PLATE XLI.
A Silicified cup-shaped Sponge, from Touraine.
(Chenendopora Parkinsoni, of Michelin.
Spongites Townsendi, of Mantell.)
This beautiful plate of a petrified zoophyte allied to the Spongia, formed the frontispiece to Mr. Parkinson's second volume. The fossil delineated is from Touraine in France, and is one of the most perfect examples of this kind hitherto observed. It belongs to a group of cup-shaped Amorphozoa, (as these organisms are now named by naturalists, from the great irregularity of shape which they assume,) termed Chenendopora. The original organic substance is transmuted into silex, and the interstices are filled up with carbonate of lime. The same species occurs in the greensand in the Vale of Pewsey in Wiltshire, and, I believe, also in the white-chalk; for many cyathiform flints from the South Downs appear to have the same internal structure.
In the so-called "gravel-pits," near Faringdon, in Berkshire,—which are quarries of a loosely-aggregated grit of the greensand, almost wholly made up of the relics of shells, corals, amorphozoa, &c.—numerous sponges of this genus are met with. One beautiful species (Chenendopora fungiformis) has acquired, from its cup-like form, the local name of "petrified salt-cellar."[31]
[31] Wonders of Geology, vol. ii. p. 637; and Medals of Creation, "Excursion to Faringdon," vol. ii. p. 923.
Plate XLII.
