“CHALK ANIMALCULITES, 30a 
corals, and foraminifera might be obtained in abundance ; 
but it was not at that time suspected that the residue of the 
detritus was almost entirely composed of distinct organic 
_ structures, so minute as to require high magnifying powers, 
anda peculiar mode of manipulation, for their detection and. 
definition. 
_ M. Ehrenberg demonstrated that even the fossils disco- 
vered by Mr. Lonsdale are colossal, in comparison with the 
infinitesimal structures of which the finer particles of the 
a chalk consist ; for one cubic inch of the limestone is found 
. contain upwards of a million of well-preserved animal 
organisms. 
q _ The chalk, therefore, is an aggregation of extremely minute 
fossils and inorganic eae The yellow, soft, writing 
F chalk of the North of Europe, according to M. Ehrenberg, is 
Beomposed of about half its mass of organic remains ; but in 
“the chalk of the South of Europe, the fossils prodeeatna 
The amorphous atoms of the cretaceous limestone do not, as 
was formerly believed, arise from a precipitate of lime pre- 
‘viously held in solution, but from the disintegration of the 
Bisiembled organisms into more minute calcareous particles ; 
and these have subsequently been reunited by a crystalline 
action, into regular, elliptical, granular, bodies. 
_ M. Ehrenberg infers that the compact flint nodules have 
originated from an aggregation of pulverulent particles of 
‘siliceous organisms ; and upon this hypothesis explains the 
absence of flint nodules, and the abundance of siliceous infu- 
soria, in the beds of marl that alternate with the chalk in 
‘the south of Europe, and their presence in the chalk of 
“northern Europe, in which the marls are wanting. In other 
words, he supposes, that in the former case the siliceous 
shells of the animalcules were spread abroad and deposited 
in layers or strata ; and in the latter were aggregated into 
edule: masses. This opinion is not, however, supported by 
facts ; for, though the animal origin of lime, flint, and iron, 
= VOL. I, AA 
