Records of the Indian Museum. [Vol. XIV, 



small particles of a greenish grey colour suspended at a constant level, 

 but never in their natural position becoming consolidated even into 

 real mud. These particles are largely of a calcareous nature, as is 

 shown by the following analysis of a dried specimen from the bottom 

 of the northern part of the central region. This analysis also was 

 made by Mr. R. V. Briggs :— 



Insoluble siliceous matter 

 Alumina . 

 Oxide of Iron . 

 Lime 

 Magnesia 

 Potash . 

 Soda 



Moisture . 

 Carbonic acid . 

 Phosphoric acid 

 Sulphuric acid 

 ♦Organic matter and combined water by difference 



Per cent. 



0-98 

 1-30 

 2-25 



45-31 

 1-25 

 0-12 

 0-46 

 3-10 



33-15 

 0-17 

 0-41 



11-50 



10000 



♦Containing Nitrogen 



0-619 



On being dried the pea-soup-like mass forms a grey, very friable clay 

 in which fragments of vegetable matter are abundantly present. 



At some places the bottom is almost bare, the only growth upon it 

 being a scanty one of such plants as Potamogeton crispus, P. pectinatus, 

 Hydrilla verticillata and a species of Characeae, but over the greater part 

 of this region dense masses of CVra^ojaA^ZZt^m flourish, binding the bottom 

 together with their roots to some extent, but not sufficiently to make it 

 solid. The submerged thickets thus formed rise up to a height of at 

 least 7 or 8 feet, and sometimes almost reach the surface. In some 

 places they are in a flourishing condition even when their growing parts 

 are almost in contact with the surface film, but at others they exhibit 

 towards their upper extremities all the symptoms of ill-health, probably 

 because of the growth of algae of various kinds among them. 



Structure of the Surrounding Country. 



In order to understand the history and origin of the lake, and there- 

 fore of its fauna, it isnecessary to consider the structure of the surround- 

 ing country. The lake lies in the great Limestone Zone of the Shan 

 Plateau thus described by Middlemiss^ : — 



" In its essentials, and not considering the younger minor zones that are inlaid with 

 it, it is a rugged, rocky country. The dark grey limestone frequently weathers almost 

 black into sharp-edged honey-combed masses, into pinnacled crags and weather-beaten 

 towers and walls : into deep basins and swallow-holes (often as regular and circular in 

 outline as a gigantic amphitheatre, but sometimes funnel-shaped) : into strange vail jy 

 systems without connection one with the other, and that often end mysteriously either 

 as underground passages down which streams precipitate themselves and become lost, 

 or as marshes and lakes where evaporation helped out no doubt by subterranean per- 

 colation causes a disappearance of the waters : into innumerable caves and passages 

 beneath the ground, some now high and dry from the waters that caused them and which 

 are locally mined for the nitrates that have accumulated upon the floors from the decom- 

 position of cave animal deposits, others used as show places and tem^Dles ; others again 

 unknown to fame and rich in their virgin beauty of stalactitic growths." 



^ General Report of thf Geological Survey of India for 1S99-1900 : "Report on a 

 Geological Reconnaissance in parts of the Southern States and Karenni," p. 130. 



