ixvi. SBNEEA OB PEENS : 



Veins arcuateTy anastomosing at the base, forming costal areoles r 

 vermles simple or forked, parallel, connirent with the thiclenecl 

 margin. 



Fronds rigid, opaque, pinnato-pinnatifid. Rhizome arbor- 

 escent. — The tree-like habit, elevated receptacle, thick indu- 

 sium, and arcuately-anastomosed basal veins, indicate a distrnot 

 group, with which, however, we are but little acquainted. 



Ex. ; S. cyatheoides, Mfs. \ S. pallida, Blc. and Am. 



S. Sonleytiana, Gaud. \ S. squarrosa, G-aud. 



§ 4. PliBtTEOaEAMMEa). 

 (a) Veins consisting of a cosCa only. 



22. MONOGRAMMA, SchTcuhr, Orypt. Gewdch. 82. 



Vaginulaeia, Bie; COCKLIDII sp., Kaulfuas; Geammitidis Bp., -itttcf J 



PtEEIDIS Sp., ^ItC*. ; PLEUEOaEAMMATIS Bp., JWe; ASPLENII Sp., ^WOT^B ; 



ACEOSTICHI sp.,8wwrtz; T^HITIBIS B^.,\Mett&niTi8. 



Son sub-immersed, non-indusiate, linear elongate near the 

 apex of the frond, the reoepteoZe formed of a portion of the costa^ 

 Veins reduced to the costa only. 



Fronds small graminiform or rachiform, simple or forked. 

 Rhizome creeping. — Curious little plants of extreme simplicity of 

 structure. 



§ Mortogramma. — Sori lying in a longitudinal depression of the gramini^ 

 form iVonds. , 



Ex. : M. graminea, Sclihuhr. \ M. iUrcata, I)esv. 



§ VagvnvZa/ria. — Sori occupying a vaginiform es:pausion of the rachiform 

 fi-onds. 

 Ex. : M. trichoidea^ J. Sm. 



(b) Veins consisting only of a casta, (md the intramarginal recep- 

 tacles parallel mth it. 



23. DICLIDOPTBRIS, Srachemridge, United States Expl. 



Bxped. xvi. 135, Atlas, t. 17. 



Sori immersed, non-indusiate, linear, continuous, sub-costal ; 

 the receptacle formed of a simple vem proceeding from each side 

 the eosta, near its base, and running parallel with it ; sunk in a 

 deep oblique furrow open towards the costa, over which the two 



