WHITE 



LETTER III 



THE fossil-shells of this district, and sorts of stone, such as 

 have fallen within my observation, must not be passed over 

 in silence. And first I must mention, as a great curiosity, a 

 specimen that was ploughed up in the chalky fields, near the 

 side of the Down, and given to me for the singularity of its 

 appearance, which, to an incurious eye, seems like a petrified 

 fish of about four inches long, the cardo passing for a head 

 and mouth. It is in reality a bivalve of the Linnaean Genus 

 of Mytilus, and the species of Crista Galli ; called by Lister, 

 Rastellum; by Rumphius, Ostreum plicatnm minus ; by D'Ar- 

 genville, Auris Porci, s. Crista Galli; and by those who make 

 collections, Cock's Comb. 1 Though I applied to several such 

 in London, I never could meet with an entire specimen ; nor 

 could I ever find in books any engraving from a perfect one. 

 In the superb museum at Leicester House, permission was 

 given me to examine for this article; and, though I was dis- 

 appointed as to the fossil, I was highly gratified with the sight 

 of several of the shells themselves in high preservation. This 

 bivalve is only known to inhabit the Indian Ocean, where it 

 fixes itself to a zoophyte, known by the name Gorgonia. The 

 curious foldings of the suture the one into the other, the alter- 

 nate flutings or grooves, and the curved form of my specimen 

 are much easier expressed by the pencil than by words. 



Cornua Ammonis 2 are very common about this village. As 

 we were cutting an inclining path up the Hanger, the labor- 

 ers found them frequently on that steep, just under the soil, 

 in the chalk, and of a considerable size. In the lane above 

 Wall-head, in the way to Emshot, they abound in the bank in 

 a darkish sort of marl ; and are usually very small and soft : 

 but in Clay's Pond, a little farther on, at the end of the pit, 

 where the soil is dug out for manure, I have occasionally ob- 

 served them of large dimensions, perhaps fourteen or sixteen 

 inches in diameter. But as these did not consist of firm stone, 

 but were formed of a kind of terra lapidosa, or hardened clay, 

 as soon as they were exposed to the rains and frost they mould- 

 ered away. These seemed as if they were a very recent pro- 



