in the Neighbourhood of Edinburgh. 267 
in a pelagic bed analogous to one of recent times, the other must 
have been the result of a fresh-water deposit, which, while it was 
no less hostile to the growth and increase of marine shells or co- 
rallines, must have flowed through marshy tracts, wherein grew 
all the plants observable in our coal-fields. Accordingly, in com- 
paring the limestone of Burdiehouse with such a limestone as we 
find at Aberlady, which appears to be formed of one almost. un- 
interrupted aggregate of coralline productions, or with the conti- 
guous encrinitic limestone of Gilmerton, or with a zone of lime- 
stone filled with numerous varieties of marine remains, which crops 
out in a line of nearly SS.W. to NN.E., from Bathgate to Lin- 
lithgow, what doubt can remain, that while the limestone of 
Burdiehouse is of fresh-water origin, that of the other sites enu- 
merated must be of marine origin ? 
But it is not with such unequivocal marine deposits, that I 
would dwell long for a comparison, as the line of demarcation is 
but too obvious. I would prefer drawing a line of difference with 
such a limestone as I have studied in Derbyshire, which is illus- 
trative of an estuary. 
The lowest visible portion of the great mass of Derbyshire 
limestone may be seen at Sherbrook, near Buxton. It is very 
crystalline, unstratified, and it contains no organic remains what- 
ever. In the beds above it stratification commences, and the 
limestone encloses numerous encrinites, corallines, producti, &c. 
In still higher beds, such as we find at Ashford, indications are 
rather afforded of a marine estuary, than of an uninterrupted or 
open sea. Although this limestone abounds with acknowledged 
marine productions, among which corallines are pre-eminent, I 
discovered that in some sites the plants of coal-fields were mixed. 
with them, although very sparingly. Among various plants which 
I collected, one of them was the Sphznopteris artemisizfolia of 
Avotrne Bronenrart (See Pl. 46. of his “ Histoire des Vege- 
tauw Fossiles.”.) Other species, some of them new, and perhaps 
L12 
