, 1865 (Englishexamples) “nearlyan inch in length ”; Johnston, 
1865 (English examples), 18 lines long and 5 lines wide; Dalyell, 1853 
(Scotch examples), at rest, 5—6 lines long and about 2^ inches long when 
extended ; Blanchard, 1893 h, 24 mm. long and 10 mm. wide (in alcohol); 
Livanow, 1902, 15 mm. long and 3 mm. wide; Johansson, 1909, 10—30 
mm. long and 2—6 mm. wide. 
Distribution, Habits. P. tessellata is an extraordinarily active and 
restless animal, starting into movement upon the slightest disturbance. 
It is very prolific, carrying, according to Houghton, as many as 200 young, 
and more than 300, if we are to believe O. F. Muller. 
Its range appears to be confined to Europe and, perhaps, adjacent 
parts of Asia; the single example recorded by Blanchard (1892 g) from 
Chile (on the body of a rat, Myopotamus coypu ) may probably have been 
introduced, as that writer believes, by artificial means. It is nowhere 
abundant and is of rare occurrence in the British Islands. Fleming 
(1822) first included it among the British species. Brightwell (1842) 
described a single example from the River Wensum, at Costessy, near 
Norwich, and Houghton (1865, p. 88), who considered it to be less rare 
than generally supposed, obtained it in weedy pools and found it “not 
uncommon in the Shropshire Union Canal.” Johnston (1865) catalogues 
a specimen from Holy Island Lough, and recently, I have taken from a 
stagnant, weedy pond at Histon, near Cambridge, a single individual of 
which coloured figures accompany this description. 
In Scotland it is “ rarely disseminated ” according to Dalyell (1853), 
who records it from Coldingham Loch, Berwickshire, the counties of 
Edinburgh and Linlithgow and the Island of Bute. 
Scharff (1898) states that it is rare in Ireland and in addition to 
Tuam and Lough Neagh, where it was found by Thompson (1844), re¬ 
cords it from Clonbrock, from Santry, Co. Dublin, and from Glenomeragh, 
Co. Clare. 
Hosts. There appears to be no doubt that P. tessellata is parasitic 
upon various species of waterfowl aud particularly upon the fresh-water 
ducks ( Anatinae) although, in the instances of parasitism cited below, 
we cannot state with certainty in every case whether the descriptions 
apply to this leech or to some closely allied species such as P. meyeri. 
Weltner (1887, p. 85) states that at a farm at Wanzenau, near Strasbourg, 
the ducks and geese were nearly all destroyed by a leech, described as 
Glossiphonia ( Protoclepsis ) tessellata, which attached itself to the walls 
of the oesophagus. 
