664 Campbell . — The Structure and Affinities of 
more compressed laterally than in Angiopteris , and are also much less 
convex on the dorsal surface. In Angiopteris the whole dorsal surface of 
the sporangium is composed of cells with dense brown contents, probably 
tannin. These tannin cells in Macroglossum are confined to the upper free 
portion of the sporangium, and are also much less developed on the inner 
or ventral face. 
The annulus, which is so conspicuous in Angiopteris , is almost entirely 
absent in Macroglossum Alidae , being represented by a single transverse 
row of about half a dozen cells (Text-fig. 7, c), which are hardly at all 
thickened even in the ripe sporangium. 
Text-fig. 7. A, Sporangium, median longitudinal section, x 75. B, Surface view of 
sporangium. C, Apex of sporangium, showing place of dehiscence, st. The shaded cells are 
tannin (?) cells, d, Wall of sporangium, showing the multinucleate tapetal cells, t. x about 250. 
E, Indusial hair, x 75. 
As in other Marattiaceae, the tapetal cells remain intact until a late 
period and become multinucleate (Text-fig. 7, D, t). Between the tapetum 
and the surface of the sporangium there are two or three layers of cells. 
The dehiscence is by a cleft along the inner face, on either side of which 
the cells are narrower, but the band of narrow cells bounding the cleft is less 
conspicuous than in Angiopteris . 
Text-fig. 7, E, shows one of the much-branched indusial hairs. 
The sprus, as already stated, lies above the end of a vein, and between 
the sori lies the conspicuous ridge which reaches about half-way up the 
sporangia, so that their position recalls that of the synangia of Danaea , 
where, however, the ridge between the synangia is narrow and reaches above 
the level of the synangium. 
