80 THE POTOMAC OE YOUNGER MESOZOIC FLORA. 



more numerously divided and much finer, and the pinnules are longer and 

 proportionately more slender in the Potomac plant. 



Cladophlebis petiolata, sp. nov. 



Plate XXII, Fig. 8. 



Frond bipinnate or tripinnate ; rachis of primary pinnae comparatively 

 stout and rigid; pinnules, or reduced ultimate pinnae, alternate, oblong, 

 acute, somewhat falcate, narrowed to the base into a winged petiole, cut 

 into ovate subacute teeth; lateral nerves in each tooth composed of a 

 slender midnerve, which sends out alternately on each side simple nerves. 



Locality: Red clay ball in the banks of Dutch Gap Canal; very rare. 



This plant is in form a good deal like Thinnfeldia variabilis, from the 

 72d mile-post, near Brooke. The nerves, however, are fewer, coarser, 

 and more remote. It seems to be a distinct new species. 



Cladophlebis in.equiloba, sp. nov. 



Plate XXV, Fig. 8. 



Frond bipinnate or tripinnate; primary rachis slender; pinnules or 

 reduced pinnaj petiolate, lauceolate-acute, alternate; leaf-substance thick; 

 basal lobe on the upper side of tlie pinnules or pinnaj ovate-obtuse, erect, 

 and much larger tlian the other lobes or teeth; the other lobes or teeth of 

 the pinnules ovate-acute, and directed towards the tij) of the pinnules; 

 pinnules towards the summit of the primary pinnae sparingly and acutely 

 toothed: nerves of the lobes and teeth not seen. 



Locality: Fredericksburg; very rare. 



This small plant seems to show the upper portion of a primary pinna 

 in which the ultimate pinnae are reduced to lobes and teeth. It seems to 

 be a distinct species. 



Cladophlebis pachyphylla, sp. nov. 



Plate XXV, Fig. 9. 



Ultimate pinnae linear, with a comparatively stout rachis; pinnules 

 subopposite, with a dense leathery leaf-substance, ovate-falcate, acute, 

 remotely placed, separate to the base, free on the upper side, and cut 



