of the AUunium in India. 311 



flat pieces of tufFaceous limestone loose on the surface. These 

 bones are silicified." ..." The third spot is about 150 yards 

 from the last ; and here I found dicotyledonous wood only. 

 . . . They lie on the black regur soil ; and I see nowhere 

 else that they could have come from but out of it " (Geol. 

 Papers, op. cit. p. 766). It would therefore appear that, in 

 some parts, the organic remains of the regur have become 

 transformed into kunker, which, under the circumstances, 

 does not appear extraordinary. 



Thus we have the kunker lying in loose nodules on the 

 surface, occurring in seams like flints ; appended to or enclosing 

 organic remains, or in the form of layers embodying hetero- 

 geneous material ; sometimes transforming the organic remains 

 of the regur into its own substance. Hence, if we were to 

 substitute the terms " flint " and " chert " for the nodular 

 and so-called " sheet " kunker, the desci-iption would apply 

 equally well, mutatis mutandis^ to the Upper Chalk and 

 Greensand. 



Now, as regards the flints and chert, I happen to be living 

 on the New Red Sandstone (at Budleigh-Salterton, Devon) 

 where the surface is covered generally with the silicified 

 debris of the Upper Chalk and Greensand which once over- 

 lay it in their integrity ; and I observe that, together with other 

 fossils, there are a great number of sponges, especially belong- 

 ing to the Lithistina (Prof. Zittel's " Megamorina " and " Te- 

 tracladina "). Taking one of these I find : — 1st, that a flint 

 may be appended to it ; 2ndly, that the flint may enclose it ; 

 3rdly, that the flint may have so extended into it as to oblite- 

 rate all trace of the structure of the Lithistid ; 4thly, that a 

 mould only of the Lithistid structure may remain in the in- 

 truding flint j further, that in most cases the flint is homo- 

 geneous and nodular, while, on the other hand, the fragments 

 of chert are heterogeneously composed and tabular — indica- 

 ting that the former was more exclusively concretionary than 

 the latter. On the surface of some enclosed specimens of 

 Lithistina that I have knocked out from flint, the stelliform 

 discoid stage in the development of the lithistid spicule re- 

 mains on the surface, showing that nothing more than the 

 thin, circular, discoid, one had disappeared, which is a com- 

 mon occurrence even among recent specimens. 



Apart, however, from the siliceous material which we call 

 " flint," there may be a simple silicification of a calcareous 

 shell, which would be a facsimile of the original form. Or, as 

 I have shown in the sponge-spicules from the Carboniferous 

 Limestone near Glasgow in Scotland, and Sligo in Ireland, 

 respectively, the original material of the organic remains may 



