162 J. SMITH ON THE GENERA OF FERNS. 



Obs. This very distinct genus is founded upon a solitary 

 species found in Guiana, of which 1 have seen only one spe- 

 cimen, and which at first sight might he taken for a large 

 pinnate species of Adiantum, having the smooth ebeneous 

 character of that genus, but from which it is distinguished 

 by its reticulated venation ; and its venose sporangiferous 

 indusium will distinguish it from any of the proximate genera 

 with continuous marginal sori. 



56. Amphiblestra, Presl. 



Veins costasform, pinnate; venules transversely and irre- 

 gularly anastomosing, producing variously directed simple or 

 forked free veinlets which terminate in the areoles. Sporan- 

 giferous receptacle transverse, marginal, constituting a linear 

 continuous sorus. Indusium narrow, linear. 



Fronds 2 feet or more high, stijntate^ tripartite, branches 

 pinnate, pinnatijid towards the apex. Pinnae ovate-oblong, 

 acuminate, repand-dentate, 8 inches long bg 2 to S wide, the 

 terminal one broad and auriculaied at the base. 



Species. A. latifolia, Presl. (Pteris, Humb.) Ilbist. Presl, 

 Pterid. t.Q.f. 1. 



Obs. I have not had the opportunity of examining this 

 fern, and have consequently adopted the genus entirely upon 

 the authority of Presl aided by Humboldt's description of 

 the species; and what is singular is in its being the only 

 known example in Pteridece having a venation similar to the 

 extensive genus Drynaria in Polgpodiea, and Gymnopteris in 

 Acrostichiea. 



57. DoRYOPTERis, J. Sm. in Hook. Journ. of Bot. 



(Pteridis sp. Linn. Radd. Litobrochise sp. Presl) 



Venation internal, nearly uniform, reticulated, areoles 



elongated, oblique. Sporangiferous receptacle transverse 



marginal, constituting a linear continuous sorus. Indusium 



narrow, linear. 



Fronds simple, cordate, lobed or digitate-palmate, smooth, 

 coriaceous. Stipes and costa ebeneous. Veins hidden within 



