170 J. SMITH ON THE GENERA OF FERNS, 



row of oblong, linear, contiguous immersed sori ; indusium 

 revolute, vaulted. 



Fronds pinnate or bipinnatifid, uniform^ or the fertile con- 

 tracted, margin serrulate or spinulous. 



Species. 1. W. onocleoides, Willd. 2. W. thelypteroides, 

 Fursh. 3. W. Japonica, Sw. 4. W. radicans, Sw. 



Illust. Schk. crypt, t. Ill, 113. Bauer's Gen. Fil. t. 17. 



Ohs. The more compound anastomosing of the veins, the 

 sporangia being deeply immersed, and the revolute vaulted 

 indusium, are the principal points of difference between this 

 genus and the foregoing. 



Tribe IV. AsPLENiEiE, J. Sm. 



Sori elongated, oblique to the midrib or axis of venation. 

 Venides free or anastomosing, sporangiferous on their supe- 

 rior or inferior sides (tmilateral), or on both sides (bilateral), 

 constituting simple or binate sori, each furnished with a spe- 

 cial lateral attached linear plane or vaulted indusium. 



Obs. The technical distinction between this tribe and the 

 preceding, is in the sori oi AspleniecB being produced on the 

 sides of free or combined venules, and forming an angle more 

 or less oblique with the midrib or axis of venation, and there- 

 fore never parallel with the midrib or margin as in Pteridea. 



This tribe contains about 200 described species, which 

 have hitherto been principally included under the two genera, 

 Asplenium and Diplazium of authors ; the first characterized 

 by the venules being sporangiferous on their superior or inner 

 sides only, whereas the species constituting Diplazium pro- 

 duce sporangia on each side of the venule, each side being 

 also furnished with its own indusium, the margin of the one 

 free superiorly, and the other inferiorly, which character is 

 in a number of species very constant to all the fertile venules; 

 but in a greater number of species, the twin or binate sorus is 

 found only on the lower or primary venules, the superior 

 ones producing a single superior sorus as in true Asplenintn. 

 Another form of double or twin sori is exhibited by the supe- 

 rior and inferior venules of each two fascicles being sporan- 



