Evans: HepaTIcAE oF Puerto Rico 501 
apex, sometimes indistinctly apiculate, entire, 0.4-0.5 mm. long, 
0.08—0.14 mm. wide, lobule ovate to ligulate, obtuse ; bracteole 
connate on both sides at the base, linear, shortly bifid with obtuse 
sinus and obtuse or acute divisions, margin entire, 0.25 mm. long, 
0.07.mm. wide above connate base; perianth slightly exserted, 
obconical from a narrow base, broad at the apex and with a short 
beak, 0.4 mm. long, 0.35 mm. wide, terete below, sharply fine- 
keeled above, the keels extending upward and outward as acute 
or truncate horns, smooth or slightly roughened near the apex ; 
or inflorescence usually occupying a short branch, rarely terminal 
ona leading branch; bracts and bracteoles as in L. erocellata ; 
antheridia in pairs: spores oblong, greenish, with a thick, brown- 
ish, minutely verruculose wall, averaging 23 in short diameter 
(pl. 24, f. 1-7). 
On living leaves. First collected by Sintenis (45, 136); 14 
miles south of San Juan, Heller (678, 680) ; near Mayaguez, Heller 
(4566 p. p., 4567 p. p.); Cayey, Evans (70a p. p.). 
L. exocellata and L. elliptica are very closely related species. 
They are not only strikingly similar in appearance but are likely 
to grow mixed together on a single leaf, and for these reasons they 
have been much confused by students of the hepaticae. Even 
Spruce, who first recognized the first species, considered its validity 
aS somewhat doubtful and suggested that it might perhaps be 
looked upon as a variety of L. edliptica. 
According to its author, Z. exocellata may be distinguished 
from Z, elliptica by the following differences: the plants are a little 
larger, their leaves are sometimes narrowed at the base (2. @., obo- 
vate-lanceolate) and are constantly evrocellate, the leaf-cells are 
More indistinct and with somewhat thickened walls, the infrafloral 
Underleaf is conspicuously pentagonal and bicuspidate, the peri- 
chaetial bracts are narrower and the perianth is larger. 
Unfortunately several of these differences are not to be relied 
upon, and this applies particularly to those which concern the leaf- 
Cells. In his full descriptions of the two species in question, Spruce 
States that the cells of L. elliptica are “ valde leptodermes,” while 
Nose of L. exocellata are “intus sinuatae, parietibus, subincrassa- 
tis,” As a matter of fact the cell-walls are very thin in both 
Species but show almost invariably minute and distant trigones 
