PTERIS. 109 



Sori linear, continuous, or interrupted, generally only occu- 

 pying the sides of the segments. 



Indusium plane, linear, with its base often sporangiferous. 



In the section Litobrochia, the veinlets instead of being 

 direct, are reticulated. They are mostly large branching Ferns, 

 of a flaccid- texture. 



In the section Lonchitis, the veinlets are also reticulated as 

 in Litobrochia, yet they differ in the position of the sori, 

 instead of being linear, and occupying more or less of the 

 sides of the segments; it is situated in the sinus of the seg- 

 ments, and is more or less the form of a segment of a circle. 



In the section Campteria the difference is in the venation, 

 taking a midway character between the true Pteris and 

 Litobrochia. The veinlets are direct except a single row of 

 costal venules, which anastomose. 



Thus in the above the transition from Pteris through 

 Campteria and Lonchitis to Litobrochia, is so gradual, that 

 the example of Kunze has been followed, in retaining them 

 as sections, in preference to separating them entirely from 

 Pteris. 



