264 Robert Hiirkness, Esq., on Fossil Footprints. 



forming a portion of the land from which it was separated. 

 But the separation itself would produce climatic influences, 

 such as would ultimately prove destructive to many forms of 

 vegetation, leaving only such plants as were capable of en- 

 during the new conditions produced by the separation ; and 

 as we find distinct specific forms both of plants and animals 

 occupying the detached land, so we are induced to infer that 

 these have had their origin in distinct specific creations 

 adapted for the conditions under which they were placed. 

 With regard to the disappearance of species, although there 

 can be little doubt that in some instances unfavourable cir- 

 cumstances such as we have supposed may have operated in 

 the destruction of some, yet, still, there is reason to believe 

 that unfavourable circumstances alone have not produced the 

 destruction and disappearance of the numberless species of 

 organic forms which have been occupants of the earth since 

 the first creation of animal life, until the present day. In 

 the different geological formations, which are each marked 

 by organisms peculiar to some extent to itself, we find, with 

 a few exceptions, that animal forms rarely disappear sud- 

 denly. We perceive them on their first occurrence few in 

 number, but gradually increasing until they attain the 

 maximum development, and from this they by degrees 

 lessen in quantity until they at last disappear, waxing 

 and waning like the monthly moon. It would seem from 

 the information which we derive from geology, that there is an 

 innate principle of decay in species, as well as in the varieties 

 which are obtained from them. Perhaps the rapid tendency 

 of varieties to disappear, results from the specific principle 

 of decay acting with greater vigour in these forms which 

 possess a modification of the specific characters. It would 

 seem also, that the creation of a species has not usually fol- 

 lowed the destruction of another, the place of which it was to 

 occupy; but rather that after the maximum development 

 had been attained, the new form makes its appearance, gra- 

 dually filling up the void caused by the decline of its prede- 

 cessor. Neither does it appear, that a species which has 

 once become extinct, is ever revived ; the Creator manifest- 

 ing the illimitability of his power, by calling into being new 



