FRESH-WATER FISHES OF SIAM, OR THAILAND 381 



Specimens from the Menam Chao Phya were reported by Hora 

 (1923b) as in fairly close agreement with Regan's type; and a spec- 

 imen from the upper waters of the Menam Mun sent to Dr. L. F. de 

 Beaufort was regarded by him as representing L. siamensls. 



It has been possible to separate L. bicolor Fowler, described from 

 specimens 4.1 to 9.7 cm. long, from fishes that are considered repre- 

 senting normal variation in L. siamensis, of which species Fowler 

 makes no mention. The location of the nasal barbel over the eye, as 

 in Fowler's figure, would be a significant character, but as the text 

 makes no reference to this unusual feature it is assumed the figure may 

 be defective. Similarly, L. alhicollaris Fowler, described from a sin- 

 gle specimen, 11.4 cm. long, is believed to be L. 'bicolor and, therefore, 

 L. siamensis. The species, as originally described, was differentiated 

 from L. bicolor by having 16 as against 14 anal rays, larger adipose 

 fin, dorsal spine with about a dozen retrorse serrae as against 6, 13 

 denticles on pectoral spine as against 9 or 10, and entirely white caudal 

 fin and a pale nuchal collar. Examination of a large series of spec- 

 imens of this type shows that there is, within narrow limits, con- 

 siderable variation in the number of serrations on the dorsal and 

 pectoral spines. Thus, in a lot of 10 fishes from the Meping, the well- 

 developed dorsal serrae varied from 7 to 12 (average 9.6) and the 

 pectoral serrae varied from 9 to 16 (average 14.5). The size of the 

 adipose fin, with its base much longer than that of the anal and its 

 origin separated from the dorsal base by a space only half the length 

 of that base, would be a significant character, but these points dis- 

 appear among the 10 figures showing variation in L. albicollaris 

 (Fowler, 1937). The pale nuchal collar is not distinctive; and in- 

 stead of a pale or white unmarked caudal fin, as called for by the de- 

 scription, 7 of the 10 figures of variation have black spots on the caudal 

 lobes as in L. bicolor. 



Vernacular names borne by this fish are pla kayeng hin and fla hot 

 hin. The fish makes a croaking sound (kot), which may be quickly 

 repeated a number of times ; the sound is heard when the fish is free 

 in the water and also after it is taken from the water. 



LEIOCASSIS STENOMUS (Cuvier and Valenciennes) 

 FiGUBE 84 



Bagrus stenomus Cuvier and Valenciennes, 1839, vol. 14, p. 415 (Java). 



The inclusion of this species in the present catalog is based on the 

 taking of a specimen in the Chantabun River in Southeastern Thai- 

 land. The fish is otherwise known from Java, Borneo, Sumatra, and 

 Malaya. The specimen in hand, 9.1 cm. long, obtained June 3, 1927, 

 when caught was of a light brown color with irregular dark brown 

 markings in large pattern on head and body, and a small rounded 



