J. SMITH ON THE GKNERA OF FERNS. 161 



and rachis ebeneous usually smooth. Pinnae genei'ally oblique, 

 truncate or cuneate at the base, or dimidiate and soriferovs on 

 the upper margin only \ petiole articulated with the rachis or 

 base of the lamina, 



Examp. 1. A. reniforme, Linn. 2. A. lunula turn, Burnt. 

 3. A. macropliyllum, Sw. 4. A. pedatum, Jjifin. 3. A. Cap- 

 illus veneris, Lin7i. 6. A. formosum, R. Br. Illust. Schk. 

 Crypt, t 115 to 122. Hook, et Gre^v. ic. fil. t. 132. Hook, 

 gen.fil. t. Q^. b. 



Ohs. This extensive natural genus contains about seventy 

 described species, and is readily distinguished from its allies 

 by the sporangia being produced on the under side of tlie 

 indusium, which is either formed of a reflexed creiiule, and 

 then reniform, or it is oblong or linear, according to the 

 more or less entire or crenulate character of the margin of 

 the frond. The species with reniform indusia are distin- 

 guished from those species of Cheilanthes which have a similar 

 indusium, not only by the indusium being sporangiferous 

 but also by its being produced on the converging apices of 

 two or more venules, whereas the sori of Cheilanthes are 

 seated on the apices of single venules, which terminate in 

 the axis of the indusium ; therefore Adiantum radiatum of 

 Linnaeus is in accordance with that character a true Cheil- 

 anthes. 



55. Hewardia, J. Sm. 



Costa central; veijis uniform, reticulated, forming elon- 

 gated oblique areoles. Indusium marginal venose and spo- 

 rangiferous on its under side, at length replicate and invo- 

 lute, constituting a linear continuous marginal sorus. 



Fronds from 1 fo 2 ftet high, stipitate, dichotomous, the 

 branches G to S inches long and pinnate. Pinnte alternate, 

 petiolated, {but not articulated) ovate-elliptical, oblique at the 

 base, 4 to b inches long by tivo inches wide, the midrib disap- 

 pearing towards the apex of the pinncc. Sori continuous on 

 both margins. 



Species. H. adiantoides, J. Sm. in Hook. Journ. of Dot. 

 Illust. Hook. Journ. ofBot. v. iii. 1. 1 G, 1 7. ^ook. Gen. Fil. t. 89. 



Vol. IV — No. 27. X 



