> Se aes Rag” Seis Oe See 
ae 
, eee eres 
on the Geology of Hast Florida. AY 
Strombus gigas is common ae but it is not found so far north 
as Tampa bay. ' 
Leaving Key West we soon arrived at Tampa ay on the west- 
ern side of the peninsula, and here the surveying duties of the 
_ expedition commenced. We visited frequently many of the Keys 
which stretched across the mouth of Tampa bay, and several points 
on both sides of the bay, and in every locality I collected all the 
_ Species of shells Icould find, in order to study their geographical dis- 
tribution. The shellsare not g lly very abundant on the island 
beaches, but on Mullet Key, whose eastern shore faces the bay, 
there is an immense accumulation of bivalves, about four feet in 
depth, the decaying animals of which render the atmosphere 
quite offensive. The most abundant shell is Ninus cancellata, 
Lam., which has generally both valves united, and the whole de- 
posit: is remarkably like that of a pliocene formation. Near this 
shore is the principal entrance to Tampa bay. On the north- 
ern beach of this island, I found Chama arcinella and Strombus 
pugillus far more numerous than any where else. While on 
Mullet Key we find so many bivalves entire, on Palm Key, a 
long island the most southern of the group, there is a very wide 
beach seaward upon which are comparatively very few shells and 
in bad condition. On the bay side the shells are more numerous, 
water-worn, and with separated valves. The most abundant 
shell i 1s a Species of Mactra like the M. solidissima but smaller. 
Key has a similar group of shells. On North Passage 
=e numbers of a testaceous fragments a 
_ On Egmont. Key I found a ease specimen of Natiea canrena. 
Pecten dislocatus is very abundant here. Nearly all the bivalves 
are disunited at the hinge and water-worn; the surf rolls in a 
quick succession of waves, which s soon — —_ shells as many 
be cast ashore alive. - 
_ The shores of Tampa bay sie a range of jovi land, dhanety 
wooded with pitch pine and the usual undergrowth of palmettos, 
‘Yarely a live oak or other tree of great size. Frequent clumps 
of mangroves are seen, with their dark green foliage and rugged 
irregular trunks and roots, the front rank standing in the water, 
Senerally dead and picturesque in appearance. High-water mark 
18 defined by a line of pele: and other marine substances. 
Under this ll shells of vari- 
SEconp Snizs, Vol. I, No. 4.--uly, 1846. 6 
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