PISIDIUM. 135 



the surface of the water ; is found in the Thames at Wit- 

 ney, Henley, &c, as well as in the Severn (Strickland). 

 Scarborough (Bean), the vicinity of Bristol (Jeffreys), and 

 of Bath (Clark), the water-courses of the meadows near 

 Wareham in Dorsetshire (Brown), &c, are among its 

 English localities. In Wales, it has been procured by Mr. 

 Jeffreys in the neighbourhood of Swansea and of Cardiff, 

 at Ragland Castle in Monmouthshire, &c. 



In Ireland, observes Mr. Thompson, " although not very 

 common, it is widely distributed over the island, and is 

 known to me as occurring in every portion except the ex- 

 treme south 11 (Ann. N. H. vol. 6, p. 196) : in the river 

 LifFey (where it is plentiful), it attains a very large size, 

 and is taken in the Main, near its junction with Lough 

 Neagh (as well as in the rejectamenta of the latter), at 

 Limerick, Miltown Malbray, Ballitore in Kildare, &c. It 

 is found near Edinburgh, as well as in many other parts of 

 Scotland (Brown). 



It is generally distributed throughout Europe, and occurs 

 fossil in the pleistocene freshwater beds of the Thames. 



