66 LEJEUNEA. 
leaf is inserted on an exceedingly narrow base, the fold is often nearly 
parallel to the stem, or is not unfrequently flattened out, and the lobule 
yroper is represented by a marginal tooth some way above the base of the 
bat or is quite obsolete. 
The leaves are infinitely more varied in outline than those of Frullania, 
being in some species broader than long, in others narrow and almost’ 
subulate ; and although quite entire in more than half the number, yet 
Jeaves toothed in various ways—sometimes even ciliate or spinose—are 
frequent ; while in Drepanolejeunea palmifolia, Mart., they are so deeply 
Jaciniate as to be almost pinnatifid. The smooth surface, prevalent in 
most Lejeune, becomes scabrous in certain subgenera, and in a few is even 
echinate or setulose, e.g., in the Cololejewnea calcarea of Europe and its 
Javanese ally CL venusta, Lac.; also in Trachylejeunea acanthina, Spruce, 
from the Andes, and 7’r. papillata, Mitt., from New Zealand. 
It is in the subgenus Odontolejeunea nob., with its large spinoso-dentate 
leaves, recalling those of a Scapania, that we find the nearest allies of 
Jubula. Some species, indeed, have leaves so like those of J. Hutchinsie 
that were it not for the large and nearly flat lobule—as contrasted with 
the small saceate lobule of Jubula—they might on a merely cursory view 
be referred to that genus. Other features common to both have been 
already pointed out. 
Modifications of the lobule in Lejewnea, although useful for distinguish- 
ing species, are rarely available as subgeneric or sectional distinctions— 
for the organ itself is liable to become obsolete in many species, and in 
all is variable in size—except in the case of the horn-like lobule of L. calyp- 
trifolia and its allies, and in the subgenus Ceratolejewnea, where the 
lobules of the two lowest leaves on a branch—rarely of any upper leaves— 
are swollen out into a large kidney-shaped bag, involving the diminished 
lobe, and perforated in the centre of the depressed upper face. This 
curious structure is found to have originated in the lobule having been 
chosen as the nidus of certain minute insects, whose eggs or larve are 
occasionally found within the sac; but as it is limited to certain species 
of the group, where it is a constant feature, while from others it is as con- 
stantly absent, and in a few it exists in only a limited degree ; as more- 
over, I have occasionally seen these abnormal sacs in all stages without 
any occupant, and have noted an initial enlargement of the lobule while 
both leaf and branch were still so young as to be quite rudimentary ; I 
cannot doubt that the “utriculi” (as they have been called) have in many 
cases become inherited, and are as necessary to be taken into account in 
describing a species as any other part of the plant. This is a parallel case 
to that of the ant-inhabited sacs of T'ococa and other Melastomacee.* In 
a few species of Lejewnca the lobule is itself bilobed, but the segment next 
the stem is very rarely styliform, after the manner of Frullania. 
The texture of the leaves is thinner and tenderer than in Frullania, 
and corresponds more to that of Jubula. The cells are mostly subeequi- 
lateral hexagons (in reality short hexagonal prisms) and of medium size, 
or rather small ; scarcely ever to be called large, but not unfrequently 
minute. The leaves of certain species are, however, ocellate near the 
hase by the interposition of a group of larger cells ; very rarely are similar 
* IT may have to return to this subject when I come to treat of the probable 
origin and use of the inflated or saccate leaf-lobes which occur normally in 
Lejeunea, Frullania, and a few other genera of hepatice, 
