DESCRIPTION OF THE SPECIES. 69 



The smaller forms of this species are somewhat like Pecopteris horealis 

 Brong-., which, as Ileer has shown, occurs in Kome, Greenland. Pecopfrris 

 lihcirita Heer in the Jurassic flora of Cape Boheman,' has the pinnules 

 constricted at base, and is a good deal like some of those found in this 

 species. But neither one of these species is near enough to the Potomac 

 plant to be identified without hesitation with it. 



The leaf substance of all the specimens of this plant must have been 

 thick and leathery, for the pinnules aiul lobes make deep impressions in 

 the shale, and some of the rounded small pinnules and lobes leave round 

 pits. The epidermis of the pinnules seems to have been thick and durable, 

 for the specimens often have a dark l)rown shining- surface. I have, with 

 a good deal of hesitation, placed in this species .some of the sjiecimens 

 given in the figures named 



Among- described fossils, Schenk's Aleihnpteris cycadina stands nearest 

 to the plant now in question. The resemblance is considerable between 

 the form given in PI. VI, V\g. 2, and Schenk's Foss. Flor. d. nordwest- 

 deutsch. Wealdenformatioii, PI. X, Fig. 2. 



Cladopiileius latifolia, sp. nov. 



riate III, I'ig. 1 ; Phito VI, Kij;. 4. 



Frond bipinnate or tripinnate; principal rachis .slender, with a keel in 

 the middle; pinna' ([uite remotely placed; pinmiles I)road, very oljtuse, 

 with undulate margins; alternate, sub;iuriculat(!, and roundeil kIV at base, 

 attached by the middle of the base, separate and rather remote ; midnerve, 

 as in the genus generally, strong at l)ase, and towards the summit splitting 

 up into veins; lower lateral nerves forming copiously branched groups; 

 those higher are bifurcate, and simply forked, slender, but very distinctly 

 defined; leaf-substance thin. 



Locality : Fredericksburg. 



This beautiful species was found only at Fredericksljurg, and but two 

 specimens were obtained. 



The dimensions and character shown indicate that the plant was prob- 

 ably arborescent. It is nearly allied to no fossil known to me. It is more 



'Flor. Foss. Arctica, vol. 4, Ziiiicli, 1877, No. 1, p. 30, PI. VI, Fig. -.J. 



