184 Evans: HEpaATICAE OF PUERTO RICO 
Lejeuneae and includes an almost continuous series of species con- 
necting the very different genera Dicranolejeunea and Prionolezeunea, 
In fact, such a species as O. /unulata (Web.) Schiffn., which may 
be considered the type of the genus, is much more closely related 
to certain Décranolejeuneae than it is to Z. accedens or even to L. 
convexistipa; and L. accedens, on the other hand, is hardly to be 
separated generically from such a Prionolejeunea as P. microdonta 
(Gottsche) Steph. 
Fortunately the series may be divided into two clearly defined 
groups or genera. The first of these is composed entirely of 
species with undivided underleaves and includes the first four of 
the species described by Spruce under Odonto-Lejeunea. For 
this genus the name Odontolejeunca may be retained. In the sec- 
ond genus, which may be designated Cyclolejeunea, some of the 
species have undivided underleaves and others have bifid under- 
leaves. This genus includes most if not all of the remaining species 
described by Spruce. The slight difference in the underleaves, 
which by itself would be of but little moment, is supported by the 
much more important generic characters noted below. 
The genus QOdontolejeunea in its restricted sense is composed 
entirely of tropical species. The type of the genus, O. /unudata, 
is found in both America and Africa, but the remaining species, $0 
far as known, are exclusively American. Although occasionally 
found on bark, the species are most at home on living leaves and 
include some of the largest and most conspicuous of our epiphyl- 
lous hepatics. The plants are usually olive green in color, vary- 
ing to brownish or yellowish, but are apparently never pale green 
or whitish. In spite of the prostrate habit of the plants, the 
leaves are not closely appressed to the substratum. When dry 
they are irregularly crispate and wrinkled; when moist they are 
convex and strongly revolute along the postical margin. The 
lobes of the leaves spread widely from the axis and are commonly 
broad and rounded at the apex. On well-developed leaves the 
margin is sharply and irregularly dentate, the teeth being scattered 
and consisting of from one to a considerable number of cells. The 
lobule of normal leaves encloses a distinct water-sac and the free 
margin is appressed to the lobe (pLaTE 8, FIGURE 2). Along the 
margin are found from two to four scattered teeth, but the hyaline 
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