Diatoms in London Clay

Abstract

I DO not know if diatoms have been observed in the London clay, or not. If they have not, it may interest many to know that I have discovered triangular, quadrangular, elliptical, and discoidal forms in the London clay of Sheppey. The frustules are frequently perfect, and the markings are plainly discernible as square-sided depressions or elevations; I am not certain which. One of the discoidal forms is an old friend, for I observed it in abundance two years ago; but as I then had no knowledge of diatoms, I passed large quantities by as pyritous concretions.