48 J. SMITH ON THE GENERA OP FERNS. 



6. Ceratodactylis. J. Sin. 

 (Allosorus sp. Kunze.) 



Fertile pinnules contracted, margin abruptly reflexed, mem- 

 braneous, conniving, forming a universal indusinm ; veins 

 forked, free. Sporangia lateral. Sort linear, forked, oblique. 

 Rhizoma — ? Fronds sfipitate,2^ feet high,smooth,tripinnate, 

 the upper portion contracted, forming linear fertile pinnules; 

 sterile pinnules alternate, ohlwig-elliptical, ohlique at their 

 base. Veins twice dichotomously branched, their apices ex- 

 serted, forming hooked serrafures. 



Species. C. osmundioides. J. Sm. (Allosorus Karwinskii 

 Kunze.) — lUust. Hook, et Bauer s Gen. Fil. t, 36. 



Ohs. The solitary species upon which this genus is founded 

 is a native of Mexico. In habit the sterile portion of the frond 

 is like Osmunda, and the fertile pinnules have some analogy to 

 Ceratopteris, while the position of the sporangia and form of 

 the sori agree with Oymaogramma ; and differ from the 

 following genus more by its distinct habit and gigantic size 

 than in any real technical difference, except that the sporangia 

 of Ceratodactylis occupy a greater length of the vein than in 

 Allosorus. 



7. Allosorus, Bernh. J. Sm. 



(Pteridis sp. Linn. Sw. Phorolobi sp. Desv. Cryptogramma 

 B. Br. J 



Fertile fronds contracted, margins revolute, conniving, 

 forming a universal mr?«5/nm. Vein^ forked, free. Sporangia 

 terminal. Sori round or oblong, laterally confluent, forming 

 a broad, intramarginal, compound, transverse sorv.i. 



Rhizoma creeping, somewhat ca^spitose. Fronds hi-tri- 

 pinnate or decompound, generally smooth. Sterile pinaules, 

 dentate, crenate or laciniate. Fertile segments oval or oblong, 

 elliptical, revolute and plaited. Veins elevated, terminating 

 within the indusiiform margin, usually both branches spo- 

 rangiferous. Sporangia confluent, ultimately occupying the 

 whole under surface. 



