1898.] ScHARFF. — The Irish Freshwater Leeches. 189 



they are absent. In 1878, Mr. Templeton published a paper 

 on Aulastovia hehw (7), and I wrote a short note on Irish 

 leeches in the Irish Naturalist (vol. iv., 1895), but nothing 

 else has appeared in print on this group since Thompson' 

 " Natural History of Ireland" (vol. iv.) was issued in 1856. 



Ten species of freshwater leeches were recorded by the latter 

 as Irish, viz. : — 



Erpobdella tessulata. Glossiphoiiia eachana. 



E. vulgaris. Piscicola geonietra. 



Glossipora tuberculata. P. perccs. 



G. hyali7ia. ^ Hae^nopis vorax. 

 G. bioculata. Hirudo viedicijialis. 



with the addition of Templeton's A. heluo, this brings the 

 number up to eleven. 



Owing to the fact that some authors have described new 

 species of leeches merely from differences in colour, and that 

 these are. now recognised as colour-variations of species 

 which had been known previously, a good many of these 

 will have to be withdrawn. Mr. Templeton has founded a 

 few species on characters which are now regarded as in- 

 sufficient to distinguish them. Thus Dr. Apathy remarks 

 (i., p. 779), that Templeton's Piscicola perccB is cX^dLxly Piscicola 

 piscitivi {^geometra, L.). Moreover, Dr. Blanchard tells me 

 that he has examined Templeton's tj^pe of Aulastoma heluo 

 in the British Museum, and is convinced of its being identical 

 with the common continental horse-leech {Hcsmopis sangui- 

 suga). He also feels certain that Thompson's Glo^siphoyiia 

 eachana is nothing but the Gl. tessellata (Miill,). The eleven 

 Irish species are thus reduced to eight. The nomenclature 

 of most of these has to be somewhat altered, so as to bring 

 them into agreement with our modern requirements of 

 priority. 



In the determination of the freshwater leeches the position 

 and number of the eyes are of considerable importance, and 

 to facilitate determination a diagramatic figure of the head is 

 given. These are, like those of many other invertebrates, of a 

 very rudimentary nature. Leeches cannot probably do more 

 than distinguish light from darkness by means of them. 



