94 SOPPITT AND CARTER : UPPER AIREDALE MOLLUSCA. 



Var. normandi Dupuy. Canal at Gilstead, 1886. 



Var. cristata Nelson. Very rare. Dredge heap between 



Apperley and Calverley. 

 Var. piscinalis Nils. Canal dredgings near Calverley. 



DREISSENID^. 



Dreissena polymorpha Pall. Extremely abundant in the Leeds 

 and Liverpool Canal between Keighley and Calverley, very 

 variable in form and size, finest at the bottom of the locks. 



GASTEROPODA. 

 • ^ ^ NERITID^. 



Neritina fluviatilis L. Local, and apparently confined to the 

 canal ; Saltaire, Gilstead, Bingley and Keighley. 

 Var. trifasciata Colb. In same localities, and commoner than 

 the type. 



PALUDINID^E. 



Paludina vivipara L. Local and rare. Pond, Bradford Moor, 

 several, 1886-7. Canal, Gilstead, numerous, June 1886, on 

 which date a portion of the canal was let off ; several attempts 

 have been made since to obtain it in the same locality, but 

 without success. Ditch, Steeton (J. Ellison). 



Bythinia tentaculata L. Extremely abundant; the commonest 

 species of mollusc found in the canal ; seldom found in any 

 other habitat. Frizinghall Dam ; pond, Thackley, rather large 

 but much eroded: margin of Malham Tarn, 1887, numerous 

 and fine although dead examples. 

 Var. ventricosa Menke. Several places in the Leeds and 



Liverpool Canal. 

 Var. excavata Jeff. Canal, Apperley. 



Var. major Locard. Canal, Bingley, Apperley, and Calverley. 

 Var. zonata Baudon. Canal, Saltaire, Bingley, Calverley, and 



Apperley, not uncommon ; pond, Thackley. 

 Var. fulva Locard. Canal, Bingley to Apperley, common. 

 Var. cornea Locard. Canal, Bingley to Calverley, but not 



common. 



Var. angulata Roberts. Rare. Canal, Saltaire and Apperley. 

 The following is Mr. Roberts' description of this new variety: — 

 * Each whorl somewhat sharply angulated or shouldered above 

 the periphery, giving the shell a turreted appearance; colour, 

 reddish; length, 9-10 mill.' (Nat, 1887, p. 19). 



MoNST. decollatum Jeff. Frizinghall Dam, the most abundant 

 form; canal, Manningham. 



Naturalist, 



