IO 
Evans. — Branching in the Leafy Hepaticae. 
keel and tend to be slightly complicate. The underleaves are large and 
bifid. When a branch is formed the leaf arising from the same segment 
is broad but undivided (Fig. n), and its line of attachment extends across 
the dorsal base of the branch. The first underleaf is remarkable because 
it is apparently not attached to the branch at all, but to the stem at some 
distance below the base of the branch. It seems to be laterally inserted 
on the stem, and its line of attachment is almost transverse as in ordinary 
underleaves. This underleaf is strongly concave, but when dissected off 
presents no unusual features either in form or size (Fig. 12). In such 
a case as this it must apparently be assumed that the base of the branch 
is coalescent with the stem. The description just given applies most 
forcibly to primary branches. When these become subdivided there is 
little or no coalescence at the base of a secondary branch, the first under- 
leaf occupying much the same position as in Lepidozia. 
Figs, ii and 12. Mastigophora Woodsii. Same material as Fig. io. 
Fig. 11. Incomplete leaf at base of branch. Fig, 12. First underleaf of branch, x 40. 
Pleuroclada. — Large and conspicuous underleaves are rarely associated 
with succubous leaves in the Jungermanniaceae. This condition, however, 
is found in Pleuroclada albescens , a widely distributed species of Europe and 
North America at high altitudes. The branching in this species is in- 
variably of the Fndlania type, and the structures at the base of a branch 
show a few distinctive features. Unfortunately the succubous insertion of 
the leaves, even here, is less distinct than in such genera as Lophocolea and 
ChiloscyphuSy apparently on account of the fact that the bilobed leaves show 
a tendency to be complicate. If the line of attachment is examined it will 
be seen that the portion corresponding to the dorsal lobe is almost transverse, 
and that it is only in the portion corresponding to the ventral lobe that the 
obliqueness is clearly apparent. The leaves are strongly convex and appear 
almost hemispherical, the acute lobes being separated by a narrow sinus 
(Fig. 13). The underleaves approach the leaves in size, but are normally 
undivided and acute ; their margins are either entire or unidentate on one or 
both sides. Two and sometimes three papillae can be demonstrated on an 
