194 PETRIFIED SHELLS, &c. 



It is a remarkable fact, that the only remains of animals hitherto dis- 

 covered in India, should be fomid in trap rocks, and under quite peculiar 

 circumstances. 1st. They are found in situations where there are no 

 indications of the former existence of lakes. 2d. Both the shells and 

 matrix are destitute of carbonic acid. 3d. The former are, in many 

 instances, squeezed flat without fracture, and, in some cases, completely 

 commixing with their matrix. 



g These effects could only have been produced by the agency of heat, 

 and, consequently, the modern theory of sub-marine or sub-aqueous volca- 

 noes, will best serve to explain the phenomena. These shells were depo- 

 sited in the stratum of clay in which they are now found, and when forced 

 up by the mass of wacken beneath, they were, most probably, at the same 

 time covered by the nodular basalt. Thus we have heat, to drive off the 

 carbonic acid and soften the shells under a pressure, which assisted the 

 process, and, at the same time, flattened them, 



ni I have too numerous collateral proofs of the intrusion of the trap 

 rocks in this district, amongst the gneiss, to allow me to doubt of their 

 volcanic origin. I shall take an early opportunity of completing the his- 

 tory of the trap rocks of India, for which I have collected materials for 

 several years past. 



11 



XII. 



