Geology of Tampa Bay, Florida. 41 
origin. ‘There are also found in this bed round cylindrical stems, 
fluted and gradually tapering to a point with a slight curve, they 
are from three to four inches in length ; likewise a species of large 
radiated coral, shaped like the segment of a sphere, petrified with 
wine colored silex, and having a mammillary interior of carnelian 
or chaleedony.* The most beautiful petrifactions of this deposite 
are various species of shells that are so perfectly petrified with 
clear wine colored silex, that all their most minute and delicate 
markings are preserved ; so great is their translucency, one can 
nearly read through them. 'They appear to have petrified before 
having suffered the least from attrition or decomposition ; the spi- 
ral univalves taper toa transparent needle-like pomt. I found 
one petrified with carnelian. I obtaimed more than twenty spe- 
cimens, among others some of the following genera: Murer, 
Oliva, Cyprea, Buccinum, Cardita, Trochus, Cerithium, Pura 
and Helir, afew of which are found living at present in the 
bay, some are indigenous to the West Indies; they are washed 
out of the marl and strown along the shore by the constant action 
of the water. There are other beds of marl, apparently of a 
much more recent origin, one of which extends along the shore 
at Fort Brooke ; it is an earthy mass containing vast quantities of 
oysters and other shells, extends a few hundred feet back from 
the shore, and is several feet in thickness. I have seen dug out 
of it bones of the Manatus or sea cow, an animal that still exists 
in the southern part of the peninsula. 
Deposits of marl, and shell banks, occur at many places on the 
western coast of Florida. About thirty five miles south of Fort 
Brooke, near the mouth of the Manatu river, there is an extensive 
bank of shells ten feet or more in thickness, composed almost 
wholly of large unbroken univalves, belonging principally to a 
species of Pyrula, without any admixture of earth. I never be- 
fore saw shells of this kind in such large quantities, and from 
their volume and position, I should infer that they had been 
TL } he ay ie | Wit ; a 
from vm Pebee Bay.” In most of the geodes which we have seen from this ieealiis. 
the zoophytic structure of the mass could be readily detected. One large hollow 
spheroidal or pyramidal specimen which we have, has numerous stalactical masses 
rising inward from its base of the size and length of a man’s finger. ‘These have 
arisen from the perforation of the original animal structure by saxicavous shells 
original, copying with surprising delicacy, all the minute markings of the zoo- 
phyte.—Eds. 
Srconp Series, Vol. I, No. 1.—Jan. 1846. 6 
