202 
LIFE OF DEAN BUCKLAND. 
[CH. VIII. 
admixture and alternation of the remains of fluviatile 
and lacustrine shells with marine exuviae, indicate condi¬ 
tions analogous to those under which we observe the 
inhabitants both of the sea and rivers existing together 
in brackish water near the deltas of the Nile, and other 
great rivers. Thus, we find a stratum of oyster shells, 
that indicates either the presence of salt or brackish water, 
interposed between limestone strata filled with freshwater 
shells, among the Purbeck formations ; so also in the sand 
and clays of the Wcalden formation of Tilgate Forest we 
have freshwater and lacustrine shells intermixed with 
remains of large terrestrial reptiles, e.g,, Megalosaurus, 
Iguanodon, and Hyteosaurus ; with these we find also the 
bones of the marine reptiles Plesiosaurus ; and from this 
admixture we infer that the former were drifted from the 
land into an estuary, which the Plesiosaurus also having 
entered from the sea, left its bones in this common recept¬ 
acle of the animal and mineral exuvim of some not far 
distant land.” 
It will be remembered that in 1820 the Professor had 
visited the caves of Monte Bolca, when his friend Count 
Bretiner depicted him in his “fishing” costume. It may, 
therefore, not be uninteresting to hear the account which 
he gives in the Treatise of the quarries :— 
“ The circumstances under which the fossil fish are 
found at Monte Bolca seem to indicate that they perished 
suddenly on arriving at a part of the then existing seas, 
which was rendered noxious by the volcanic agency of 
which the adjacent basaltic rocks afford abundant evidence. 
The skeletons of these fish lie parallel to the laminae of the 
strata of the calcareous slate; they arc always entire, and 
so closely packed on one another that many individuals 
are often contained in a single block. The thousands of 
specimens which are dispersed over the cabinets of 
Europe have nearly all been taken from one quarry. All 
these fish must have died suddenly on this fatal spot, 
