FRESH-WATER FISHES OF SIAM, OR THAILAND 375 



possible identity had been made from time to time; thus, Vaillant 

 (1904), having before him photographs of the fish, wrote "the genus 

 does not seem doubtful, it is a Pangasius^'' but he did not venture a 

 specific determination. The first definite action to this end was taken 

 by Dr. Pierre Chevey, who had seen many fresh examples of the fish 

 in the market at Pnom-Penh, Cambodia, and who decided that the 

 fish represented a new genus and a new species, for which he proposed 

 the name Pangasianodon gigas. 



The separation of Pangasianodon from Pangasms, which course 

 Chevey was apparently justified in taking on the basis of the material 

 available, was prompted by the discovery that P. gigas has no teeth 

 in the jaws or on the vomer and palatines, has only a single pair of 

 barbels (maxillary), and has the eye placed entirely below the level 

 of the angle of the mouth, while in Pangasius there are bands of teeth 

 in the jaws and on the vomer and palatines, a second pair of barbels 

 (mandibulary), and the eye either above or opposite the level of the 

 angle of the mouth. 



The vernacular name for this fish is trey reoich (royal fish) among 

 the Cambodians. By the Thai and Laos it is called fla huh (huge fish) . 



The zoological interest and economic value attained by this species 

 would strongly recommend a joint investigation by Indo-China and 

 Thailand with a view to adopting measures that may prevent its 

 further decline, if they do not restore its former abundance. 



Family AMBLYCIPITIDAE 



These fishes, among the most diminutive of the local siluroids, may 

 properly constitute a separate f am.ily to include only the genus Amhly- 

 ceps, as advocated by Hora (1936a). Amhlyceps has sometimes (Jor- 

 dan, 1923) been included with Akysis and other genera to form the 

 family Akysidae, but the characters shown in the key, with others not 

 therein indicated, seem to justify the separation of the two families. 



Genus AMBLYCEPS Blyth 



Amblyceps Blyth, Journ. Asiat. Soc. Bengal, vol. 27, p. 281, 1858. (Type, Amhly- 

 ceps caecutiens Blyth.) 



AMBLYCEPS MANGOIS (Hamilton) 



Pimelodus mangois Hamilton, 1822, pp. 199, 379 (Behar). 



Amhlyceps mangois Smith, IGSId, p. 180 (Eastern, Peninsular, and Southeastern 

 Siam).— Hora, 1933, p. 617 (Pakjong).— Hoba and Mukeb-ji, 1934, p. 125 

 (Pakjong, Nakon Sritamarat, Chantabun Estuary). — Fowlek, 1939, p. 58 

 (Trang). 



Previously known only from India and Bunna, this species was 

 added to the known fauna of Thailand in 1925 by the taking of speci- 

 mens in a small mountain brook tributary to the Menam Mun near 

 Pakjong in the Eastern region. The fish was collected in the same 



