Quarterly Journal of Conchology. 19 



A LIST OF LAND AND FRESHWATER SHELLS 

 FOUND IN THE NEIGHBOURHOOD OF AOK- 

 WORTH, YORKSHIRE. 



By CHARLES ASHFORD. 

 Ackwortli is eight miles from Wakefield and three from Pontefract. 

 The circle in which the following shells were collected is tlierefore 

 contiguous to the Wakefield district, and as it lies partly upon the 

 magnesian limestone and partly upon sandstone, a number of shells 

 occur in it which appear to be absent from the Wakefield district, as a 

 comparison witli the list published in the first number of this Journal 

 will show. 



SphaBrium corneum Liniie. — Common throughout the district. 

 Sphaerium lacustre MuUer. — Sparingly in a stagnant pond near 

 the Wakefield road. 



Pisidium amnicum Muller. — Common in running streams. 



Pisidium fontinale Drapamand. — Common in ponds. 



Pisidium fontinale var Henslowana. — Common in an artificial 

 stream at Ackworth. This variety has the usual umbonal appendage 

 but slightly developed, and the late Mr. Jenyns considered it inter- 

 mediate between the well-marked variety and the nonnal form. 



Pisidium fontinale var cinerea. — Common in several ponds. 



Pisidium fontinale var pulchella. — Common in Hemsworth reser- 

 voir and other places. This is the variety 5 of Jenyns. 



Pisidium pusillum Gmelin. — Pond near Hasel Green and else- 

 where. 



Pisidium nitidum Jenyns.— R&vq. Large series of shells of this 

 difficult genus were submitted to Messrs. Alder and Jenyns, who 

 kindly determined the species as here recorded. 



Unio tumidus PhiUipson. — Common in the River Went at Went 

 Vale. 



Unio tumidus var radiata. — Not uncommon in the Went. 



Unio pictorum Linne. — River Went, less common than tumidus. 



Anodonta cygnea Linne. — Plentiful in Hemsworth reservoir and 

 the lake at Nostell. 



Dreissena polymorpha Pallas. — Abundant in Winters et reservoir. 



Bythinia tentaculata Linne. — Common throughout. 



Valvata piscinalis Muller. — Common in the niill pond, Ackworth 

 and in Winterset reservoir. 



Valvata cristata Midler. — A few specimens found in the Went, 

 attached to the tenement of a caddis worm. 



Planorhis nitidus Muller. — Once common among duckweed in a 

 roadside pond, but scarce a year or two afterwards. 



Planorbis nautileus Linne. — Extremely abundant in various 

 ponds. 



