46 Observations by T. A. Conrad 
specimen of the large shark’s tooth, (Carcharias megalodon,) a 
species occuring also in North Carolina. 
One of the most remarkable places near Tampa is a large al 
phur spring, eight miles up the Hillsborough river. About one 
hundred yards up a tributary, the spring boils up and fills a capa- 
cious basin. It is white sulphur water coming from the crevices 
of limestone and from twelve to eighteen feet deep, and so per- 
fectly limpid that the incrustations of sulphur at the bottom are 
as distinctly visible as. if the water were but an inch in depth. 
Just below the spring great numbers of mullets may be seen .scud- 
ding in all directions as the boat passes over them, but not ge ; 
of any kind seems to trespass upon the silebeambias basin... 
In the fresh water of Manatee river, a large soft-shelled turtle | 
frequently caught by the settlers who prize it as an article of 
food. I inquired the number of claws on each foot, and was an- 
swered by aman who had recently caught one, that there are five 
claws to each foot, which verifies the accuracy of Bartram, who 
describes and figures an unknown species with this character, 
which must be very distinct from the common soft-shelled tor- 
toise of the south, (Trionyx ferox.) oe 
Since writing the preceding sketch of Pafaien bay, I have ex- © 
eaninade more attentively the casts and shells contained in the 
limestone. None of these can be identified with any recent _ 
shells of. Florida or the West Indies. But what has satified me 
that this rock is geologically older than the Post-pliocene, is the 
occurrence of an extinct. species of land shells, a Bulimus which 
is silicified and. extremely perfect... No similar species of this 
genus exists in North America. All the other shells in the rock 
are decidedly of marine origin, and very large masses of anew 
species of Columnaria abound. It is remarkable that the fossils 
of this rock have no near resemblance to those either of the Mio- 
eene or Eocene, and it will most probably prove to be an upper 
' member of the latter. The local depositions of this. formation 
vary much in their fossil contents. ‘Those of the Santee river 
in South Carolina, are quite distinct from the group which char- 
acterizes the Eocene limestone at St. Stephens, Alabama. . 
_ Thave obtained casts of a species of Venus; of Nucula, two; 
Cytherea, one ; Natica, one; Bulla, one ; Bolisons,; one; and two 
lorena era, comprising a Jusemdite ‘and a Ccistallacian The 
r mi can be obtained by ieee 
