334 Bower . — The comparative examination of the 
segments is far from being constant, a fact which has been 
noted and figured in my former paper (Lc. Fig. 7) : it is shown 
obviously in Fig. 34, in which each segment divides by a 
sextant wall ( sf into two approximately equal halves, but their 
further sub-division cannot be reduced to any rule, the result- 
ing cells being triangular, or variously polygonal as seen in 
surface view from without. Longitudinal sections of the apex 
show that the apical cell is pointed, and deep in proportion to 
its width (Fig. 35), in fact very much deeper than the apical 
cells of the leptosporangiate Ferns 1 ; in all the Ferns quoted 
in the foot-note the apical cell of the leaf is proportionately 
much less deep than it is in Osmunda : in other words, the 
centre of construction in Osmunda is more deeply seated than 
in any of these Ferns, and, coupling this with the more com- 
plicated construction of the meristem, which is of a type 
characteristic of cylindrical rather than flattened structures, 
the conclusion is that the whole member is of a more robust 
order than in other leptosporangiate Ferns. 
It is obvious from an inspection of apices shown in plan 
(Fig. 34, also Phil. T rans. 1884, Plate 37, Figs. 4, 6, and 7), 
that here there can be no marginal series of cells having such 
relation to the segments of the apical cell on the one hand, 
and to the wings on the other, as in the leaves of the simpler 
type ; and I have already shown in the paper above quoted, 
that each of the lateral wings is formed from parts of two of 
the rows of segments cut off from the apical cell. The 
structure of the wings will be described later (p. 352). It may 
further be added that, as far as my observations go, the 
branching of the frond of Osmunda is exclusively monopodial. 
It will now be shown that in the Marattiaceae the di- 
vergence of the apex of the leaf from the type of the simpler 
Ferns, as regards the structure of the apical meristem, is even 
1 Compare Fig. 31 above : also Sadebeck’s Fig. 33 C. (Schenk’s Handbuch, I. 
p. 271) of Asplenium Trichomanes : also Hofmeister, Fig. 2, Plate XXXII. in his 
Higher Cryptogamia, which is drawn from Pteris aquilina : also the beautiful 
drawings of Kny on Plate XXIV. of his Memoir on Ceratopteris : also Prantl’s 
figure of Aneimia (Schizaeaceae, Plate III, Fig. 28 B). 
