IV. HYME]VOI*HYLL-A.CE^E. 



Sori marginal, terminal on the vejns, exserted or immersed in the sub- 

 stance of the frond. Receptacle erect, oblong, capitate, malleiform, clavate 

 or columnar-filiform, included or exserted. Sporangia dense, imbricate, com- 

 pressed, surrounded by a broad, horizontal or subhorizontal, complete ring, 

 opening vertically. Indusium inferior, 2-valved or + tubular to obconical 

 with the mouth truncate, dilated or + 2-lipped, mostly of the same texture 

 as the frond, opening outwardly. 



Rhizome frequently creeping. Fronds often small and membranaceous, 

 rarely subcoriaceo us, without stomata; veins free. 



Tropical and subtropical, rarely inhabiting cooler 1 zones. 



Key to the genera. 



)(c. Indusium more or less deeply 2-vaIved; receptacle mostly included; 

 surface of the sporangia divided into many i equal cells. 



No. 8. Hymenoptayllum. 



>(?.;(«. Indusium tubular or funnel-shaped, the mouth sometimes 2-lipped; 

 receptacle mostly exserted ; surface of the sporangia divided into few, 

 unequal cells. No. 9. Trichomanes. 



s. hlyjmetvophyllum:, smith. 



Sori marginal, terminal on the veins. Indusium more or lese deeply 



2-valved, of the same texture as the frond, exserted or more or less immersed 



in the margin. Receptacle mostly short and included, rarely elongated and 



prominent beyond the sporangia. Surface of the sporangia divided into many, 



± equal cells. 



Rhizome mostly creeping, often filiform. Fronds generally small, delicately 

 membranaceous, more or less compoundly divided, with mostly linear or linear- 

 oblong ultimate segments. Hk. Rk., Syn. Fil., tab. II, fig. 16; Diels, in Engl. 

 & Prantl, Nat. Pfl.Fam., l\ fig. 74. 



Tropical, and extra-tropical in the southern, rarely in the northern hemis- 

 phere. 



FiLlGES. ^ 



