W. A. Harding 
145 
Distribution, Hosts, etc. Pontobdella muricata is parasitic on 
Raid batis and other species of skate and has been recorded also from 
Torpedo marmorata. It is found in the Mediterranean, and on the 
western and northern coasts of Europe, and is of fairly frequent 
occurrence in British waters, where it is known to fishermen as the 
“skate leech ” or “skate sucker.” The egg capsules are opaque, tough, 
leathery, barrel-shaped structures about 5 mm. long and 4 mm. in 
width, attached by a pedicle to foreign bodies. One leech will produce 
a considerable number of these capsules, one after another, at short in¬ 
tervals ; the interior of some empty bivalve shell appears to be a favourite 
place for their deposition and they are found in groups containing from 
three or four to fifty or more ; fifty-four is the largest number as yet 
observed in a group (Dalyell). The process of digestion in this species, 
as in Hirudo medicinalis, is exceptionally slow, and when fully gorged 
it can live for many months without taking food. It has been stated 
that P. muricata is unable to swim ; when not too fully distended with 
blood it can and does swim, the body being somewhat flattened for the 
purpose, after the manner of other leeches. It is usually however a 
very sluggish animal, remaining for long periods attached to some 
convenient object by its powerful posterior sucker, the body tightly 
curled upon itself or more or less extended and unrolled. 
Several attempts, all of them unsatisfactory, have been made to 
account for the existence of the warts which form such a characteristic 
feature of this species. In this connection we may note the striking 
resemblance both in colour and in form between this leech and the 
thorny body of its host. 
Family II. GLOSSOSIPHONIDAE, 
Synonym: 
Clepsinidae. 
Fresh-water Rhynchobdellae with ovate, flattened , never cylindrical 
body. Differentiation of the head region into a permanent anterior 
sucker distinct from the body may occur, but never to the same extent 
as in the Ichthyobdellidae. Crop and stomach with conspicuous, paired 
lateral caeca; the stomach always with four pairs. The eggs are 
usually fixed, and the young attach themselves to the ventral surface of 
the parent. Certain species deposit their eggs upon foreign bodies and 
brood over them. 
