G. FLUSTRA, 
51 
On the fossils of the chalk in the vicinity of 
Paris. 
SMALL-MOUTHED. (FOSSIL.) 
36. Flustra microstoma. Rather thick incrustation, 
with cells not very distinct, oval, and rather prominent; 
the opening in the middle, very round and small. 
On the large fossil oyster in the vicinity of Sceaux. 
DEPRESSED. 
37. Flustra depressa. Cells oval, alternate, hori- 
zontal, and slightly punctured ; openings half-moon 
shaped, and closed with a valve. 
Adriatic. 
DISH-SHAPED. 
38. Flustra patellaria. Cells oval, flat above and 
convex below ; nearly isolated, horizontal, and sub- 
alternate. 
Mediterranean. 
OBLATE. 
39. Flustra planata. Cells oval, flat, alternate, 
and distant, bordered and closed by a membrane. 
Mediterranean. 
The succeeding genera belonging to this Order 
have hitherto been included in the general denomina- 
tion of Cellarias : but their varieties induced me to 
separate them into families ; whose species are indeed 
few, but which will probably be augmented when these 
little beings shall have been more attentively studied. 
These Polypidoms are plant-like, frequently arti- 
culated, either flat, compressed, or cylindrical. Cells 
P j, 
By 
cm 
v 
-y 
