DESCRIPTION OF THE SPECIES. 135 



entire ones, and linally into lobes and teeth ; nerves in the jjinnnles and 

 lobes, forked deeply in the basal ones, in the upper ones simple, all very 

 oblique, fine, but distinct. 



Localities : Fredericksbui\n' ; lishiny-luit above Dutch Gap Canal ; 

 entrance to Trent's Reach ; White House Bluft". 



This plant is quite widely diffused. It is comparatively abundant at 

 White House Bluff, where a number of poorly preserved specimens occur, 

 evidently in some cases being fragments of large j)ortions of the frond. 

 It is also not very rare at the entrance to Trent's Reach. In other places 

 it is very uncommon. The general aspect of this plant is much like that 

 of Thyrsopterls ai/fjusfifolia, but the distinctly winged rachis compels me to 

 separate them. It belongs to the SpheiwiAcris Mantelli type. 



Thyksopteris pachyphylla, sp. nov. 



Plate L, Fig. 3. 



Frond and pinnse unknown ; ultinuite pinna? terminated by a broadly 

 fan-shaped pinnule, which is toothed on the terminal margin; pinnules not 

 fully shown, only those near the tip of the ultimate piunee seen, alternate, 

 elliptical, acute, furnished with ovate teeth ; leaf-substance thick ; nerves 

 not seen. 



Locality: Road-side near Potomac Run. 



Only one small specimen was found, but the plant seems to be a 

 distinct new species, not near to any described fo.ssil. 



Thyesopteris pecopteroides, sj). nov. 



Plate LI, Fig. 1. 



Rachis of the penultimate pinna3 stout ; ultimate piniue closely placed, 

 opposite or subopposite, short, linear-acute ; pinnules minute, passing to 

 lobes towards the ends of the ultimate pinna3, subrhombic to ovate, decur- 

 rent to form a wing, lower ones slightly toothed ; leaf-substance thick ; 

 nerves in the pinnules composed of a midnerve, which goes off oblicinely 

 and is turned strongly outward, and sends off alternately on each side 

 branches which are forked or simple. 



Locality : Fredericksburg ; rare. 



