Deposits of Diatoms have been long known to exist in Scotland, but such deposits have so far always been of limited extent. Specimens for the microscope have been readily obtained from certain localities, such as Peterhead, but the occurrence of large deposits covering great tracts of land was unknown.

In the year 1881 my attention was directed, by Mr. Hamilton Bell, to a white substance he had obtained from the Peat of Aberdeenshire. During April, 1882, I read a short paper before the Edinburgh Geological Society in which I gave the analysis of a sample received from Mr. Bell, with particulars furnished by the Rev. Geo. Davidson, Minister of Logie Coldstone, Dinner, who also kindly furnished a list of the Diatomaceæ he had identified in the deposit. The list contains some 200 species.