CHAEACTEES OF TEIBES AND GEKEEA. 81 



the decumbent or erect nature of the rliizome, and the 

 more or less elevation of the node of articulation, and in 

 the position of the sori. The following are admitted in 

 the " Synopsis Filicum " as distinct species. 



Species :^0. neriiformis, Gav. (v v.)* ; 0. musajfolia, 

 Kunze {Bedd. Ferns, Brit. Tnd. pi. 264) ; 0. articulata, 

 Gav. (v V.) ; 0. nodosa, Willd. (v v.) ; 0. Wallichii, Rooh. ■ 

 O. Cumingii, /. Sm. 



The genus is widely distributed, being found in the 

 region of the Himalaya, Malay Archipelago, and Philip- 

 pine Islands, as also in the West Indies and Tropical 

 America. 0. neriiformis is a peculiar Fern, differing- from 

 the rest of the genus in having erect frutescent branching 

 stems, about half an inch in diameter, and rising to the 

 heig-ht of from four to six feet, bearing lateral whorls ot 

 simple fronds. It may be viewed as the only representa- 

 tive of a shrub among Perns. It is found throug-hont the 

 tropics of America and India, and in the Malay and Pacific 

 Islands. 



Tribe 2.— DAVALLIE.E, J. Sm. (Plate 2.) 



Veins free. Sori termmal, marginal, punctiform. Iii- 

 dusium forming a more or less complete cyst, opening 

 exteriorly. 



Obs. — In the " Species Filicum," 112 species of DauaW/cs 

 are enumerated, which, in the " Synopsis," are reduced to 

 seventy-nine. This number consists of species both with 

 articulate and adherent vernation ; the latter consequently 

 comes under the division Desmobrya. About forty species 

 have articulate vernation, and are comprised mider the 



* These letters indicate that the species have heen cultiTatcJ at 

 liew, as recorded in "Ferns : British and Foreign." 



