INTRODUCTION. 
Cellule*. 
Surface. 
N'erre. 
Perigonial 
leaves. 
Perichaetial 
leaves. 
Sometimes the relative size of the cellules will afford, in the absence of the fructi - 
fication, tolerably good specific marks of discrimination. Thus, in J. Taylori they are 
very large ; in J. scalaris much smaller ; and in J. Sphagni minute ; yet the form of the 
leaves, in all three, is nearly the same. When the leaves of the Jungermanniae have been 
dried, and are recovered by immersion in water, the cellules are dark in the centre, and 
have a pellucid border around them ; a circumstance which arises from the collapsion of 
the juices, and accumulation of the granules, in the middle of the cell. Just the same 
takes place in the Conferva, between the structure of which, and that of the Jungermanniae, 
there seems to be a close analogy. 
The leaves of all the species are destitute of every kind of hairiness or scabrosity. 
In one of the frondose species, J. pubescens (tab. 73), the surface of the plant, both above 
and below, is covered with white, pellucid hairs. 
In a variety of J. hamatifolia, I have seen the cellules very prominent and pointed, 
so as to give the appearance of a curiously tuberoulated leaf (See SnppL tab. 3). In all 
the other species the surface is smooth; and even shining in J. Sphagni, J. hyalina, and 
J ■ lavigata. 
Nor is there any thing which precisely accords with the nerve of Mosses in the leaves 
of these plants. The appearance of a nerve in J. albicans (tab. 15), is only caused by 
the different form of the cellules, narrower and longer than the rest: but they are not 
prominent on either surface, like the nerves of Mosses. J. prostrata, of Swartz’s 
FI. Ind. Occ., has a nerve resembling that of J. albicans. 
The perigonial leaves, or those which contain the anthers, in general differ but little 
from the rest, except in being more closely imbricated, and in having a swelling at the 
base where the anthers are lodged, as in J. asplenioides (tab. 13). Frequently these are 
wanting. In some of the frondose species, as J. Lyellii (tab. 77) and J. hibernica (tab. 78), 
the perigonium is a scale resembling a stipule in the foliaceous species; and, in J.f areata 
(tab. 55) and J. pubescens (tab. 73), the anthers are inclosed within an innovation of the 
frond, which is rolled up into a ball. 
The perichatial leaves, or those which surround the calyx, differ in general much more 
from the cauline ones. Even in the bifarious species they frequently grow from all sides 
of the stem, as in J. capitata (tab. 80) and J- emarginata (tab. 27). They are wholly 
wanting in J. Trichomanis (tab. 79): and, in J. obtusifolia (tab. 26), J. nemorosa (tab. 21), &c., 
they scarcely differ from the rest. In J. Hooketi (tab. 54) and J. concinnata (tab. 3) they 
are very concave, and entirely embrace the young fructification, seeming to answer the 
purpose of a calyx. In J. juniperina (tab. 4), J. emarginata (tab. 27), and J. scalaris, 
(tab. 6), they are united at their lateral margins, and appear almost converted into a calyx. 
In many species they are more cleft than the cauline leaves ; as for example, in J. Turneri 
(tab. 29) and J. excisa (tab. 9). In J. connivens (tab. 15) and J. seiacea (tab. 8) they are 
palmate. In J. polyanthos (tab. 62), J. Sphagni ( Suppl . tab. 33), J. reptans (tab. 75), and 
J. tnlobata (tab. 76), they resemble small scales: and in J. dilatata, J. Tamarisci, J. Mackaii, 
J. serpyllifotia, J.. hamatifolia, and J. minutissima (tab. 5, 6, 53, 42, 51, 52), the lobes of these 
are large and expanded, which, in the rest of the leaves, are small and involute, or saccate. 
