FRESH-W^TER FISHES OF SIAM, OR THAILAND 197 



for a genus of fossil mollusks. Of the possibly available names, 

 Acrossoc/ieilvs is the most promising, although as originally defined 

 it does not apply to any of the species, formerly placed in Lissochihis, 

 known from India, Thailand, Malaya, and the Indo-Australian Arch- 

 ipelago. Its availability depends on the acceptance of the view that 

 the various types of lower lip in this group (whether entire, slightly 

 notched, or completely divided with the two halves moderately or 

 widely separated) represent simply intergrading stages of the same 

 structural feature. 



These fishes inhabit mountain streams of India, Burma, Thailand, 

 Indo-China, China, Malaya, and Sumatra. Seven local species herein 

 recognized may be identified by the following characters : 



la. Dorsal fin with 8 branched rays; last simple dorsal ray denticulated; origin 

 of dorsal fin anterior to, over, or slightly behind origin of ventrals. 

 2a. Scales in lateral line 24 to 26 ; predorsal scales 8 or 9. 



3a. Depth 3.7 in standard length ; scales in transverse series from midline 

 of back to base of ventral fin 3.5-1-2.5; circumpeduncular scales 

 12 ; origin of dorsal fin somewhat in advance of ventrals ; a black band 

 from head to base of caudal fin; a dark submarginal stripe on each 



caudal lobe vittatus 



3&. Depth 2.75 in standard length ; scales in transverse series from midline 

 of back to base of ventral fin 5.5-1-2.5 ; circumpeduncular scales 14 ; 

 oi'igin of dorsal fin directly over base of ventrals ; each scale of back 



and sides with a green basal crescent ; caudal lobes plain malcolmi 



26. Scales in lateral line 29 to 38, scales in transverse series from midline of 



back to base of ventral fin 4.5 to 6.5-1-2.5 to 3 ; predorsal scales 11 to 14 ; 



circumpeduncular scales 14. 



4a. Scales in lateral line 29 to 33 ; least depth of caudal peduncle 1.5 times 



in '.ts length ; origin of dorsal fin over about tenth scale of lateral line ; 



general color lustrous golden or bronze ; each caudal lobe with a black 



Diarginal longitudinal stripe deauratus 



46. Scales in lateral line 84 to 38; least depth of caudal peduncle 2 times 

 in its length ; origin of dorsal fin over about thirteenth scale of lateral 



line ; general color silvery ; caudal lobes plain bantamensis 



1&. Dorsal fin with 9 branched rays. 

 5a. Last simple dorsal ray strongly denticulated ; origin of dorsal fin over origin 

 of ventrals ; scales in lateral line 34, scales in transverse line from mid- 

 line of back to base of ventral fin 5.5-1-2.5 ; predorsal scales 11 ; circum- 

 peduncular scales 6 schroederi 



5&. Last simple dorsal ray nondenticulated ; origin of dorsal fin before ventrals ; 

 scales in lateral line 23 to 29 ; scales in transverse line from midline of 

 back to base of ventral fin 3.5-1-2 or 2.5 ; predorsal scales 7 to 9 ; cir- 

 cumpeduncular scales 12. 

 6a. Scales in lateral line 23 to 25 ; predorsal scales 7 or 8 ; depth of body 3.1 

 to 3.2 in standard length ; distal part of caudal lobes usually black. 



sumatranus 

 6&. Scales in lateral line 26 to 29 ; predorsal scales 8 or 9 ; depth of body 3.4 



to 3.6 in standard length ; caudal lobes without black markings dukai 



590087—45 14 



