222 Evans: HEPATICAE OF PUERTO RICO 
base one or two minute teeth, each consisting of a single projecting 
cell, can sometimes be distinguished. In cases where the apical 
tooth spreads obliquely, as in D. wnidentata, it shows the same 
complexity as when parallel with the axis. Aside from the pecu- 
liarities just noted D. Rudolphiana is much like D. unidentata, 
and almost the same differential characters will serve to separate 
it from D. pellucida and D. brachyclada. 
VEGETATIVE REPRODUCTION IN DIPLASIOLEJEUNEA 
The vegetative reproduction in Diplasiolejeunea is carried on 
by means of discoid gemmae, which bear a marked resemblance 
to those found in the genera Cololejeunea, Leptocolea, and A phano- 
lejeunea. These gemmae have been demonstrated in D. pellucida 
(including the variety malleiformis), in D. unidentata, and in D. 
Rudolphiana. They have not yet been observed in D. brachyclada, 
however, and it is therefore possible that they are associated with 
certain species and never produced by others. 
In D. pellucida the gemmae are borne on the lower surface of 
ordinary leaf lobes (TEXT FIGURE 2, A) and seem to be entirely 
absent from bracts and perianths. They occur on plants of either 
sex but tend to be more frequent on male individuals. In some 
cases the leaves on one side of a gemmiparous axis will develop 
gemmae much more abundantly than the leaves on the other side. 
Apparently the production of gemmae has no marked effect 0# 
the growth of the shoot, and the leaves upon which the gemmae are 
borne show no modifications. In D. unidentata and D. Rudol- 
phiana the gemmiparous branches are very different from those of 
D. pellucida and much more highly specialized. They show @ 
definite limitation in growth, and the gemmae are restricted t0 
the youngest leaves that reach maturity, in most cases to the 
terminal pair of leaves (PLATE 17, FIGURES I and 3). These leaves 
differ considerably from normal leaves. Instead of being plane oF 
convex, when examined from above, they are distinctly concave 
in the apical portion; and instead of spreading widely from the 
axis they spread very slightly. They are also relatively narrow’ 
than normal leaves, although sometimes larger. The ™ ince 
tions in the lobule affect chiefly the apical tooth, which is dis 
tinctly shorter than on normal leaves (FIGURE 6) and tends to be 
