53 
TEREBRATULA Sella. 
TAB. CCCCXXXVII .—fig. 1. 
Spec. Char. Subquadrangular, convex; front 
considerably elevated, narrow, emarginated 
when old; sides depressed, slightly rounded. 
*W* hen young this shell is rather trigonal in consequence 
of the length of the sides and roundness of the front ; as 
it grows older it becomes squarer, the front being more 
produced as well as more elevated; the beak is very 
slightly curved ; the length and breadth are nearly 
equal ; the edges always sharp. 
A characteristic shell of the Kentish Rag Stone ; a 
series of specimens were collected in the celebrated 
quarries of that stone at Chart, near Ashford, in Kent, 
by A. Power, Esq. several years ago. I have it also 
from Sandgate, where a mass of Stone was found by 
Mr. Goodhall, containing several full sized individuals, 
one of which contained crystallized Quartz. The speci- 
men figured wa$ said to come from Hythe. 
TEREBRATULA obtusa. 
TAB. CCCCXXXVII.—^. 4. 
Spec. Char. Suborbicular, rather depressed; 
front broad, elevated ; edge obtuse. 
The lesser valve is rather wider than long; but the 
projection of the beak of the other valve makes that 
longer than wide ; their surfaces are equally and re- 
gularly convex, except near the edges, where they are 
rather suddenly bent so as to produce a squarish margin. 
I have only seen one individual of this Terebratula ; 
it was sent from Cambridge along with many specimens 
of T. biplicata, one of which has been figured upon 
Tab. 90. 
TAB. CCCCXXXVII.— figs. 2 and 3. 
These are representations of a young and a full grown 
specimen of T. biplicata, in views that appeared neces- 
sary to point out the difference between it and T. pero- 
valis, and also between it and the shells formerly con- 
