Snail-Leeches. 89 



when it assumes a linear form. Back, when arched, showing 

 the rings distinctly, marked longitudinally with fine regular 

 rows of light yellow dots, equidistant, and thinly sprinkled 

 with smaller dots of the same colour, the centre row alone 

 extending nearly the whole length of the animal. Margins 

 light coloured and transparent, having at intervals two narrow 

 dull- coloured parallel lines, which are at right angles to the 

 axis of the body. Ground-colour of body, claret. Oral sucker 

 constricted at the base, sub -triangular or lozenge-shaped, 

 forming a well-defined head, its extremitv being 1 almost trans- 

 parent. Head with a light claret-coloured patch on either 

 side, giving it, if examined without the aid of a lens, a trun- 

 cate appearance. Eyes, four, arranged in two longitudinal 

 series, converging anteriorly ; the posterior pair much the 

 largest. Posterior sucker very large, round, with about twelve 

 distinct radii. Stomachal cseca seven pairs, with three smaller 

 ones in front ; the former bifurcate, and nearly at right angles 

 to the axis of the body ; the seventh pair immediately bending 

 downwards and extending to the base of the posterior sucker. 

 Colour of the casca, a deep green. Length, about six lines." 



This species bears in form some resemblance to G. tessellata, 

 but it is smaller and not gelatinous. It deposits its ova in 

 June and July, on submerged bodies, and sits upon them. 

 The ova are generally yellow, and the whole abdominal surface 

 of this species at the breeding season is of the same colour. 

 The young attach themselves to the mother, and are carried 

 about by her, as in the rest of the family. G. marginata is 

 rare ; on one or two occasions I have found it in the Shrop- 

 shire Union Canal. It is very interesting to note the marks 

 that appear to connect different species of the leech family one 

 with another. I have already observed that G. tessellata ap- 

 proaches in some particulars to the character of a true Hirudo, 

 or red-blooded leech; in G. marginata we meet with some 

 curious resemblances to an annelid of the same family, but of 

 another genus, namely, Piscicola. Like Piscicola, G. marginata 

 is often seen extended in repose, being attached by its posterior 

 sucker, and holding out its body at right angles with the point 

 of attachment. Piscicola is often found parasitic upon fish. I 

 have found hundreds of specimens on the dead body of a 

 pike ; and it is well known to all fishermen that live fish, such 

 as trout, carp, etc., are often troubled by these worms. Par- 

 tially parasitic also in its nature is G. marginata ; if placed in 

 the same vessel with a fish, this Glossiphon will immediately 

 attach itself thereto, and remain there for days together. I 

 have little doubt that it feeds upon the mucus secretion and 

 blood of the fish. I have never seen any of the Glossiphons 

 swimming, but I should not be surprised to find G. marginata 



