Organic Remains of Burdiehouse. 295 
It would therefore seem that the coprolites of the limestone 
actually contain less foreign matter, or are less altered from their 
original nature in so far as regards solid contents, than the bones 
or scales; and this fact admits, I think, of a ready explanation. 
When a solid compact body, possessing a structure such as a bone 
or scale, has been imbedded in any situation in which water, hold- 
ing solid matter in solution, has access to it, we may expect that, 
in the lapse of time, the perishable animal matter which it con- 
tains will disappear, whilst the dissolved solid matter will be de- 
posited, by infiltration, and occupy its place, the original solid 
structure, more especially when aided by the solid organic earths, 
forming a kind of frame-work, on which the deposition will take 
place. This is just the process by which ordinary petrifying 
springs convert organic objects into the substance held in solu- 
tion. But fecal matter, being composed of the residue of di- 
gested food, and being destitute of structure or solidity, will not 
present such a frame-work. The perishable animal matter will 
simply decay, whilst its place will not be occupied by a substitute ; 
the solid animal earths will simply agglomerate into a compact 
mass ; and. therefore we shall expect to find them,—what they 
really appear to be as imbedded in the limestone of Burdie- 
house,—masses of durable animal earths, having only a compara- 
tively small admixture of foreign mineral matter. 
Cases, indeed, sometimes occur of soft animal matter being 
mineralized. Thus a silicefied oyster in the centre of the shell is 
described by Von Bucu; and Lord Greenock informs me that 
he possesses another similar fossil ; but such instances are admit- 
ted by naturalists to be comparatively very rare. 
Amongst all the fossil remains of Burdiehouse which have 
been the subject of these remarks, the phosphate of lime is pre- 
served as the standard of comparison ; and we have every reason 
to believe that whatever changes may have occurred in the na- 
ture or proportions of the other constituents, this one continues 
firm and invariable. Well, therefore, might it be called by Dr 
