in the Neighbourhood of Edinburgh. 275 
an included band of limestone, similar in mineral aspect to the lacustrine limestones 
of central France, and containing minute shells, referable to fresh-water genera.” 
Mr Murcutson has publicly pointed out to me this passage, which, from my 
residence abroad, I had not seen, but which I am sure, if I had read, would have 
escaped my recollection, from its apparently trivial importance. 
The reply which I have to make is, that if my discovery of extensive beds of la- 
custrine limestone is to be superseded by mere bands of fresh-water limestone, Mr 
Murcutson himself has been anticipated by other writers. The Rev. Mr Ung, in 
his History of Rutherglen, written at least forty years ago, states, in reference to 
certain fresh-water muscles, or unios, enclosed in a band of limestone, that “ the shells 
were commonly entire, and were probably produced in fresh water."—History of 
Rutherglen and Kilbride, p. 311. 
Granting, however, that Mr Murcutson’s limestone is thicker than what is 
usually meant by a band of limestone, the various limestones which I have enume- 
rated are not, like his, contained within beds of coal, but, on the contrary, form con- 
siderable deposits beneath beds of coal. This difference has been remarked by Mr 
De 1a Becur.—Geological Researches, p. 319. 
But waving these very subordinate considerations, I shall state in my own defence, 
that my memoir was drawn up at a time when many British geologists were inclined 
to admit, with a writer of the first weight, that no instance had yet been discovered 
of a pure lacustrine formation of the carboniferous era; and that although there 
were some instances of shells, apparently fresh water, which might have been washed 
in by small streams, they did not by any means imply a considerable extent of dry 
land. (See Lyexx’s Principles of Geology, 1st Ed. vol. i. p. 130, and vol. iii. p. 15.) 
My own discovery, however, of the fresh-water character of the limestone of Bur- 
diehouse, in conjunction with that of other similar limestones of still greater thick- 
ness and extent, viz. at Calder and elsewhere (See the Supplement to this memoir), 
have, I trust, tended to set geologists right upon the question of pure lacustrine de- 
posits existing during the carboniferous epoch. 
But after all,—these disputed claims of originality may neither belong to myself 
nor to any other British geologist. The far older speculations of M. Dretuc and of 
M. ALEXANDRE Bronenrarrt, refer all the varieties of strata comprehended in coal- 
measures to a lacustrine origin; while their theory upon the alternation of these 
strata with marine deposits has, in some few respects, coincided with the principles 
which I have sought to establish in the present memoir.—( Tableau des Terrains, 
par Bronenuret, p. 280, &c.) 
With a third charge I was industriously assailed during the meeting of the Bri- 
tish Association of Science at Edinburgh. It was contended that I had given an er- 
roneous position to the limestone. My present memoir will however show, that the 
view which I originally entertained on this question remains unaltered. I went over 
the ground with some of our most distinguished geologists, among whom was Dr 
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