FRESH-WATER FISHES OF SIAM, OR THAILAND 481 



la. Lateral line continuous. 

 2a. Scales in lateral line 26 to 33 ; 2 rows of scales on cheeks. 



3a. Predorsal scales 8 or 9 ; depth 2.3 to 2.4; interopercle feebly serrated; 



anal rays III, 8 or 9 ; second and third anal spines subequal kopsii 



3&. Predorsal scales 17 to 22 ; depth 2.5 to 2.8 ; interopercle smooth except for 

 a single spine at posterior angle; anal rays III. 9 or 10; second anal 



spine longer than third commersonii 



26. Scales in lateral line 35 to 46; predorsal scales 25 to 33; 7 or 8 rows of 

 scales on cheeks ; interopercle serrated ; anal rays III, 9 or 10. 

 4a. Scales in lateral line 35 to 41 ; depth 2.3 ; second anal spine equal to 



third in length and stoutness thomasi 



4b. Scales in lateral line 43 to 46 ; depth 1.9 to 2.2 ; second anal spine much 



longer and stouter than third wolffii 



2c. Scales in lateral line 51 to 53 ; 4 or 5 rows of scales on cheek ; depth 2 ; 



anal rays III, 13 or 14 ; second anal spine shorter than third siamensis 



2d. Scales in lateral line 60 to 80 ; interopercle entire. 



5a. Scales in lateral line 60 to 70 ; depth 1.8 ; anal rays III, 14 to 16 ; second 

 anal spine as stout as but shorter than third ; spinous dorsal fin with- 

 out a sharply defined black edge ranga 



56. Scales in lateral line 70 to 80 ; depth 2.5 ; anal rays III, 13 ; second and 

 third anal spines nearly equal ; spinous dorsal fin with a sharply 



deQned black edge baculis 



16. Lateral line discontinuous, interrupted under eighth dorsal spine and re- 

 sumed a few scales farther back ; 2 rows of scales on cheeks ; predorsal 

 scales 13 to 16; scales in lateral line 27 to 30; anal rays III, 8 to 10; 

 second anal spine shorter than third. 

 6a. Supraorbital ridge with 3 or 4 spines on its posterior edge ; depth 2.8 to 

 3.3; least depth of caudal peduncle 1.5 in its length and equal to post- 

 orbital part of head gymnocephala 



66. Supraorbital ridge smooth, with a single spine posteriorly ; depth 2.3 to 

 2.7 ; least depth of caudal peduncle about equal to its length and longer 

 than postorbital part of head buruensis 



CHANDA KOPSII (Bleeker) 



Ambassis kopsii Bleekeb, 1858 (186), p. 253 (Singapore). — Fowlee, 1935a, p. 146 

 (Bangkok). 



Fowler (1935a) records from Bangkok this species of the East 

 Indies, Philippines, and Malaya. The writer found it widely dis- 

 tributed in the Gulf of Siam, on both coasts, but always in salt water. 

 It is suggested that the Bangkok specimens referred to by Fowler may 

 have been market fish from the gulf, as fish from the nets in the upper 

 part of the gulf are sent regularly from Paknam to Bangkok by boat 

 and rail. 



CHANDA COMMERSONII (Cuvier and Valenciennes) 



Amiassis commersonii Cuvieb and Valenciennes, 1828, vol. 2, p. 176 (Bourbon, 



Malabar, Java, Batavia). 

 Ambassis commersoni Hoea, 1924a, p. 485 (Tale Sap). — WEaBER and de Beaufort. 



1929, vol. 5, p. 406 (Siam). 

 Amhassis safgha Fowler, 1937, p. 232 (Rayong) ; 1939, p. 41 (Huey Yang). 



A species of very wide distribution (Australia, east coast of Africa, 

 India, East Indies, Philippines, and other localities), this species is en- 



