OF CEYLON AND INDIA. 
337 
The thallus, however, is very different ; instead of being 
nearly cylindrical, it is flat, narrowly elliptical in section, 
abont 1 mm. thick in the middle, and tapering oft* to the 
sides (PI. XVII., flgs. 1, 3). Its breadth is usually about 
3 mm., but in one or two cases the thallus is broader, and 
almost seems as if it tended to become crustaceous, like that 
of some of the Hydrobryums. It is frequently branched, 
the branching being all in the horizontal plane and exoge- 
nous. Along the middle of the lower sidé runs what may 
almost be called a continuous foot, composed of root-hairs 
closely matted and mixed with a gummy excretion as already 
described for Tristicha. 
In the middle of the thallus, as seen in cross section (PI. 
XVII., flg. 3), is a vascular bundle like that of the preceding- 
species, while the wings or sides of the thallus, as seen in 
fig. 4, are composed of large-celled parenchymatous tissue, 
with epidermis above and below. I have not seen in this 
species any sign of the tangential division of the cortex of 
the thallus that is so marked a feature in the very similar 
thallus of some of the Dicræas. Nor do the margins of the 
thallus seem to fall away here as in some of the latter. 
The secondary shoots arise on the upper margins of the 
thallus, in the angles of the branching, just as in P. subula- 
tus. They differ from the latter chiefly in the smaller size 
of the leaves (^.e., so far as can be judged from specimens 
taken at the end of the year ; during the purely vegetative 
season they may quite well be much larger), and in th e fact 
that the lower leaves do not fall away to expose a scar- 
covered axis. The leaves in the specimens that I have seen 
rarely exceed 5 cm. in length. In structure ond arrange- 
ment on the stem they are like those of the preceding species, 
and the branching takes place as there from the lower axils 
of dithecous leaves. 
Flowering occurs, as usual, at the beginning of the dry 
season ; this species shows what one is surprised not to find 
more commonly in the order, cleistogamic flowers, fertilized 
