552 FILICALES 



first, that the latter are not marginal, excepting very occasional examples 

 in O. palmatiim, which is held as a derivative and outlying species : but 

 secondly, the general comparison of characters, morphological and anatomical, 

 of the sporophyte, of the sporangia, and of the gametophyte, indicates a quite 

 separate position for the Ophioglossaceae. It suggests that the most that 

 can be said is that some analogy exists between the Marsiliaceae and 

 Ophioglossaceae in the position of their spore-producing parts ; but the 

 way in which this analogy has been attained is quite a different question. 

 It seems probable that they represent quite distinct evolutionary sequences : 

 a well-founded hypothesis has been stated above of an origin of the Ophio- 

 glossaceous spike quite distinct from that of the sporocarp in the Marsiliaceae. 



