ASPIDIUM. 21 



GENUS V. 

 ASPIDIUM. 



The distinctive differences between the several divisions may 

 be briefly given as follows: — 



ASPIDIUM. SwARTz. 



Veins costaeform; venules compoundly anastomosing, from the 

 sides of which free veinlets extend, which end within the 

 areoles. 



Sporangia formed on the angles or points of confluence of 

 the veinlets. 



Sori circular, in a row on either side of the veins or primary 

 anastomosing venules. 



Indasium mostly orbicular and central, although instances 

 occur with it reniform. 



Fronds simple, lobed, pinnate, or bipinnate; margin entire, 

 sinuated, or laciniated. 



SAGENIA. Presl. 



Veins forked; venules acutely and angularly anastomosing, 

 forming unequal areoles. 



Sporangia situated on the angles or points of confluence of 

 the veinlets, or on the apex of a free veinlet. 



Sori circular, in a row on either side of the ultimate midrib, 

 or irregular. 



Indusium orbicular or reniform. 



Fronds pinnate or bipinnate; pinnse lobed or sinuously- 

 pinnatifid. 



Distinguished from Aspidium by the absence of the irregular 

 free veinlets. 



CYHTOMIUM. Presl. 

 Veins pinnate; the lower exterior venule free and fertile. 



