i5 
Evans . — Branching in the Leafy Hepaticae . 
appendicular organs which spring from these regions would not be at all 
surprising. Similar unions, in fact, are frequently met with between bracts 
and bracteoles and are not unusual between ordinary leaves and underleaves. 
As members of the subgenus Barbilophozia , L. attenuata and L. 
Floerkei may be considered. Both of these species are widely distributed 
in the northern parts of Europe, Asia, and 
North America. In L. attenuata the leaves are 
commonly trifid, although bifid leaves are not 
unusual. They are attached by an oblique line, 
but often show more or less tendency to be 
complicate, the dorsal lobe being connected 
with the rest of the leaf by a rounded keel. 
Sometimes the dorsal portion is attached by 
an almost transverse line. The underleaves 
are minute and inconspicuous, and were not 
made out in the material studied on account of 
the thick felt of rhizoids. When a -branch is 
developed (Fig. 19) the leaf belonging to the 
same segment is undivided and acute, corre- 
sponding clearly to the dorsal lobe of an 
ordinary leaf. At some little distance from 
the incomplete leaf, on the ventral surface of 
the shoot, another leaf-like structure, which 
is also undivided and acute, can be discerned. This should apparently 
be interpreted as an appendage of the first segment of the branch 
but distinct from the first underleaf. It differs from the homo- 
logous appendage in L. Wenzelii in being 
entirely free from the incomplete leaf. The 
first branch-leaf in L. attenuata is small and 
often undivided ; it is usually covered over 
by the next stem-leaf on the same side as the 
branch. The remaining leaves of the branch 
show no special modifications. 
A study of L. Floerkei adds further sup- 
port to the interpretation just given of L . at - _ F J G * 20 - p°Ppozia Floerkei. 
ienuata. I he leaves in L . Floerkei are normally x 27. 
trifid and the distinct underleaves are bifid. 
At the base of a branch a structure like that shown in Fig. 20 can be 
demonstrated. The first underleaf of the branch (at the left-hand end 
of the figure) is similar to the other underleaves, but is undivided ; the 
incomplete leaf is also undivided and clearly represents a dorsal lobe ; 
between the two and somewhat coalescent with the leaf is a broad 
bifid structure, which is evidently homologous with the lobe-like tooth 
