131 
FECTEN BeaverL 
TAB. CLVIIL 
Spec. Char. Depressed, orbicular, smooths with 
irregular longitudinal costae ; ears as wide as 
the shell, nearly equal. 
The costae vary in size and distance in the same shell, 
and there are between the principal ones now and then a 
small one or two : the shell is thin. 
Among many specimens I have not seen so perfect an 
example to identify the species as this, lent me fron& 
the Oxford Museum, to which Mr. Beaver presented it ; 
it is from the Rev. Mr. Beaver’s quarry at Childrey, 
near Wantage, Berkshire. I take advantage of the 
opportunity thus allowed me of publishing the spe- 
cies ; at the same time I beg leave of my friends and 
correspondents to say, that I shall still be glad of infor- 
mation or specimens, as it is very irregular in some of 
its characters, and the outside is as yet but imperfectly 
known. I have specimens of the same from Hamsey, 
Sussex, which Mr. Mantell kindly sent me, that identify 
a similar stratum (Chalk marl), but the shells being more 
mutilated and smaller, may indicate something relating 
to its age. 
The upper figure is from an impression of the shell 
taken in clay ; I have been able to seperate a portion of 
the shell from a Hamsey specimen, sufficient to shew that 
it is smooth : this figure, therefore, exhibits the outside : 
the lower figure shews the inside of the shell which 
adheres by its outside to the stone, or rather hard marley 
chalk, in which it lies. There are a few spots of pyrites 
about it. 
