Flora of the Ceylon Littoral. 13. 
the last, which appears to occur more abundantly in dry localities, 
are common weeds throughout the tropics. 
Of climbers we may mention Passifiora fcztidci (naturalised),. 
Tylophora asthmatica, neither characteristic of the coast, and the 
striking Dioscoreaceous plant Gloriosa superba, with its scrambling 
stems arising from an underground tuber, and beautiful flowers. 
These all scramble over the shrubs or trail on the ground at the 
back of the formation. 
The well known cosmopolitan tropical Cuscuta- like Cassytlia 
filiformis (Lauraceae) is often found on various woody members of 
the strand flora. Of the remaining plants we have found in such a 
habitat, but few are characteristically maritime. Stachytarpheta 
indica, var. jamaicensis, introduced from tropical America, is appa¬ 
rently confined to the coasts, the type being a common inland 
roadside weed. Leucas zeylanica, a common lowland plant, is often 
met with on the sea-shore, where it assumes a dwarfed habit and 
and becomes more or less succulent. 
The differences between our observations, made at different 
times of the year, suggest that there is a certain periodicity in the 
development of the Ceylon coast-flora, though our data are not 
sufficient to enable us to go into details. Very little is known of 
such phenomena in these tropical climates, where the seasonal 
variations, though perfectly definite, are not nearly so extreme as 
in many other parts of the world. A year’s careful study of the 
fluctuations in such a flora as that of the Ceylon coast would 
probably reveal many interesting facts in regard to the periodic 
development of many of the species. 
At several points on the shore of Ceylon ( e.g . Negombo, 
Bentotta) fresh-water pools occur in the sand not many yards from 
high tide level. These pools appear to owe their origin to fresh¬ 
water springs occurring in these localities, and at Negombo the 
natives can be seen digging down into the sand to get at this water, 
which they drink. At other localities these springs evidently rise to 
the surface and are the cause of the fresh-water pools which are 
found there. The floor of most of these pools, which often contain 
but little water, is covered by a very luxuriant algal flora, made up of 
comparatively few species of gelatinous Cyanophyceae. The 
commonest genera are Nostoc and Lyngbya, the former constituting 
little gelatinous yellow or greenish clumps amongst the sand at the 
bottom of the pools, whilst the latter gives rise to a yellowish web, 
covering the bottom or partly floating at the surface of the deeper 
