1898.] ScHARFF. — The t7'ish Freshwater Leeches. 193 



CNATHOBDELLTE. 



Famii^y GnATHOBDKIvLID^. 



The members of the family Gnathobdellhiae have a gullet provided with 

 three toothed jaws. 



Hlrudo tnedlcinalls, L. 



The common Medicinal Leech lives in ditches, ponds, and slow- 

 flowing rivers. It grows to a length of 4 inches. There are very- 

 numerous colour variations, but as a rule the back is olive-coloured 

 and marked with 6 brown lines. I have never seen an Irish Medi- 

 cinal Leech, and my efforts to get a specimen have hitherto proved 



fruitless, but O'Flaherty in his **West or H-Jar Connaught " refers to 

 them (they are called dallog in Irish) as being common on the south side 

 of Lough Mask in 1684, and the late Sir W. Wilde stated that in 1849 it 

 w^as still found in pools and wells in the vicinity of the same lake. He 

 also mentioned that in summer the leech-gatherers sat with their legs in 

 the water on which the creatures fasten and are thus obtained. 



Hdemopis sangrulsug^a (L)- 



Hitmopsis vorax, Thomps. (= H.hehio, Tempi.) 



The Horse-leech {^H. sanguisuqa) agrees with the Medicinal Leech in 

 possessing ten eyes, and some varieties of the latter resemble it so much 

 that it sometimes becomes difficult from external characters to decide 

 which species a specimen belongs to. In such a case we must observe 

 the animal when at rest. Whilst the true leech is able to contract itself 

 into an oval, olive- shaped form, the horse-leech does not possess that power. 

 As a rule, however, the brown longitudinal lines on the back distinguish 

 the true leech from the Horse-leech, which is generally uniformly 

 greenish or spotted with black. 



The teeth of this leech are unable to pierce the human skin or that of 

 the higher vertebrates generally, though it occasionally penetrates into 

 the nostrils of horses and cattle. Its usual food consists of worms, 

 larvae of insects, and tadpoles, whose juices it sucks up. 



The Horse-leech is common throughout Ireland. 



