Evans: HeEpaTicAE oF Puerto RIco 559 
floriferous, more rarely short and sterile; bracts unequally bifid, 
the lobe obliquely spreading, ovate to oblong, 0.65 mm. long, 
0.45 mm. wide, apex rounded to very obtuse, margin as in leaves, 
lobule lanceolate to narrowly oblong, 0.3 mm. long, 0.09 mm. 
wide, acute to obtuse at the apex; bracteole free, similar to the 
underleaves but relatively longer, measuring 0.6 mm. in length 
and 0.5 mm. in width, bifid about one sixth ; perianth when young 
about half exserted, afterwards pushed outward through the 
growth of the basal region, oblong to oblong-obovate, 1 mm. 
long, 0.5 mm. wide when well developed, narrowed toward base, 
broad and rounded or truncate at the apex with a short but dis- 
tinct beak, sharply five-keeled, the antical keel extending from the 
apex to about the middle of the perianth, the others extending 
nearly to the base, surface of perianth more or less roughened 
from projecting cells: ¢ inflorescence basal or intercalary on a 
short branch; bracts in two to five pairs, strongly inflated, un- 
equally bifid, the lobe obtusely pointed, the lobule sharper and 
often apiculate ; bracteoles present at base of spike, smaller than 
the underleaves and more deeply bifid; antheridia in pairs : mature 
sporophyte not seen (f/. 22, f. 1~T0). 
On trees. North slope of the Luquillo Mountains, Heéler 
(4719 p. p., 4721 Pp. p.). El Yunque, Evans (27, 33). First col- 
lected on the island by Schwanecke. 
So far as we know at present &. /rifaria is the only American 
species of Euosmolejeunea, in which the inflorescence is autoicous. 
Even here unisexual individuals occasionally occur, but, since they 
are usually found in the same mats as typical bisexual individuals, 
their presence need not often confuse us in recognizing the species. 
The monoicous inflorescence doubtless accounts for the frequency 
of perianths in Z. trifaria as compared with dioicous forms. 
Probably the closest ally of Z& ¢rifaria, in the West Indies at 
least, is the dioicous E. opaca. If for any reason there is difficulty 
in demonstrating the inflorescence, the slight differences in the 
vegetative organs are usually distinct enough to separate these 
two species. £. opaca is a little less robust than £. ¢rifaria, the 
lobes of its leaves are less convex, the leaf-cells are plane or nearly 
so, and the trigones of both leaves and underleaves are less con- 
spicuous. Of course all of these vegetative characters are vari- 
able and largely dependent on external conditions, so that the 
positive determination of immature or poorly developed specimens 
is not always possible. 
