562 Evans: HeEpaTicAE oF PuERTO Rico 
approximately circular in outline. In the most elongated cells 
there are frequently four or five intermediate thickenings between 
two trigones. In most of the species the thickenings show a strong 
tendency to become confluent and thus to obliterate the pits. 
Enough of the latter, however, usually persist to enable a cell to 
communicate with most if not all of the cells which surround it, 
but not infrequently lateral communication between cells is com- 
pletely cut off. On account of the peculiarities of the wall the 
cavities of the cells acquire a wavy contour, not unlike what 1s 
found in the cells of Herberta and several other genera of the 
Jungermanniaceae. 
The underleaves are usually contiguous or imbricated (FIGURE 
16). They vary in outline from oblong or obovate to orbicular or 
quadrate and are attached by an arched line of insertion. The 
broad apex is rounded or truncate, and the base, which varies from 
rounded to cuneate, is usually abruptly decurrent. The apical 
region is toothed as in the leaves, the teeth sometimes extending — 
down the sides as far as the middle. The lateral margins are 
more or less involute (from below), and the median basal region is 
distinctly gibbous, the bulge sometimes partially concealing the 
line of attachment. ; 
The female branches are short and destitute of subfloral inno- 
vations (FIGURE 15), They usually arise in abundance from both 
stem and primary branches. Their leaves are reduced to four or 
five pairs, including the involucre, and there is a gradual transition 
from the minute basal leaves, closely appressed to the branch, and 
the large and widely spreading perichaetial bracts. All of the 
leaves are distinctly modified (FIGURE 21). The innermost bracts 
are deeply and unequally bifid, the lobule being narrower than the 
lobe but often fully aslong. Both are long-acuminate and usually 
bear scattered teeth, especially near the apex. The bracteole 15 
free and also bifid, with long-acuminate divisions separated by 4 
narrow sinus. Both lobules and bracteole tend to be more of les 
revolute along the margin. 
The perianth projects beyond the involucre for about half its 
length and is ovate or oblong in outline, bearing a distinct beak 
at the rounded or slightly retuse apex. It is strongly compresse 
with a high and narrow postical keel. The sharp lateral keels #* 
cee Me ath 
