74 Dr. G. A. Mantell on the Animaleulites of the 
been laid before this Society. My friend the Rev. J. B. Reade 
(of Stone, Bucks),a gentleman well-known as an eminent observer, 
was the first to investigate the flints of the English chalk in 
search of those curious bodies termed Xanthidia ; several species 
of which were discovered by him, and are figured and described in 
the ninth number of the ‘ Annals of Natural History.” Mr. H. 
Hopley White subsequently pursued the inquiry, and contributed 
a notice on flint Xanthidia to the first vol. of the ‘ Microscopical 
Journal,’ illustrated with figures of several new forms. 
Many interesting remarks on the microscopical examination of 
flint and chalk by Mr. Reade are inserted in the fourth edition 
of my ‘ Wonders of Geology,’ as well as in my recent work, ‘ The 
Medals of Creation’; which also contains an account of some dis- 
coveries by my assistant Mr. Hamlin Lee, and by my son*. 
I propose on the present occasion, to lay before the Society the 
general results of a microscopical examination of numerous spe- 
cimens of chalk and flint, from the south-east of England, with 
the hope of exciting those who have more leisure and greater 
ability than myself, to pursue the inquiry, and not from an undue 
estimate of the importance of the facts embodied in this commu- 
nication. 
With a view to conciseness, it will be convenient to arrange 
my observations under three heads, viz.— 
I. On the organic composition of the white chalk. 
II. On the organic structure and minute fossil bodies of chalk 
flints. 
III. On the animaleulites of the tertiary strata of England; 
and on the occurrence in the British seas of livmg genera and 
species of infusoria, identical with many that occur fossil in the 
miocene deposits of Virginia. 
I. On the White Chalk.—Mr. Lonsdale long since demon- 
strated that the white chalk of England was largely constituted 
of minute shells, corals, and foraminifera, which bodies might be 
readily detected by brushing the chalk in water and collecting 
the sediment ; but it was not at that time suspected that almost 
the whole of the residue of the detritus was composed of distinct 
organisms, so minute as to require the highest magnifying powers, 
and a peculiar mode of manipulation, to develope and define. 
Ehrenberg, who has determined several hundred species of ani- 
malculites from the chalk, states that some layers of that lime- 
stone are so rich in fossil remains, that a cubic inch is made up 
of at least one million of recognizable forms. In his memoir 
“On numerous Animals in the Chalk Formation which are 
still to be found m a livmg state,” are particularized all the 
* See ‘ Medals of Creation,’ vol. i. chap. vii. 
