West. — A Contribution to the Study of the Marattiaceae. 409 
reference to the last-named genus, it is interesting to note that the majority 
of the stems which exhibit pronounced dorsi ventral ity are generally more 
elongated and less bulky than the radial ones. 
The general conclusions which may be drawn from a comparative 
study of the morphological, anatomical, and histological characters of the 
Marattiaceae may be briefly summarized as follows : 
1. The modern representatives of the Marattiaceae, as exemplified by 
the six genera Angiopteris , Archangiopteris , Danaea , Kaulfussia , Macro- 
glossum y and Marattia , undoubtedly form a very natural and homogeneous 
group, as is shown by the following characters which they share in 
common : 
i. Arrangement of the vascular strands in the stem. 
ii. Structure of the vascular strands in the stem ; e. g. anomalous 
position of the protophloem ; structure and irregular distribution 
of the endoderms ; position of the protoxylem ; structure of the 
xylem and phloem elements. 
iii. General morphology of the frond. 
iv. Arrangement of the vascular strands in the petiole. 
v. Absence of sclerenchyma from the stem-tissues. 
vi. Bud-protection devices. 
vii. Anatomy of the root. 
viii. Presence of an endotrophic mycorrhiza (West, 70). 
ix. Apical meristems of stem and root. 
x. Presence of lysigenous mucilage canals (West, 68). 
xi. Presence of tannin cells or tannin ducts (West, 68). 
These genera also show a striking similarity with regard to their 
xii. Spore-producing members, e. g. the radiate uniseriate type of 
sorus (cf. Bower, 8). 
xiii. Embryogeny (cf. Campbell, 17, 18, 19, 20, 21). 
xiv. Gametophytic structures, e. g. prothallia, sexual organs (cf. Camp- 
bell, 17, 19, 20, 21). 
2. The Marattiacean Ferns occupy an isolated position among modern 
Vascular Cryptogams. 
Considered from the point of view of their morphological, anatomical, 
and histological characters, as summarized above, the Marattiacean Ferns 
are very sharply marked off from all other modern groups of Vascular 
Cryptogams, with the possible exception of the Ophioglossaceae. But 
whilst admitting with Campbell (20, p. 218) the possibility of a common 
origin for the Marattiaceae and Ophioglossaceae from the same primitive 
stock, the present writer is of the opinion that these two families have 
proceeded along widely divergent lines from this common plexus, with the 
result that by comparing individual surviving genera from these two families 
