AS 
UNIO concinnus. 
TAB. CCXXIII.---Figs. 1 and 2. 
Spec. Cuar. Transversely oblong-ovate, depressed, 
nearly smooth, thick ; posterior side very small ; 
beaks prominent, recurved. 
Auwosr three times as wide as long, regularly convex, 
with a gently curved back; the thickness of the shell 
is remarkable ; the lines of growth are sharp; in other 
respects the surface is smooth. The front is slightly 
incurved near the anterior end. 
This neat species was lent me by the Rev. W. 2. 
Conybeare, who obtained it from the lower beds of the 
inferior Oolite, at Cropredy, near Banbury, in Oxford- 
shire : it exhibits the form of the hinge remarkably well. 
