86 THE OLDER MESOZOIC FLORA OP VIRGINIA. 



Mesozoic by the single species presently to be described. Saporta says that 

 Baiera seems to have preceded Salisburia, and that the Gingkophyllum gras- 

 seti, Sap., from the Permian of Lodove, has at the same time some of the 

 characters of the true Salisburia and of Baiera. It is interesting to note 

 that the Upper Carboniferous beds of Southwest Pennsylvania and West 

 Virginia contain a plant, Baiera Virginiana, F. and W., which, if it is not a 

 Gingkophyllum, is a true Baiera. The absence of the base of the leaf 

 leaves this point in doubt. This fossil occurs in the same beds with a plant 

 closely allied to Salisburia, viz., Saportea, F. and W. The Saportea does not 

 appear in the Virginia Mesozoic, or at least it has not yet been found. It 

 would seem that the type of Baiera and Salisburia appeared together in the 

 closing era of the Paleozoic. In this connection I may be permitted to call 

 attention to the remarkable apparent scarcity of coniferous plants in the 

 Virginia older Mesozoic. It is not to be supposed that they were not present 

 in that era. I think that the great predominance of Ferns, Cycads, and 

 Equisetum, the latter in individuals at least, in the fossils found in the Vir- 

 ginia Mesozoic, is due to the fact that these plants grew near the shores of 

 the lakes and on islands in them, and thus their remains were more readily 

 preserved in the sediment accumulating in the still shallow waters. Such 

 quietly accumulated sediment was the only material that could preserve the 

 foliage of plants. That coniferous plants were not wanting in the Mesozoic 

 is shown by the fact that wherever the strata are of such a character as to 

 indicate the presence of bodies of water in motion, such as rivers or floods 

 from the highlands, then we do find abundant traces of coniferous vegetation. 

 Thus in the sandstones of the lower series we find coniferous wood usually 

 silicified, but it is especially in the upper series or that characterized by the 

 large amount of granitic sand that we find the greatest amount of coniferous 

 relics. Here the materials are sometimes silicified, but generally they occur 

 in the form of lignite and jet. In many places we may find layers of some 

 extent, and sometimes a foot thick, of lignite formed by the drifting of trees 

 and their branches and the piling up of the same. Often isolated trees 

 which must have been a foot or more in diameter occur imbedded in the 

 sandstones and shales of the upper measures, but which are now flattened 

 by pressure. The wood seems to have had a fine uniform grain and to have 



