Robert Harkness, Esq., c?/^ Fosdl Footprints. 26*3 



these different continents. Indeed, at this period it seems 

 that the fauna of these continents had a more intimate con- 

 nection than that which now obtains in the two portions of 

 America separated by the narrow isthmus of Darien. Pro- 

 bably the vegetation which has in part its representing 

 species in Europe, is a portion of the flora of this epoch ; and 

 it would seem that such plants as are exclusively American, 

 have liad a more recent specific origin. 



This leads to the conclusion that such plants as are of 

 extensive distribution had an existence anterior to our pre- 

 sent fauna; and that certain vegetables were older than 

 mammalia might be expected, inasmuch as this prior exist- 

 ence was necessary in order that herbivorous quadrupeds 

 might be supported. The faunas and floras which now exist 

 are made up of animals and vegetables as widely differing from 

 each otlier as the areas these occupy are remote. The ani- 

 mals and plants of America have, on the whole, not only a 

 specific but generic character peculiarly their own, and the 

 same remark applies to other large districts of country. In 

 Australia the fauna is very imperfect, being represented by 

 only two families, the Marsupials and Rodents ; and in many 

 of the large islands of the Pacific it is questionable whether 

 Mammalia has any aboriginal representatives, such forms 

 as are met with having probably been introduced by the aid 

 of man. With districts having distinct faunas and floras, 

 and with the probability that such species of plants as have 

 extensive geographical distribution, are of a more ancient 

 origin than those having a local habitat, we may infer that 

 the forms making up the faunae as well as the floras which 

 now prevail, were not called into existence at one period, be- 

 cause such a supposition would lead to the conclusion that the 

 different continents made their appearance above the surface 

 of the water at the same time, or else that large tracts of 

 land existed above the surface of the sea unoccupied for a 

 considerable time by any inhabitants ; a circumstance which 

 is contradicted by the evidence which all the geological for- 

 mations afford. It is probable that in the case where one 

 portion of land became detached from another, that it would 

 retain for a while all the plants which flourished upon it when 



