SPECIMENS FROM BURMAH. 
177 
bed, extending over a small area near the lowest bottom 
of the pond to which the water had subsided. Other 
beds of sediment at the bottom of the pond were found 
crowded with bivalve shells deeply embedded in mud, to 
the exclusion of shells of the more locomotive univalves. 
These facts seemed to throw light on the appearance in the 
Petworth and Purbeck marbles of only one species of uni¬ 
valve shells, and the non-existence of these univalves in 
other beds of the same marble which contain exclusively 
bivalve shells. Another point was the collection of fish in 
one spot. The fish which had survived were congregated 
with the surviving molluscs in the remaining shallow water, 
and, if this dried up entirely, the first bed of mud formed 
by the returning water of the next flood would bury them 
in one stratum, after the manner of fish that are entombed 
in miscellaneous shoals in the strata of Solenhofcn and 
other places. Another phenomenon in the pond was the 
occurrence of recent footsteps of animals and birds on the 
surface of the soft beds of mud and sand since the water 
had subsided. These illustrate many similar footprints 
which have been discovered upon the slabs of stone in the 
new red sandstone formations. 
From all parts of the world came specimens and collec¬ 
tions, on which Buckland was asked to report. Thus in 
1827 he was called upon to examine some fossil animal 
and vegetable remains collected by Mr. Crawfurd on a 
voyage up the Irawadi from Rangoon to Ava of five 
hundred miles. The specimens were principally collected 
from a tract of country on the east bank of the Irawadi, 
near the town of Wetmasut, about half-way between Ava 
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