260 Robert Harkness, Esq., on Fossil Footprints. 



a mammifer which was probably insectivorous, gives us the 

 earliest evidence of the existence of mammalia ; and although 

 this tooth appertains rather to the Keuper than to the Varie- 

 gated sandstone, it shews that highly organised beings were 

 inhabitants of our earth at a period little posterior to that 

 when Tortoises, Saurians, and Batrachians tenanted the land 

 and sea- shore. 



The absence of any deposits of a fluviatile nature, in any 

 of the older formations is doubtless the cause of the want 

 of evidence concerning terrestrial animals in the older epochs. 

 It is only from such fragments as by accident find their way 

 into the rivers and streams draining the solid ground, that 

 we derive any information of the occupants of the land ; and 

 even this circumstance, as well as the numerous causes 

 which operate to aid and assist in the destruction of the 

 fragments which by accident find their w^ay into the water, 

 tend to render the occurrence of these fragments in the solid 

 crust of the earth a matter of great rarity. During the pe- 

 riod of the deposition of the trias, there is every reason for 

 believing that an abundant and luxuriant vegetation pre- 

 vailed ; and that this was of such a character that its foliage 

 was well capable of being preserved. Yet although the Va- 

 riegated or Bunter sandstone has been extensively wrought in 

 Great Britain for building purposes, it has never furnished any 

 distinct trace of the vegetation which at this period obtained 

 on the earth's surface. Even in our own time, the foliage 

 which each year is cast from the vegetation now prevailing 

 so entirely disappears, that it is only under some peculiar 

 circumstances, that we find any well-marked traces of it 

 after a short time ; therefore we can seldom expect to find 

 such evidence of terrestrial inhabitants, which at remote 

 epochs have been tenants of the land, in any of the deposits 

 which have resulted from marine agency. On the whole, it 

 would appear that the fossil remains which occur in the 

 various strata are an exception to the general rule, which 

 indicates that the destruction and disappearance of organic 

 forms prevailed more particularly, so far as terrestrial beings 

 w^ere concerned. 



We may therefore conclude, that along with reptiles, 



