290 CHARACTERS OF TRIBES AND GENERA. 



from which they differ in having pinnate fronds, and 

 the pinnce articulate with the rachis, these difierences 

 induce me to consider them as forming a transition genus. 



Sp. P. Burkeana {Eook. Sp. Fil, 2, i. 126, B.) ■ P. arti- 

 culata {Sooh. Sp. Fil., 2, t. 126, A.). 



The first is a native of South Africa, and the latter of 

 Mauritius, Borbon, and Madagascar. 



165. — LiTOBEOCHiA, Presl. (1836). 

 Pteris. sp. auct., Hooh. S2}. Fil. 



Vernation fasciculate, erect or decumbent, often Cfespitose. 

 Fronds pinnate or bi-tripinnate, decompound, deltoid, 1 to 

 10 feet or more in height ; ultimate segments broad and 

 often unequally lobed. Veins evident ; venules wholly or 

 partially anastomosing, forming unequal areoles, the ex- 

 terior venules sometimes free. Sporangiferous receptacles 

 linear, transverse marginal, seated in the axis of an inflexed 

 special indusium. 



Type. Pteris comans, Forst. 



Illust. Hook, and Bauer Gen. Fil., t. 65 B. ; Moore Ind. 

 Fil., p. 32 ; .J. Sm. Ferns, Brit, and For., fig. 97 ; 

 Hook. Syn. Fil., t. 3, fig. 31 h. 



Obs. — In habit the species of this genus are similar in 

 general appearance to those of the following genus Pteris, 

 but are technically distinguished by their anastomose vena- 

 tion. 



The species vary greatly in size, in the circumscription 

 of the fronds, and in their mode of growth ; occasionally, 

 indeed, separate parts of a single frond differ so widely that 

 in the herbarium they are apt to be viewed as distinct 

 species. 



In the " Species Filicum" thirty-nine species are enume- 



