DESCRIPTION' OF THE Sl'EUlES. |51 



even of those placed by him in the genus, as in I'l. XLV, Fig. 2, given 

 ])y him of PhilHps's Si)henoptcrls lanceolata, whicli he makes Sckroptcris 

 PhlUipsii. Saporta shows quite satisfoctorily that Brongniart's genus 

 PacJii/pteris, which has for its type P. ovata, was established under the 

 mistaken idea that the specimen furnishing the type had in the pinnules 

 only a midnerve. It is identical with Phillips's Nmropkris hevigata. This 

 Saporta makes a Scleropterls with the name <S'. kcrif/nta. 



Zigno, however, takes this plant as belonging to his genus DicJioptcris, 

 because it appears to have the nerves, several in number and parallel, pro- 

 ceeding obliquely from the rachis. But an inspection of Zigno's figure 

 shows that this idea of the nervation arises from the fact that he has not 

 drawn the true point of insertion of the lateral nerves, which is forther 

 within the apparent rachis, and at this point the nerves most probal)lv 

 unite. Zigno has taken the margin of the wing for that of the i-achis. 

 According to this, Pachypteris ought not to be considered as a genus. 

 Brongniart's Pachypteris ovata would be Sclcropteris kevigata Sap., while 

 Saporta makes Brongniart's Pachypteris lanceolata, and Phillips's Sphenopte- 

 ris lanceolata, Sclcropteris PhilUpsii. 



SCLEKOPTERIS ELLIPTICA, Sp. nOV. 

 Plate XXVIII, f^igs. 2, 4, 6; Plate XXIX, F\'^. I. 



Frond bipinnatc or tripinnate, arborescent; principal rachis stout and 

 woody ; ultimate rachises rather slender, straight, and winged; ultimate 

 pinn;iD alternate, linear, terminating abruptly in a pinnule like those lower 

 on the pinn;v; pinnules or segments thick and leathery, narrowly elliptical, 

 acute, opposite, narrowed at base into a sort of petiole, decurrent to form a 

 narrow wing; nerves immersed in the thick leaf-substance, inconspicuous, 

 diverging flabellately from a short common or mother nerve which does 

 not extend beyond the base of the pinnules, branches once or twice forked 

 or simple. 



Localities: Fredericksburg; lignite deposit near Potomac Run; fish- 

 ing-hut above Dutch Gap Canal; Kankey's; near Telegraph Station. 



The plant is not very rare at Fredericksburg. The two fine specimens 

 figured in PI. XXIX, Fig. 1, and PI. XXVIII, Fig. G, come from that 



