Evans: HEPATICAE OF PUERTO RICO 250 
In the first type of lobule the keel is strongly arched, and it is 
usually possible to distinguish between a more or less inflated 
basal portion and an apical portion which is plane or nearly so, 
although rarely closely appressed to the lobe (PLATE II, FIGURE 1). 
The lobule is attached to the stem by an exceedingly short line, 
and the basal portion of the free margin is more or less involute. 
The apex is marked by a distinct tooth, usually but by no means 
always consisting of two cells in a row, and the sinus beyond this 
tooth is lunulate (FIGURE 5). Somewhere in connection with the 
apical tooth a hyaline papilla may be demonstrated. It may be 
at the very apex of the tooth, as in the African Cololejeunea 
(Leptocolea) cuneifolia Steph.,* but it is much more usual for it 
to be situated near the base of the tooth, either on the proximal 
side or on the surface turned toward the lobe (FIGURE 5). Not 
far from the apical tooth and also on the proximal side a second 
tooth is usually developed. This is commonly shorter and less 
definite than the apical tooth, but sometimes the differences be- 
tween them are not strongly marked. In certain species, for 
example in the New Zealand Lejewnea (Leptocolea) laevigata Mitt.,t 
there is even a third tooth between the second tooth and the base 
of the lobule. A marked deviation in appearance from the 
lobules just described is to be found in the paleotropic C. (Lepio- 
colea) lanciloba Steph.t and in some of its immediate allies. In 
these the lobule is plane or nearly so, and the apical tooth is 
represented by a broad and blunt lamina (FIGURE 13). Even here, 
however, the hyaline papilla is found at the apex of the lobule, and 
the second tooth is distinct and in its normal position. Such 
lobules may therefore be regarded as having been derived from 
the first type. 
The lobule of Lejeunea microscopica and its allies is built up 
on an essentially different plan, although agreeing with the first 
type in having a short line of attachment and an arcuate keel. 
It is usually larger in comparison with the lobe, and the revolute 
free margin frequently involves the apex itself. The apical tooth 
* Hedwigia 31: 166. pl. 10. 1892. 
T Fl. Nov. Zeland. 157. 1855. 
t Hedwigia 34: 250. 1895. See also Evans, Trans. Conn. Acad. 10: 452. 
pl. 50. f. I-7. 1900. 
