Among the flints whose forms depend on the organic bodies they enclose, are some which bear so close a resemblance in shape to Fungi, that they are provincially called in Sussex "petrified mushrooms;" several of them are figured above ([Lign. 25]). In these fossils there are openings at the base, and a groove on the margin of the upper part, in which the structure of the enclosed body is generally more or less distinctly seen; and upon breaking one of these bodies, a section of a funnel-shaped zoophyte is obtained. The origin of these flints will be understood by reference to the four interesting specimens here delineated, one-sixth of the natural size in linear dimensions.
Lign. 26:—Ventriculites from the Chalk, Lewes.
| 1. | A perfect specimen in Chalk, shewing the external net-like surface. |
| 2. | An expanded specimen, displaying the inner surface studded with cells. |
| 3. | A Ventriculite with the lower part enveloped in Flint. |
| 4. | Part of a Ventriculite; the base invested with Flint: the root-like fibres are seen at a. |
VENTRICULITES.
This zoophyte, to which the name of Ventriculite has been given to denote its usual shape, was a hollow inverted cone, terminating at the base in a point, whence radicles or root-like processes were sent off, by which the animal was firmly attached to the rock. The outer integument was disposed in meshes like a net (see [Lign. 26, fig. 1]), and the inner surface was beset with regular circular openings, the orifices of tubular cells ([fig. 2]); each of which was probably occupied by a polype. The substance of the Polyparium, or general support of this family of animalcules, which alone occurs in a fossil state, appears to have been analogous to that of the soft Alcyonia, and to have possessed a common irritability; the entire mass contracting and expanding, as is the case in many recent zoophytes.[AQ]
[AQ] See 'Wonders of Geology,' 6th Ed., p. 610; 'Medals of Creation,' p. 273-276; and 'Geological Excursions round the Isle of Wight,' pp. 179-184, for an account of the silicification of these and other Zoophytes.
The flints, [figs. 3, 7, 8, 9, Lign. 25], were evidently formed in the manner exemplified in [fig. 3, Lign. 26]; figs. 2, 4, 6, are illustrated by [fig. 4, Lign. 26]; for the chalk specimens, [Lign. 26], shew that all these flints have been moulded around Ventriculites, and that their diversity of figure has arisen from the quantity of silex that happened to permeate the substance of the zoophyte; if but a small portion, flint like figs. 2 and 4, were the result; if the quantity were considerable, the larger fungiform examples were produced.