288 CHARACTERS OF TRIBES AND GENERA. 



Tribe 21.— PTERIDB^ (Plate 21). 



Fronds varying from simple, entire, to decompound mnl- 

 tifid, and from 1 to 10 or more feet in heiglit, and (with 

 the exception of Boryopteris) of a thin flaccid texture. Veins 

 free or anastomosing, their apices combined forming a 

 transverse, marginal, sporangiferous receptacle, seated in 

 the axis of an exteriorly attached inflexed special indusium 

 forming oblong or continuous marginal sori. 



Obs. — I have already explained under Cheilantliece my 

 reasons for separating it from Fteridece, which as now 

 restricted contains about one hundred described sjjecies of 

 which the genera Ptei is and Litoirochia contain the principal, 

 which technically differ in the venation of the first being 

 free and in the second anastomosed in various ways. 



Sect. 1. — Veins anastomosing. 



163. — DoETOPTEEis, /. Sm. (184,1). 

 Pferis sp. auct., sect. LitrohrocJiia, Hook. Sp. Fil. 

 Vernation fasciculate, erect, rarely sarmentose. Fronds 

 simple, cordate-hastate, or palmately-lobed ; prnnas entire 

 or lobed, smooth, opaque, castaneous, stipes and rachis often 

 ebeneons. Veins internal, reticulated. Eeccptacles trans- 

 verse marginal, seated in a narrow exterior attached 

 indusium, forming a linear continuous sorus. 

 Type. Tteris pedata, Linn. 

 Ulust. Hook, and Bauer Gen. Fil., t. 65, B. : Hook. Fil. 



Exot., t. 31 ; J. Sm. Ferns Brit, and For., fig. 98. 

 Obs. — This is a small group of pretty Ferns, with the 

 same general character as regards texture, colour, and 

 smoothness as Fellcea and Gassebeera, but technically distin- 



