96 
Proceedings of the Royal Society 
even when diligently searched for, I think it right to present to the 
Society for preservation the five topazes in which the cavities were 
found. — I am, ever most truly yours. 
(Signed) D. Bkewster. 
Alleely, Feb. 1, 1863. 
2. On the Polarization of Eough Surfaces, and of Substances 
that reflect White or Coloured Light from their Interior. 
By Sir David Brewster, K.H., F.K.S. 
3. On a Clay Deposit with Fossil Arctic Shells, recently 
observed in the Basin of the Forth. By the Eev. Thomas 
Brown, F.E.S.E. 
The author having stated the circumstances which led to his 
discovering this bed with its fossils near the harbour at Elie, re- 
ferred to a drawing of the section, and explained the position and 
contents of the different strata. 
Specimens of the shells were exhibited, as named by Dr Otto 
Torrell of Lund, who had supplied important information as to their 
distribution. They are all, without exception, now living in the 
Arctic Seas. A majority of them are exclusively Arctic. Several 
are new to the British glacial deposits — viz., Thracia myopsis^ 
Pecten groenlandicus, Grenella decussata, G. Jcevigataf Turritella 
erosa,f and a new Yoldia found in Spitzbergen in 80° north lati- 
tude.J It was shown how strongly this evidence goes to prove the 
former existence of a Boreal or Arctic climate in Scotland. 
The shells seem also to indicate some considerable rise in the 
level of the land. They are deep-water species— some of them very 
markedly so. Four distinct series of facts appear to show that 
they have not been washed up and transported, but are lying in 
the clay-hed where they originally lived. As the deposit is now 
rather above high-water mark, the fair inference would seem to be 
“ Most probably, but much injured.” 
t “ Almost certainly tliis species, yet cannot be positively asserted.” 
J The other species are — Saxicava rugosa, large form, Tellina ‘proxima^ 
Aiitarte compressa, Leda truncata, L. pygnicea, Natica groenlandica, large form. 
Fragments also occur which seem to belong to Cyprina Islandica and Mya 
tnmcata. 
