on the Geology of East Florida. 37 
since been corrected. . I have explored the shores of the Gulf of 
Mexico, and employed the lead to procure the small species living 
in deep water, to compare the existing fauna with that of the 
Miocene period, and the result is that of three hundred and forty 
seven species, about forty seven are yet living, making) about 
fourteen per cent. of recent species of shells; this accords with 
European Miocene strata sufficiently near in the per-centage of 
existing testacea, so far as such evidence is available, to establish 
a synchronous origin. This conclusion is confirmed by the close 
resemblance of the two groups of fossils, though the species are 
generally distinct. A considerable number of identical forms 
willno doubt be discovered when our collections shall be more 
complete. I have a small Corbula from Dax, which cannot be 
distinguished from C. inequale, Say, ip the Virginia Miocene, and 
even this evidence of cont eposition, slight as it may 
seem, has force and interest ‘for any one who carefully. compares 
the fochils of remote formations. 
With these introductory remarks, I proceed to give slight 
sketch of an expedition to Florida in the winter of 1842, made 
in reference to new observations on Tertiary formations. A sur- 
_Yeying expedition under Capt. Powel having been ordered by the 
Secretary of the Navy, Mr. Upsher, I was kindly permitted to 
join the steamer Poinsett, destined: for the survey of Tampa bay. 
It was through the interest of members of the National Institute 
that I went on behalf of the Society, in order to furnish its cab- 
inet with specimens of the rocks, fossils, and recent shells of 
Florida. As I have not yet had access to the specimens I sent 
the Institution, my slight sketch of ‘Tampa bay and the Florida 
Keys is more imperfect than it would otherwise be... Supplemen- 
tary observations will, however, in future be published, with a 
list of such fossils as I found on the Keys. In-an expedition of 
this kind, too little time is afforded to. study any one locality 
thoroughly, but the many points at which we landed, afforded a 
800d opportunity, seldom enjoyed, of observing the geographical 
distribution of the more common: species of shells inhabiting the 
northern coast of the Gulf. During a stay of three months upon 
the Florida coast, those ‘speciesonly were obtained which can be 
identified with, supposed. extinct forms of the Miocene period. 
The erent therefore of the recent shells of that era is 
