498 Evans: HEpATICAE OF PuEeRTO RIco 
are rough and often spinose. In Leftolejeunea also the leaves are 
usually ocellate and the inflorescence autoicous, while in Drepano- 
lejeunea, the leaves are rarely ocellate and the inflorescence is 
usually dioicous. It must be admitted, however, that there are 
species which it is difficult to assign definitely to either genus, and 
in such cases we must rely upon a combination of characters 
rather than upon any single generic difference. 
Four species of Lepéolejeunea are now known from Puerto 
Rico, all of which are widely distributed in the American tropics. 
The commonest of these is probably Z. e//iptica, which has already 
been recorded by Stephani. * The range of this abundant species 
extends through the islands of the Pacific into the East Indian 
archipelago. 
Leptolejeunea exocellata (Spruce) 
Lejeunea (Lepto-Lejeunea) exocellata Spruce, Hep. Amaz. et 
And. 195. 1884. 
Pale green, becoming brownish upon drying ; stems 0.05 mm. 
in diameter, closely adherent to substratum, once to thrice pinnate 
with widely spreading branches but less copiously branched than 
the preceding species: leaves distant, the lobe widely spreading, 
plane or nearly so when moist, appressed to substratum, ovate to 
obovate, 0.45 mm. long, 0.25 mm. wide, attached by a very short, 
oblique line of insertion, margin entire or nearly so, antical margin 
not arching across axis, apex obtuse to subacute ; lobule oblong- 
rhomboidal, inflated, 0.14 mm. long, 0.09 mm. wide, keel slightly 
arched or almost straight, usually continuous with postical margit 
of lobe, roughened from projecting cells, free margin plane, al 
pressed to basal ocellus of lobe, bicrenulate at the ape%s he 
passing by a straight line or by a lunulate sinus to end of keel’ 
leaf-cells thin-walled, plane or nearly so, averaging 15 /# in - 
eter at edge of lobe and 19 2 in the middle and at the base a 
gones and intermediate thickenings minute but usually distinct 
never confluent ; basal ocellus, the only one present, 50 Ae 
27 # wide, projecting postically and forming a cylindrical vie 
with the plane lobule, usually overlapped and almost con fe 
by adjacent cells of lobe: underleaves distant with ere — 
* Hedwigia, 27: 285. 1888, 
