FOSSIL BODIES OF ROTALIÆ.
Fossil remains of the soft parts of Foraminifera. Lign. 113.—When examining chalk[325] and flint under the microscope with the view of discovering the fossil bodies described by M. Ehrenberg, I observed that the cells of the Rotaliæ in flint were frequently occupied by a substance varying in colour from a light amber to a dark brown, and closely resembling in appearance the body of the recent foraminifer deprived of its shell. Under a high power, the folds of the membranous sacs and the connecting tube were apparent, and I felt convinced that the substance filling the cells was not inorganic, but the original animal tissues in the state of molluskite.[326] In short, that the animal had become immersed and preserved in the fluid silex like the insects in amber. The appearance of the first discovered example of this kind is represented in [Lign. 117].
[325] In 1845.
[326] Molluskite: a name by which I proposed to distinguish the carbonaceous substance resulting from the soft bodies of testaceous mollusca.
Lign. 117. Rotalia in Flint, with the fossilized body of the animal in the shell: highly magnified.
(Seen by transmitted light.)
SOFT BODIES OF FORAMINIFERA.
In a paper read before the Geological Society in 1845,[327] I ventured to affirm the animal nature of the fossils in question; but the supposition was regarded by geologists as very startling and unsatisfactory; and as the specimens were enveloped in flint, the appearance was attributed to the infiltration of mineral matter of a different colour from the surrounding silex, into the empty chambers; a circumstance of frequent occurrence in Ammonites, Nautili, and even in the foraminifera; for the latter are often filled with chalk, flint, silicate of iron, crystal, &c. as in [Lign. 116]. In these instances, I conceive the shells were either empty when immersed in the fluid chalk or flint, or speedily became so by the decomposition of the soft parts of the animal. But in the fossils under consideration, I believe the live animal was suddenly enveloped, and hermetically sealed, as it were, in its shell, and that putrefaction was thus prevented. The uniformity in colour, and the structure of the substance in the cells, appeared to me incompatible with its assumed mineral origin, and I resolved to follow up the inquiry by an examination of Rotaliæ in chalk; in the hope that by dissolving the shell in acid (as in recent foraminifera), the body of the animal might be detected in an unmineralized state. After many fruitless attempts, several examples of the soft bodies of Rotaliæ were obtained from the grey chalk of Dover, in an extraordinary state of preservation.[328]
[327] Notes of a Microscopical Examination of the Chalk and Flint of the South-East of England, with Remarks on the Animalculites of certain Tertiary and Modern Deposits. Published in the Ann. Nat. Hist., Aug. 1845.