202 Mr. R. Walker on Clays, containing Fossils, 
P. pellucida, Lattorina littoralis, L. littorea, and many broken 
fragments of other littoral shells. The third bed, although 
distinct enough, seems to be merely a mixture of the materials 
of the second and fourth beds; the only shells observed were a 
few straggling specimens of Littorina. In composition, the 
fourth bed has a greater resemblance to estuary silt than to any 
other kind of deposit: it shows no traces of lamimation, and, 
with the exception of occasional thin layers of sand, it bears no 
other marks of stratification. From this bed the mammalian 
bones and the following shells were obtained ; the latter seemed 
to be distributed through the mass, as far as it was pierced. Of 
the bivalve shells, the most common was Tellina proxima, of 
which specimens of all sizes were in abundance; and, as usual 
with this species, the valves were covered with a yellow epider- - 
mis, which in most cases, however,adhered more firmly to the clay 
than to the shell. There were likewise a considerable number 
of specimens of Scrobicularia piperata, Mytilus edulis, Cardium 
edule, and two or three examples of Saxicava rugosa. Of the 
univalves, Rissoa ulve was in the greatest abundance—in some 
places completely crowded, more especially where there was a 
lamina of sand. Littorina littorea was plentiful; there were two 
specimens of Nassa incrassata, and two or three of Helix hispida. 
The univalves were all full-grown specimens; but none of the 
bivalves, with the exception of Scrobicularia and Tellina, had 
attained full dimensions. They were all very friable, and in the 
case of Mytilus and Cardium it was scarcely possible, im many 
instances, to remove them from the clay without breaking. In 
every instance both valves were adherent ; and there can be no 
doubt whatever that the animals lived and died where their shells 
were afterwards found. All the marine shells of the preceding 
list are living in the littoral zone of the adjacent sea, with the 
exception of Tellina proxima, which does not appear to be living 
now in any part of the British seas, and is considered a charac- 
teristic shell of the glacial deposits of Scotland ; they are all 
included in Geikie’s Catalogue of Organic Remains from the 
Glacial Deposits of Scotland*; they are likewise included in 
Wood’s ‘ Mollusca of the Crag ;’ so that as species they must 
have existed during many of the physical changes that have oc- 
curred on the earth toward the latter epochs of its history. 
Of vegetable remains noticed, there were pieces of the branches 
of the birch and the oak, together with a few nuts of the latter. 
Of the birch-branches, however, there was little else than the 
bark preserved, which did not appear to be at all wasted. There 
were also a few fragmentary impressions of leaves, and many 
impressions and remains of what appeared to have been marsh- 
* The Glacial Drift of Scotland. 
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