Evans: HEPATICAE OF PuERTO Rico 549 
similar to one another that the greatest care must be exercised in 
Separating them. At the same time the differential characters, 
although so slight, appear to be constant. : 
In L. stricta the leaves are much more sharply pointed than in 
ff, subacuta and commonly end ina row of from two to four cells ; 
the leaf-cells have slightly thinner walls and the trigones are in 
consequence a little more prominent ; the underleaves differ in 
being about as long as broad (measuring 0.075 mm. in length) 
and in having less divaricate lobes. The material of Z. stricta 
studied by the writer is from Liebmann’s original collection and 
was kindly communicated by Herr Stephani. The specimens are 
destitute of female flowers and perianths, but these organs, which 
are fully described by Gottsche,* afford a few additional differences, 
the bracts being winged along the keel and the keels of the peri- 
anth being denticulate in the upper part. 
In Harpalejeunea ovata the leaves are very similar in shape to 
those of 7. subacuta, and the apices of the lobes vary from obtuse 
to short-acuminate. The northern species, however, is a little 
more robust, but at the same time the leaf-cells, which measure a 
little larger than those of 7. sudacuta, are more delicate in texture 
and show more distinct trigones. The underleaves of H. ovata 
measure 0.08 mm. in length and 0.1 mm, in width and the apical 
sinus is shallow and commonly lunulate, in many cases being 
scarcely evident. The perichaetial bracts and bracteoles agree 
pretty closely in the two species, but those of /7. suéacuta are rela- 
tively broader and the bracteal lobes are more nearly equal in 
size. 
HARPALEJEUNEA UNCINATA Steph. 
Harpalejeunea uncinata Steph. Hedwigia, 35: 97. 1896. 
Pale green, often becoming brownish upon drying, growing in 
depressed mats: stems 0.0 35 mm. in diameter, prostrate but rather 
loosely adherent to substratum, sparingly branched, the branches 
widely spreading : leaves contiguous to slightly imbricated, the 
lobe widely spreading (in outer part), convex, sometimes reflexed 
at the apex, falcate-ovate, 0.3 mm. long, 0.15 mm. wide, attached 
by an almost longitudinal line of insertion, margin entire near 
antical base, otherwise irregularly crenulate or denticulate from 
Projecting cells, antical margin decurrent by a single cell, strongly 
ite Geman hetcuemincee ee 
* Mex. Leverm. 108. 1863. 
