56 DICKSONIK.E. 



62. A. Telfairiana, Wall, in Index. Aspidium Telfairia- 

 num, Wall. Cat. n. 385. Mauritius, Mr. Telfair. — Of this 

 and the two preceding species I have seen no specimens. 



Doubtful Species ; country unknown. 



63. A. Wiegeltii, Roera. Herb. Presl, Pterid. p. 61, (name 

 only). 



TiiiBE II. DICKSONIEJE, Gaud. 



Sori globose or subcylindrical, situated upon the back 

 (WooDsiE^) or at the apex of a vein or veinlet (Eudick- 

 soNiEiE) or at the confluent angle of reticulated veins (Hypo- 

 DERRiDE^). Involucre inferior (having its origin from beneath) 

 globose or cylindrical, free, sometimes covering the whole 

 sorus, closed at the top, at length bursting at the summit; 

 more frequently cup-shaped, open at the mouth, the mai'gin 

 entire or 2-lipped, naked or fimbriated or crinite, wholly or in 

 part formed of the substance of the frond, or more membranace- 

 ous: sometimes it constitutes a shallow, very indistinct, fringed 

 cup, of which the membranaceous portion is so small as to be 

 concealed by the capsules, never wholly wanting. — Tnfied or 

 creeping Ferns, generally snuill, rarely arborescent , inhahit- 

 ing various climates, from the extreme Arctic regions to the 

 Tropics. 



Obs. It has heen found, I believe, by all botanists to be far more difficult 

 to divide the several groups of Cryptogamic plants into natural and tangi- 

 ble sections, than the so-called higher orders of Phaenogamous plants. 

 They are seen to pass so insensibly, the one into the other, and to be con- 

 nected by so many different links, that it is next to impossible to define them 

 by words', and in vain to expect that the several individuals who study them 

 should arrive at the saine conclusion in regard to their respective limits, 

 artificial though, in a linear series, they must still, in a measure, necessa- 

 rily be. The several genera, for example, which I here bring under one 

 group or Tribe, others have, with perhaps equal justice, thought worthy of 

 being broken down into at least three separate ones, Pemnemacece, Dickso- 

 niea:,\n(\ Hymenophyllcce. Nay, with regard to the last-mentioned group, 

 Presl has not deemed it right to include it in the true Filices at all. The 

 Tribe Dicksoniete is here intended to embrace those Ferns which have an 

 involucre resemliling, or approaching to those of CyathecB, but whose fronds 

 exhibit a totally different aspect, rarely arborescent, never or very seldom 

 aculeated, extremely variable in composition, and also, in texture, from the 

 most delicate reticulated membrane to a firm coriaceous substance : with 

 capsules generally subglobose, and stipitate with a moderately broad incom- 

 plete elastic vertical ring, rarely sessile and angularly compressed with a 

 broad complete oblique ring; such forms as are common in Ct/atheie, 

 (whence Presl constituted of them and of the Gleicheniacece the suborder 

 Helicogyrata), but which are by no means universal in Cyathece ; and 

 on the other hand we possess such capsules or analogous ones in Loxsoma, 

 Thyrsnpteris and in the Hymenophylleous genera of the present Tribe. It 

 must be allowed indeed that the characters here derived from the fructifica- 



