30 
never to be seen, no one would doubt the propriety of re- 
ferring it toit: added to this, it occurs among decidedly 
fresh-water shells, such as Paludina lenta (M. C. ¢. 31.) 
in sandy clay in the lower freshwater formation of Hord- 
well. 
Brander’s fig. 95. does not accord in form with the 
shell before us: but as he has referred it to Mya Picto-. 
rum of Linneus, and as we know of no other shell 
found at Hordwell at all resembling it, it is. probable 
that his figure was taken from a specimen so mutilated 
as to give a very different idea of the shell, to that he 
had formed by observing a number of individuals. The 
shells themselves are exceedingly fragile, and the earth 
they are imbedded in so loose, that it is not often a cast 
can be preserved tolerably entire; so that his specimen 
might be much broken before it was drawn*. 
We are indebted to the zeal and perseverance of our 
kind friend Charles Lyell, jun., Esq. for the knowledge 
of this Unio, which we consider a valuable addition to 
the list of freshwater fossils. It occurs in abundance, 
but it required much care to save two or three speci- 
mens. 
The several fossils formerly published as Uniones 
require reconsidering before they can be established in 
the situation assigned them ; for they present characters 
and occur under circumstances not compatible with the 
habits of that genus, or not fully explained: 
* The only way to keep the shells is to soak them in gum- 
water soon after they are picked up, first drying them care- 
fully. 
