OF SELBORN E. 
7 
L E T T E R IIT. 
- TO THE SAME. 
The foffil-fhells of this diftrid, and forts of flone, fuch as 
have fallen within my obfervation, muft not be paffed over in 
filence. And firft I muft mention, as a great curiofity, a fpecimcn 
that was plowed up in the chalky fields, near the fide of the Dozvn, 
and given to me for the fingularity of it's appearance, which, to an 
incurious eye, feems like a petrified fifli of about four inches long, 
the cardo paffing for an head and mouth. It is in reality a bivalve 
of the Linn^ean Genus of Mytilus, and the fpecies of Cr'ijla Galli; 
called by Lifter, Rajlellum; by Rumphius, OJlreum pUcatum minus ; 
by D' Argenville , Juris Porci, f. CriJIa Galli; and by thofe who make 
colledlions cock's comb. Though I applied to feveral fuch in 
London, 1 never could m.eet with an entire fpecimen ; nor could 
I ever find in books any engraving from a perfed one. In the 
fuperb mufeum at Leicejler-houfe permiffion was given me to exa- 
mine for this article; and, though I was difappointed as to the 
foffil, I was highly gratified with the fight of feveral of the fiiells 
themfelves in high prefervation. This bivalve is only known to 
inhabit the Indian ocean, where it fixes itfelf to a zoophyte, known 
by the name Gorgonia. The curious foldings of the future the one 
into the other, the alternate flutings or grooves, and the curved 
form of my fpecimen being much eafier expreflTed by the pencil 
than by words, I have caufed it to be drawn and engraved. 
Cornua Ammonis are very common about this village. As we 
were cutting an inclining path up 'The Hanger, the labourers found 
them 
