FERN CONFERENCE. 



503 



have been used by me as evidence in laying out the Filicinecs 

 in series as above stated ; such evidence is of greater weight 

 within narrow circles of affinity than in comparison of more 

 remotely related organisms. It is, however, worthy of note that 

 in the Liverworts a single initial is not present as in the Moss 

 sporogonium. The epibasal half of the zygote divides into four 

 quarters by principal walls, which might be compared with those 

 found in apices of the Marattiaceous type ; but it would be a 

 mistake to put too fine a point upon such a comparison as this. 



4. The evidence from the geological side is interesting and 

 important, even while allowing a liberal discount for imperfect 

 representation of the Flora of any given period. The general 

 conclusion of Paheophytologists is that though in the Devonian 

 and Carboniferous periods Ferns of the Marattiaceous type were 

 among the most prevalent of plant-forms, Leptosporangiate Ferns 

 were apparently uncommon or even absent, and there are those 

 who hold that no undoubted remains of them have been found 

 in those strata ; in the Khaetic series of transition between the 

 Trias and the Lias, Ferns allied to our present Gleicheniacece 

 appear to have been common, and other leptosporangiate forms 

 appear in more recent rocks. Whether or not the Leptosporau- 

 giatcB were actually absent during the earlier periods, there can 

 be no doubt that the Eiisjporangiatce, which are now so restricted 

 both in number of genera and species, and also in geographical 

 area, were in the ascendant at the Carboniferous period. It may 

 be urged that the more delicate structure of the sporangium of 

 other forms prevented their preservation ; but, on the other hand, 

 the annulus is a firm band of tissue, and quite as likely to be 

 preserved as many of the tissues which retain their characters in 

 geological specimens. It will also be pointed out that very many 

 of the fossil Ferns show no fructification at all. This is true, but 

 as far as the positive and well-ascertained facts go, they appear 

 to point to the conclusion that the Eusporcuujiatce were the prior 

 forms, or at least that their period of prevalence was prior to 

 that of the Lcptosporangiatce. 



It may, however, be objected that the leaves of the Marat- 

 tiacecB are commonly of a highly branched type, while those of 

 certain Hymenopliyllacece are simple, and the simpler form is the 

 more likely to be the original. It is true that the Marattiacecv 

 cultivated in gardens have branched leaves, but this is not the 



