29 
The large upper valve, of which two figures are given 
at fig. 3, is filled with a similar stone superficially stained 
with Iroa: it seems to correspond in some respects with 
Delamarck’s description of O. pectinata: it was sent me 
by the Rey. Mr. Steinhauer, from the upper Coral rag, at 
Westbrook, near Melksham, Wilts. 
All the species of Oysters are so variable in their contour, 
that it is difficult from description to determine them. 
OSTREA palmetta. 
TAB. CXI.—Fig. 2. 
Spec. Cuar. Ovate-roundish, obscurely one-eared, 
depressed, with a plaited margin; plaits diverg- 
ing from a longitudinal space ; beaks straight. 
Tus shell is but slightly curved, it is flatter and the plaits 
are few and more irregular than in O. gregarea, but it may 
‘prove to be a variety in a young state. 
Found in Marston field, near Oxford, by Mr. Baker, 
in a somewhat redder soil than the preceding. The upper 
valve easily separated, and allowed the inside of the other 
to be properly seen; there was but a small piece of earth 
in it. 
