FRESH-WATER FISHES OF SIAM, OR THAILAND 297 



bun River. Additional localities for specimens in the British Museum 

 are the Mewang, Central region, collected by Vernay, and the Patani, 

 Peninsular district, collected by Annandale and Robinson. Material 

 studied by Fowler came from Bangkok, Pitsanulok, Khao Nam Poo, 

 the Mepoon in Central Thailand, and the Mekong at Kemarat in 

 Eastern region. In collections by Deignan, this species was obtained 

 from the Nan River at Nan, the Meping at Chiengmai, and the 

 Mechem, a tributary of the Meping. 



The largest specimens examined were 22.5 cm. long. Full maturity 

 is attained at a much smaller size; thus, a fish 6 cm. long from the 

 Meyom at Prae, Central Thailajid, June 28, 1927, contained ripe eggs. 

 No observations on spawning habits have been made. 



Eight color variations in fish from Kliao Nam Poo, Central Thai- 

 land, are given by Fowler (1935a). Many other types of color varia- 

 tions occur, including a pale body with no mark except a narrow dark 

 longitudinal stripe, which may be wholly or partly lacking. 



The general color and markings serve to afford the fish concealment 

 in clear, shallow, sandy streams. -In some cases the writer was able 

 to determine the presence of the fish most readily by the shadows they 

 cast on the light sandy or gravelly bottom. Wliere there is current 

 the fish always head upstream. When they are frightened they bury 

 themselves in the bottom sand with great rapidity. 



Vernacular names borne by the fish are pla sai (sand fish), pla son 

 sai, pia hluey (banana fish) , and pla rah hluey. 



NEACANTHOPSIS, new genus 



Similar to Acanthopsis but with the eyes mostly in the anterior half 

 of the head, the concealed bifid spine partly suborbital and partly 

 preorbital and extending under middle of ej^e, and incomplete lateral 

 line. Body slender and strongly compressed ; head compressed ; snout 

 contracted, overhanging the small mouth ; 3 pairs of barbels (1 rostral, 

 2 maxillary); eyes subcutaneous; scales minute, deficient on head; 

 dorsal fin beginning over base of ventrals, its branched rays in reduced 

 number (8 against 10 or 11 in Acanthopsis) ; caudal fin truncate 

 (forked or emarginate in Acanthopsis) . 



Genotype. — Neacanthopsis gracilentus^ new species. 



This genus differs from Lepidocephal/us chiefly in having no scales 

 on vertex or other parts of head and only one pair of rostral barbels. 



NEACANTHOPSIS GRACILENTUS, new species 

 FlQXTRB 61 



Description. — Very elongate, head and body strongly compressed; 

 depth 7.3 times in standard length; length of caudal peduncle two 

 times its depth and equal to depth of body; head 5 in length, its 



