NATURAL HISTORY OF SELBORNE. 9 
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 alternate flutings or grooves, and the 
curved form of my specimen being much easier expressed by the 
pencil than by words, I have caused 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 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 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. 
* Our author was mistaken in referring this fossil to the A/ytzlus crista galli of Linnzeus. 
Mr. Bennet, who has explained the subject in a note to his edition of Selborne, refers it 
to the Ostvea carinata of Lamarck, a species peculiar to the green-sand formation, upon 
which the village of Selborne is built, and which from its white colour would be easily 
confounded with the chalk, especially at a time when geology was much less : ttended to 
than at present. 
