3. THYKSOPTERIS. 15 



22. G. (Mei-i.) pectin ata, Pr. (character given in the section). G. glaucescens, 

 //. B. K. Hk. Sp. !./>. 11. Mertensia Hermann!, Hk. et Gr. Ic. F. t. 14 (excl. 

 synonyms}. Mertensia nervosa, Klfs. Gleichenia, Ilk. Sp. 1. p. 12. t. 5. A. 



Hab. Tropical S. America, common. /3. Brazil. The only species of this section, and 

 not to be confounded with any other. Glabrous or pubescent beneath, very frequently 

 glaucous. Sori of 8-10 capsules. M. nervosa, Klfs., is merely a young form of this. 



4. Stipes zigzag , repeatedly di- or trichotomous, the ultimate branches bearing 

 a pair of forked pinnae : a distinct pair of pinnae also arises from the base of the 

 forked branches (not of the frond). Segments never decurrent. Sp. 23. 



23. G. (Mert.) dichotoma, Willd. (character given in the section). Hk. Sp. 1. 

 p. 12. G. Hermann!, Dr. (not Hk. & Gr.). Besides the many synonyms given in 

 Sp. Fil. 1. c., I may add M. pteridifolia, Pr. Epim. p. 23. t. 14 (a terminal fork 

 only) ; M. rufmervis, Mart. Hk. Sp. I. p. 11. G. Klotzschii, Hk. Sp. 1. p. 13. 

 t. 5. B. M. revoluta, Kl. Hb. nostr. (not of H. B. K.). M. crassifolia, Pr. Epim. 

 p. 23. 1. 13. G. ferruginea, Bl. (not Desv.}. Hk. Sp. 1. p. 10. Mett. in Miq. Ann. 

 Mus. Bot. L. 'Bat. 1. p. 50. M. emarginata,#rac. Ml. U. S. Expl. Exp.p. 297. t. 42 

 (very ferrugineo-tomentose beneath, and with the segments often emarginate ; 

 as they are in the glabrous var. of G. dichotoma). 



Hab. Tropical and subtropical regions, almost universal, in the New and in the Old 

 Worlds ; Pacific Islands, and as far north as Japan. As G. pectinata is a solitary species 

 of its section, so is G. dichotoma of the present one. Besides being most extensively 

 geographically distributed, it is very variable in the size of the pinnae and in the shape 

 of the segments, and in being more or less glabrous or densely tomentose beneath, green 

 or glaucous, and very variable in the texture of the frond : but the pairs of accessory 

 pinnse at the base of a fork are invariably present. There are also abnormal or 

 aberrant forms. Among them I have specimens with lobes of the pinnse free (pin- 

 nules), and more or less deeply pinnatifid, from Penang and Java. I have others from 

 Java, which Mettenius (Ann. Mus. Bot. L. Bat.) calls var. alternans, in which the 

 primary divisions of the stipes are scarcely dichotomous, but alternate, " frondes 

 insequaliter dichotomse." In regard to size, some of the pinnse are 1-1 4 ft ! and some 

 are 6 in. br. Occasionally, the lowest pair of lobes is much elongated, reflected, and 

 pinnatifid. 



SUB-ORD. II. POLYPODIACE.E. 



Sori dorsal or marginal, subglobose, of many capsules, with or without an involucre, 

 usually pedicellate, more or less completely surrounded with a jointed vertical and 

 elastic ring, and bursting transversely (except in Hymenophyllese). TRIBE I.-XIII. 

 GEN. 3-G1. TAB. I. f. 3-12, and TAB. I.-VIII. f. 13-61, inclusive. 



A. INVOLUCRAT^E. Sori furnished with an involucre (except in Alsophila). 

 TRIBE I-VIII. GEN. 3-47. 



TRIBE I. CYATHE.E. 



Son dorsal, globose, often at or near the forking of a vein. Caps, numerous, often 

 very compact, sessile or stalked, generally on an elevated receptacle, often mixed with 

 hairs, obovate, usually with a broad, vertical, or suboblique elastic ring. Invol. (want- 

 ing in Alsophila) inferior, including the sorus, lateral and resembling a scale on the 

 under side of the sorus, or cup-shaped, often, when young, enveloping the sorus, eventually 

 opening at the summit, or breaking down, with a more or less regular margin. Gaud, 

 very generally arborescent. Tropical or subtropical. GEN. 3-8. 



GEN. 3. THYRSOPTERIS, Kze. 



Sori globose, marginal, collected into a panicle distinct from the sterile pinnae. 

 Caps, sessile, on a globose receptacle. Invol. inferior, cup-shaped, the mouth entire. 

 Fronds decompound, sterile portions bipinnate with lanceolate, incised pinnules ; 

 fertile ones 3-pinnate, of which each pinnule becomes a raceme of stalked involucres. 

 TAB. 1. f. 3. 



