VALVATA. 27 



Var. III. ovata. Four whorls, shorter, more tumid. 

 Var. IV. elongata. Sometimes eight whorls, 

 longer. 



- V. pellucida. White, transparent. 



Family III. VALVATIDJE. 

 Genus. VALVATA. 



1. V. PISCINALIS (inhabiting fish ponds). 



Somewhat globular, rather solid, nearly opaque, brownish 

 yellow ; wlwrls six, very convex ; spire blunt ; suture very 

 deep ; mouth circular ; umbilicus deep. 



Found in lakes, canals, and rivers throughout the 

 British Isles. 



Var. I. depressa. Flatter, umbilicus larger. 

 Var. II. sulcylindrica. Spire more raised. 

 Var. III. acuminata. More raised and pointed. 



2. V. CKISTATA (crested, i.e. with branchial plume). 



In shape a circular coil, glossy, light horn-colour, 

 rather solid ; whorls five ; mouth circular ; umbilicus very 

 large and open. 



This species frequents canals, lakes, ponds, &c. 

 It may generally be found at the roots of weeds in 

 muddy ponds. 



