46 NEPHELIDJB. 



inch and a half behind the mouth the female aperture is very distinct, 

 but the male one is invisible. The vent is very large ; and the sucker 

 is shallow with a thin rim. 



(a) Regent's Park. Zoological Society. 



6. AULOSTOMA. 



Aulostoma, Moq.-Tandon, Monogr. 312. 



Pseudobdella, Blainville in Diet, des Sc. nat. xlvii. 246 & Ivii. 559. 



Aulostomum, Diesing, Syst. Helm. i. 461. 



Char. Body elongate, narrowed forwards, depressed, soft, acepha- 

 lous, composed of many equal segments, the sexual orifices between 

 the 24th and 25th, and the 29th and 30th : penis cylindrical : mouth 

 oblique, suctorial, with the upper lip almost lanceolate and protruded 

 in a semi-ellipse ; the gullet with twelve long plaits. Eyes 10, in a 

 curved line : anal sucker rather small, centrally attached with a ven- 

 tral aspect ; vent large and semilunate. Ova in a free fibrous cocoon, 

 multiparous. Lacustrine, often resident on the humid margin. 

 Carnivorous. 



1 . A. gfulo. 



Hirudo maxime apud nos vulgaris. The Horse-Leech or Blood-Sueker, 



Raii Hist. Insect. 3. 

 Horsleech, Mouf. Theat. Insect. 323, fig. 

 Hirudines venenatae, Horse-Leeches, Sibb. Scot. Illustr. ii. 3. 34. Hill, 



Hist. Anim. iii. 16. Quekett in Zoologist, i. 17 & 88. 

 Hirudo sanguisuga, Merret, Pinax, 207. Mull. Verm. i. ii. 38 ; Zool. 



Dan, Prod. 220. Penn. Brit. Zool. iv. 70. Turt. Gmel. iv. 68 ; 



Brit. Favn. 129. Stew. Elem. ii. 356. Watson, Diss. Inaug. 



de Hirud. 13. Johnson on the Medic. Leech, 30. Templeton in 



Loud. Mag. Nat. Hist. ix. 235. Dalyell, Pow. Great, ii. 22. pi. 3. 



f. 1-10. 

 Hirudo vorax, Johnson on the Med. Leech, 62. 

 Haemopsis sanguisuga. Hardy in Tynes. Nat. Club Trans, i. 96. 

 Hsemopis nigra, Savig. Syst. Annel. 116. 

 La Sangsue noire, Blainville in Diet, des Sc. nat. xlvii. 249. 

 Pseudobdella nigra, Blainv. lib. cit. Ivii. 660, Atlas Hirudin, f. 1. 



Egidy, Bluteg. 111. f. 66. 

 Haemopsis sanguisorba, Brightwell in Ann. 8^ Mag. Nat. Hist. ix. 12. 

 Aulostoma gulo, Moq.-Tandon, Monogr. 313. pi. 5. f. 1-6. 

 Aulostoma nigrescens, Cuv. Regn. Anim. iii. 215. Williams, Rep. 



Brit. Assoc. 1851, 238. 

 Aulostomum gulo. Dies. Syst. Helm. i. 461. 



(3. nigra, " Hirudo elongata, per totum corpus nigerrima," John- 

 son, Med. Leech, 32. 

 Hab. Stagnant waters : common. 



Obs. In extension about 4" in length ; when contracted somewhat 

 granulous. Dorsal surface of a dark olive-green colour or almost 

 black, ventral surface yellowish-green ; but the leech is variable in 



