332 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



The action to provide a generic name for the fishes that had been 

 called Wallago was taken by Myers (1938) in proposing the new genus 

 Wallagonia, with W. leerii as the genotype. 



Two species of Wallagonia from Thailand are recognized herein, as 

 follows : 



la. Mouth extending far posterior to eye ; gill rakers 21 ; anal rays 86 

 to 93 attu 



1&. Mouth extending to vertical from front of eyes; gill rakei-s 9; anal rays 

 64 to 72 miostoma 



WALLAGONIA ATTU (Bloch) 



Silurus attu Bloch, in Schneider, 1801, p 378, pi. 75 (Malabar). 



Wallago attu BleekeR, 18(55, (356), p. 175 (Siam).— Satjvage, 1883b, p. 154 

 (Menam Chao Phya). — Weber and de Bkaufokt, 1913, vol. 2, p. 201 (Siam). — 

 HoKA, 1923b. p. 165 (Bangkok).— Vipulya, p. 225 (Bangkok). — Fowlee, 

 1934a, p. 87 (Ghiengmai, Chiengsen) ; 1939, p. 43 (Krabi). 



The range of this striking species covers Java, Smnatra, Ceylon, 

 India, Burma, Thailand, and Indochina. In Thailand it is found 

 in the larger streams. Specimens have been obtained from the Menam 

 Chao Phya at various points between Bangkok and Paknampo, from 

 the Menam Nan near its mouth, and from the Mekok at Chiengrai. 

 Fowler records the species from the Meping at Chiengmai and the 

 Mekong at Chiengsen. 



It is one of the largest, most powerful, and most predatory of the 

 local catfishes. A length of nearly 2 meters is attained. Some ex- 

 amples examined by the writer have been over a meter long, and many 

 up to 60 to 75 cm. long have been seen in the fishermen's boats and in 

 the markets of the river towns. 



The presence of the fish in a given place is usually made known by 

 its pursuit of small fishes at or near the surface and by its habit, at 

 such times, of jumping entirely out of the water and falling back with 

 a loud splash. When small cyprinoids known as a pla soi are running 

 upstream in their annual migration, the pla khao (as this fish is always 

 known to the Thai) remain with the schools and gorge themselves. 

 Their great size, large mouth, and formidable teeth enable them to 

 kill and devour almost every kind of fish. 



WALLAGONIA MIOSTOMA (Vaillant) 



Wallago viiostoma Vaiu:.ant, 1902, p. 44 (Tepoe, Borneo). — Smith, 1933a, p. 75 

 (Central Siam). 



This large catfish had been known only in rivers of Borneo and 

 Sumatra until it was recorded from Thailand in 1933. It is found 

 in the larger rivers of the Central district, but it has not been common 

 in recent years. The upper Menam Chao Phya, in the Paknampo 



