INTRODUCTION. 
Frequently, on their falling away from the leaves, as in J. excisa ( Suppl . tab. 2) and some 
others, the leaves appear injured and jagged, as if the cellules had been torn off ; and it 
is not improbable but that, in certain states of the plant, this may really be the case ; so 
that each of these particles may be looked upon as a cellule. Their color, when first 
formed, too, is generally green, turning to brown in an older state, as in J. nemorosa, and 
to a fine red in J. exsecta. 
SECTION III. 
On Jungermannia as a Genus, and on the Arrangement of 
the British Species. 
As far as my experience enables me to offer an opinion, from my acquaintance with 
the British and many foreign species, the plants that at present form the genus J unger- 
mannia, however numerous, cannot be divided into other genera by means of characters 
taken merely from the fructification. In this respect, those which seem most allied in habit, 
often differ essentially ; so that, with regard to the Jungermannia frondosa, for example, 
which at first sight appear to demand a separation, unless there are made almost as many 
genera as species, I do not know any character which they have in common, by which 
they might be discriminated from the Jungermannia foliosa. 
Jungermannia nemorosa, resupinata, umbrosa, and undulata, have a peculiar habit about 
them, and have, moreover, a remarkably compressed calyx, truncate at the mouth ; and 
we may think here to have discovered a character by means of which they may be removed 
from the rest of the genus : but an examination of other species will convince us of the 
inadequacy of this character ; since J. asplenioides and J. complaiiata, two plants very 
different in other respects, have a calyx of the same shape. 
A still stronger peculiarity of habit seems to unite J. serpyllifolia, J. hamatifolia, 
J- calyptrifolia, and J. minutissima, in which also the singular structure of the capsule, and 
especially its short valves, seems to claim for them the privilege of being considered a 
distinct genus ; yet there are two species, J. Mackaii and J. platyphylla, which connect 
them by an easy gradation with J. dilatata and J. Tamarisci. 
The following character of the genus I would propose as liable to fewer objections 
than any that has yet been given. 
CLASS AND ORDER. 
Cryptogamia, Hepatic®. Schreb. 
(NATURAL ORDER. 
Hepatic®. Juss. Be Catid. Plant® Cryptogam®, Calyptrat®, Deoperculat®. Mohr.) 
GENERIC CHARACTER. 
Receptacidum fructus commune nullum. 
Cal. Perichatium monophyllum tubulosum, rarius nullum. 
