246° THE MEDALS OF CREATION. Cuap. VIL. 
of the mass appears to have been sufficiently flexible to ex- 
pand and contract without laceration. This opinion is based 
ee eG, ba 
on the fact, that in many specimens the zoophyte is anearly — 
flat circular disc (Lign. 81, figs. 1, 2) ; and in others a sub- — 
cylindrical pouch. In the former state the outer reticulated — 
structure is elongated, while in the latter, it is corrugated ; 
hence I am led to conclude that the original possessed a 
common irritability, and was able to contract and expand 
like many of the flexible polypiaria. The openings on the 
inner surface are cylindrical, and very regular ; the flints 
often present sharp casts of them, which appear like rows 
of minute pillars. When the flint filling up the cavity of | 
a Ventriculite can be extracted, it is a solid cone, studded 
with papille, the casts of the cells, as in Lign. 82, fig. 4. 
In the flints, the substance of the Ventriculites is gene- 
rally as translucent as that of the Choanites, and defined by 
its rich purple, sienna, or grey colour ;* but towards the 
base and margin it is more or less calcareous ; and in many 
examples the whole, or a large portion of the zoophyte, is in 
this state. But this fact does not invalidate the inference 
that the original was flexible; for in these instances the 
tissues may have been immersed in fluid chalk before their — 
envelopment in flint.f The chalk specimens are commonly 
A 
as friable and earthy as the surrounding stone, from which | 
they are distinguishable by their ochreous colour. 
The stain always observable in the tissues of the chalk — 
Ventriculites and other zoophytes, while the surrounding 
* Pict. Atlas, pl. xlv. fig. 9, represents a beautiful transverse sec- — 
tion of the lower part of a Ventriculite in flint, richly coloured. PI. 
xliii. fig. 16, is a pebble containing the base of a Ventriculite; the 
orifices on the top have been produced by the transit of the radicle 
processes ; for the fossil is drawn in an inverted position, a common 
error before the origin of these flints was ascertained. 
+ A piece of sponge dipped in liquid plaster of Paris, and after- 
wards inclosed in a transparent substance, as glass, would present 
such an appearance. 
