MILNE AND OLDHAM : MOLLUSCA OF BOWDON DISTRICT. 32 I 



Ringway, Dunham, Peelcauseway, Millington, Northen 

 Etchells. 



P. fontanus var. albida. In the summer of 1885 all the 

 specimens taken in one of the ponds at Ashley Mill were 

 white or light grey, in the previous and succeeding years 

 the same pond only produced examples of the typical 

 colour. No reason for the variation could be discovered. 



P. nautileus. Ashley, Ringway, Warburton, Ross Mill, 

 Hale. The specimens from the last locality — a small pond 

 in a copse, full of branches and twigs — usually show a pro- 

 nounced scalariform tendency. 



P. nautileus var. crista. Occurs with the type at Ringway, 

 also at Bow Green and Bowdon Vale. 



P. albus. Found commonly throughout the district. 



P. spirorbis. Not uncommon. Found at Hale Moss, Part- 

 ington, Sale, Northenden, Baguley, Baguley Moor, Daven- 

 port's Green, Baguley Hall, and Ashley. It is frequently 

 associated with Bullmus hypnorinn, while P. vortex prefers 

 the society of Physa fotitinalis. 



P. vortex. The commonest Flanorbts, found equally in 

 ponds, ditches, and streams all through the district. 



P. carinatus. Ashley, Hale, Hale Moss, Peelcauseway, 

 Rostherne, Millington, Knutsford. 



P. umbilicatus. Much scarcer than the last species; plenti- 

 ful in the ditches in Sale meadows, elsewhere only in 

 Hampson's pit and a pond near Baguley Hall. 



P. corneus. Found only in Hampson's Pit, and here perhaps 

 introduced, but thoroughly naturalised. 



P, contortus. Baguley Hall, Knutsford, and Carrington Moss. 

 The latter locality — a backwater of Sinderland Brook, where 

 it was among Ranunculus — has now been destroyed by the 

 Manchester Corporation's improvements. 



Bulimus hypnorum. Hale Moss, Partington, Baguley Moor, 

 Bnguley, and Baguley Hall. In all these localities it is 

 associated with Plafiorhis spirorbis. 



