284 Scientific Intelligence. 
origin but regularly stratified and alternating with marls and | 
In September, 1855, 1 visited with Elie de Beaumont and several mem 
urged in this Journal (vol. xxviii, p. 365) upon the dite 
gypsum. For a report of my remarks on that oceasion see the Bm 
de la Société Geologique de France, [2], xii, 1806, 
I have subsequently shown in the memoir just cited in the last volun 
of this Journal that the formation of these stratified gypsums by 
double decomposition of bicarbonate of lime and sulphate of 
involyes the production of carbonate of magnesia, which unless ¢@ 
ll be found to 
specimens, one penetrated by seams of gypsum, gav 
per cent of dolomite mingled with clay. The Paris gypsums 
no exception to the genera} rule. ; nos 
ath the oy sateen series and in the lacustrine gro 
the lower travertine, or St. Owen limestone, occur beds > (opal), and 
very fissile, shaly matter, enclosing concretions of nee hey 
consisting of a hydrated silicate of ie asy identical wi 
may be div 
formed in the mois’ on ks 
__ I propose to send you very soon a supplement to my so : 
describing some recent & 
