1915] HUTCHINSON—PELLIA EPIPHYLLA 135 
the successive divisions follow an antheridial sequence; if, how- 
ever, the wall is inclined and somewhat removed from the central 
position, the cell divisions which follow are similar to those of a 
developing archegonium. In the former case the vertical wall is 
followed by a curved wall on either side, which cuts the vertical 
wal] as shown in figs. 7 and 8. Two similar walls, rotated about 
the central axis through an angle of 90° (figs. 8, 9), complete the 
separation of the peripheral region from the central spermatogenous 
region. The first two of these walls may be nearly parallel at the 
base (fig. 7), or they may be at right angles; similarly the second 
pair. Such an antheridium is characteristic of the Jungermanniales. 
Occasionally the outer cell, mentioned above, is divided into 
quadrants by walls at right angles to the vertical wall (figs. 10, 11), 
in which case four wall cells are cut off by periclinal divisions, 
giving also four spermatogenous cells. The process is similar to 
that characteristic of Sphaerocarpus or Marchantiales. 
Fig. 14 illustrates the result of a combination of these two 
methods of development. In fig. 15 is shown a double antheridium; 
the two halves have become completely separated by the vertical 
division and each has developed independently. The process may 
be compared to the characteristic development of the double 
antheridia of Anthocerotales. 
When the first wall formed in the outer cell is inclined and 
somewhat removed from the median position, it is followed by a 
second and a third wall, each of which is similarly placed, but 
revolved with respect to each other through an angle of 120° about 
the vertical axis (figs. 17, 18, 26, 27, 28). A transverse wall divides 
the central cell into the cap cell and the spermatogenous initial 
(fig. 19). The characteristic archegonial development is followed 
until the massive spermatogenous group begins to be formed (figs. 
22, 28), instead of the axial row. 
Occasionally this critical third wall of the antheridium is inclined 
inward instead of outward, as described above (fig. 23). Two 
walls similarly inclined complete the separation of the peripheral 
region from the central spermatogenous initial (figs. 24, 25). This 
form is similar to that last described with the exception of the incli- 
nation of the walls and the resulting lack of the cap cell. 
