132 



In the ^ariety disciformis the centre of the lower disc 

 is nearly convex. 



A local but widely dispersed shell, inhabiting stag- 

 nant water and slow streams. 



Lays six eggs (Chautereaux). 



In this neighbourhood it is procured rather plenti- 

 fully in the Musco-sic dike, and others at Beeston and 

 Lenton, in the Trent above Beeston Ryelands, in the 

 Leen at Lenton, under the Seven Arches in the Not- 

 tingham Meadows, and in a stream at Radford Grove. 



It is procured at Bristol (Miller), in Wiltshire (Mon- 

 tagu), Essex (Sheppard), London (Grey), Norwich 

 (Bridgman), River Waveney, near Shotford Bridge, 

 Northamptonshire (Bloxam), River Eythrope, Stone, 

 Buckinghamshire (Reade), Mill-pond, Ross, Hereford- 

 shire (Winstanley), Kendal (Gough), Darlington, Dur- 

 ham (Graham). Widely spread, but local, in Ireland 

 (Thompson). It is not found in Scotland. 



On the continent, in France (Draparnaud), in Ger- 

 many (Pfeiffer), and in Sweden (Nilson). 

 Mr. Morris has found it fossil near London. 



Planorbis vortex [The Whorl Coil Shell]. Linnceus. 

 Figures 95 and 96. 



This very depressed, many whorled, common shell, 

 was first described by Lister, in 1668. It is shining, 

 fragile, pellucid, and horn-coloured. Upper disc deeply 

 concave, lower disc flat. There are six to seven nar- 



