FRESH-WATER FISHES OF SIAM, OR THAILAND 345 



other reddish shades. It is a good food, although somewhat inferior 

 in flavor to the pla bieiv ( Walla go dinema Bleeker) . 



Family HETEROPNEUSTIDAE 



This family was established by Hora (1936a) to accommodate the 

 two known species of Heteropneustes. The distinctive characters as- 

 signed to the family seem entirely valid, although osteological and' 

 other features indicate very close relationship with the Clariidae. 



The outstanding anatomical character is a pair of long, hollow 

 cylinders extending backward on each side from the gill cavity among 

 the muscles of the back; these are air sacs that serve as primitive 

 lungs and enable the fish to breathe atmospheric air, although Giinther 

 asserts that they receive water and have a special musculature by 

 which water is expelled at intervals. These fishes live in stagnant 

 ])ools and ditches deficient in oxygen, and no useful purpose would 

 seem to be served by the respiratory tubes if their function is simply 

 to receive the same vitiated water. 



Genus HETEROPNEUSTES MuUer 



Eeteropneustes Mullee, Arch. Anat. I'hysiol., 1840, p. 115. (Type, Silurus fos- 

 silis Bloch.) 



HETEROPNEUSTES FOSSILIS (Bloch) 



Silurus fossilis Bloch, 1797, vol. 11, p. 36, pi. 370, fig. 2 (Tranquebar). 

 Saccohraiichus fossilis Bleeker, 1S65 (356). p. 175 (Siam). — Sauvage, 1883b, p. 



154 (Menam Chao Phya). 

 Clarisilurus kemratensis Fowlek, 1937, p. 133, figs. 5, 6 (Kemarat). 

 Heteropneustes kemratensis Fowieb, 1939, p. 50 (correction of generic name) 



(Trang). 



Throughout its range in India, Burma, Ceylon, Indo-China, and 

 Thailand, this is primarily a fish of ponds, ditches, swamps, and 

 marshes, but it is sometimes found in muddy rivers. Its air-breath- 

 ing apparatus enables it to exist in almost any kind of water. The 

 extensive collecting done in Thailand has not shown the fish to have 

 a wide distribution, but special search in suitable localities should 

 extend its known range. Specimens have been taken in a small lake 

 off the Menam Chao Phya near Paknampo, in a lake off the Menam 

 Xan near its mouth, and in Bung Borapet. There is also a record 

 for the Nakon Nayok. In Bung Borapet it has been found in as- 

 sociation with other air-breathers {Anahas, Tnchogaster, Ophiceph- 

 alics, and Clarias), in cut-off parts of the swamp. 



A maximum length of 30 cm. is attained in Thailand. The usual 

 length is about 20 cm. An example, 27 cm long, taken in Bung Bora- 



