154 GEOLOGICAL SURVEY 
Corbula oniscus, Con. Pectunculus stamineus, Con. 
Tellina papyria, Me Lithodomus politus, a: 
“ — Ravenelli, ‘ Nucula bella, Con. 
Lucina pandata, ‘ Ostrea sellaeformis, s 
symmetrica, tf “ Georgiana, 2 
Cytherea zquorea. ‘ “ Camera, 4 
: McCordia, Ruffin. Perna silicea, «s ; 
se ovata, Rogers. 
Crustacea. Cirripedia. 
Crabs’ claws. Balanus humilis, Con. 
Polyparia. 
Three or four species of corals, undetermined. 
PLantTs.—EXOGENS. 
Silicified wood. Quercus, the leaves. 
Lignite. Fagus, fe 
Salix. 
From this list we obtain the following numerical proportion of species. 
Gasteropoda, 53 species, or 64 per cent. 
Lamellibranchiata, 30 & Sb ont 
83 species. 
The predominance of Gasteropods among these fossils indicates the littoral character of the for- 
mation. The Auricule are land shells, living on marshes and other places that are occasionally 
overflowed by the tide, and the existence of even a single species is interesting in this connection. 
Of the Lamellibranchiata nearly all the genera are living on the coast, at this moment. So that 
the whole group, taken with the remains of plants found in the formation, makes the inference a 
fair one, that the buhr-stone was deposited on the coast of the Eocene sea. 
CatcaREous STRATA OF THE CHARLESTON Basin. 
A line joining the points indicated, in the preceding pages, as the localities of the buhr-stone 
proper, will give, with sufficient accuracy, the boundary, towards the North, of these strata. 
Commencing at the Upper Three Runs, and tracing a line thence to Lemon Swamp, we cross 
S. Edisto one mile above Johnson’s bridge, and Rocky Swamp at Stroman’s mill. Turning east 
from this, the line will cross N. Edisto, at the mouth of Limestone Creek and Cawcaw Swamp, a 
few miles higher; passing the head of Lime-hill Creek, the line continues to Stewart’s mill, on 
Four-hole Swamp, and crosses to Stout’s Creek; after which it follows the windings of the Santee, 
to Mayzick’s Ferry. 
On the West the line may be drawn from the mouth of Lower Three Runs to the Ashepoo, and 
thence to the Ocean. 
