88 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



almost perfect agreement. The only character mentioned by Fowler 

 as distinguishing woliii from Cultro'ps siamensis is the length of the 

 pectoral iins. This feature, however, is variable, and the variation 

 seems to cover Culter woJfi. While in Hora's type specimens the pec- 

 torals were a little less than the head in length and in C. wolfli are 

 appreciably longer than the head, in many specimens from the type 

 locality of CuUrops sicumensis the pectorals have been found to be 

 longer than the head and reach the base of the ventrals, and in others 

 from the same place, taken at the same time, the pectorals have not 

 exceeded the length of the head. 



The usual vernacular name given to this fish is pla tong plu. In 

 some parts of Thailand the fish shares with Paralauhuca the name pla 

 paep. On the Nakon Nayok Kiver a designation sometimes used is 

 pla paep kwai {kwai^ water buffalo), probably in allusion to its 

 larger size as compared with Paralauhuca. 



Genus PARACHELA Steindachner 



Parachela Steindachner, Sitzb. Akad. Wis. Wien. math-nat. CI., vol. 83, p. 404, 

 1881. (Type, Parachela ireitensteini Steindachner.) 



PARACHELA WILLIAMINAE Fowler 



Parachela vnlliaminae Fowlek, 1934a, p. Ill, fig. 63 (Mekong at Chiengsen). 



The genus Parachela, characterized by the absence of ventral fins, 

 was known from a single species from Borneo until R. M. de Schauen- 

 see, on February 10, 1933, in the Mekong at Chiengsen, Northern Thai- 

 land, made the surprising capture of a specimen 10.8 cm. long, which 

 represented a species differing from Steindachner's type in such char- 

 acters as squamation and number of anal rays. Only a single speci- 

 men is known. In addition to having no ventral fins, this species is 

 characterized by the insertion of the dorsal fin entirely over the anal, 

 by the very long anal (with 35 branched rays), and by the long pec- 

 toral, which extends past the origin of the anal. 



Subfamily Rasborinae 



This subfamily is rather numerously represented by both genera and 

 species in the fresh waters of Thailand, and individuals of various 

 species may be abundant. In most of the genera the fish are too small 

 to have a direct economic value to man, but in several genera, and espe- 

 cially in Luciosoma, there are species whose size entitles them to con- 

 sideration in the markets. The following key will separate the genera 

 lepresented in Thailand : 



0. One pair or two pairs of barbels (rostral and maxillary) ; symphyseal knob 

 on lower jaw present or absent. 

 2a. No symphyseal knob; maxillary barbels very long, rostral barbels short; 

 branched anal rays 5 Esomus 



