FITZGERALD: SHELLS OF HARROGATE AND DISTRICT. 19 



In addition to the rivers and becks aforementioned there are 

 two or three lakes and several smaller streams of water which 

 all have an effect upon the distribution of aquatic moUusca. 



The present list comprises seventy-five species and thirty- 

 two varieties. There are yet many species which may be expected 

 to be found, as for instance Neritinafluviatilis, Valvata piscinalis 

 and cfistata, Flanorbis nitidus and nautileus, Helix rtipestris 

 Pupa ruigens and two or more of the Vertigoes, and very probably 

 Achatina acicula, it occurs just outside the boundary of this 

 district, namely at Boston Spa, from whence Mr. John Emmet, 

 F.L.S., has kindly sent me a few. 



To Mr. Wm. Nelson, Curator, and Mr. J. W. Taylor, F.L.S. 



Ex-President of the Conchological Society, and to Mr. George 



Roberts, of Lofthouse, my thanks are due for having named the 



shells submitted to them. To Mr. F. T. Walker, of Birstwith 



I am under a very great obligation for having placed his notes 



on the Mollusca of Birstwith and District at my disposal. In each 



case where he has met with any species within this district I 



have appended his initials, and in every other instance, unless 



otherwise stated, I have collected the specimens myself 



Sphaerium corneum (L.). — Fairly common and generally 



distributed in the mud of ponds and ditches. Fullwith 



Stream ; Plumpton Lake ; Ripley Park Lake ; River Nidd 



near Ripley ; Stagnant water, Sewage Farm ; Stone Rings 



Quarry; Staveley Pond, and Knaresborough. It occurs in 



a sub-fossil state along the banks of the river Tutt at 



Staveley. 



S. corneum van nucleus (Stud.). — I obtained specimens 



of this variety at Plumpton Lake, and at Ripley I obtained 



some which very closely approach the var. flavescens 



(Macgill). 



S. lacustre (Miill.). — Local but fairly abundant where it occurs. 



Ripley, Burnt Gates (Brickponds) (F.T.W.). 

 Pisidium annnicunn (Miill.). — Sparsely distributed and by no 

 means common. Fish Pond Wood, Ripley Park ; Rilston 



