150 



lake on Cromaglaam Mountain near Killarney and not 

 found elsewhere. 



ANcrLus. 



The shells of this family (two species only of which 

 occur in the fresh water of Great Britain) are patella- 

 shaped, fragile, aperture lengthened-oblong or oblong, 

 apex recurved. Margin entire. 



The animal bas a wide head with a pair of tentacles 

 of a triangular form. 



Ancylus fluviatilis [The Common River Limpet], 



Miiller, 



Figure 111. 



111. 



This is the Patella lacustris of Linnaeus, Donovon 

 Turton, &c., and the Patella fluviatilis of Montagu and 

 Da Costa. 



Described by Lister in the year 1678. 



Somewhat conical, being nearly as high as broad. 

 Having almost imperceptable strioe; apex far back, and 

 bended over like a scrole. Margin acute ; aperture 

 roundish-oval ; colour, pale-horn. The epidermis fre 

 quently encrusted. 



Usual length three lines and breadth two lines and a 

 half. The largest specimens taken near Nottingham 

 are four lines long by three lines broad. 



