t 
Evans: HEPATICAE OF PuERTO RICO 275 
connection between the branches and the rudimentary leaves as 
in certain other members of the genus. 
One of the closest relatives of A. exigua is the rare type species, 
A. microscopica, specimens of which have been received from Mac- 
vicar. The two species equal each other in delicacy and are of 
about the same size. The lobes of the leaves are also very much 
alike and the lobules are almost identical in structure. The two 
species agree further in their paroicous inflorescence. In. A. 
microscopica, however, the cells of the lobes are less strongly convex 
and the margin consequently is either entire or very vaguely 
crenulate; along the keel the roughness is better marked although 
less conspicuous than in A. exigua. There are also slight dif- 
ferences in the bracts. In A. microscopica the lobes average about 
0.25 X 0.09 mm. and the cells near the apex are often distinctly 
conical instead of merely convex as in A. exigua. Sometimes one 
of the bracts in the British species bears an antheridium in its 
axil, and the lobe of such a bract is usually less roughened than an 
ordinary perichaetial bract. The lobule measures about 0.18 X 
0.07 mm. and shows two teeth much as in A. exigua. The peri- 
anths, so far as can be judged from Pearson’s d iption, are very 
much alike. The differences in the gemmae will be considered later. 
Goebel’s Lejeunea heterophylla has never been formally pub- 
lished, but in his Pflanzenbiologische Schilderungen he alludes 
to some of its most striking peculiarities and shows them ina 
figure. The specimen he studied grew on the leaves of Vittaria 
remota in Puerto Rico, but nothing more definite about the locality 
is stated. According to his account the species is allied to A. 
exigua; it is said, however, to produce leaves with lobules and 
rudimentary leaves practically destitute of lobules in definite 
succession and to have a five-keeled perianth. In a letter from 
Goebel he states that he has preserved no specimens of L. hetero- 
bhylla and would prefer to have the species considered as in- 
adequately published. In any case the five-keeled perianth would 
serve to distinguish it from A. exigua. 
In Lejeunea Sintenisii, which is known only from the type 
material collected by Sintenis (136), the plants are said to be much 
branched and to be dioicous. According to Stephani’s figure the 
leaves are similar to those of A. exigua except that the lobe projects 
