Evans: HEPpPATICAE OF PuERTO RICO 197 
the ordinary leaves but also the underleaves, the lobes of the peri- 
chaetial bracts and the lateral keels of the perianth. The develop- 
ment of trigones in the leaf-cells is likewise subject to a great deal 
of variation. What may be considered a typical condition is 
described above and figured on the plate (FIGURE Ig), but in many 
cases the trigones are poorly developed and difficult to demonstrate 
and the walls appear as if they were uniformly thickened. Between 
these two extremes are all possible gradations. 
Aside from its difference in habitat C. Chitonia is a more robust 
plant than C. Peruviana and has more densely imbricated leaves 
and underleaves. The lobe is broad and the lobule narrows grad- 
ually toward the end of the keel, the apical sinus being long and 
very shallow. In C. Peruviana the lobe is narrower and usually 
more gradually pointed, and the lobule narrows more abruptly,,the 
apical sinus being shorter and deeper; in the majority of the leaves 
there is a distinct angle between the end of the keel and the 
postical margin of the lobe, and in many cases the outer part of the 
lobule is curved abruptly backward and forms a sort of tooth at 
its junction with the lobe, as already described by Spruce. The 
apical tooth of the lobule in C. Peruviana is shorter than in 
_ C. Chitonia and is scarcely curved. Ocelli are found in both 
species and the leaf-cells are very much alike, but the walls in 
C. Chitonia tend to be more strongly thickened. The underleaves 
of C. Peruviana are extremely variable, being sometimes undivided 
and sometimes more or less bifid; and their margins, although 
usually sharply dentate, are occasionally entire. They tend, how- 
ever, to be much more toothed than in C. Chitonia and when bifid 
often show acute divisions. On the smaller branches the under- 
leaves are commonly revolute on both sides, a peculiarity rarely 
seen in the larger species. Spruce describes the perichaetial bracts 
of C. Peruviana as being much smaller than the leaves ; this is 
true of the inner bract only (that next the innovation), the outer 
bract being of about the same size as the leaves. The same 
marked inequality occurs also in C. C/itonia (FIGURE 23), but the 
bracteal lobes are broader and the bracteole has blunt instead of 
acute divisions and seems to be invariably entire. The perianths 
in the two species are very much alike. 
In his original description of Odontolejeunea subbifida, Stephani 
