324 



TRANSACTIONS OF THE 



figured by Sternberg and Brongniart occur in the oolite 

 groupe. We should probably have been more cor- 

 rect had we placed this among the smaller foliaceous 

 Cryptogami. 



As relates, therefore, to the evidence which these 

 fossil plants furnish as to the relative age of the formation 

 wherein they are deposited, we are led to the conclusion 

 that it is of secondary origin, perhaps coeval with the 

 oolites. They have no resemblance to any of the plants 

 of the Richmond coal field that have come to our know- 

 ledge, and decidedly bear the impress of a more modern 

 character. 



In this view we are confirmed by the lignites and sili- 

 cified wood in some of these beds, which indicate a 

 geological age much less remote than the coal fields of 

 the Alleghanies, for instance, and still further removed 

 from that of Richmond. 



The large broken masses of silicified wood are un- 

 questionably remains of vasculares or dicotyledonous 

 plants or trees, no member of whicJi series has yet been 

 observed in our coal vegetation. They resemble in some 

 respects the silicified wood of the Portland oolite of 

 England, and like them exhibit no marks of perforation 

 by the Teredo. 



The silicified fragments found by Mr Nuttall near the 

 James river are described as "^penetrated with quartz 

 of an opaque white colour, destitute of the resinous 

 fracture, and easily crumbling into an almost impalpable 

 sand." The latter character prevails in the Fredericks- 

 burg lignites, and some of them are coated with small 

 quartz crystals. 



Again, we have other lignites which are broken up 

 and abundantly intermixed with the grits, and even in 

 the finer argillaceous seams ; which fragments occur only 



