378 
Simorre, &c. This tooth was found in the neighbourhood of the City 
of Conception, in Chili. This is the tooth on which M. Cuvier esta- 
blishes his species of the mastodon of de Humboldt. 
At Harwich, as well as at the next promontory of Walton, blue clay 
appears, and most probably extends through the whole of the inter- 
vening marsh. At Walton, by digging in different parts of this stra- 
tum, and by the action of the waves against its edge, the bones of 
several large animals have been discovered. These I have ascertained 
to belong to the ox, stag, Irish fossil elk, hippopotamus, rhinoceros, 
and elephant, of which mention was made in the preceding letter. 
But both at Harwich and at Walton are prodigious beds of fossil 
shells, highly ferruginous, and reaching thirty or forty feet above the 
clay stratum. Dispersed in these beds of fossil shells, polished bowl- 
dered fragments of bones are frequently found, which, like the shells, 
are strongly impregnated with iron ; so much so, as to have acquired 
a very considerable degree of hardness, and to emit a sharp ringing 
sound when struck against any hard body. These fragments of bones 
being washed by the waves out of their matrix, are frequently found 
on the beach. 
From the smallness of these fragments, few being above six inches 
long, and hardly any possessing twelve inches in length ; and from 
their being almost all reduced to one shape by bowldering, previously 
to their being placed in their present bed, no grounds have existed, 
on which any opinion could be founded as to the animal to which 
they belonged. But within these last few years, a tooth was found 
on the beach at Harwich, possessing the colour and appearance of 
the fragments of bones so strongly, as to leave no doubt of its having 
been imbedded in the same bank of shells. This tooth was shown to 
me by my much lamented friend and companion in these pursuits, 
Dr. Menish, by whom, at my request, it was shown to the members 
of the Geological Society. Its figure had been much injured by 
