THE NATIONAL INSTITUTION, 



177 



of the Patnxent, below Benedict. As we trace the strata south, the species found 

 on St. Mary's river, make their appearance, and 3'et the group of the latter locality 

 compared with that nearest to Benedict, will be found to hold scarcely one kind of 

 fossil in common. I have seen from Italy and Great Britain, organic remains so 

 similar in general character, though mostly of species different from those of the 

 medial tertiary of the Union, that I could not doubt the geological relations to be 

 the same, and hence the inference, that a comparison of tertiary formations in dis- 

 tant countries, will exhibit by peculiarity of forms, and not unfrequently identity of 

 species, the evidence of having originated at the same period of time. According 

 to the classification of formations upon the relative amount of recent and extinct 

 forms, that which we have designated as the medial tertiary formation, comes 

 within the limits of the miocene. Yet, it is singular that a greater amount of dif- 

 ference should exist between the eocene and miocene, or two consecutive divi- 

 sions of the tertiary, than obtains between secondary and tertiary, or between 

 the devonian and carboniferous systems. No single form connects the lower 

 with the medial tertiary formation, even when they are in juxtaposition ; yet three 

 species of organic remains link the upper secondary with the lower tertiary 

 group of this country. It is, therefore, not unlikely that some deposits may yet 

 be found, which occupy a position between the lower and medial tertiary, con- 

 nected with both by the interchange of a certain number of forms, as is the case in 

 Europe. There may be such a formation, circumscribed within narrow limits, or it 

 may have been swept away in one of those unfathomed revolutions, which have so 

 mysteriously and so frequently passed over the surface of the globe. 



The following table will exhibit the most prominent characters of the supracre- 

 taceous formations of the Atlantic coast, premising, however, that of the two new- 

 est of these, the relative position is yet undetermined. 



Table of Atlantic Svpr a cretaceous Deposits. 



Elevation above 

 the sea. 



Localities. 



