FRESH-WATER FISHES OF SIAM, OR THAILAND 219 



OSTEOCHILUS SIMUS (Sauvage) 



Rohita sima Sauvage, 1878b, p. 238 (Mekong, Indo-China) ; 1881, p. 177 (Mekong, 



Indo-China ) . 

 ? Osteochilus sima Fowler, 1935a, p. 117 (Srisawat). 



The original description of this species from Pnom-Penh, on the 

 Mekong in Cambodia, differs considerably from that of 3 years later. 

 Thus, the fish was first credited with strongly fringed lips, 2 pairs 

 of barbels, 48 scales in the lateral line, and dorsal rays 19 (including 

 simple rays). With additional material, also from the Mekong, 

 Sauvage reported the species as having an entire upper lip and fringed 

 lower lip, only rostral barbels, 38 scales in the lateral line, and 17 

 dorsal rays. These differences can hardly be reconciled, and doubt 

 must exist as to the real peculiarities of the species. The fish re- 

 mained unnoticed until 1935 when Fowler gave a description of two 

 specimens, 16.1 and 18 cm. long, from Srisavrat, Central Thailand; 

 these specimens, however, differ in essential features from one or 

 both of the descriptions of Sauvage, having the upp«r lip entire and 

 the lower lip papillate but not fringed, a single pair of barbels 

 (rostral), 36 scales in the lateral line, 7 scales between the lateral 

 line and the base of the ventrals (as against 5 or 5.5 scales according 

 to Sauvage), end of snout with 2 horizontal rows of pores (as against 

 2 or 4 large pores in some specimens according to Sauvage), and 

 dorsal fin with 5 simple and 15 branched rays. A further difference 

 is that whereas the Thai specimens have the back and side olive, 

 with a dark basal spot on each scale, and a conspicuous blackish 

 crescent on the side above the pectoral fin, Sauvage assigns to his 

 fish a brilliant, uniform coloration. 



Determination of the true status of 0. simus and of the Thai 

 material so identified must await comparison with Sauvage's speci- 

 mens if they are still existent. 



Genus ACANTHORHODEUS Bleeker 



Accmthorhodeus Bleekee (411), Versl. Meded. Akad. Wet. Amsterdam, ser. 2, vol. 

 4, p. 252, 1870. (Type, Acanfhorhodeus macropterus Bleeker.) r!--i. Ji oii i 



ACANTHORHODEUS DEIGNANI, new species 

 FiGXJEE 39 



Description. — Dorsal outline a regular curve from snout to caudal 

 peduncle; ventral profile somewhat more strongl}^ arched; depth 2.4 in 

 standard length ; least depth of caudal peduncle equals its length and 

 1.5 in head ; head 4.2 in length ; eye 2.5 in head and 1 in interorbital 

 space ; snout less than eye ; mouth very small, subterminal, maxillary 

 extending about 0.5 distance between tip of snout and eye; a small 

 maxillary barbel. 



