560 Evans: HeEpATICAE OF PUERTO RICO 
TRACHYLEJEUNEA 
The genus Zrachylejeunea is not a very clearly defined group 
of species. It is characterized primarily by the roughness of its 
leaves and perianths. This roughness is due in part to very 
convex cell-walls, in part to the presence of a large median tubercle 
or wart on each cell. The roughness commonly affects the anti- 
cal surface of the lobe, the postical surface of the lobule and the 
outer surface of the perianth, but in some species is scarcely evi- 
dent except on the keels of the latter organ. Roughness of this 
character is by no means confined to 7rachylejeunea. We find it, 
for example, equally well marked, in many species of Co/olejeunea 
as well as in a few species of Sérepsilejeunea and in certain other 
genera of the Lejeuneae. Aside from their roughness the leaf- 
cells of Zrachylejeunea are variable; sometimes they are thin- 
walled throughout, sometimes provided with conspicuous local 
thickenings. Ocelli are usually present at the base of the lobe. 
The species belonging to the present genus are commonly more 
robust than in either Harpalejeunca or Strepsilejeunea, The lobes of 
their leaves are mostly blunt-pointed and are never acuminate 
(except in the very aberrant 7. acanthina (Spruce) Schiffn.) ; the 
lobule is inflated and bears a slightly curved apical tooth with a 
hyaline papilla at its proximal base ; the underleaves are rotund 
and bifid with a narrow sinus and suberect pointed divisions. The 
? inflorescence is borne on a short branch which, in most species, 
does not innovate ; the perianth is sharply five-keeled in the upper 
part and the keels, although sometimes obsoletely winged, are 
never produced as horns. 
Comparatively few species of 7rachylejeunca have been de- 
scribed. The majority of them grow on trees or on rotten logs 
in tropical forests, but a few are found in the South Temperate 
Zone. Two species have been recorded from the West Indies : 
IT. Spruceana Steph.,* from Guadeloupe, and 7. prionocalyx 
(Gottsche) Schiffn.,+ from Cuba. Neither of these species has 
yet been found on Puerto Rico, but a third species, Lejeunea 
(Trachy-Lejeunea) Aquarius Spruce, occurs in recent collections. 
* Hedwigia, 35: 138. 1896. 
fT Bot. Jahrb. 23: 592. p/. 75, f. 8-12. 1897. 
