GENERAL ACCOUNT OF THE DEPOSITS. 15 



stopped by the stalagmite, which would slowly absorb the water 

 and allow time for the chemical reactions which resulted in the 

 phosphatizing of a portion of it." 



With such additional supporting evidence therefore I have no 

 hesitation in receiving the theory of Mr Holmes as the true expla- 

 nation of the origin of the phosphate of lime in our Neocomian 

 nodules. 



There yet remains however one remarkable fact left quite un- 

 accounted for by this theory, that is, the condition of the derived 

 fossils and fragments from the coral rag of Upware. 



These limestone fragments are not in the least phosphatised, 

 but are quite in their original condition as now seen in the coral 

 rag quarries ; and yet the fragments are imbedded well in the 

 heart of the coprolite bed. I can only suggest that this purer 

 carbonate of lime was uncongenial to the phosphatic matter, which 

 was taken up more readily by the more argillaceous fragments. 



