214 THE GEOLOGICAL HISTORY OF PLANTS. 



Macquarii, and by leaves not distinguishable from those 

 of the modern American species, C. Americana and G. 

 rostrata. There are also chestnuts and oaks. But the 

 poplars and willows are specially abundant, being repre- 

 sented by no less than six species, and it would seem 

 that all the modern types of poplar, as indicated by the 

 forms and venation of the leaves, existed already in the 

 Laramie, and most of them even in the Upper Cretaceous. 

 Sassafras is represented by two species, and the beautiful 

 group of Viburnum,) to which the modern tree-cranberry 

 belongs, has several fine species, of some of which both 

 leaves and berries have been found. The hickories and 

 butternuts are also present, the horse-chestnut, the Ca- 

 talpa and Sapindus, and some curious leaves which seem 

 to indicate the presence of the modern genus Symphoro- 

 carpus, the snow-berry tribe. 



The above may suffice to give an idea of the flora of 

 the older Eocene in North America, and I may refer for 

 details to the works of Newberry, Lesquereux, and Ward, 

 already cited. I must now add that the so-called Mio- 

 cene of Atanekerdluk, Greenland, is really of the same 

 age, as also the "Miocene" of Mull, in Scotland, of 

 Antrim, in Ireland, and of Bovey Tracey, in the south of 

 England, and the Gelinden, or "Heersian" beds, of Bel- 

 gium, described by Saporta. In comparing the American 

 specimens with the descriptions given by Gardner of the 

 leaf-beds at Ardtown, in Mull, we find, as already stated, 

 Onoclea sensibilis, common to both. The species of 

 Sequoia, Gingko, Taxus, and Glyptostrolus are also iden- 

 tical or closely allied, and so are many of the dicotyledo- 

 nous leaves. For example, Platanoides Helridicus is 

 very near to P. nobilis, and Corylus Macquarrii is com- 

 mon to both formations, as well as Populus Arctica and 

 P. Richardsoni. I may add that ever since 1875-'76, 

 when I first studied the Laramie plants, I have main- 

 tained their identity with those of the Fort Union group 



