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The British Leeches 
Distribution, Hosts, etc. Piscicola geometra is widely distributed 
in Europe and not uncommon in the British Islands. It attacks 
probably most of our species of fresh-water fish and at times is found 
in considerable numbers by breeders of trout, when these fish are 
examined during the spawning season. This little leech attaches itself 
firmly by the posterior sucker to some convenient object, and stretching 
itself out like a rod and swaying its body to and fro lies in wait for its 
prey. With the anterior sucker it strikes at and fixes upon any passing 
fish with remarkable speed and precision and, letting go its hold 
posteriorly, is carried off attached to its victim. It remains upon its 
host for some days, drawing blood chiefly from the fins, and drops off 
when gorged. The process of digestion is comparatively short. The 
dark brown opaque elliptical cocoons are about T5 mm. long and 
attached to some foreign body. 
The rings in this small species cannot be distinguished without the 
aid of a lens. In preserved specimens they frequently become merged 
into irregular groups and a correct count is often an impossibility. If 
not carefully “ fixed ” the pulsating vesicles usually collapse when the 
leech dies and in carelessly preserved material they may be incon¬ 
spicuous or entirely obliterated. 
Genus: Pontobdella, Leach, 1815. 
Synonym : 
Albione, Savigny, 1822. 
Marine leeches, ectoparasitic on skates and rays. Body long and 
cylindrical, without pidsating vesicles or branchiae, covered by papillae 
which usually project as conspicuous spiny or warty protuberances but 
may be partly or entirely retracted. Anterior sucker discoid and 
excentncally attached, posterior sucker centrally attached and cam- 
panulate. Without eyes. Complete somite formed of four rings. 
Apathy (1888 c) has shown that the two species described by Leach 
(1815) viz. Pontobdella verrucata and P. areolata, together with the P. 
laevis of de Blainville (1827) merely represent different stages in the 
appearance of P. muricata due to the partial or entire retraction of the 
warty papillae. 
