30 ON A POST-TERTIARY LACUSTRINE SAND, 



above facts : indeed, I have rarely tried a sample from any 

 of these clays, either near a fresh or brackish stream, in which 

 a careful washing would not eliminate abundance of Diatoma- 

 ceous remains. Of course, some will be richer than others, 

 but I have found them in all. Let it not be thought that too 

 enthusiastic a view has been taken of the subject, I have 

 sent a set of slides illustrative of all the above-mentioned 

 deposits to the Editors of this Journal, and I think they will 

 bear me out in the assertion that neither their richness nor 

 their interest has been overstated.* 



From these facts it appears that not the surface merely, 

 but the whole mass of these tidal deposits, is penetrated by 

 these minute and wondrous organisms ; while from the fact 

 of their being found at Neyland at a depth of 40 feet below 

 the present surface, and close upon the rock which forms the 

 original bed of this estuary, the mind is irresistibly led to the 

 conclusion that they have existed there from the time when 

 the waters first rolled over the spot, when silence and soli- 

 tude reigned supreme where now resounds the " busy hum " 

 of the hundreds who are employed in bringing one of the 

 great arteries of commerce and civilization to its ocean home. 



In making out the list of the forms in the Neyland 

 deposits, I have carefully abstained from inserting the names 

 of any but those which I could identify with certainty, either 

 from Mr. Smith's work or from information furnished to me 

 by Mr. Roper, to whose kind assistance I am deeply indebted 

 during the time I have been studying the subject. Being but 

 a beginner in the study, I thought this the best plan to adopt; 

 but I am sure, from what I have observed, that were these 

 deposits well examined by other and more experienced inves- 

 tigators than myself, the list might be far more extended, and 

 many new forms brought to light. Still, if I shall have been 

 the means of drawing attention to the subject of these deep 

 deposits, or of extending in any way, however small, the 

 boundaries of this interesting field of research, I shall feel 

 amply recompensed for any trouble I have taken in this 

 matter. 



On a Post-Tertiary Lacustrine Sand, containing Diatoma- 

 CEOus Exuvi^, from Glenshira, near Liver ary. By Wil- 

 liam Gregory, M.D., F.R.S.E., Professor of Chemistry. 



This remarkable deposit was sent to me in February last by 

 the Duke of Argyll, who had found it in the valley of Glen- 



* The slides sent us by Mr. Okeden are uncommonly rich in the various 

 forms of Diatomacfice. — Eds. 



