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 beinsr 

 mineralized. Thus a silicefied oyster in the centre of the shell is 

 described by Von Buch ; 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 



