DESCRIPTION OF THE SPECIES. 277 



ANaiOSPERM/E. 



The angiosperms of the Potomac llora form an important element in 

 it. In number of species, howevei', they are far inferior to the conifers 

 and ferns, and do not e([ual these in the extent of their diffusion. The 

 localities at which angiosperras occur in notaljle amounts, in the strata 

 in place, are the 72d mile-post; bank near Brooke; White House Bluff; 

 the two localities at Baltimore and at Frederioksl)urg. The plants at 

 Fredericksburg are much more archaic in type than those of the other 

 localities. 



It is, then, only from Fredericksburg northwards that we find this mod- 

 ern element playing an important part in the flora of the beds in place. 

 All of tjie localities in this more northern portion of the Potomac area do 

 not contain any considerable proportion of these plants. None occur at 

 the hill-side near Potomac Kun, and only a few fragments are found on the 

 road-side near by, as well as near Telegraph Station. The two localities 

 at Baltimore show the Variegated Clay or upper mend)er of the Potomac 

 in place over the plant-bearing beds. At Brooke the Eocene caps the fos- 

 siliferous strata. Only a few imperfect fragments of angiosperms occur in 

 the strata in place in the innuediate vicinity of Dutch Gap t'anal ; but at 

 Deep Bottom, where the Eocene caps the Potomac, angiosperms predom- 

 inate in the fossils found in the disturbed bowlders of sandy clay and clay 

 which come from the destruction of beds that once lay upon the sand of 

 the lower Potomac These are of more recent type, as are those of the 

 Brooke localities, White House Bluff, and the two Baltimore localities. 

 l?ut, as has been stated before, these beds can not be separated in age. 

 The Lower Potomac era seems to have had a flora that was rapidly chang- 

 ing. In the lower and middle strata, ferns, cycads, equiseta, and con- 

 ifers predominated, giving the flora a Jurassic facies, but with these were 

 mingled a considerable number of angiosperms, mostly of archaic type. 

 The strata of Dutch Gap Canal and at Fredericksburg give us a good type 

 of this portion of the formation. Towards the n[)[)er part of the formatioa 



