118 THE POTOMAC OR YOUNGER MESOZOIG FLORA. 



the reduction of the lobes to mere supports for the sori. The singleness of 

 the sori in the lobes, their great size, and anterior position form peculiar 

 features. 



ASPLENIOPTERLS PINNATIFIDA, Sp. nov. 

 Plate XXir, Figs, l-i, (i. 7. 



Frond tripinnatifid ; rachis of the primary pinna or of the frond very 

 stout, rigid, and straight; pinUiT or pinnules alternate, varying much in 

 length according to position, with strong rigid rachises : sterile piniuiles 

 linear-lanceolate, subacute, lower ones very long, much diminished in 

 length in ascending, cut more or less deeply into crenate and rounded 

 teeth and lobes; lateral nerves in each lobe flabellate diverging, with the 

 branches forked or simple, nerves very strong and distinct; fertile pinna:> or 

 pinnules very long, with strong rigid rachises, linear, subacute ; lobes or 

 teeth reduced to thick leathery supports, which bear the narrowl}'^ elliptical 

 sori on the anterior face ; the sori very long, almost as long as the lobes, 

 .standing one in each lobe, apparently included between the two branches 

 of a nerve that forks at the insertion. 



Locality : Fredericksburg. 



This remarkable })lant is rare. I can not feel sure that the sterile 

 forms, Figs. 1-3, with rounded lobes belong to the same species with the 

 form depicted in Figs. 6, 7, possessing narrow subacute fructified lobes, 

 but the nervation and general character of the segments of the pinna; 

 indicate that they belong to the same species. The partially fructified 

 form PI. XXII, Fig. 7, has the lobes on the upper side mostly sterile, indi- 

 cating how they are modified in the development of the sori. 



ASPLENIOPTERIS ADIANTIFOLIA, Sp. UOV. 

 Plate XVI, Fig. (i. 



Sterile frond not seen ; fertile frond bipinnate or bipinnatifid ; pin- 

 nules or lobes reduced to leathery thick pedicels or supports, which bear 

 on their anterior or upper margin narrowly elliptical or oblong sori ; sori 

 proportionally very large. 



Locality : Fredericksburg ; very rare. 



