134 



Planorbis spirorbis [The Rolled Coil Shell}. 

 Miiller. 



Figures 97 and 98. 



Described by Dr. Pulteney, about 1790, in his Cata- 

 logue of Dorsetshire Shells. 



Bears a strong resemblance to Planorbis vortex, so 

 much so that much confusion occurs when the distinc- 

 tive differences are not known. The two discs are con- 

 cave, semi-transparent, but often coated with a black 

 incrustation. Body whorl not much larger than the 

 preceding one. There are six convolutions. Not so 

 thin as Plauorbis vortex. The form of the aperture is 

 so marked a feature that it can at once be recognised 

 from Planorbis vortex, it is almost round. 



Usual diameter a quarter of an inch. Specimens 

 have been obtained here four lines in diameter. 



I^iome writers on British conchology describe it as a 

 widely spread abundant species, even more so than 

 Planorbis vortex. In this county it seems anything but 

 abundant. 



Inhabits ponds, canals, ditches and marshes. 



Our localities are — a dilch below the Railway Sta- 

 tion at Beeston, a wet meadow at Stanton-onthe- 

 Wolds, and the bogs at Bulwell. 



More distantly at Bristol (Miller), Wiltshire (Mon- 

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

 (^Bridgman), River Eylhrope, at Stone, Buckingham- 

 shire (Reade), Kendal^ one locality (Gough), Newcastle 

 (Alder). In Ireland, widely spre.id (Thompson), Scot- 



