FRESH-WATER FISHES OF SIAM, OR THAILAND 15 



The Menam Chao Pliya is the outstanding physical feature of the 

 country and it is to Thailand what the Nile is to Egypt and the Mis- 

 sissippi is to the central part of the United States. With its tribu- 

 taries and the other streams with which it is connected by canals, it is 

 the main channel of communication and provides the means of trans- 

 portation for two of the great products, teak logs in rafts and rice in 

 barges. It is furthermore a perennial source of invaluable fertilizer, 

 wliich, in the form of silt, is brought down by the annual floods and 

 deposited on the inundated ricelands. 



This is the region of greatest abundance and variety of fish life, 

 which, in consequence of the vast watery areas resulting from the 

 annual inundations, is afforded boundless opportunity for reproduc- 

 tion and growth. Connected with the teeming streams are extensive 

 marshes and swamps, which are annually converted into lakes, to 

 which the fishes resort for spawning purposes ; with the subsidence of 

 the flood waters and steady evaporation during the long period of 

 drought, the lakes shrink and many of them revert to marshes and 

 swamps before another flood season comes. 



Peninsular Thailand, formerly sometimes referred to as Lower 

 Siam or Southern Siam, may be considered as extending from Koh 

 Lak to British Malaya, with a frontage on the Gulf of Siam and the 

 Indian Ocean except where, on the west, it is bordered by the Tenas- 

 serim Range and the Menam Kra. The topography is varied, 

 consisting of coastal flats, plains, and forest-clad mountains, with 

 numerous small streams and several of some magnitude. The Menam 

 Bandon, a short tidal water, is entered by the Tapi and the Kirirat, 

 which are fair-sized rivers flowing northward and draining rather 

 extensive mountain and plain areas. Farther south, occupjnng an 

 extensive plain op the east side of the peninsula, is the large Tale Sap, 

 or Inland Sea. This consists of an inner lake that is fresh and an 

 outer lake that is brackish and discharges into the Gulf of Siam at 

 Singora. The Tale Sap, with its much smaller Tale Noi connected 

 with its northern arm, provides conditions very favorable for fish life. 

 At the southeastern corner of Peninsular Thailand the Patani Plain 

 is drained by the Menam Patani and the Menam Saiburi, which rise 

 in the mountain range forming the Malayan boundary ; while on the 

 west side the only noteworthy stream is the Menam Trang. 



Eastern Thailand, much the largest of the natural geographical 

 divisions, consists principally of a saucer-shaped plateau, which is 

 flooded during the wet season and suffers from a scarcity of water 

 during the dry season. The Mekong forms the northern and eastern 

 boundaries; on the west the Pechabun Mountains and Dong Phya 

 Yen Range separate it from the central plain; and on the south the 

 Dong Pek Scarp divides it from Cambodia. Drainage is principally 

 by the Menam Mun, a very sizable stream that enters the Mekong 



