Conglomerates, and Marls of Devonshire 
21 
everyone knows to his cost -who has collected fossils which require 
to be polished, it is possible that the nucleus might have received 
the silex it contains in common with the bed of limestone of which 
it was a part, and, therefore, before the deposition of chalcedony on 
its surface, by which it was converted from a common limestone 
pebble into a Beekite. Probably the siliceous character of some of 
the nuclei may be attributable to one of these modes and some to the 
other, but it does appear certain that the crust was deposited on the 
surface and was in no way derived from the nucleus as has been 
sometimes supposed. I recently met with a fact strikingly confirm- 
atory of this. I found a Beekite, or rather two, formed on the two 
portions into which a stone had been broken, apparently after the 
cementation of the conglomerate had taken place ; the fragments were 
so nearly in contact, and fitted each other so perfectl}^ that no doubt 
of their having been originally united could be entertained. The 
two additional surfaces which had been formed by the fracture were 
coated vdih. chalcedony in the ordinary manner. 
On whatever surface chalcedony is deposited it appears in most, 
perhaps in all, cases to assume a tubercular character, hence the 
tubercles on the surface of the Beekite ; but whilst this property 
will always be present, the exact arrangement will probably depend 
somewhat on the nature of the surface on which it is deposited. 
Suppose decomposition to commence at various points or centres on 
the surface of the calcareous pebble, the chalcedony deposited on 
these points would form the central tubercles ; let the decaying 
process extend from and around these centres, the chalcedony 
deposited around each tubercle would form a ring ; in like manner a 
succession of rings would be formed until they touched, after which 
a more comprehensive one might invest two or more of the systems 
already formed, until the whole surface was covered. Should the 
centres of decomposition be at veiy different distances on different 
specimens, or on different parts of the same specimen, this w^ould 
produce the different scales of the type on which, as has been said, 
the chalcedony is sometimes arranged. 
In a paper on " The Composition, Structure and Formation of 
Beekite," by Mr. Arthur H. Church, F.C.S.,=:< the following analysis 
of Beekite (i. e. the chalcedonic crust) are given. 
Philosophical Magazine for February, 1862. 
