Proc. Roy. Socy. of Edin.~] 
[Vol. XXY. 
Fig. 1 . — Stone from the shore of a loch at Lismore, showing the incrustation of 
calcium carbonate caused by the metabolic processes of minute lithophilous 
algre. Reduced one-half natural size. 
Fig. 2. — Waterworn and polished stones from Loch Ness shore at Loc^iend, of 
various geological formations. Reduced one-quarter natural size. 
[Plate 1 . — Referred to on page 968. 
a 
Mr George West. 
