210 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



Menam Chao Phya were killed on May 7, 1926, by the encroachment 

 of brackish water from the river ; 15 dead fish were picked up on the 

 surface of the pond. 



Fowler's Thynnichthys thai is clearly this species, agreeing perfectly 

 therewith in proportions, fin formulae, scales in lateral and trans- 

 verse series, etc. The only point of difference that Fowler mentions 

 is the number of predorsal scales, given as 21 or 22 in T. thai and 30 in 

 T. thynnoides on the authority of Weber and de Beaufort. These 

 authors, however, say "about 30 irregular rows." As a matter of fact 

 the predorsal scales are not easy to count, owing to their crowded, 

 irregular arrangement, and different persons may obtain different 

 figures for the same fish. Specimens in the U. S. National Museum 

 show a range from 22 to 28. 



In Thailand, fishermen, with their usual aptitude, call the fish pla 

 Met tee (small-scale fish), a name that is almost everywhere in use. 

 A variation on the Pasak River is pla nang Met. On some sections 

 of the Menam Chao Phya the name pla 'pi^om is heard. At Patalung 

 and on the Tale Sap in Peninsular Thailand the fish is called fla ling. 



Genus OSTEOCHILUS Gunther 



OsteocMlus GiiNTHEK, Catalogue of the fishes in the British Museum, vol. 7, p. 40, 

 1868. (Type, OsteocMlus melanopleurus (Giinther) ^=Rohita melanopleura 

 Bleeker.) 



The osteochilids are common in the streams, canals, and lakes in 

 most of Thailand, and in some places and at certain times may be 

 abundant. All species form part of the local food consumption, and 

 some are regularly sent to the larger markets. 



Recognition of these fishes is effected easily by examination of the 

 fringed lips, the broad confluence of the lower lip with the isthmus, 

 the sharp bony edge of the lower jaw, and the long dorsal fin with 10 

 to 18 branched rays. 



A basis for differentiation and classification adopted by Weber and 

 de Beaufort is the presence or absence of large rostral pores, which may 

 contain horny tubercles. In some species there are only three such 

 pores, situated at the front of the snout ; in other species there are two 

 to four rows of pores on the front and sides of the snout ; and in addi- 

 tion there may be minute pearl organs promiscuously disposed on head 

 and body. In some species there is no vestige of pores at any stage of 

 growth in any of the material at hand. 



Fifteen species are recorded for Thailand : 



la. Maxillary and rostral barbels present. 



2a. Scales in lateral line 45 to 54. 



3o. Scales in lateral line 47 to 49; scales between midline of back and base of 



ventral fin 8.5-1-7 ; predorsal scales 15 or 16 ; circumpeduncular scales 



20 to 24 ; 3 pores in a transverse row on front of snout ; a large black 



blotch on caudal peduncle borneensis 



