192 MOLLUSCA OF MID-WEST YORKSHIRE. 



P. nautileus (L.). — Common in ponds at Stony Rock, Osmond- 

 thorpe and Black Hills, Leeds ; occurs in Malham Tarn. 



P. nautileus var. crista (L.). — Pond at Osmondthorpe, 

 rather common ; pond near Roundhay, Leeds. 



P. albus Miill. — Waterloo Lake, Roundhay ; stream at Mean- 

 wood, and mill-goit at Adel ; canal at Saltaire ; Carlton 

 pond near Snaith. 



P. spirorbis Miill. — Common in Malham Tarn moss j Star- 

 botton, Linton, Wetherby, and Newton Kyme, Wharfedale ; 

 Sicklinghall ; Castleford ; ponds at Camblesforth and at 

 Carlton near Snaith ; ditch near Balne Moor ; Barlow 

 Common near Selby. 



P. vortex (L.). — Pond at Gisburn; pond at Blackhills, Leeds; 

 Carlton Pond near Snaith ; stream, Allerton Bywater ; 

 pond at Church Fenton ; canal at Burton Hall and ditch 

 near Selby. 



P. carinatus Miill. — Canal at Ripon ; ponds, Askham and 

 Dringhouses near York ; canal at Selby ; common in 

 ditches, Church Fenton ; Castleford ; reservoir at Cross 

 Stamford Street, Leeds ; abundant in a pond at Baildon 

 Green. 



P. carinatus var. disciformis Jeff. — Castleford. 



P. complanatus (L.). — Ponds near Masham ; Naburn Lock, 

 plentiful ; Dringhouses or Askham Bog, common ; Bishop- 

 thorpe near York ; Wetherby and Healaugh ; Leventhorpe 

 pastures and ponds at Black Hills and Roundhay near 

 Leeds ; Carlton near Snaith ; ditch near Balne Moor. 



P. complanatus var. rhombea (Turt.). — Brickpond at 

 Stanks, Seacroft, near Leeds. 



P. corneus (L.). — Common in ponds at Masham and in the 

 canal near Ripon ; Askham Bog, common ; near Church 

 Fenton ; common in ponds at Black Hills and Osmond- 

 thorpe near Leeds ; common in pond on Baildon Green. 



J.C, iv., April, 1884. 



