380 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



Among a lot of these fishes caught in the Chao Chet Kiver November 

 26, 1923, was one, 11.5 cm, long, with very large ovaries. The largest 

 examples met with have been 17 cm. long, taken during November 

 and December at Paknampo. Fishes up to 15 cm. long are common. 



The general color of this species is white or pale yellow with black 

 or dark brown cross bands wider than the interspaces. The bands 

 vary in shape, size, and position; usually there is a band involving 

 the head, another from the nape and subdorsal region to the pectoral 

 and ventral fins, another from the adipose fin to the anal, and always 

 one across the caudal peduncle at the base of the caudal fin. The indi- 

 vidual bands may be interrupted or variegated by light spots or stripes. 

 The bands always extend on the dorsal, adipose, anal, ventral, and 

 pectoral fins, which may be entirely black or dark brown or particol- 

 ored in various patterns. 



Figure 83. — Leiocassis siamensis Regan. Drawn by Luang Masya; courtesy of the 



Thailand Government. 



Leiocassis siamensis was described by Regan from a single specimen, 

 9 cm. long, taken in the Bangpakong River and sent to the British 

 Museum by the Siamese Museum in 1897. From its nearest known 

 relative, L. poecilo'pterus^ it was separated chiefly by a difference in 

 the ratio between the length and width of the head, the head being 

 significantly wider in the present species. Other differences, as 

 brought out in Regan's description and in specimens referable to L. 

 siamensis from the type locality and numerous other places, are more 

 slender body, greater length of the maxillary barbels, absence of a 

 posteromedian process in the band of vomeropalatine teeth, slightly 

 more slender caudal peduncle, and slightly longer dorsal spine, most 

 or all of which features might depend on age, size, or individual 

 variation. A color difference is that whereas L. siam£nsis has a dark 

 brown or black spot or bar on each caudal lobe, the colored figure of 

 L. 'poecilopterus given by Bleeker (1862 (301), vol. 2) shows a con- 

 tinuous submarginal dark band extending from one lobe to the other. 



