400 PROCEEDINGS oE THE GEOioGiCAL socrETY. [May 22, 



In conclusion, I have great pleasure in thanking the Rev. Mr. Bon- 

 ney, of St. John's College, for the kindness he has shown me in many 

 ways throughout this investigation. 



DisctrssloN. 



Prof. Phillips was glad that his casual remark had produced 

 such satisfactory results as the papers he had heard. It was satis- 

 factory to find that the bulk of the phosphatic nodules exhibited 

 such marked traces of an organic origin. Though he had to some 

 extent been prepared for this, it appeared that the view might be 

 extended much further than would at first sight have been antici- 

 pated, lie drew an analogy between the preservation of the forms 

 of sponges in their silicified fossils with that of the soft organic 

 bodies in the Greensand by phosphatic matter. In each case the 

 surrounding water contributed a large amount of either flint or 

 phosphate of lime, whinh was segregated and accumulated round 

 certain centres or nuclei of organic bodies. 



Prof. Ramsay inquired from what sources the abundance of phos- 

 phatic matter requisite for the production of these fossils could have 

 been derived. In such thin strata, which seemed to indicate a 

 transition from a land to a marine surface, it was a matter of great 

 difficulty to his mind to account for so great an abundance of phos- 

 phatic matter. 



Mr. GonwiK-AusTEis^ remarked that phosphoric acid was largely 

 present in sea-water, and instauced the present seas, where, as on 

 the Newfoimdland banks, fish existed in enormous quantities, and 

 no doubt also phosphatic matter. The Cambridge beds, though 

 so rich, were by no means unique of their kind. He referred to a 

 paper communicated some years ago to the Society by Mr. Payne, 

 as afli'ording many interesting particulars with regard to such beds. 

 He considered that much of the phosphate attaching to decaying 

 animal matter might have been derived from comminuted excre- 

 mentitious deposits floating in the water. 



The Rev. T. G. Bostney remembered a fact quoted by the late 

 Dr. Mantell as to the large quantities of dead Mollusca which had 

 been observed floating down some of the American rivers, and 

 which had been regarded as a plentiful source of phosphatic matter. 

 Small fishes might also have furnished a considerable quantity, and 

 their value as manure was recognized at the present day. With 

 regard to the nodules being Alcyonaria or sponges, he observed that 

 what spicules he had seen appeared more like those of sponges. He 

 agreed with Mr. SoUas as to the foraminiferal origin of many of the 

 green grains. He did not agree with Mr. Pisher in attributing all 

 the nodules to the bed in which they were found, but thought that 

 a considerable portion might be referred to the upper part of the 

 Gault. In proof of the washing the Gault near Cambridge had 

 undergone, he mentioned the occui'rence there of a number of 

 boulders of rocks quite foreign to the district. 



