INTRODUCTION TO CRYPTOGAMIC BOTANY. 535 



ing to the tip of the veins. These processes are not, however, 

 of the nature of indusia, but are hard and coriaceous, and 

 entirely of the same substance as the rest of the frond. The 

 species of Prosaptia are analogues of Davallia, but not, I 

 I think, very closely related ; nor do I see how it can be reduced 

 to Poly podium. The tribe is essentially tropical or subtropical. 



10. Adiantiace^, Pt. 



Sori linear, lineari-oblong, or globose, mostly marginal, seated 

 on the tips of the veins, in most cases soon becoming confluent. 

 Indusiuni spurious, formed from the reflected margin of the 

 frond. Rhizoma globose or creeping, rarely arboreous. 



607. The transition from the indusiate to the nonindusiate 

 ferns is made by this tribe, which is very near to Dicksoniacew. 

 The indusium is, however, essentially spurious, being nothing- 

 more than the reflected margin of the frond. Those cases 

 require to be carefully distinguished where the indusium, 

 though marginal, springs from a nerve, and is perfectly dis- 

 tinct, which is the case in Actiniopteris (Fig. 110, h). This 

 false mdusium may be either scarious or coriaceous, but more 

 frequently the former ; it is, in fact, the same organ with the 

 spurious indusium oi Dichsonia, the true indusium being sup- 

 pressed. The tribe is divisible into two sections, containing 

 the species more especially allied to Lonchitis and Adi- 

 antum. 



608. The first is known by the sori being constantly seated 

 in the sinuses of the frond, the indusium being lunate or linear. 

 Lonchitis has reticulate venation, Hypolepis pinnate. Of the 

 various characters assumed by the indusium of the latter, and 

 its confluence with Poly podium, I have already spoken in the 

 general observations. The species are tropical or subtropical. 

 Hypolepis tenuifolia extends to New Zealand. 



609. The second section has linear or subglobose sori, at first 

 distinct, but very soon becoming confluent, seated at the mar- 

 gin of the frond. Haplopteris has distant parallel simple 

 veins, springing from the costa ; the indusium is infra-marginal, 



situated iu a groove parallel with the margin, and not in the margin 

 itself, and remarks that the simple venation separates them from Poll/" 

 podiacece. 



