LEJEUNEA. 73 
“ perianthiis lateralibus obovato-oblongis dorso concaviusculis ventre con- 
vexis, margine oreque inciso-ciliatis ;” and under “§ 2, Typice. Perianthium 
ambitu teretiusculo ventre lateribus tergoque etiam carinatis,” is placed No. 
35, L. lunulata (Web.) “ perianthiis lateralibus obovatis compressis ventre 
obtuse carinatis apice oreque spinuloso-dentatis.” A comparison of the 
descriptions of the perianths of these two species shows plainly how very 
near they are to each other. The perianth of L. lunulata is in fact as 
much compressed as that of L. transversalis, obtusely keeled beneath, 
and margined with a similar sharply-toothed wing; so that, on placing 
the perianths side by side, we at once pronounce them to belong to 
two closely-allied species, as they really do, although there are differ- 
ences of ramification and foliage amply sufficient to keep them apart. 
The species of Lejewnea are perhaps the most elegant and delicate of all 
hepaticee. They abound in the wooded plains and mountains of all 
tropical countries, but are rare and of few species in the temperate zones ; 
and they have been so seldom gathered by any one previously conversant 
with the order, that they have been less generally studied than most 
others. Careful observation of their habits, aspect, and structure, in their 
native forests, as well as in the cabinet, has led me to the conclusion that 
the entire genus is divisible, and ought to be divided, into subgenera. 
This task I have set myself, and how far or how well I have succeeded in 
performing it, I must leave to the judgment of others. I can at least 
claim that all my subgenera are natural groups, and (as nearly as I could 
make them) of approximately equal value. Some of them, indeed, seem 
.to me more distinct than most of those separated as “genera” in the 
Synopsis. I may instance Sfictolejeunea, which, besides the unique 
character of the leaves and other appendages being beset with pellucid 
dots, has the flattened urniform perianth dilated at each apical angle into 
large round auricles, often bordered with white, that give it a remarkable 
resemblance to the head and ears of that curious Andine rodent, the 
chinchilla. Odontolejewnea, also, is a very distinct and natural group, of 
whose affinity to the genus Jubula I have already spoken. 
Whoever shall carefully study these plants will plainly perceive that 
several of my subgenera of Lejewnea are equivalent to certain genera of 
Jungermaniee, of whose right to that rank no one seems to have any 
doubt: It follows that either some recombination is needed among the 
latter, or else that the genus Lejewnea should be broken up into several 
genera. Without venturing to decide this knotty point, I would suggest 
that although, when the hepaticze of the whole world, or of a notable 
portion of its surface, are under consideration, a good deal of subdivision 
may be found requisite ; for a local flora or a limited area, too many genera 
will tend to produce confusion rather than precision, especially where 
several of the genera are monotypic; so that, on the whole, it seems 
desirable to make our genera as comprehensive as possible. For the sake 
of reconciling both views of the question, I have named all my subgenera 
by prefixing to the word Lejewnea some characteristic term—thus, Sticto- 
Lejeunea, from the dotted leaves: Priono-Lejeunea, from the finely serrated 
leaves; Diplasio-Lejeunea, from the two-ranked stipules, &c. For groups 
previously separated as genera which I adopt, wholly, or in part, as sub- 
genera, I have retained only so much of the name as may conveniently be 
added on to Lejeunea, thus Bryo-Lejeunea for Bryopteris, Thysano-Lejeunea 
for Thysananthus, &c. This merely for uniformity; but, whether as 
genera or subgenera, it matters not which name, of each pair of synonyms, 
is adopted. 
TRANS. BOT. SOC. DIN. VOL, XV. K 
