FOSSIL FAUNA. 99 



PLATE XL. 



Fossil Corals, &c. 



Fig. 1. The shells of Oysters, and other moUusca, are subjected to the ravages of a parasitical 

 sponge, {Cliona, of Dr. Grant,) which is beset with minute siliceous spines or spicula, 

 and inhabits hollows formed in the substance of the shell. Shells thus honeycombed, 

 as it were, may often be found on the sea-shore with the excavated parts filled up by 

 sponge. I have shells collected by my eldest son on the shores of New Zealand, that 

 are hollowed out in a similar manner, and occupied by sponge. Whether these cavities 

 are produced by mechanical means, or are the result of the decay and absorption of the 

 shell induced by the growth of the parasite, are questions still undetermined. There 

 are several kinds of shells found fossil, which were infested with a similar parasitical 

 sponge ; and when the cavities thus produced have been filled up by flint, and the 

 shell has subsequently decomposed, or been worn away, the surface of the flint is 

 studded with the casts of the cells, in the form of small irregular globular bodies, 

 connected by filaments or strings of flint. The fossil, fig. 1, is a fossil of this kind, 

 described by Mr. Parkinson as being " covered with minute round bodies, the nature 

 of which is unknown;" fig. 12, is an enlarged view of five of these globular casts 

 connected by filaments. 



The origin of these fossils was first pointed out by the Rev. W. C'onybeare.' The fibrouo 

 shells of a fossil genus of bivalves named Inoceramus, of which several species abound in the 

 Chalk, appear to have been particularly subjected to depredations of this kind. Hence among 

 partially water-worn flints, specimens of the siliceous casts are common; figs. 8, and 10, are 

 examples from the Hackney gravel-pits. 



Mr. Morris has named these fossils, Clionites ; fi^. 1, is C. Parkinsoni. 



Figs. 2, 4, 7, are portions of a recent species of jointed zoophyte (Isis), from a modern concre- 

 tionary deposit on the shores of the Mediterranean, Sicily. 



Fig. 3. A branched fossil coral (3IiUepora ramosa, of Dr. Fleming), imbedded in compact oolitic 

 limestone from Wiltshire. A portion of the surface magnified is represented in fig. 11. 



Fig. 5, appears to be a fungiform Spongite ; its locality is not mentioned. 



Fig. 6. Portion of a fossil coral \Ceriopora), from Switzerland. 



' See Medals of Creation, vol. i. p. 396, fig. 94. 



