326 CHAKiCTEKS OF TEIBES AND GENEEA. 



the superior venules having unilateral sori as in true 

 Asplenntm. 



The following species, taken from " Ferns, British and 

 Foreign," are sufficient to illustrate the genus. They are 

 widely diffused throughout the tropics of both hemispheres, 

 with the exception of D. iheJijpteroides, which is found in 

 l^orth America. 



* Vernation erect. 



■j- Fro'iids simple. 

 Sp. D. plantagineum, Siv. (v v.). 



ft Fronds pinnatifid. 

 D. Zeylanicum, RooJc. (v v.). 



ttt Fronds jnnnafe, 



D. pallidum, BJ. ; D. graudifolium, Siv. (v v.) ; D. Jug- 

 landifolium, Siu. (v v.) ; D, alternifolium, BI. (v v.) ; D. 

 fraxinifolium, JVcdJ. ; D. celtidifolium, Kiukc ; D. Lobbi- 

 annm, Hooh. 



tttt Fronds hipinnatifid or hijjinnate. 



D. Shejiherdi, LinJc. (v v.) ; D. coarctatum, Link, (v v.) ; 

 D. striatum, Pr. (v v.) ; D. expansum, WiUd. (v v.) ; D. 

 diversifolium. Wall, (v v.) ; D. conchatum, Moore (v v.) ; 

 D. polypodioides, Bl (v v.) ; D. Sohkuhri, Mett. ; D. 

 Klotzschii, Moore (v v.) ; D. lobulosum. Wall. ; D. costale, Pr. 



** Vernation decnrnhcnt. 

 D. sylvaticum, S'w. (v v.) ; D. dilatatum, Bl. (v v.) ; D. 

 arborescens, Sid. (v v.) ; D. vestitmu, Pr. ; D. Thwaitesii, 

 /. Sni. (v V.) ; D. flexuosum, Pr. ; D. thelypteroidcs, Pr. 

 (v V.) ; D. Franconis, Melt, (v v.). 



