FRESH-WATER FISHES OF SIAM, OR THAILAND 409 



the Bangpakong Kiver, a very muddy stream where ovigerous fish 

 gather in immense numbers, local names are pla hot khao {khao^ 

 white), and pla uh hua san {hua san=sh.0Tt head). On the Menam 

 Chao Phya a name in use is pla hot nu (nw=mouse). A Tapi River 

 designation is pla hot pah huat {pah huat^\\zdiv6. mouth) , while in the 

 Tale Sap one may hear the names pla hot and pla hua on. 



TACHYSURUS GAGORA (Hamilton) 



Pimelodus yagwa Hamilton, 1822, pp. 167, 376, pi. 10, fig. 54 (Bengal). 



Arius macracantlius Guntheb, 1864, vol. 5, p. 167, 2 figs. (Siam). — Saxjvage, 1881, 



p. 162 (Siam). 

 Arius gagora Day, 1878, vol. 2, p. 465, pi. 107, fig. 2 (Siam). 



This common fish of India is known from Thailand by a specimen, 

 7.5 inches long, in the British Museum, obtained in the Jamrach pur- 

 chase. It was described by Giinther, as Arius m/icr acanthus^ but it 

 was regarded by Day (doubtless properly) as the same as Hamilton's 

 Pimelodus gagora. 



In India the fish reaches a length of 3 feet. 



TACHYSURUS SCIURUS (H. M. Smith) 



Arius sciurus Smith, 1931a, p. 30 (Tapl River). 



In the type locality, the Tapi River near Bandon, Peninsular Thai- 

 land, this fish is common and it is said to reach a length of more than a 

 meter. The largest specimens observed by the writer were 60 cm. 

 long ; the type was 25 cm. The only other locality where the fish has 

 been met with is the lower Menam Chao Phya at Paknam, where a 

 specimen 18 cm. long was taken on November 10, 1923. 



In the Bandon market eggs of this fish were seen exposed for sale 

 during a number of days in September 1923. They had been removed 

 from the mouths of the males in agglutinated clusters, looking like 

 bunches of grapes, the largest clusters being 18 cm. long and the eggs 

 1,4 to 1.5 in longest diameter. 



This species belongs in the groups of tachysurids that Bleeker (Atlas 

 Ichthyologique) called Pseudarius, characterized by having the gran- 

 ular or molarlike palatal teeth in two large separated patches. Its 

 nearest relative is T. microcephalus, reported only from rivers of Bor- 

 neo. In that species, however, the smaller head is much broader than 

 deep (as contrasted with a head whose depth equals its breadth), the 

 maxillary barbels extend beyond the head (instead of reaching only 

 one eye-diameter beyond the eye), and the dorsal and pectoral spines 

 are much stouter. 



The local vernacular name is pla hot. 



