[328] To Henry Deane, Esq. of Clapham Common, I am indebted for some of the most illustrative specimens hitherto obtained.
Lign. 118. The Soft Bodies of Foraminifera; extracted from Chalk: highly magnified.
(Viewed by transmitted light.)
| Fig. | 1.— | An exquisite example of the body of a Rotalia; the sacs partially collapsed. |
| 2.— | Body of a Rotalia; the sacs distended with a dark granular substance. |
These marvellous relics were obtained by subjecting a few grains of the chalk to the action of weak hydrochloric acid, by which the calcareous earth and the shells it contained were dissolved; the residue, consisting of particles of quartz and green silicate of iron, and remains of the animal tissues, were placed, in the usual manner, in Canada balsam. Two exquisite specimens of the bodies of Rotaliæ thus obtained are figured in [Lign. 118].[329]
[329] I communicated this discovery to the Royal Society. See Philos. Transactions, 1846, p. 465.
In these fossils the sacs are generally more or less distended with a dark substance, as in [Lign. 118, fig. 2]: but in some, they are empty and collapsed in folds, just as membranous pouches would appear under similar conditions; as in the exquisite fossil, [Lign. 118, fig. 1].
The sacs regularly diminish in size from the innermost to the outermost cell, and vary in number from fourteen to twenty-six; being more numerous than in the recent species of Rotaliæ that have come under my notice. In some instances small papillæ are seen on the outer surface of the integument; apparently the vestiges of the pseudopodia.[330]