JOURNAL 



OF THE 



ROYAL MICROSCOPICAL SOCIETY. 



JUNE 1881. 



TRANSACTIONS OF THE SOCIETY. 



VI - — The Diatoms of the London Clay. By W. H. Shrubsole, 

 F.G-.S. With a List of S]jecieSf a7id Retnarks. BylF. Kitton, 

 Hon. F.RM.S. 



(Bead 13th April, 1881.) 



Plate V., Fig. 1. 



In 1877-8 I carefully watched the sinking of a well at Sheerness, 

 and embodied the results of my observations in a paper published 

 in the 'Proceedings of the Geologists' Association,' vol. v. p. 355. 



One day, when examining clay from the shaft, I noticed 

 some forms which I afterwards ascertained were Foraminifera, and 

 being desirous of finding more species of that group, the possibility 

 of meeting with other microscopical organisms did not occur to me. 

 When, therefore, I saw in the clay at a subsequent period, small 

 disks, apparently of pyrites, I noted the fact, but did not examine 

 them further. Being familiar with the manifold forms in which 

 pyrites occurs in the London clay, I concluded that these disks were 

 but concretions of that mineral on a small scale. 



In the paper referred to, I described them as " very minute 

 disks of iron pyrites, each having a boss in the centre, and having 

 the edge slightly turned uj) all round. They ivere 'perfectly uni- 

 form (by a mistake, the words were printed ' uniformly perfect '), 

 as mueh so as if cast in one mould,'' and it is strange, therefore, 

 that some one acquainted with diatoms (which at that time I was 

 not) did not point out that the description given would in some 

 respects apply to many of the discoidal forms of the Diatomaceae. 



Subsequently, after I had found diatoms in the sand and mud 

 along the coast of Sheppey and elsewhere, I repeatedly examined 

 the London clay in the hope of finding kindred forms, always 



EXPLANATION OF PLATE V., Fig. 1. 



Fig. I. — London clay with diatoms in situ (from a drawing liy Mr. A. Ham* 

 niond, F.L S.) x about 100. 



Rer. 2.— Vol. I. 2 D 



