THE NATIONAL INSTITUTION. 
171 
which, for the most part, reliance must be placed on uninformed agents, it will be 
absolutely necessary to issue very minute instructions, to be observed by the col¬ 
lector, that they may, with the least expenditure of time, do the best possible with 
the country they live in. More especially every inducement should be held out to 
all correspondents to send in wet preparations of the animals which occupy the 
shells, and dissection of parts, illustrative of their anatomy, preserved in spirits. 
If the National Institution could succeed in establishing branch institutions in 
the various quarters indicated above, a measure which I would urge upon the early 
attention of the members, the harvest of species waiting to be gathered in would 
be accomplished so much the more speedily. 
Respecting the willingness of gentlemen, especially those to whom I have re¬ 
ferred, to undertake exchanges, I take this opportunity to bear testimony to the 
great liberality and promptitude which I have invariably found to actuate natural¬ 
ists, though personally strangers to each other. I have attributed these noble 
qualities as much to the gentle influences exercised by their quiet pursuits, as the 
wish to extend the humanizing results which always attend the cultivation of 
science. 
Washington University of Baltimore, Dec. 10, 1841. 
OBSERVATIONS ON A PORTION OF THE ATLANTIC TERTIARY 
REGION, WITH A DESCRIPTION OF NEW SPECIES OF 
ORGANIC REMAINS: BY T. A. CONRAD. 
Several circumstances combine to give interest and importance to the tertiary 
deposits of the Atlantic coast of the Union. These chiefly consist in variations 
from the usual characteristics of European tertiaries. The first which I shall 
notice is the remarkable connection of secondary with tertiary, or cretaceous with 
eocene deposits, by means of the following fossils, which I discovered in a tour in 
the Southern States in 1832, ’33 viz : Nummulites Mantelli, (nob;) Gryphcea vomer, 
(Morton;) Plagiostoma dumosum , (Morton.) The white limestone of Alabama, which 
contains these fossils, is connected with the green-sand formation of New-Jersey, by 
three species of shells : Ostrea panda, Ostrea cretacea, and Gryphcea vomer, (Ostrea 
lateralis, Nillson.) The (second important disagreement with foreign tertiaries is 
the absence of any trace of fluviatile remains. The Gvathodon, a bivalve inhabiting 
estuaries where the water is scarcely saline, and fresh during the inundations of the 
rivers, is the only evidence, hitherto obtained, of the occurrence of fresh water 
streams—a remarkable fact, considering the great extent of land which evidently 
was present in the tertiary periods. The third peculiarity of the American tertiaries 
is the abrupt line of demarcation between the fossil groups which they contain; show¬ 
ing no gradual passage or interchange of forms, although the relative levels, above 
the sea, are of no important variation among the three divisions into which I have 
grouped the tertiaries, for a convenient but temporary purpose. No one, I pre¬ 
sume, would refer this wide difference of zoological character to any relative con¬ 
dition of sea or land, caused by earthquakes, or by an elevation of the beds above 
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