. R82 Scientific Intelligence. 
with a light yellowish mud. The latter is easily removed by washing and 
decantation. e casts thus obtained are so perfect that not only the 
genus, but often the species of the Polythalamia, can be recognized. 
Mingled with these are frequently found spiral or corkscrew-like bodies, 
which Ehrenberg considers as casts of the shells of young mollusks. 
With reference to the perfection of these casts of the Polythalamia, and 
the light they throw upon the structure of these minute animals, Ehren- 
are thus petrified, and separately exhibited. By no artificial method cam 
such fine and perfect injections be obtained.” . 
Having repeated the experiments of Ehrenberg upon the Zeuglodon 
limestone, I can confirm his statements in every particular, and would only 
add, that besides the casts of Polythalamia and small spiral mollusks, there 
is also a considerable number of green, red, and whitish casts 0 minute 
anastomosing tubuli, resembling casts of the holes made by burrowing 
sponges (Cliona) and worms. 
In the Berlin Monatsbericht, for July, 1855, Ehreriberg gives an ac 
parts. 
The interesting observations of Ehrenberg which are alluded to above, 
have led me to examine a number of the cretaceous and tertiary rocks of 
North America in search of Greensand and other casts of Polythalamia, 
&e. The following results were obtained : = 
Ist. The yellowish limestone of the cretaceous deposits of New Jersey — 
occurring with Teredo tibialis, &c., at Mullica Hill, and near Mount Hor — 
ley, is very rich in Greensand casts of Polythalamia and of the tubuliform 
bodies above alluded to. 
2d. Cretaceous rocks from Western Texas, for which I am indebted 1 
Major W. H. Emory, of the Mexican Boundary Commission, yielded @ — 
considerable number of fine Greensand and other casts of Po ee 
and Tubuli . 
i—_ 
3d. Limestone from Selma, Alabama, gave similar results. L 
4th. Eocene limestone from Drayton Hall, near Charleston, South Caro- 
lina, gave abundance of similar casts. reget 
5th. A few good Greensand casts of Polythalamia were found in the — 
residue left on dissolving a specimen of marl from the Artesian Well e 
Charleston, S.C.; depth 140 feet. oe 
