68 J. SMITH ON THE GENERA OF FERNS. 



slit longitudinally, forming two narrow laminae, with the 

 sporangia rising from the base or axis of the slit or groove and 

 pointing outwards, distinguishes this genus from Tceniopsis, 

 which is characterized by the sporangia being produced in a 

 similar groove, but which is situated on the disk, within the 

 margin of the frond; and although I have separated Taniop- 

 sis from Vittaria, chiefly on that character, yet their habits 

 scarcely indicate any distinction. 



The simple venation of botli Tceniopsis and Vittaria is 

 scarcely reconcileable with this section of Polypodiece, except 

 in viewing them in connexion with Pteropsis, 8ic., and also 

 with the two following genera, with which they perfectly 

 agree in habit. I am disposed to view them as forming a 

 transition through PolyfcBnium to the reticulated venation of 

 Antrophyum. 



34. PoLYTiENiUM. Desv. 

 (Vittariae sp. IVilld. Antrophyi sp. Kaulf.) 



Venation uniform, elongated, transversely and distinctly 

 anastomosing, forming elongated, linear areoles. Sporangia 

 occupying the lengthened, transverse venules, immersed, 

 forming generally three, linear, parallel, continuous sori. — 

 Fronds simple, linear-lanceolate, coriaceous. Veins imynersed, 

 obscure, marcjin of the sporangiferous grooves indiisiiform. 



Species. P. lineatum; jDesv Illust. Schk. crypt, t. 101, *. 



.35. Antrophyum. Kaidf. 



Venation uniform, reticulated, sides of the areoles more or 

 less sporangiferous. Sporangia immersed, rarely superficial, 

 forming linear, continuous or interrupted reticulated sori. — 

 Fronds simple, linear-lanceolate or elliptical, coriaceous, with 

 or without a midrib, sporangiferous, grooves indusiiform. 



* COSTATA. 



Examp, I. A. cayenn^nse; Spreng. 2, A. lanceolatum ; Kaulf 



** ECOSTATA. 



3. A. coriaceum ; Spi-eng. 4. A. Boryana; Spreng. b. A. 



