AND STRUCTURE OF THE BELEMNITE. 403 



the precipitation might have been entirely siliceous, and then 

 beds, or parts of beds, entirely of flint, would have been form- 

 ed. The particles of silex, in gathering themselves into balls, 

 have occasionally drawn along with them some carbonate of 

 lime. Hence those masses are composed of two substances, 

 pure silex in the centre, and Silici-calce on the surface." 



" These flints, after their formation, having remained some 

 time in a state of softness, which permitted them to yield to the 

 compression occasioned by the weight of the superior masses, 

 seems to be indicated by their frequent flattened form, or per- 

 haps that form indicates, that the force which has united the 

 particles, assisted probably by this weight, has exerted its action 

 more in a vertical than a horizontal direction ; the siliceous 

 particles disseminated in a bed, in a state of semi-fluidity, will 

 have descended to the lower part of the bed, and there have 

 united." 



I confess it is difficult to follow the meaning of M. Dau- 

 buisson throughout this theoretical disquisition. I have en- 

 deavoured to render the quotations as intelligibly as possible, 

 but still there is much obscurity in what he says, particularly 

 respecting the descent of the siliceous particles, because 

 exposed to pressure. Unless he could have shown that that 

 pressure had acted more directly on the silex than on the 

 carbonate of lime which contained it, it is not easy to con- 

 ceive how it should have changed its position either up or 

 down. 



Although I have extended these extracts much beyond 

 what may appear to have been necessary j yet the materials, on 

 the whole, will be found meagre and unsatisfactory, and very 

 inadequate to afford any conclusive deductions on the forma- 

 tion of either Chalk or Flint. Some of them must be altogether 

 rejected ; but from others a few scattered hints may be elicit- 

 ed., 



