FRESH- WATER FISHES OF SIAM, OR THAILAND 127 



p. 402) reaffirmed the assignment of E. ogilhii to Mystacoleiicus. This 

 matter may be briefly considered I'rom the nomenclatural and the 

 morphological viewpoints. 



The genus Rohtee was established by Sykes in 1939, with three new 

 Indian species included, ogilhii, vigorsi, and pangut. No species was 

 singled out as the type by anj^ indication, designation, or implication; 

 but nevertheless Jordan (1919, pt. 2, p. 210) stated, apparently with- 

 out warrant, that R. vigorsi is the orthotype, which term is defined 

 as "the type of a genus as indicated or distinctly implied by the origi- 

 nal author." The first designation of a type in Rohtee was by Bleeker 

 (1863 [314] ) when "/?. ogilhyi'''' was definitely selected. 



It is evident therefore that if the species Rohtee ogilhii really belongs 

 in the genus Mystaxsoleucus, as claimed by Hora, then Rohtee is the 

 proper generic name for the various species now called Mystacoleiicus, 

 the latter being a synonym. It also follows that the various species, 

 other than ogilhii, now known as Rohtee must take another generic 

 name. 



These changes in nomenclature, however, would be very unfortu- 

 nate and are believed to be unnecessary. While R. ogilhii has a pro- 

 cmnbent predorsal spine, the writer holds the opinion (1) that this 

 feature alone does not justify the separation of the species from its 

 congeners with which it is otherwise in complete agreement and (2) 

 that the general facies, the backward origin of the dorsal fin with 

 reference to the ventral fins, the more numerous scales (55 in lateral 

 line in R. ogilhii as against a maximum of 39 in any species of Mystaco- 

 leucus), the longer anal fin (with 13 or 14 branched rays as against 6 

 to 10 in Mystacoleucus) , and similar features should be given greater 

 weight collectively than the procumbent spine. 



Of the four local species of Mystacoleucus, two have been known for 

 a long time and two have recently been described as peculiar to Thai- 

 land, They may be differentiated as follows : 



la. Branched anal rays 6 ; last simple dorsal I'ay osseous and denticulated ; 

 barbels 4 ; scales in lateral line 33 to 35 ; predorsal scales 12 or 13 ; circum- 

 peduncular scales 16 ; dorsal fin yellow to red, with a sharply defined 



black edge; caudal fin with no black edge argenteus 



15. Branched anal rays 7 to 10. 



2a. Last simple dorsal ray nonosseous and nondenticulated ; no barbels ; scales 

 in lateral line 31 or 32 ; predorsal scales 8 or 9 ; a large black spot 

 occupying apex of dorsal fin ; free margin of dorsal and caudal fins not 



sharply edged with black atridorsalis 



2&. Last simple dorsal ray osseous and denticulated ; 4 barbels ; scales in 

 lateral line 24 to 29 ; free margin of dorsal and caudal fins with sharply 

 defined black edge ; front edge of dorsal fin black. 

 3a. Predorsal scales 6 to 8; some scales of back and side with a dark basal 



crescent chilopterus 



3&. Predorsal scales 9 or 10; each scale of back and side with a black basal 

 crescent marginatus 



