360 THE MEDALS OF CREATION. Cuar. X- 
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 Rotaliz thus obtained 
are figured in Lign. 118.* 
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 Rotaliz that have come under my notice. In some 
instances small papillee are seen on the outer surface of the 
integument ; apparently the vestiges of the pseudopodia. T 
Not only is the form and general character of the animal 
substance preserved, but even its flexibility ; for in one 
instance, the body, released by the solution of the chalk and 
shell, was uncoiled and pressed out, as shown in Lign. 119, 
Jig. 4. 
In one specimen, (figured in Philos. Trans, 1846, pl. xxi, 
fig. 10,) the membrane of the largest sacs is much corru- 
gated, and disposed in numerous duplications, probably 
owing to the empty state of these segments, when immersed 
in the chalk; but the discoidal contour of the original is 
* I communicated this discovery to the Royal Society. See Philos, 
Transactions, 1846, p. 465. 
+ Admirably as my excellent engraver, Mr. Lee, (of Prince’s Square, 
Kennington,) has executed the lignograph, 118, I would refer the 
reader to the steel plate in Philos. Trans. 1846, pl. xxi. for figures of 
these marvellous fossils, 
