Evans: HeEpaTicaE oF Puerto Rico 5 
tolgjeunea and with other genera of the Leyewneae Holostipae. In 
addition to the papilla just mentioned there is a second papilla at 
the junction between the free margin and the axis, and a third 
papilla is also to be observed at the antical base of the lobe. Of 
course these two papillae, as Leitgeb * has pointed out, are usual 
in the Lejewneae, but in Stictolejeunea they are remarkably large 
and conspicuous. 
The leaf-cells are plane or nearly so and their walls are slightly 
thickened (FIGURE 8). Except in the basal portion of the lobe the 
thickening is fairly uniform and there are no distinct trigones. 
Ocelli are numerous and form a striking feature of the plants (F1c- 
URE 3). They never occur in groups but are scattered through- 
out the lobes, underleaves and perianths. On a robust individual 
there may be thirty or more on a single lobe. The ocelli are 
scarcely larger than the other cells and are distinguished by their 
thin walls and more refractive contents. Many specimens of 5S. 
sguamata are also characterized by peculiar hyaline cells, the pro- 
toplasmic contents of which have disappeared. These cells form 
a scarious border along the margins of lobes, lobules and under- 
leaves. At the apex of a lobe they sometimes form a zone three 
or four cells wide, and this zone gradually narrows out and disap- 
pears on both antical and postical margins (FIGURE 9). On the 
underleaves and along the free margin of the lobule the hyaline 
- cells are usually in a single row. Cells of this character are 
apparently never developed in S. Kunzeana and they are far from 
constant in S. sguamata (see FIGURE 10). They seem to be most 
frequent in exposed situations and doubtless enable the plants to 
cling more closely to the substratum. Similar hyaline cells are 
found in the genera Neurolejeunea, Cololejeunea and Diplasiole- 
jeunea, 
The underleaves in Stictolejeunea are broadly orbicular in out- 
line and undivided (FIGURE 1). They are usually large and loosely 
imbricated. At the base they are abruptly and narrowly decur- 
rent for a short distance, and the line of attachment is distinctly 
arched. When rhizoids are present they grow out from a basal 
disc (FIGURE 7), and their tips are frequently branched. 
One of the most important characters of the genus, as Spruce 
* Unters. iiber Lebermoose 2: 1 5. 1875. 
