CHARACTERS OF TRIBES AND GENERA. 103 



OBS. This genus is distinguished from Pleopeltis prin- 

 cipally by the venules being more compoundly anastomose, 

 the fronds being smooth, and the sori destitute of indusae- 

 form scales. It comprehends a considerable number of 

 species, all, with two or three doubtful exceptions, natives 

 of the tropical and sub-tropical regions of the Eastern 

 hemisphere. 



P. pustulata (Forst.) (v v.) ; P. Billardieri (E. Br.) (v v.) ; 

 P. vulgare, Pr. (v v.) ; P. longipes, J. 8m. (v v.) ; P. pel- 

 tidea (Link.) (v v.) ; P. terminales (Link.) (v v.) ; P. 

 glauca,/. 8m. (v v.) ; P. nigrescens (Bl.) (v v.) ; (P. toccata, 

 /. Sm., 1857) ; P. longissima, Bl. (v v.) ; P. Schom- 

 burghiana, J. Sm. Lond. Jour. Bot. i. p. 196 (Polypodium 

 Scliomburgiana, Kze. in ScJik. Supp. Fil. t. 42). 



OBS. This is a native of British Guiana, and is peculiar 

 in being an example of Phymatodes, thus showing that the 

 genus is not entirely restricted to the Eastern hemisphere. 

 It, however, may be called an aberrant species ; it has a 

 remarkable caudex, from half an inch to an inch in 

 thickness, densely covered with long lanceolate, acumi- 

 nate, silky scales, very much resembling the well-known 

 Hare's-foot ~Fern,Davallia canariensis ; the fronds are distant, 

 short, stipate, oblong, elliptical, 1 to H feet in length, and 



2 to 3 inches in width, smooth, coriaceous, with thickened 

 margin; the sori are large, round, or oblique oblong, 

 forming a medial row on each side of the mid-rib. The 

 peculiarity of this Fern has led Klotzsch to place it under 

 a distinct genus, which he names Mecosorus. Another 

 remarkable American species is Polypodium (PJiymatodes) 

 lifrons, Hook. "Species Filicum," and Hook. Fil. Exot., 

 t. 52. The character of the caudex is described as being 

 long, slender, naked; the sterile fronds being elliptical, 



3 to 4 inches in length, the fertile narrow, linear, 5 to 6 



