OF CEYLON AND INDIA. 
401 
The thallus in cross section is convex above, and shows a 
general construction like that of Hydrobryum lichenoides or 
H. olivacenm. The leafy shoot developes a few small leaves, 
rarely more than five or six, of about 5 to 10 mm. in length, 
and hairy above. 
The growth of the seedling plants is fairly rapid. For 
example, on 21st May, 1898, the seeds were just germinating, 
and on 19th July the rocks were thickly carpeted with plants, 
many of which were from two to three inches long and 
much branched. During the next four or five months the 
plants seem to be purely vegetative. The flowers, when 
they begin to form, develop very rapidly. The usual period 
for this process appears to be December. Nearly all of the 
leafy shoots then form flowers. By this time the plants have 
grown to great lengths, and form a dense interwoven felt- 
work upon the rocks, as may be seen in hitherto existing 
herbarium specimens, Avhich as distributed consist of 
fragments of very many different plants inextricably mixed. 
PI. XXXVII., fig. 2, shows a thallus, which is just forming 
flowering shoots in the middle of December. The apex is 
still growing, and forming leafy sheets as usual, while a 
little further back the flowering shoots occur in various 
stages of development. At the tip of a root the flower shoot 
apparently develops as figured here, without any long period 
during which the axis is purely vegetative, while further 
back on the thallus the old vegetative shoots may be seen 
changing to flowering shoots. In either case, however, the 
process is essentially the same. While the shoot is only 
leafy, the growing point lies below the surface of the thallus, 
but now it begins to elongate and come above it. The 
leaves, hitherto thin and comparatively simple, grow out 
at their bases, changing function and form like those of 
a lily bulb ; the sheathing part of the leaf thus becomes much 
enlarged. The axis remains in the horizontal position, or 
rather the position parallel to the substratum, which in this 
species it occupies from the very beginning. The upper side 
of each sheath becomes fleshy, whereas the lower retoains 
