1907.] Fresh-water Algal Flora of Ceylon. 217 



development of gelatinous forms in these regions — in many localities to the 

 practical exclusion of other types of growth. But competition, encouraging 

 the growth of the more successful gelatinous forms, cannot always be the 

 explanation of the absence of tangled or tufted growth ; such competition can 

 scarcely play a part on an embankment. Here it seems as though the 

 highly mucilaginous substratum afforded by the prevailing gelatinous 

 adhesive growth is not a suitable base for growth of a higher type. A more 

 complete analysis of the prevailing conditions will probably cast more light 

 on the matter. 



The subaerial algal flora of the uplands of Ceylon has a certain superficial 

 resemblance to that of a damp region in the temperate zone, but it differs in 

 its luxuriant development and in the important part played by the blue- 

 green element. The light-conditions in particular, but also the temperature 

 during the day (at least at most times of the year) are distinctly tropical — 

 witness the wealth of the Phanerogamic vegetation. The green algal 

 element, which is of considerable importance in the subaerial vegetation 

 of our parts, is still quite crowded out by the more successful blue-green 

 forms ; their success is here again probably, to a large extent, due to adequate 

 protection from the strong illumination. It should be noted, however, that 

 I met with terrestrial species of Vaucheria ( V. sessilis (Vauch.) DC.) at one 

 or two points round about Nuwara Eliya — forms which, as far as my observa- 

 tions go, are entirely wanting in the lowlands. 



The subaerial algal vegetation at places like Kandy (rainfall, 82 inches) 

 and Peradeniya is approximately intermediate in its character between that 

 of the lowlands and uplands, although on the whole savouring more of the 

 former (cf. table on p. 215). In the wet regions of the lowlands we 

 have a profuse subaerial flora, which is probably in the main due to the high 

 temperature, whilst in the true uplands the rich algal growth is the result 

 of a rather high rainfall. At Peradeniya and neighbourhood both factors are 

 not so strongly developed, the temperature being low compared with that of 

 the low country, and the rainfall less than at Nuwara Eliya and neighbour- 

 hood. In correspondence with this we find a marked decrease in the extent 

 of development of subaerial algal vegetation at Peradeniya and in the 

 surrounding country. In the wet jungles on the hillsides round Peradeniya, 

 however (e.g., at Hantane), we meet with a state of affairs rather like that on 

 Pedrotallagalla, although on a less luxuriant scale. Otherwise the subaerial 

 algal vegetation in these regions stands behind both that of the lowlands 

 and uplands, and cannot even compare, for instance, with that at a place 

 like Matara (rainfall only 69 inches !). The character of the algal vegetation 

 is of particular interest. Tufted and tangled growths are fairly well repre- 



