420 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



The two genera of this family that are to be found in Thailand may 

 be differentiated by the following characters : 



la. Upper jaw protractile; mouth of moderate size with its corners abruptly- 

 bent downward ; vomer toothed ; pseudobranchiae present ; branchial mem- 

 branes free from each other and from isthmus ; pectoral fins with their upper 

 base at or below longitudinal axis of body Aplocheilus 



1?». Upper jaw not protractile; mouth small with its corners obtusely bent down- 

 ward ; vomer toothless ; no pseudobranchiae ; branchial membranes united 

 across isthmus ; pectoral fins with upper base well above longitudinal axis 

 of body Oryzias 



Genus APLOCHEILUS McClelland 



Aplocheilus McClelland, Asiatic Researches, vol. 19, p. 301 (as -cJielus, p. 261), 

 1839. (Type, Aplocheilus chrysostigmus McClelland.) 



This genus was established by McClelland in 1839 with three species 

 listed thereunder, chrysostigmus (new), melastigmus (new), and 

 panchax^ first described as Esox 'panchax by Hamilton in 1822. Mc- 

 Clelland made reference to a fourth species of Aplocheilus and pub- 

 lished a figure of it based on a drawing in the Hamilton collection. 

 No name was given to the species which, on the figure, was indicated 

 as new. This figure was the basis for Bleeker's Aplocheilus mcClel- 

 landi. The genus was composite and no type was indicated. In 1846 

 Cuvier and Valenciennes, ignoring McClelland's Aplocheilus.^ created 

 the genus Panchax and placed therein four species, including Hamil- 

 ton's Esox panchax^ which they renamed Panchax huchanani.^ to- 

 gether with Panchax pictum, which is a Betta of the family Ana- 

 bantidae. The designation of a type species in Aplocheilus seems 

 to have been first made in 1863 when Bleeker ((301), 1863, vol. 3, p. 

 140), in a synopsis of his family Cyprinodontoides, definitely named 

 Aplocheilus chrysostigmus McClelland as the type. This action was 

 unfortunate because other published opinions of Bleeker indicate that 

 what he did in this case was opposite to what he intended to do, for 

 chrysostigmus is a synonym of jmnchax, which Bleeker, in the same 

 synopsis, placed in the genus Panchax. 



As a contribution to the question of the proper generic name for the 

 fishes that have been placed in Aplocheilus by Weber and de Beaufort 

 and other recent authorities, reference may be made to an interesting 

 point raised by Dr. L. F. de Beaufort in a letter dated September 20, 

 1938, from which the following is quoted : 



It is true that Bleeker, Atlas Ichthyologique, III, 1863, p. 140, made A. 

 chrysostignia the type of the genus, but he did it in the belief that this species 

 shows the characteristics of the genus, as understood by Bleeker. This is clear 

 from the following. In 1853 (Verb. Bat. Gen., XXV, p. 144) Bleeker considered 



