BYTHINIA. 141 
Vars. I. and II., form the ends of a series of which the - 
intermediate forms are met with in the canal at Pontypool. 
Var. I. efascidta (Pickering). Without bands. 
Var. Il. dévo-purpitrea (Lloyd). Dark purple all over. 
Var. III. dlbida (Nelson & Taylor). White. 
Genus.—BYTHINIA Gray. 
Shell ovate, conical, perforated ; azzzaZ with eyes sessile. 
1. B. TENTACULATA (wth tentacles) Linné. Pi. VIII., f. 7. 
Somewhat conical, rather solid, glossy, semi-transparent, horn-colour; 
whorls 6, convex; mouth oval, angulated above; zmbzleces hardly 
perceptible ; opercatdum thick. A. 125 mm. B. 6; mm. 
Found in slow rivers, canals, ponds, etc., distributed 
throughout every part of the British Isles. The finest 
specimens I have seen were taken in the Trent near 
Nottingham. 
Var. I. prodicta (Menke). More slender than type. 
Var. II. ventricisa (Menke). Spire shorter, tumid. 
Var. III. excavdta (Jeff.). More tumid, suture deeper. 
Var. IV. d/bida (Rimmer). White. 
Monst. decol/étum (Jeff.). Upper whorls wanting. 
2. B. LEAcutt (after Dr. Leach) Sheppard. Pi. VIIL, f. 8. 
Conical, thin, moderately glossy, semi-transparent, horn-colour ; 
whorls 5, very convex; mouth almost circular, with slight angulation 
above; zmbilicus small, but distinct; oferceudum as in last species. 
A. 64 mm. B. 5 mm. 
