404 WILLIS : MORPHOLOGY OF THE PODOSTEMACEÆ 
extra ribs, so that the fruit, which is otherwise like that of 
Hydrobryum lichenoides, becomes ten- to twelve-ribbed, and 
not unlike the fruit of H. Griffithii. The internal structure 
of the fruit is like that of F. metzgerioides, but the large 
placenta bears four (or perhaps at times three or five) seeds 
instead of two. 
In general, therefore, the genus may be looked upon as 
closely similar to Hydrobryum. Its most interesting special 
features are the endogenous branching and the reduction of 
the number and increase of size of the seeds, and their 
germination in situ in one species. 
GENERAL SUMMARY AND DISCUSSION. 
Having described the more important features of the 
general morphology and life-history of the Indian forms, 
we may go on to discuss them in connection with the 
general conditions of life which were considered in the 
introduction, and to consider their bearing on some of the 
general questions of morphology, ecology, evolution, &c.* 
We have already briefly outlined (p. 277) the way in 
which the general life-history of these plants is connected 
with the seasonal distribution of the rainfall, describing 
the way in which the seeds germinate at the beginning of 
the rains, giving rise to small primary axes from which the 
thalli, which form the most important morphological feature 
of the order, bud out. In all but Lawia the thallus is of 
“ root ” nature, with endogenous secondary leafy shoots which 
ultimately become floriferous, the flowers opening with 
the fall of the water in the early part of the next dry 
season, and shedding the seeds upon the rocks. All these 
features will now be dealt with in a general way. The most 
interesting general morphological points are perhaps the 
* Summaries of the chief features of general importance are given after 
each genus described above ; cf. pp. 303, 325, 339, 362, 369, 374, 395, 404. 
