J. SMITH ON THE GENERA OF FERNS. 173 



Obs. Swartz first separated this as a genus from Asplenium, 

 by the circumstance of the sori being double, which character 

 embraces a considerable number of species; but in many of 

 them the double or binate sori are produced only on the 

 lower exterior venule of each fascicle, the other venules pro- 

 ducing a single unilateral sorus on the superior side only as 

 in true Asplenium; therefore if it were not for the sake of 

 having some character whereby to divide the old extensive 

 genus Asplenium, the circumstance of double sori would be 

 unworthy of notice as a generic distinction. Some of the 

 original species of Diplazium are by the above character now 

 excluded, and constitute the genus Callipteris, which is chai-- 

 acterized by having anastomosing venules. 



69. Asplenium, Linn. J. Sm. 



(Acropteris, Link. Darea, Willd. Caenopteris, Berg. Athy- 

 rium, Roth. Allantodife sp. R. Br.) 

 Veins forked or pinnate; venules darect^ free, sporangife- 

 rous on their superior side, constituting unilaterallinear sori. 

 Indusium plain or vaulted, and cylindrical. 



* Asplenia vera. 



Fronds simple or pinnate, margin entire or crenate, Sori 

 usually equal on both sides of the midrib. 



Examp. 1. A. Phyllitidis, Wall. 2. A. vittaeforme, Cav. 

 3. A. serratum, Linn. 4. A. Brasiliense, Sw. 5. A. attenu- 

 atum, R, Br. 6. A. oligophyllum, Kaulf, 7. A. marinum, 

 Linn. 8. A. Trichomanes, Linn. 



niust. Schk. Crypt, t. 67, 69. Hook, et Grev. Ic. Fil. t. 137, 

 220. 



** Acropteris, Link. J. Sm. 



Fronds simply forked or digitate, pinnate or bipinnate, seg- 

 ments serrate, or primarily laciniated; costa undefined or want- 

 ing; veins radiating from the base of the segments, or forming 

 an acute angle with the evanescent costa. 



Examp. 9. A. septentrionale, Stv. 10. A. australe, Sw. 

 11' A. radiatum, 5?^'. 12, A, Rnta-muraria, -Lmn. 13. A. 



