140 
CORBULA rotundata. 
TAB. DLXXII.—/fig. 4. 
Spec. Cuar. Obovate with produced beaks, gib- 
bose, concentrically sulcated ; sides nearly 
equal, the posterior slightly truncated. 
Tue lesser valve of this is probably smooth, but the 
specimen is too much worn to be depended upon. 
Found in the Crag of Suffolk. The specimens figured 
are from Holywells, presented by the late Mrs. Cobbould. 
CORBULA obscura. 
TAB. DLXXII.—/fig. 5. 
Spec. Cuar. Obovate, gibbose, smooth ; posterior 
side flattened, so as to form an angle upon the 
surface. | 
Syn. Corbula (new species). Trans. Geol. Soc. 2d 
series, vol. il. p. 320. 
A smauu shell much resembling Corbula Pisum, but 
smaller and flatter. 
An abundance of this species of shell, which appears 
to be a Corbula, is firmly imbedded in the sandy stone 
above the coal in the district of Brora, and has been 
preserved by R. J. Murchison, Esq., Sec. G.S. 
