114 
PLAGIOSTOMA duplicata. 
TAB. DLIX.—/fig. 3. 
Spec, Cuar. Obliquely obovate, convex, costated ; 
costae numerous, sharp; between each of the 
coste is a sharp elevated line ; beaks rather 
prominent. 
Tur coste, which are sharp-edged, are about 25 in 
number: alternating with them is a set of much smaller 
but equally sharp elevations, which appear characteristic 
of the species. 
The larger specimen is from the Oolite at Malton, the 
other apparently from Cornbrash ; but the label has un- 
fortunately been lost. We have a group with one an 
inch and a half leng; but we do not know from what 
country it came. 
