46 J. SMITH ON THE GENERA OF FERNS. 



Obs, Distinguished from the last genus by the sori being 

 produced on the lateral veins, and therefore oblique to the 

 midrib ; but in more than one species the soriferous venule is 

 very short, and consequently the sori connive and appear to 

 be parallel to the midrib. The oblong sori of Grammitis is 

 the only character that distinguishes it from a number of 

 species of the first section of the following genus Polypodium, 

 their habit being similar ; and I have great doubts in which 

 genus many of the species of Grammitis of Blume should be 

 placed. 



4. PoLYPODiUM. Linn. J. Stn. 



(Adenophorus. Gaud. Prosaptia. Presl. Marginaria. Bury. 

 Davalliae sp. Sw. Hook. Grev.) 



Veins simple, forked or pinnate, free. Sporangia terminal or 

 lateral, superficial or sometimes immersed. Sori round, rarely 

 oval or oblong, transverse — uniserial, solitary or irregular — 

 Rhizoma creeping, sometimes emspitose. Fronds ranging 

 from a few inches to '^ or 4: feet high; anid frora simple to 

 decompound, multifid, coriaceous or memhraneous, smooth, 

 villose or gla)idiilose. Sporangia sometimes seated in a deep 

 cyst or cavity, which forms elevated protuberances on the 

 upper side of the frond. 



Obs. This genus, as now characterized, still contains about 

 100 species, which vary much in habit and in the division of 

 their fronds. In a few species the sporangia are seated in a 

 deep cyst-like cavity, out of which they protrude. In Poly- 

 podium contiguum (Davallia Sw.) and a few other species, this 

 cavity is formed nearly vertical with the direction of the vein; 

 and, being open exteriorly, forms with the margin a cup-like 

 indusium, not much unlike the urceolate indusium of Davallia, 

 which form constitutes the genus Prosaptia of Fresl. In 

 two species from Java, and one from Ceylon, the cavity is 

 oblong, and slit in the direction of the vein ; and in one of the 

 Java species, its margin is beset with rigid hairs ; but accord- 

 ing to my view these forms cannot be considered otherwise 

 than as characterizing a small group of Polypodium. The 

 genus Adenophorus of Oaudichaud is formed from three or 



