70 
eimens do not possess it in the smaller valve ; the beak 
of the other valve is large but short, its circular aperture 
reaches to the beak of the small valve ; the front is even. 
The length varies so much, that some specimens are 
nearly orbicular. 
Frequent in the Chalk. Mr. Mantell obtained his 
specimens from the gray Chalk Marl at Hamsey. Al- 
though they are larger than those before us, we see no 
reason for thinking them distinct. It occurs also in the 
Greensand below, and in the Clay above, the Chalk. We 
have a small specimen from Horningsharn ; and nume- 
rous pyritous casts of both the long and short varieties, 
some with the shell remaining, from Southend and the 
Isle of Sheppy on the opposite shore, through the kind- 
ness of the Rev. Mr. G. Hope, and Mr. Frembly. It 
also occurs at Dax, as we are taught by specimens given 
us by Dr. Grateloup, who has named it T. aquensis. 
Figs. 3 & 4. represent the long variety taken out of 
Chalk in Sussex. Fig. 5. shows the short variety : — one 
specimen is out of Chalk, the other is a cast in Pyrites 
from Southend. 
TEREBRATULA Pisum. 
TAB. DXXXVI.— figs. 6 & 7. 
Spec. Char. Suborbicular, rather square, thick, 
depressed, plaited ; plaits numerous, simple, 
sometimes granulated ; front slightly elevated, 
beak small, incurved. 
In some specimens of this Terebratula the plaits are 
neatly granulated, in others they are quite smooth. 
Without some other character we could not consider 
them as belonging to different species. The front is 
elevated in only one or two of the largest specimens. 
Presented long ago by G. A. Mantell, Esq. who col- 
lected the specimens in the Marl-pit at Hamsey in 
Sussex. 
