120 Bower.— Is Eusporangiate or Leptosporangiate 
division of the archesporium took place, not its mere repetition ; 
but the resemblance is undeniable : there is thus in the sporo- 
gonium itself an indication of how the Eusporangiate sporan- 
gium may have been derived, however vague and uncertain 
that indication may be thought to be ; whereas there is as 
yet no rational suggestion as to the mode of origin from the 
Bryophyta of the sporangium as it is seen in the Lepto- 
sporangiate Ferns. 
Passing on to the apical meristems, the characters of these 
have been used by me as a basis for disposing the Filicineae 
in series, as above stated. It is to be remembered that such 
evidence cannot be expected to apply with equal force in all 
cases, and that it is of greater weight within narrow circles of 
affinity, than in the comparison of more remotely related 
organisms. It is, however, worthy of note that while a single 
initial is present in the young sporogonium of the Moss, in 
the Liverworts a single initial is not found, though in certain 
of the Jungermannieae four cells, which hold a central position 
at the apex of the sporogonium, suggest in some measure that 
structure which is characteristic of the meristems of the Ma- 
rattiaceae : it would however be unwise to rest strongly on 
such a point as this. 
In comparing the Hymenophyllaceae with the Mosses the 
mere vegetative characters of the gametophyte have been 
brought forward as weighty evidence : if we are to depart so 
far from the methods of classification applied to the higher 
plants, and consider vegetative characters in plants widely 
diverse in other respects, as much might I think be said for 
the similarity between, for instance, the prothallus of the 
Marattiaceae or Osmundaceae and the sexual plant of the 
Anthoceroteae : the flattened but massive green thallus, which 
may in either be branched, is not dissimilar in the two cases. 
The point of distribution of the sexual organs may appear to 
be an obstacle, they being on the upper surface in the An- 
thoceroteae, while in the Marattiaceous prothallus they are 
commonly on the lower; but Jonkman 1 specially states and 
1 La generation sexuee des Ma!rattiacees, pp. 13-17. Figs. 53-57. 
