OP CEYLON AND INDIA. 
349 
Dicræa dichotonna, Tul. 
(Plates XIV., XX.) 
This species, as explained in the preceding paper, includes 
the four forms, D. dichotoma, Wightii, rigida, longifolia, 
originally described by Gardner and Wight, but which I do 
not think are deserving of even varietal rank, depending 
apparently on differences due to the different depths from 
which the material was taken. I have carefully examined 
the herbarium material, and have also collected for myself 
in the Paikara river, and though further examination on the 
spot is required, I do not think there is any good evidence 
at present for separation of the forms named. 
Habitat . — Like D. olongata, this species grows in rather 
rapid and broken water. In the Paikara river it is frequently 
mixed with Hydrobryum olivaceum, var. griseum, the only 
other form that occurs in that locality. 
Dry Season Appearance . — A stone covered with fruiting 
material is shown in PI. XIV. (top, right). Brown withered 
thalli about 5-8 cm. long, thin, ribbondike, more or less 
zigzag, may be seen attached to the rocks for at least the 
greater part of their length, though the ends are usually 
more or less free. Standing vertically upon these are the 
fruiting shoots, very like those of D. elongata, in fact it is 
not always easy to tell which is which when, as sometimes 
happens, only the lower part of the thallus of the latter 
bears fruits. Under water plants may be found in January 
at any rate, which illustrate the mature structure sufficiently 
well, but it is desirable that the life-history should be fully 
worked out. 
Mature Structure .— seen at the end of December, the 
thalli are about 10-15 cm. long or more, lying very closely 
down upon the rock, and with much less marked difference 
between the creeping and drifting parts than in D. elongata. 
Usually the basal 3-5 cm. are attached to the rock, and the 
rest free, but in a line with the creeping part, and often 
attached at one or two points by haptera. The haptera 
