Evans: THE HEPATICAE OF THE BAHAMA ISLANDS 211 
right angles to the substratum and give a very strange 
appearance to tufts where they occur abundantly. In R. phyl- 
lobola the deciduous leaves are less modified, and the shoots upon 
which they are borne develop internodes of the usual length and 
continue their growth for a longer period. Even here, however, 
the shoots acquire a characteristic appearance when a long series 
of leaves has fallen away leaving the underleaves behind. In 
R. Brittoniae the conditions are much the same as in R. phyllobola, 
the internodes being so long that the underleaves do not overlap. 
The modifications shown by the deciduous leaves, although slight, 
are not without interest. The lobes are smaller than on ordinary 
leaves, and the lobules are so reduced in size that they consist of 
only afew cells. The postical margins of the lobes are distinctly 
rounded at the base and form acute angles with the axis. The 
marginal crenulations are usually better marked than on normal 
leaves, but this difference is not always apparent. The separation 
takes place very close to the line of attachment, the basal cells 
being usually torn across. In all cases the rudimentary lobules 
are left behind. The leafy shoots which arise from the deciduous 
leaves, at first bear small and simple leaves, as in other members of 
the genus, but these soon increase in size and complexity with the 
further development of the shoot. The underleaves, as a rule, 
make their appearance very early. The tendency to develop 
shoots with deciduous leaves is much less marked in R. Brittoniae 
than in its allies, the majority of the plants forming normal shoots 
only. 
The relationship between R. Brittoniae and R. phyllobola is 
very close, the leaves, underleaves, and perianths being much alike 
in the two species. Even the leaf cells agree closely in structure 
and are very nearly equal in size. There are, however, two im- 
portant differences: in R. phyllobola the inflorescence is autoicous, 
and the bracteoles of the antheridial spikes are restricted to the 
base, except of course when only one or two pairs of bracts are 
present; in R. Brittoniae, on the other hand, the inflorescence: is 
dioicous, and the bracteoles are found along the whole length of 
the antheridial spikes. The species is also a little more robust than 
R. phyllobola, and the underleaves are larger and have broader 
and usually blunter divisions; in R. phyllobola, for example, the divi- 
