366 



found in the neighbourhood of the City of Conception, in Chili. This is 

 the tooth on which M. Cuvier establishes his species of the mastodon of 

 de Humbold. 



At Harwich, as well as at the next promontory of Walton, blue clay 

 appears, and most probably extends through the whole of the intervening 

 marsh. At Walton, by digging in different parts of this stratum, 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, sta^, 

 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 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 attrition ; so that, although no doubt could be enter- 



