378 BULLETIN 18S, UNITED STATES NATIONAL MUSEUM 



Menam Nakon Nayok, and the Menam Bangpakong. Reporting on 

 a collection made in the Menam Nan by Dr. Harmand, Sauvage 

 (1883b) gave merely the name of this fish. In July 1923, 40 years 

 later, the writer collected in the Bangpakong two specimens that were 

 17.3 and 18.6 cm. long, and 5 years later, in June, he found another 

 fish, 17 cm. long, in the Bangpakong and one, 23 cm. long, in the Niikon 

 Nayok, a branch of the Bangpakong. In August 1929 a Boy Scout 

 collected a fish, 14 cm. long, from the Nakon Nayok. The list of known 

 specimens is completed by mentioning a specimen, 24 cm. long, without 

 data, received by the Siamese Bureau of Fisheries in 1928 from effects 

 of the old Siamese Museum, which long ago ceased to function as a 

 natural history depository. 



Owing to its peculiar shape and coloration, this fish is always dis- 

 tinguished by local fishermen and given special names, including fla 

 hayeng hin (hin, rock or stone), pla kayeng nu [nu, mouse), pla 

 hayeng wang {wang^ swamp or marsh) , and pla hot mu. 



BAGROIDES MACRACANTHUS Bleeker 



Bagroides macraeanthus BijJeker, 1854 (106), p. 88 (Sumatra). — Saitvage, 1881, 



p. 161 (Siam). 

 Pseudodagrichthys macraeanthus Bleekee, 1865 (347), p. 34 (Siam). — Bleekee, 



I860 (356), p. 175 (Siam). 



This species seems to be peculiar to Sumatra and Thailand. There 

 are very few Thai records, and the fish must be considered very rare. 

 A specimen, 22 cm. long, from the fishery at Koh Yai, on the Menam 

 Chao Phya above Bangkok, obtained in January 1926, agreed with 

 Bleeker's description with the exception that the dorsal, anal, ventral, 

 and pectoral fins were more or less black and the caudal was white, 

 in this respect suggesting B. macropterus. 



A length of 24 cm. is attained in Sumatra. 



The local fishermen applied the name pla kayeng hai hao. A speci- 

 men 12.6 cm. long was collected by a Boy Scout in the Nakon Nayok 

 in January 1930. The Scout gave the local vernacular name as pla 

 kayeng wang^ applied also to B. macropterus in the same region. 



Genus LEIOCASSIS Bleeker 



Leiocassis Bleeker (189), Act. Soc. Sci. Indo-Neerl. (Siluri), vol. 4, p. 139, 

 1857-58. (Type, Leiocassis micropogon Bleeker.) 



The leiocassids are small fishes of fresh- water streams with strongly 

 contrasted (mostly black and white) coloration. Their center of abun- 

 dance is Java, Borneo, and Sumatra, with their range extending to 

 Malaya, Thailand, and Cambodia. 



Leiocassis leiaconthibs Weber and de Beaufort, previously known 

 only from Sumatra, has been reported by Herre and Myers from Johore 



