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Coal. The roots of the plants are formed in the seat earth 
below the coal, which tends to prove that they grew where 
they are laid, and were not washed from a distance to the 
position they now occupy. The land was again submerged, 
and probably became an estuary, whilst the Bone-bed was 
being gathered together. That it is an estuary deposit 
receives confirmation from several sources; we shall find that 
the fish remains belong to two distinct groups : one of them, 
the Elasmobranchii, of which the sharks and rays are exist- 
ing representatives, are confined entirely to salt water; whilst 
the second group, the Granoidei, have several living represen- 
tatives which are only found in fresh water, as the Lepi- 
dosteus, Amia, and Calamoichthys of the rivers of America ; 
whilst others, as the sturgeon, can live either in salt or 
brackish water. By the supposition of the land being 
lowered sufficiently to form an estuary deposit, it is not 
difficult to conceive the detached spines and teeth of the 
Elasmobranchs being washed towards the shore by the tides, 
and there mixed with the Ganoids from the river. This also 
appears probable when the broken and fragmentary condition 
of the remains are considered, for being constantly subject 
to attrition by each succeeding wave, the condition in 
which they are found would be the natural result. 
After some time the land was lowered still more, and 
the mud brought down by the stream, was deposited in 
deeper water, forming the bed of blue shale resting on the 
Bone-bed. The overlying strata of alternating beds of coal, 
shale, and sandstone, leads to the inference that the elevation 
and subsidence of the land occurred repeatedly. 
Before proceeding to the enumeration of the fish 
remains I have been able to identify from the Bone-bed, 
I wish to acknowledge my indebtedness to the Earl of 
Enniskillen, Sir Philip de M. G. Egerton, and W. P. Sladen, 
Esq., who have kindly placed their valuable collections at 
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