22 THE OLDER MESOZOIC FLORA OP VIRGINIA. 



plate xxviii, fig. 12, in his work on the Rhsetic Flora, represents the lateral 

 nerves much as they are in our plant, but the chief difference seems to lie in 

 their greater slenderness and remoteness, being in M. gigantea, one millimeter 

 apart, while in the Virginia plant they are not more than one-half millimeter 

 apart. Schenk's figure does not show the entire midrib, but Nathorst gives 

 a figure of this plant in his " Floran vid Bjuf," plate ix, fig. 1, in which 

 the flat, broad midrib is well shown and where we see a non-striated border 

 on each side, which evidently is the insertion of the lateral nerves concealed 

 by the thick epidermis investing the midrib. The nerves of the Swedish 

 plant also agree closely with those of the Virginia fern, except that they 

 appear to maintain a course more oblique to the midrib. As this feature is 

 not shown in Schenk's plant, where they are soon perpendicular to the 

 midrib, it is probably due to oblique compression. Macrotozniopteris lata, 

 Tceniopteris lata, of Oldham and Morris, as depicted in fig. 1, plate II, of 

 the " Palseontologia Indica," series ii, 1, is strikingly like our plant. The 

 chief difference seems to be that the Indian plant has a more prominent, a 

 more woody, and narrower midrib than the Virginia fern. I am strongly 

 inclined to think that these three plants are all representatives of the same 

 type-form, differing only in such minor features as would be produced in 

 regions so remote from one another as Virginia, Northern Europe, and 

 India. 



Formation and locality. — This is the most widely diffused, abundant, and 

 characteristic plant in the Mesozoic strata of Virginia. It abounds in the 

 strata connected with the main coal seam, and is found everywhere in the 

 Mesozoic at this horizon and above it to the top of the series. It is often 

 found alone, but very commonly occurs with Equisetum Rogersi, and the two 

 often occur alone. It must have grown in the same localities with the Equi- 

 setum or very near to it. 



Macrotaeniopteris crassinervia, Feist. 

 Plate V, Fig. 5; Plate VI, Figs. 1,2. 

 Frond simple, coriaceous, margins thickened, length ? width up to 17 centime- 

 ters. Midrib prominent, rounded, and rigid. Lateral nerves strong and cord like, 

 slightly thickened towards the insertion, one millimeter, and sometimes a little over, 

 apart, single, making a right angle, or one a little less than a right angle, with the 

 middle nerve, or midrib, parallel. 



