71 
Measuwrement.—The transverse and conjugate axes... 11-25 x 9-0 
ore 
The thickness... oh he PE SARZO 
The angle of rim—circa. ... 4 eget 
FOSSIL OPERCULA. 
(GASTROPODA.) 
EXPLANATION OF THE PLATE. 
[.—Stivr1mn.—The Operculum of Euomphalus sculptus 
(SowERBY). 
(Natural size). 
The fossil with its operculum in place. 
Exterior of the operculum. 
Section on the diameter of the operculum. 
Whorl of the operculum. 
II.—Laasstc.—The Opercula of Neritopsis (Sr). 
(Enlarged). 
Exterior of the quasi Peltarion wnilobatum, Eupes- 
DESLONGCHAMPS. 
Interior of the same. 
Exterior of the quasi Peltarion bilobatum, Kups- 
DESLONGCHAMPS. 
Interior of the above. 
