376 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



locality in 1927 and 1929, and in the Peninsula and the Southeastern 

 district in 1928. 



The maximum length is about 12 cm. 



The fish bites viciously, and can live out of water for a long time. 



The most noteworthy account has been given by Hora (1933). In 

 a discussion of this highly specialized diminutive catfish of uncertain 

 ancestry, Hora says: "The most remarkable structure of Amblyceps 

 is the development of the fold of skin in front of the pectoral 

 fin * * *. This is no doubt a special acquisition for respiration in 

 the fast currents characteristic of its natural haunts." 



In his general account of Amblyceps, Hora ( 1933) devoted some space 

 to a notice of three Thailand specimens sent to the Indian Museum by 

 H. M. Smith, and quotes from a letter from the latter as follows : 



These [specimens] are from Pak Jong, a mountain district in east-central Siam, 

 March 12, 1927. Other localities represented in our collection are Nakon Sritama- 

 rat, Peninsular Siam, and Chantabun Estuary, south-east Siam. The last locality 

 is peculiar in that the water is brackish, but the single specimen could easily have 

 come down from hill streams in the Chantabun basin, where, however, the species 

 has not yet been collected. 



In the course of a paper on fishes from the Southern Shan States, 

 Hora and Mukerji (1934) refer to 19 other Thai specimens sent for 

 examination. Their conclusion is that without further study of a large 

 amount of material from Burma and Thailand "it is difficult to sepa- 

 rate the Thailand form as a distinct species, variety, or even as a local 

 race." 



The vernacular name at Pakjong is pla dak. 



Family BAGRIDAE 



The bagrid catfishes in Thailand fall into four rather strongly dif- 

 ferentiated genera. The outstanding family characters are: 4 pairs 

 of barbels (nasal, maxillary, mandibulary, and mental), of which the 

 maxillary pair may in some species extend to or on the caudal fin ; pos- 

 terior nostrils well separated from the anterior and having a barbel 

 on their margin; jaw teeth villiform in bands, vomeropalatine teeth 

 in a single oval patch or in a curved band ; gill membranes free from 

 the isthmus and either united to or separated from each other ; marked 

 development of the adipose fin, which in some species may be nearly 

 half the standard length of the fish; dorsal fin arising in advance of 

 the ventrals, with a pungent spine serrated or smooth on its posterior 

 side and with 6 or 7 branched rays; and caudal fin well developed and 

 forked. Other characters, which will differentiate the genera, are as 

 follows : 



la. Eyes subcutaneous ; gill membranes various. 



2a. Gill membranes united to each other ; vomerine teeth in a curved band or 

 an elliptical patch ; dorsal spine with teeth on its posterior side directed 

 T2pward-_„ Bagroides 



