JOURNAL OF CONCHOLOGY. 275 



THE MOLLUSCA OF BIRSTWITH, YORKSHIRE. 

 By F. T. walker. 



AaiTATIC. 

 Sphaerium corneum L. A pond at Hampsthwaite is the only 



locality I know of. 

 S. lacustre Mull. Brick-ponds near Burnt Yates; also at Ripley 



and Hampsthwaite. It seems to be much commoner 



than corneum. 

 Pisidium fontinale Drap. Brick-ponds at Burnt Yates and 



Hartwith Dam. 

 P. fontinale var. cinerea Alder. Found abundantly on Rennie 



Crags, near Birstwith. 

 P. pusillum Gmelin. Ditches near Ripley. 

 P. nitidum Jenyns. Pond at Hampsthwaite. 

 Unio tumidus Phil. Stream at Ripley, and a pond near the 



stream. 

 Anodonta cygnea var. rostrata Rossm. Stream at Ripley. 

 A. anatina L. Stream at Ripley. 

 Planorbis albus Mull. Hartwith Dam. 

 Limnaea peregra Mull. Very common. 

 L. palustris Mull. Ditches at Ripley. 

 L. truncatula Mull. Hartwith Dam and Ripley. 

 Ancylus fluviatilis Mull. Plentiful on stones in the Nidd. 



TEERESTRIAL. 

 Arion ater L. Very common. 

 A. hortensis Fer. Very common in gardens, &c. 

 Limax flavus L. Rennie Crags. 

 L. agrestis L. Very common. 

 L. maxinnus L. Very common. 

 Vitrina pellucida Mull. Very common in damp woods, &c. 



