11 



the shell implies, roprcsent caps. It is a very shining 

 shell. The specimens procured near Beeston are three- 

 eighths of an inch broad, one-third of an inch long, and 

 one-fifth of an inch ventricosjB. Forbes gives the size 

 as occasionally seven lines by five and a half lines.- 



It inhabits stagnant water, and, although not a com- 

 mon shell, it is locally abundant. There are three 

 localities in this neighbourhood where it is found, and 

 in each of them it does not spread over more than a 

 score yards. These localities are, a brook which runs 

 below the village of Beeston, another at Highfield 

 House, and a third in another brook at the same place. 

 The specimens are much larger at Beeston. The more 

 distant places are, Clumber Lake (Jeffreys), in a small 

 pond at Corby, Cumberland, Ulleswater, and the West- 

 moreland Lakes (Brown), Prestwiek Car, Northumber- 

 land (Brown), near Newcastle (Alder), Manchester 

 (Brown), small brook communicating with river Lea 

 (Hanley), at Scarborough (Bean), at Lichfield (Thomp- 

 son), Hornsea, Yorkshire (Strickland), Brookham Com- 

 mon, Surrey (Jenyns), near Bristol (Jeffreys), near Lon- 

 don (Grey), Devonshire and Wiltshire (Montagu); in 

 Ireland, in the Grand Canal, Cork, and Youghal 

 (Thompson), and in Tallagt Pond, Phoenix Park, Dub- 

 lin (, Warren), Forbes's foreign localities are Sweden, 

 Germany, Belgium, France, and Italy. 



I am not aware that it has ever been found fossil. 



The Pisidlums differ but little from the Cyclas tribe, 

 except in size; the animal, however is different, hav- 

 ing only a single syphon, whilst the Cyclas has a double 

 one. The hinge has one tooth in the right valve, and 

 usually two teelh in the left, and also lateral teeth. 



