THE NATURAL HISTORY 
[LETT. 
one into the other, the alternate flutings or grooves, and the 
carved form of my specimen are much easier expressed by the 
pencil than by words. 
Cornua Ammonis are very common about this village. As 
we were cutting an inclining path up the Hanger, the labourers 
found them frequently on that steep, just under the soil, in the 
chalk, and of a considerable size. In the lane above Well-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 observed 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 mouldered away. These 
seemed as if they were of very recent production. In the 
chalk-pit, at the north-west end of the Hanger, large nautili 
are sometimes observed. 
In the very thickest strata of our freestone, and at con- 
siderable depths, well-diggers often find large scallops ovpectines, 
having both shells deeply striated, and ridged and furrowed 
alternately. They are highly impregnated with, if not wholly 
composed of, the stone of the quarry. 
LETTER IV. 
TO THOMAS PENNANT, ESQ. 
As in a former letter the freestone of this place has been only 
mentioned incidentally, I shall here become more particular. 
This stone is in great request for hearthstones and the beds 
of ovens ; and in lining of lime-kilns it turns to good account ; 
for the workmen use sandy loam instead of mortar ; the sand of 
Avhich fluxes, and runs by the intense heat, and so cases over 
the whole face of the kiln with a strong vitrified coat like glass, 
that it is well preserved from injuries of weather, and endures 
