DESCRIPTION OF THE SPECIES. 75 



margins, in tlie lower portions of tlio pl.ant with crenate margins; mid- 

 nerve pecopteris-like, rigid, and prolonged to near the snnnnit of the 

 pinnnles; lateral nerves very regularly once forked, with branches sub- 

 parallel; leaf-substance thick and leathery. 



Localities: Fredericksburg, very rai-e; more common but still rare at 

 fi.shing hut above Dutch Gap Canal; found also in the banks of Dutch 

 Gap Canal, and in the red clay ball occurring in these banks. 



Tliis plant is rare at all the localities where it occurs. It is found in 

 fragments that are too small to give a good idea of the character of the 

 frond. That represented in Fig. 5 was found in the red clay ball which 

 occurs in the right-hand bank of Dutch Gap Canal. To judge from the 

 size of the rachis in Fig. 5 the plant must have attained very considerable 

 dimensions. This specimen shows a ridge on each side of the rachis. 

 This is one of the forms that possess some of the features of Pccopteris 

 and Alcthopicris. It does not bear much resemblance to any previously 

 described fossil known to me. It seems to be nearest to rccoptcris Wliit- 

 hicnsis of Lindley and Ilutton. It appears also to be like CladopMehis 

 Virginiensts of this w^ork, but can not be united with it by transitional 

 forms. 



Cladophlebis crenata, sp. nov. 



ri.atc IX, Figs. 7-0; Plato X, Figs. 1, 2; Plato XIII, Figs. 1-3; Plato XIX, Fig. I ; Plato XX, Fig.f.. 



Frond bipinnate or tripinnate; racliis of the primary and secondary 

 pinnae strong and rigid; pinna? mostly alternate, rarely opposite, going off 

 at an angle of 45'^, and closely placed; pinnules alternate, oblicpiely 

 rounded at base above, and slightly decurrent on the lower side; in shape 

 ovate-acuminate and falcate ; margins with distinct crenate toothing ; 

 midnerve as in genus; lateral nerves of the basal lobes of the pinnules 

 fasciculate and palmately diverging, those of the upper lobes once or 

 twice forked. 



Localities: Fredericksburg, most common; 72d mile-post, near Brooke; 

 hill-side near Potomac Run; rare. 



The crenate lobing of the pinnules seems to be a constant featm-e, 

 and there does not appear to be any tendency to pass into entire pinnules. 



