148 J. SMITH ON THE GENERA OF FERNS. 



Obs. This tribe is entirely composed of species which 

 formed the extensive genus Acrostickum, as characterized by 

 Swartz, Willdenovv, and others ; and contains above 100 

 described species. It is readily known from Polypodie(s by 

 the sporangia not being produced in defined, round, or linear 

 masses, but closely occupying the whole, or some portion of 

 the fertile disk, which in the genus Olfersia, and some 

 species of Polyhotrya, is not confined to the inferior disk 

 alone, the contracted rachiform segments being sporangi- 

 ferous on all sides. The contracted state of the fertile frond 

 does not admit the venation to be clearly seen, but in the 

 genus Cyrtogonium it is in general very evident, and forms 

 the principal receptacle of the sporangia as in PolypodiecB. 

 The chief characters upon which the following genera are 

 founded are derived from the various modifications of the 

 veins of the sterile fronds, which exhibit structure analogous 

 to the several sections of the preceding tribe; therefore the 

 amorphous sori must be viewed as the only distinction be- 

 tween them, and even that is not always to be depended on, 

 as it has been shown that Stenosemia, in some states, assumes 

 the character of Acrostichiece. 



Sect. I. Orthophlebie^. 



Veins simple, forked, or costseform and pinnate; venules 

 direct, their apices free. 



38. Elaphoglossum, Schott. 

 (Acrostichi, sp. Auth. Olfersise, sp. Presl.) 



Veins simple, or forked, internal; venules parallel, their 

 apices free and clavate, terminating within a thickened mar- 

 gin. 



Fronds simple, entire, oblong, or linear -lanceolate, smooth, or 

 squamose ; margin of the fertile fronds usually membraneous. 



Examp. 1. E. simplex, {Su).) 2. E. apodum, (Kaulf) 

 3. E. viscosum, {Sw.) 4. E. conforme, (Sw.) 5. E. squa- 

 mosum, {Sw.) 6. E. villosum, {Sw.) Illust. Hook, et Grev. 

 Ic.Fil.t. 2, 4, 21, 22, 99. 



