3. THTESOPTEEIS. 15 



22. G. (Mn-t.) pectinata,TT. (character given in the section). — G. gkucescenSj 

 H. B. K. Wc. Sp. l.p. 11. Jlertensia Hermanni, Bt et Gr. Ic. P. t. 14 {excl. 

 synonyms). 



Hab. Tropiciil S. America, commoa everywhere. ^Tbe only species of this sectioD, and 

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

 glaucous, Sori of 8-10 capsules. 



§ 4. Stipes zigzag, repeatedly di- or trickotomous, the ultimate branches hearing 

 a pair of forked pinrUB : a distinct pair of pinnce also arises from the base of the 

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



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

 p. 12. G. Hemiaiuii, Br. {not Hk. & Gr.). Besides the many synonyms given in 

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

 only) ; M. rufinervis. Mart. Bk. Sp. 1. p. 11. G. Klotzschii, Jlk. Sp. l.p. 13. 

 i. 5. B. 'M.TeYohita,, Kl. Sb.nostr. {Twt of H.B.K.). M. crassifolia, Pr. i"/??!/}. 

 p.23.t.l3. G.feiTngmesL,Bl.{notI>esv.). Hk.Sp.J.p.lO. Mett.inMiq.Ann. 

 Mus. Bot. L.BaZ. \.p. 50. M. emarginata, Brack. Fil. U. S. Expl. Exp. p. 297. t. 42. 

 (very fermgineo-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. pectinaia is a solitary species 

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

 geographically distributed, it is very variable in the size of the pinoEe 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 fi-ond : but the pairs of accessory 

 pinnae 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 pinnae free (pin- 

 nules) and more or less deeply pinuatifid, from Penang and Java. 1 have others from 

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

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

 inaequaliter dichotomse." — In regard to size, some of the pinnae are l-lj ft. 1., and some 

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

 pinnatifid. 



Sub-Ord..II. POLYPODIACE^. 



Sori dorsal or marginal, subglobose, of many capsnles, with or withoict an involucre. 

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

 elastic ring, and bursting transversely {except in Hymenophylleae). Tribe I.-XIII. 

 Gen. »-61. Tab. I. f. 3-12, and Tab. I.-VIII. f. 13-61, inclusive. 



A. Involuceatje. Sori furnished with an involucre {except in AlsophUa). 

 Tribe I.-VIII. Gen. 3-47. 



Tribe I. Ctathe^. 



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

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

 hairs, (Novate, usually with a broad, vertical, or subeblique elastic ring. Invol. {want- 

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

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

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

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



Gen. 3. Thtrsopteris, Kze. 



/SbW 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. 



