1898.] SCHARFF. — The Irish Freshwater Leeches. 191 



or white underneath and greenish grey above with a narrow median 

 light stripe. This leech, which swims well, is parasitic on freshwater 

 fishes, principally the Perch. 



n 



I have already mentioned that P.percce of Templeton must be looked 

 upon as a variety of this species. According to Thompson, it has only 

 been obtained in the North of Ireland. The only southern locality known 

 is the River Dodder (county Dublin) where the Dublin Museum speci- 

 men was obtained by Mr. William Boshell parasitic on a Gudgeon {Gobio 



iluviatilis). 



FAMII.Y Gl^OSSIPHONIID^. 



Glossiphonia stagrnalls (L-) 



Glossipora bioculata, Thomps. 



The members of the family Glossiphoniidce are distinguished from the 

 Ichthyobdellidce by having the anterior sucker fused with the body. They 

 all live in fresh water, certain species occurring in every pond or brook. 

 From the fact that some of them live parasitically on water-snails, they 

 have been spoken of as snail-leeches, and as such they form the subject 

 of a most interesting article by the Rev. W. Houghton (4). Owing to the 

 transparency of their bodies, many of the species are particularly suitable 

 for the study of the structure and internal anatomy of leeches. 



n, 



Mr. Houghton gives a figure of G. stagnalis (4. fig. 7-9), but we find a 

 better one in Moquin-Tandon's work (6. pi. xiii. fig. 16-26). The two eyes 

 are plainly visible with a lens. They distinguish the species at once from 

 all other Irish forms. This species is very quick in its movements, either 

 rapidly progressing like a looper caterpillar or swinging to and fro attach- 

 ed by the posterior sucker. It is flesh-coloured or light grey with 

 brown or reddish dots, and grows to the length of about 10 mm., which 

 is less than half an inch. 



Thompson has recorded the species from Lough Neagh (8). We 

 possess specimens in the Dublin Museum from Co- Antrim (H. L. 

 Jameson); from Co. Fermanagh (C Langham) ; and from Co. Dublin 

 (R. F. Scharff). 



Glossiphonia heteroclita (L) 



Glossipora hyalina, Thomps. 



The six eyes are arranged in such a manner that without a strong lens 

 only three are visible. The Rev. Houghton describes the species as 



being the most transparent of the family (4). The general colour is a 



