DESCRIPTION OF THE SPECIES 159 



at several points, the outer ones onco or twice forking and Turned out- 

 wards, the t'ontral nerve branching several times, branches flabellately 

 diverging; all tlie ultimate branches from deep forking are long. 



Localities: Road-side near Potomac Run; Fredericksburg; very raie. 



This plant makes a close apjjroach to Zigno's Dichopteris Viskmica, the 

 main difference being tlie more coi)ious brancliingof tlie central nerve, as 

 sliown in tlie pininiles of PI. LXV, Fig. 3, magnihed in Fig. 3". In that 

 sliown in PI. LXll, Fig. 2, from Fredericksburg, the pinnules are some- 

 what falcate, and are united at base. It is apparently a fragment of the 

 terminal portion of a pinna. 



Ctenopteris angustifoj.ia, sp. nov. 



Pl.ito LXV, Kij,'. 2; Plato LXVII, Fi-;. 4. 



Frond unknown: ultimate ijiiuia- long, with rather stout rachises, pin- 

 nules linear or narrowly oblong, in proportion to width (|uite long, slightly 

 curve<l forwards, separate to the base, or united to form a wing on the 

 rachis of the pinna', cut away obliquely on the upper side at base, and 

 sliglitly decurrent on the lower side, attached by the entire base, termi- 

 nated by from one to three acute or spinous teeth, and having a varying 

 number of the same placed irregularly on botli nuu'gins. The nerves 

 l)roceed from the rachis at different points along the entire base of the })iu- 

 nulcs; the outer ones simple or forking once, the central ones forking sev- 

 eral times, the ultimate branches being long, slender, and slightly diverging. 



Locality : Road-side near Potomac Run ; rare. 



There is some difference in the two specimens figured, which, how- 

 ever, may be due to different positions on the frond. 



Ctenopteki.s longifolia, sp. nov. 



Plain l.XVII. Fi^r. 5. 



Frond unknown ; rachis of the ultimate pinmv very broad but not 

 a[)i)arcntl\- very woody ; piniudes placed very remotely, opposite, going 

 off obHquely, very long, linear, narrowed gradually and slightly towards 

 tlu^ base and slightly decurrent, tips not seen ; nerves not well made out, 

 but apparently as shown in Fig. 5"; that i.s, sevei'al, departing independ- 



