12 



The ligament is situated on the shorter side of the 

 shell ; but in the Cyclas it is on the longest side. 



PisiDiUM AMNicuM. Muller. 



Pisidium amnicum is much larger than any other 

 branch of this family, being 6^ lines in length and 3f 

 in breadth. The anterior side of the shell is much 

 produced and tapering, whilst the hinder side is short 

 and blunt. The umbones are not prominent. Very 

 conspicuous longitudinal strioe-like raised markings 

 are spread over the shell. It is somewhat of a olive- 

 ash colour, and the interior is blueish-white. 



Rivers and gentle streams are its favourite haunts, 

 partly burying itself in the mud. 



An abundant shell, although it appears very rare in 

 this neighbourhood, only one specimen having been 

 procured, and this was dredged from a brook which 

 crosses the Railway half-a-mile below the Beeston 

 Station. 



It is found in the river Avon, near Salisbury (Maton), 

 in the North Avon (Montagu), in the New River, Lon- 

 don (Hanley), the river Thames, at Witney and Henley 

 (Strickland), the river Severn (Strickland), the river 

 Mole, near Guilford (Millet), Bristol and Wiltshire 

 (Jeffreys), Bath (Clark), near Wareham, Dorsetshire 

 (Brown), Scarborough (Bean), Newcastle (Alder) ; in 

 Wales, near Swansea and Cardiff (Jeffreys); in Scot- 

 land, near Edinburgh (Brown); and in Ireland, in the 

 river Main and the river Liffey, at Limerick, Miltown, 

 Malbray, Ballitore, and Kildare (Thompson), and 

 Dublin (Brown). 



Generally distributed throughout Europe. Germany 

 (Pfeiffer), Sweden (Nilson). 



It occurs fossil in the Pleistocene fresh-water beds of 

 the river Thames (Forbes). 



