Evans: HEpaTICAE OF PuERTO RIco 187 
Brownish or yellowish green, scattered or loosely caespitose, 
often mixed with other Leyeuneae: stems 0.17 mm. in diameter, 
irregularly branched, the branches widely spreading : leaves imbri- 
cated, the lobe widely spreading, convex and more or less revolute 
along postical margin, falcate-ovate, 1.7 mm. long, 1 mm. wide, 
attached by an almost longitudinal line of insertion, antical margin 
arching across or just beyond the axis and strongly curved from 
base to apex, postical margin approximately straight, apex broad 
and rounded, whole margin sharply dentate, the teeth scattered, 
each consisting usually of a cell with a strongly thickened outer 
wall arising from a base two cells wide, postical margin with two 
teeth much larger than the others and separated from each other 
by a broad lunulate sinus; lobule suborbicular in outline, 0.35 mm. 
long, the strongly inflated inner half lying parallel with the axis 
and bulging beyond the free margin, outer half appressed to lobe, 
free margin curved from base to end of keel, usually bearing three 
scattered teeth, two side by side at about the middle of the margin, 
the other midway between these and end of keel, the teeth blunt, 
commonly two or three cells long and one or two cells wide at 
the base, often curved toward the lobe; cells of lobe plane or 
nearly so, averaging 18 yw at the margin and 30» in median and 
basal regions, walls thin but firm, trigones triangular, rarely con- 
fluent, intermediate thickenings numerous, oval: underleaves con- 
tiguous or slightly imbricated, broadly orbicular, 0.7 mm. long, 
0.85 mm. wide, attached by a narrowly arched line of insertion 
and apparently strongly biauriculate at base, the auricles subquad- 
rate in form; apex broad and rounded, often revolute ; margin 
sharply denticulate, the majority of the teeth minute and consist- 
ing of single projecting cells, one or two teeth in the basal region 
often larger than the others and broadly triangular in outline: 
inflorescence dioicous: © inflorescence sometimes on a leading 
ranch, more frequently on a short branch, innovating on one or 
on both sides, the innovation usually floriferous and sometimes 
repeatedly so; bracts obliquely spreading, slightly plicate at the 
very base, ovate to oblong, 0.95 mm. long, o. ) mm. wide, apex 
rounded to subacute, margin sharply dentate as in normal leaves ; 
bracteole free, orbicular-obovate, 0.75 mm. long, 0.7 mm. wide, 
middle portion convex postically with a plane or revolute border, 
margin irregularly denticulate or dentate with scattered teeth ; 
perianth obovate in outline, 1.25 mm. long, 0.95 mm. wide, 
cuneate toward base, broad and truncate or slightly retuse at the 
apex with a distinct beak, antical face plane, postical face with a 
distinct keel, broad and rounded below, narrow and sharp above, 
lateral wings extending to or below the middle of the perianth, 
two or three cells broad, each bearing about twelve sharp and 
