Capsules either few (1 — 2), placed in the axils of imbricating, clasping 

 indusia, which form spikes along the margin of the fertile segments or nu- 

 merous, ranged in 2 — 4 regular, close rows, which cover one side of close, 

 distichous spikes at the apex of the fertile fronds or segments ('). Ring com- 

 plete, operculiform, crowning the apex of the capsule. Stomium vertical. 



Rhizome creeping or erect. Fronds small and erect or long and twining. 



Tropical and extra-tropical. 



Key to the genera. 



:tc. Capsules 1 — 2; indusium present. Fronds very long and twining. 



No. 10. liygotiium. 



jjc.:^. Capsules numerous, in 2—4 rows; indusium wanting. Fronds 



small and erect. No. 11. SIchieaea. 



lO. LYOODIUM:, Swartm. 



Sporangia 1 — 2, placed in the axils of imbricating, clasping, scale-like 

 indusia, which form spikes either on separate, contracted segments or in lax 

 rows along the edge of normal segments. 



Rhizome creeping. Fronds very long, twining, pinnate. Pinnae (^) stalked, 

 opposite, the pairs placed on very short, alternate, primary petioles which are 

 often inconspicuous and sometimes quite wanting; veins free or anastomosing. 

 Hk. Bk., Syn. Fil., tab. IX, fig. 68; Diels, in Engl, k Prantl, Nat. Pfl.Fam., 

 I*, fig. 195. ; See Supplement 1. 



Tropical and extra-tropical. 



Arrangement of the sections. 



$ 1. EULYGODIUM. Veins free. 



§ 2. HYDROGLOSSUM. Veins anastomosing. jSee the App endix. 



. (') The characters of the african and american genera are not mentioned here. 

 (') The segments indicated here as pinnae are properly the branches of forked pinnae, 

 the very short stalks of which are forming the so-called primary petioles, 



