HIRUDINID^. 47 



depth of colouring, and is either prettily and thickly spotted, or spa- 

 ringly spotted, or unspotted. Anterior pair of eyes approximate, the 

 posterior widest asunder and apart. In some individuals the ventral 

 surface is scarcely different in colour from the dorsal, and in these 

 a yellovr line runs along the edges. 



(a) Islington, J. F. Stephens. 



(b) Lough in Holy-Island, Dr. Johnston. 



(c) The Whiteadder, Berv^rickshire, Dr. Johnston. 



Fam. IV. HIRUDINID^. 



Obs. This family is suctorial. Cutting into the skin they suck 

 the blood of vertebrate animals, and only fall away when gorged. 

 The alimentary canal is deeply incised and lobed, with the hinder 

 pair of lobes elongated in an intestinal manner. In these the blood 

 will often remain for days and weeks undigested. They endure long 

 abstinence without any apparent loss of bulk. They are lacustrine, 

 but wiUingly remain out of the water, where they seem to spend the 

 greater portion of their summer life. They become hidden in winter. 

 The ova are involved in a free sponge-like capsule. 



7. H-ffiMOPSIS. 



Hsemopsis, Savig. Syst. Annelid. 107 & 115. Moq.-Tandon, Monogr. 



317. Diesing, Syst. Helm. i. 462. 

 Hippobdella, Blainville in Did. des Sc. nat. xlvii. 251, Ivii. 560. 



Char. Body elongate, widening backwards, depressed, of numerous 

 distinct segments, with the sexual orifices between the 24th and 

 25th, and the 29th and 30th : acephalous : mouth large, with the 

 upper lip protruded and almost lanceolate : jaws 3, small, equal, 

 oval, not compressed, with a few blunt denticles: eyes 10, on a 

 curved line, six approximate on the first segment, two on the second, 

 and two on the third : vent small and round : anal sucker large, 

 obliquely terminal. Ova in a spongy cocoon. Lacustrine. 



1 . H. sanguisuga, greenish-black on the dorsal, and a yellowish- 

 green on the ventral surface, marked with irregular spots : eyes 

 indistinct. Length 4" ; breadth 5'". 



Hirudo depressa fusca margine laterali flavo, Linn. Faun. Suec. 364. 



Sanguisuga, Petiv. Gazoph. 7- tab. 130. f. 7* 



Hirudo sanguisuga, Linn. Syst. x. 649, xii. 1079 ; Faun. Suec. 2nd edit. 



505. 

 Hirudo sanguisorba, Lam. Anim. s. Vert. v. 291; 2de edit. v. 521. 



Payraudeau, Annelid. 8f Mollusq. de Corse, 17- 

 Hsemopis sanguisorba, Savig. Annel. 115. Dies. Syst. Helm. i. 462. 

 La Sangsue des ehevaux, Cuv. Rbg. Anim. Illust. Annel. 49i 



