201 
TEREBRATULA biplicata. 
TAB. XC. 
Serre. Cuar. Oblong, gibbous; beak prominent; 
sides rounded; front straightish, when full 
grown, elevated with two distant large plaits. 
Fic. 1. 
G. sides rather angular, straightish towards 
the front, smaller and broader than 2. Figs. 2, 
3, 4, and 5. 
a —— 
Or the two varieties of this shell, the larger one is longer 
in proportion to its width, and more gibbous: the younger 
shells of either seem scarcely to be plaited, and are rather flat. 
I was favored with some of the shells, &c. found in dig- 
ging in the Castle Hill, Cambridge, by Dr. Clarke and 
H. Warburton, Esq. about ten years since; among the. 
parcel from the latter gentleman was the middle specimen 
here figured; it was among the marly goult with the green 
and irony sand, &c. see Brit. Min. tab. 184. Its resem- 
blance to those surrounding it made me place it here, as 
I think they ought to be identified. It is, however, larger, 
and the shell not much more altered than recent shells 
sometimes are. I possess the same variety from Limerick, 
but more mutilated, the sheli not more changed, but having 
become a shelter for small worms: also another specimen 
not infected with worms: they appear to be of the same 
age and size. Hunstanton Cliff in Norfolk affords the 
