366 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



The species resembles P. micronemus, but it may be distinguished 

 therefrom by the very different arrangement of the vomero-palatine 

 teeth and by the more niunerous anal rays, as shown in the key. 



PANGASIUS MICRONEMUS Sleeker 



Pangasvus micronemus Bleekek, 1847 (7), p. 8 (Java). 

 Pangasius micronema Hoea, 1923b, p. 167 (Nontaburi). 



Formerly known only from rivers of Java, Borneo, and Sumatra, 

 this species was shown by Hora to inhabit Thailand, and in 1937 Herre 

 and Myers reported it from Perak, in Malaya. In Thailand the fish 

 appears to be confined to the Menam Chao Phya. Specimens have been 

 taken from Bangkok to Paknampo, but the fish is not common any- 

 where. 



A length of more than 50 cm. is reported for the Indo-Australian 

 Archipelago. The largest observed in Thailand have been 45 cm. long, 

 and various examples 30 to 40 cm. long have been examined. 



The very short maxillary barbels (less than half the length of the 

 head), in association with the disconnected vomero-palatine teeth in a 

 regular crescentic band,, enable one to identify this species without 

 much difficulty. 



Throughout its local range this fish bears the name pla sawai, borne 

 by various other species. A distinctive appellation recorded by Hora 

 (1923b) for Nontaburi on information supplied by Dr. Malcolm Smith 

 is pla sangkawart tong to. 



PANGASIUS PANGASIUS (Hamilton) 



Pimelodus pangasius Hamilton, 1822, pp. 163, 376, pi. 33, fig. 52 (Bengal). 

 Pangasius pangasius Hoea, 1923b, p. 167 (Bangkok). — Vipulya, 1923, p. 227 

 (Bangkok, Bang-pa-in, Lopburi River, Menam Chao Phya). 



In addition to inhabiting India and Burma, this fish frequents Java 

 and Thailand. It was first recorded for Thailand by Hora (1923b) 

 and it has since been found to range throughout the Menam Chao Phya 

 and to occur also in the Menam Sak and the Meklong. It used to enter 

 Bung Borapet at the flood season and was often abundant at the mouths 

 of the outlets of the swamp. 



In April and May 1928 a klong on the extensive grounds of the 

 residence of the Adviser in Foreign Affairs in Bangkok was pumped 

 out and the presence of some large examples of this fish was disclosed ; 

 they had gained access from the Menam Chao Phya by way of other 

 klongs and had evidently been in this place for some years. Seven 

 examples were caught with a cast-net on May 2 and three were ex- 

 amined. The three largest were 85, 89, and 90 cm. long, and the last 

 was 20 cm. deep and weighed 18 pounds. In all these large individuals 

 the band of vomero-palatine teeth had become reduced in a thin line 



