J, SMITH ON THE GENERA OF FERNS. 67 



Species. 1. P. fnrcata; Desv. 2. P. angustifoUa; Desv. — 

 Illust. Hook, et Grev. Ic. Fil. t. 7. Hook, gen.fil, 



Obs. Distinguished from Tcenitis by the sori being pro- 

 duced on the exterior side of the venation, close to the 

 margin. 



32. T^Niopsis. J. Sm. 

 (Vittariae sp. Auth. Haplopteridis sp. Presl.) 



Veins simple, parallel, their apices transversely combined 

 by the sporangiferous receptacle which is immersed in a 

 groove, forming a linear-continuous intramarginal sorus. 



Fronds simple, long and linear^ or lanceolate ^ plane, or the 

 margin revolute. Venation obscure, costa indistinct. Sporan- 

 gia seated in a groove, the margins of which are indusiiform. 



Examp. 1. T.revoluta; {Don.) 2. T.lineata; {Sw.) 3. T. 

 graminifolia; (jfiCaw//.) 4. T. scolopendrina ; (Pteris; Bory, 

 Willd.) Illust. Schk. crypt, t. 101. 6. 



Obs. The veins being simple, and their apices combined 

 near the margin by a continuous anastomosing vein which 

 produces the sporangia, distinguishes this genus from any of 

 the preceding; but from the following it is more difficult to 

 characterize it, on account of their habits being similar, their 

 separation depending entirely on the difference of position of 

 the sori. 



33. VlTTARIA. Sm. 



Veins simple, their apices transversely combined by the 

 sporangiferous receptacle, which is immersed in a marginal 

 groove, forming a linear continuous sorus. — Fronds simple, 

 from a few inches to 2 feet long, linear or lanceolate, plane. 

 Venation obscure. Costa usually indistinct, the margin slit 

 longitudinally, forming a sporangiferous groove, the margins of 

 which are indusiiform. Sporangia vertical. 



Examp. l.V.zosterifolia; ?^j7W. 2, V. ensiformis ; Sw. 3. 

 V. elongata ; Sw — Illust. Hook, et Grev. Ic. Fil. t. 187. Hook, 

 gen.fil. t. 68. B. 



Obs. The circumstance of the margin of the frond being 



