194 Evans: HEpaTICAE OF PUERTO RICO 
The most important of the characters which separate the genus 
just described from Odontolejeunea are drawn from the vegetative 
organs and concern both leaves and underleaves. The margin of 
the lobe, for example, in Cyclolejeunea, is extremely variable with 
respect to its dentation ; in some species it is minutely and regu- 
larly crenulate or denticulate from projecting cells (PLATE 10, 
FIGURES 2, 4); in others it varies from entire to coarsely dentate 
on the same individual (PLATE 8, FIGURE 16); in Odontolejeunea 
the margin of the lobe is always sharply dentate. The lobule in 
Cyclolejeunea bears a single tooth on the free margin, and the 
hyaline papilla is also marginal, being borne at the proximal base 
of this tooth (PLATE 8, FIGURE 22; PLATE Q, FIGURES IO, 17); in 
Odontolejeunea the free margin of the lobule bears several teeth 
and the papilla is displaced from the margin. The underleaves in 
the two genera are very different with respect to their method of 
attachment to the axis, the line of insertion in Cyclolejeunea being 
short and scarcely arched (PLATE 8, FIGURES 16, 17) instead of 
long and sharply arched as in the other genus. Radicelliferous 
discs are found in both genera but are not a constant feature in 
Cyclolejeunea, the underleaves in certain species giving rise directly 
to rhizoids. Other differences in the underleaves, relating to the 
presence or absence of an apical sinus, have already been alluded 
to. The perichaetial bracts of Odontolejeunca are characterized by 
being practically elobulate, while those of the new genus have 
well developed lobules (PLATE 8, FIGURE 23). In the vegetative 
reproduction, finally, we find a very striking difference which is 
probably to be considered generic; in Odontolejeunea this 1s 
carried on by means of the leafy propagula already described; in 
Cyclolejeunea the vegetative reproduction is by means of peculiar 
marginal gemmae in the form of discs, similar in some respects to 
those found in Cololejeunea and its allies, but differing from them 
in the details of development and germination. These gemmae 
will be discussed after the description of species. 
Cyclolejeunea Chitonia (Tay]l.) 
Lejeunea Chitonia Tayl.; Lehmann, Pug. Plant. 8: 27. 1844 
(misprinted ‘‘Z. Ciitonta’’). 
Odontolejeunea subbifida Steph. Hedwigia, 35: 117. 1896. 
