334 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



vomerine teeth are in specimens that are in general agreement in other 

 respects, with the exception that the pectoral rays as given by Cuvier 

 and Valenciennes, Giinther, and Day are 1, 11 while in the Thai speci- 

 men they are 1, 14. 



This fish is given the name fla dong by the people of the Trang 

 district. 



Genus SILURICHTHYS Bleeker 



Silurichthys Bleekee (189), Act. Soc. Sci. Indo-Neerl. (Siluri), vol. 4, p. 268, 1858. 

 (Type, Silurus phaiosoma Bleeker.) 



In these fishes the anal and caudal fins are completely confluent, a 

 feature iiot found in any other local genus of the family. The anal 

 fin is very long, and the ventrals and dorsal are inserted far forward. 

 The caudal fin is normally asymmetrical, with the lobes of unequal 

 length. A pair of long barbels arises from the side of the anterior 

 nostril and another pair is inserted behind the chin. 



The two species of Silurichthys ascribed to Thailand are differen- 

 tiated as follows : 



la. Anal rays 53 to 58; dorsal fin over ventrals; caudal fin obliquely truncate or, 

 in fully developed examples, with pointed lobes, of v?hich the upper is much 

 the longer phaiosoma 



1&. Anal rays 67 ; dorsal fin in advance of ventrals ; caudal fin rounded. 



leucopodus 



SILURICHTHYS PHAIOSOMA (Bleeker) 



FiGUEE 76 



Silurus phaiosoma Bleekeb, 1851 (49), p. 428, 1S51 (Sambas, Borneo). 

 Silurichthys phaiosoma Smith, 1933a, p. 77 (Chantabun River). — Fovi'ler, 1934a, 

 p. 87 (Chantabun). 



This species, known from Sumatra, Borneo, Bangka, Billiton, Singa- 

 pore, and Malacca, has an apparently restricted range in Thailand, 

 where it was collected for the first time for the Siamese Bureau of 

 Fisheries in 1927. On February 7 of that year five specimens, the 

 largest 7 cm. long, were taken in the Chantabun River near the town 



Figure 76. — Siluriclithys phaiosoma (Bleeker). Drawn by Luang Masya courtesy of 



the Thailand Government. 



