J. SMITH ON THE GENERA OF FERNS. 177 



Illust. Hook, et Grev. ic.fil. t. 150. Hook. ic. Plant, i. 183. 

 Hook. gen.JiL t. 57. A. and C. 



Obs, The reticulated venation distinguishes this genus 

 from Scolopendrium, both agreeing in having twin sori facing 

 each other. The somewhat divergence of the sori in A. rhizo- 

 phylla, is in my opinion not sufficient character to allow of 

 its separation as a genus, especially as such divergence may 

 be viewed as the result of the shorter angular anastomosing 

 of the venules, caused by the usual narrow and lobed nature 

 of the frond. 



73. Allantodia, B. Br. Wall. J. Sjw. 



Veins forked ; venules angularly anastomosing and reticu- 

 lated, the marginal veinlets free. Sporangia produced on 

 the superior side of the alternate primary venules, consti- 

 tuting unilateral linear sori. Indusium vaulted, cylindrical. 



Fronds pinnate, 1 to 2 feet long., pinnce- linear -lanceolate^ 

 entire^ smooth. 



Species. A. Brunonis, Wall, Illust. Wall. PI. As. rar. ic. 

 t. 52. 



Obs. I have already noticed that the original species of 

 this genus as constituted by Mr Brown, agree in liabit and 

 form of venation with the species that Roth had previously 

 characterized as a genus under the name of Athyrium, which I 

 have already given as forming a section of the genus Asple- 

 niitm, and which also includes Mr Brown's original species of 

 Allantodia, that genus being here restricted to one known 

 species differing entirely in habit and venation from Athyrinm, 



74. Hemidictyum, Presl, J. Sm. 

 Asplenii sp. Linn. 

 Veins forked; venules parallel till near the margin, then 

 anastomosing and reticulated, combined by a transverse con- 

 tinuous marginal vein. Sporangia produced on the superior 

 side of the parallel venules, constituting unilateral linear sori. 

 Indusium plain. 



Vol. IV No. 28. z 



