Cxii. GENERA OF FERNS : 



CRASPEDOPHYiLtiM, Presl ; PTYCHOPHYLLTJM, Presl ; SPH.BEOCIONIUM, 

 Preil ; MECODIUM, Presl ; DERMATOPHLEBIUM, Presl. 



Sori involucrate, i.e., seated within an extrorse-marginal ob- 

 long or sub-orbicular two-valved involucre ; the veins continued 

 into the receptacle, which is free included cylindrical or globose 

 at the apex, and bears sessile or sub-sessile lenticular or turbinate 

 spore -cases. Veins dichotomously branched, simple and costa- 

 Uke in the ultimate segments, or simple parallel from a central 

 costa in undivided fronds ; venules free. 



Fronds simple or decompoundly divided, pellucid membrana- 

 ceous. Rhizome creeping, usually filiform. This group, which 

 is rather extensive, is in general well-distinguished from Tricho- 

 wtawesbythe involucres consisting of two separate valves, instead 

 of being blended into a cup. In some few species, however, where 

 the valves are combined below, this difference becomes merely 

 one of degree. 



Hymenoglossum, Veins simple from a central costa (fronds simple.) 

 Ex. : H. cruentum, Cav. 



Hymenophyllum. Veins simple costa-like in the ultimate segments. 



H. organense, Hook. 

 H. pvUchellum, Schlech. 

 H. seruginosum, Carm. 

 H. unilaterale, Willd. 

 H. dilatatum, Sw. 

 H. demissum, Sw. 



Ex. : H. hirsutum, Sw. 

 H. elegans, Spr. 

 H. senceum, Sv>. 

 H. tunbridgense, Sm. 

 H. fuciforme, Sw. 

 H. crispatum, Wall. 



Order POLYPODIAOE^]. 



1 LYGODE.E. 



(a) Veins free. 



158. LYGODIUM, Swartz, Schrad.Journ.l8W,u. 7, 106. 



UdEifA, Cavanilles; HTDBOGLOSSUM, Willdenow, in part; GISOPTERIS, 

 Bernhardi; ODONTOPTEEIS, Eernhardi; CTEISIUM, Michatix; ARTHEO- 

 LYOODES, Presl; EAMOITDIA, Mirbel; VALUPILIX, Thouars ; OPHIO- 

 GLOSSI sp., Auct. 



Fructifications forming compressed distichous spikelets, ex- 

 sorted on the marginal teeth. Spore-cases included beneath 

 ovate cucullate imbricated persistent scariose bractiform indusia, 



