74 THE POTOMAC OR YOUNGER MESOZOIC FLORA. 



Cladophlebis acuta, sp. nov. 



Plate V, Fig. 7; Plate VII, Fig. 6; Plate X, Figs. 6,7; Plate XI, Figs. 7,8; Plate CLXVI, Fig. 5. 



Frond bipiniiate or tripinnate, arborescent; principal rachis stout and 

 rigid; pinnpe with stout rigid rachises go off at an angle of 45'^ and cui've 

 upwards; pinnules alternate, united at base, falcate, ovate to oblong, 

 acuminate; midnerve rather stout and rigid, prolonged to near the summit 

 of the pinnules; lateral nerves furcate, Avith branches subparallel. 



Localities: Hill-side near Potomac Run, rather common; rare at 

 fishing hut above Dutch Gap Canal. 



This plant has some of the features of the Pecopteria type combined 

 with those of Cladophlebis. The pinnules show sometimes an inclination 

 forward along the rachis. In the tj-pical forms, such as PI. XI, Fig. 8, the 

 pinnules are united at base and decidedly falcate. PI. XI, Fig. 7, and 

 PI. V, Fig. 7, give forms with unusually long and slender pinnules. They 

 probably represent ultimate pinnas changed in the upper jjart of the frond 

 to pinnules. PI. X, Fig. 6, differs from the normal foi-ms a good deal, and 

 hesitatingly I unite it with the species now in cpiestion. 



Cladophlebis acuta is more like Dunker's Neuropteris Albertsri from the 

 Wealden of Germany than any other previously described fossil, and is no 

 doubt quite near the Wealden species. Schenk, in Foss. Flor. nordwest- 

 deutsch. Wealdenformation, PI. VI, Fig. 4, gives a form with the name 

 Alethopteris Alberfsii, which resembles our plant more than do the figures 

 of Dunker. Heer, in Flor. Foss. Arctica, vol. 6, Pt. 2, Pis. XVI, XXVIII, 

 XLVI, has given a number of figures of a plant which he identifies with 

 Dunker's species, but which he calls Pteris Albertsii, making it a Pteris 

 without any evidence from fructification. The Potomac fossil is very close 

 in form to the figure he gives from Unter Atanekerdluk, PL XVI, Fig. 6. 



Cladophlebis oblongifolia, sp. nov. 



Plate VII, Figs. 3-5. 



Frond bipinnate or tripinnate; arborescent; ultimate pinn;T? long and 

 linear, with rigid and comparatively stout rachises; pinnules alternate, 

 oblong, very slightly falcate, in the upper part of the frond with entire 



