266 Dr Hibbert on the Limestone of Burdiehouse 



whatever, we find plants enclosed in a calcareous deposit in the 

 greatest profusion imaginable, what conclusion remains, but that 

 such a deposit is more indicative of a fresh-water river or lake, 

 than of a sea or estuary ? 



Other points of evidence are perhaps less forcible, although 

 they all tend to the same conclusion. 



We find, for instance, that if the inland waters which depo- 

 sited the limestone of Burdiehouse, were actually unfavourable to 

 the existence in it of acknowledged marine mollusca or conchi- 

 fera, they were not unfavourable to countless myriads of ento- 

 mostraca, one genus of which, the Cypris, is the recent inhabi- 

 tant of fresh- water marshes ; and it may be fairly suspected that 

 other genera associated with it were equally so. 



I will not at present dwell upon the presence of the fish dis- 

 covered in the Burdiehouse limestone, although some of the ge- 

 nera are found enclosed not only in such sandstones and shales 

 as are crowded with plants, but even in coal itself. I shall here- 

 after shew, that if their presence does not afford an analogical 

 proof, it is at the least circumstantially presumptive, that the 

 Burdiehouse limestone has had a fluviatile origin. 



In short, the evidence, in a general point of view, leads to the 

 following conclusion. 



There are, it is well known, numerous deposits of limestone 

 belonging to the carboniferous group of rocks, in which, to the 

 exclusion of any vegetables of a Tropical Flora, nothing but ma- 

 rine products, such as corallines, or acknowledged shells of ge- 

 nera hitherto found in open seas only, have been discovered. 

 With a calcareous deposit of this kind, the comparison of another 

 calcareous deposit, destitute of all corallines or marine shells 

 whatever, yet containing, in an abundance perfectly remarkable, 

 the plants of tropical marshes, along with the entomostraca of 

 marsh waters, can surely lead to no other conclusion but the fol- 

 lowing : — That while the first formation must have taken place 



