14 The Natural History of Selborne 



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 hard- 

 ened clay, as soon as they were exposed to the rains and frost they 

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

 duction. 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 considerable 

 depths, well-diggers often find large scallops or pectines, 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. 



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