70 
I found this siliceous shell at Chute: its valves easily 
separated from the cast of the inside, which is composed 
of sandy’ marle, mixed with the green granular Talc 
which characterizes the stratum in which it abounds, and 
gives it the name of green sand. 
CHAMA plicata. 
TAB, XXVI.—Fig. 4. 
Spec. Cuar. Transversely ovate; beak short; deeper 
valve with a narrow channelled wing. 
SE 
Haxr an inch long, three-fourths wide; wing small, ear- 
shaped, deeply folded at its commencement, flatter and 
obtuse at its termination; hinge-tooth obscure or none: 
margin of the shell crenated within the edge. Surface of 
adhesion small. I have not seen the flatter valve of this. 
T. J. L. Baker, Esq. presented me with this specimen from 
Halldown: it is Silex coloured by oxide of Iron. 
