239 
effervescence, at the same time red fumes were given off, due, 
doubtless, to the presence of Pyrites. Analysis showed it 
to consist of 
Silica, Soluble 43°10 
Ferric Oxide and Alumina 26:07 
Ferrous Carbonate 10°41 
Tron Pyrites 1°52 
Potash 4°41 
Lime 1:89 
Magnesia 1:79 
Water 9°34 
100: 
He considered that there had often been a mistake made 
in reporting the amount of Carbonate of Lime in these Marls. 
The absence of such a substance was known by the want of 
action of the Acetic Acid, Nitric Acid however acted upon 
the Ferrous Carbonate, as was demonstrated. This specimen 
was from Prof. Cook’s “ Middle Bed,” which runs parallel to 
the Atlantic coast. The mode of analysis he had used was 
by grinding it up very finely with hot Oil of Vitriol when 
the green color disappears and a white, pasty mass results, 
consisting for the most part of the Silica. Examination with 
a lens, shows the casts of Foramenifera very perfectly 
preserved. 
Pror. A. M. Epwarps said that these casts of the 
chambers of Foramenifera were not confined to the Green- 
sand marls, as had been shown by the late Prof. Bailey. It 
was Prof. Ehrenberg who first pointed out the character of 
these green grains, and that they had been formed by the 
infiltration of Ferruginous Silicates into the chambers of 
the Forameniferous Shells, so that the animal matter which, 
during life, occupied that space was replaced by the mineral 
matter. He had found that these green grains were distribu- 
ted in various strata, from the Silurian to the Tertiary. In 
1857, Prof. Bailey showed that the same mode of replace- 
ment was taking place within the shells of the Foramenifera 
of the present day, for when specimens of those brought up 
