23 



hood is in length 3f inches, and in breadth *2^ inches. 

 Sir Oswald Moseley has sent me a specimen, procured 

 from his lake at Rolleston Hall, which measures 4 

 inches and one-tenth long, and If inches broad. It is 

 thought advisable to give the dimensions of two fine 

 adult specimens, as dredged in the river Trent, in order 

 to illustrate the great diversity of form in this species. 

 The one measured inches and three-eighths long, by 

 only! I broad; wtiilst the other measured 3 inches 

 long, by 1| inches broad. 



The internal colour of the shell is mostly of a silvery- 

 white, although it is not unfrequently salmon-coloured. 

 The interior of the shell is very pearl-like in appearance. 



The immediate localities of Unio pictorum are the 

 following: — The river Trent; the river Soar, about 

 Thrumpton Park; the lake at Hightield House (where 

 it is very large) ; a sheet of water at WoUaton ; and 

 the canal near Beeston. 



Other localities are, the rivers Kennet, Avon, Ouse, 

 Aire, Don, and Severn, and the canals in the neigh- 

 bourhood of London, Hull, and Birmingham (Forbes), 

 in Chillington Pool (Jeffreys), in the lake near Rolles- 

 ton Hall, neur Burton (Sir Oswald Moseley), the 

 Shrewsbury Canal and near Eyton (Eyton), Scar- 

 borough (Bean), ponds at Wynyard . (Sir VV. C. Tre- 

 velyan, Barl.), the river Brothay, near Ambleside 

 (Brown), near London (Grey), Birmingham and Wilt- 

 shire (]Monlagu). 



Abroad, it is found in Germany (Pfeiffer), Sweden 

 (Nilson), and from Sweden to Naples (Forbes). 



As a fossil it is found in the tertiary formation, at the 

 time of the drift, at which period the greater portion 

 of Great Britain was covered by the sea (Forbes). 



The varieties of some authors to be found in this 

 neighbourhood are :— 



