FRESH-WATER FISHES OF SIAM, OR THAILAND 425 



head, their origin midway between tip of snout and posterior end of 

 anal base ; pectorals slightly longer than ventrals. 



Coloration: Body translucent, the blackish peritoneum showing 

 through the abdominal walls ; back minutely speckled with black, the 

 spots concentrated medianly and forming a rather well-marked stripe 

 from occiput to caudal fin ; a straight black line on side from over ven- 

 trals to base of caudal; a black line running along base of anal fin, 

 above it a similar line which diverges anteriorly and joins the basal 

 line at posterior end of anal fin, the two continued as a single line on 

 under side of caudal peduncle; top of head, opercles, preorbital, and 

 lips with black specks forming line on lips; a few widely scattered 

 black specks on lower side of body ; dorsal, caudal, and anal rays faintly 

 outlined with black. 



Type and paratypes. — The type (U.S.N.M. No. 107958) is an 

 ovigerous female 16.3 mm. long, taken in a small canal in Bangkok, 

 Central Thailand, May 10, 1934. Of four other specimens obtained at 

 the same place and time three 17 mm. long were females with well- 

 developed eggs and one 15.5 mm. long was apparently a male. Para- 

 types are uTs.N.M. No. 109789. 



Remarks. — Of the described species from southern Asia and the 

 Indo-Australian Archipelago, the present form most closely resembles 

 Aplocheilus javanicus Bleeker, recorded from fresh and brackish 

 waters of Java, Singapore, Malaya, and other localities. The differ- 

 ences, while not wide, seem to justify the recognition of the Thai fish 

 as distinct. Thus, javanicus has 7 dorsal and 21 to 24 anal rays, as 

 against 6 and 19, respectively, in minutilhcs; the squamation is quite 

 similar, 29 or 30 scales in the lateral line in the former and 27 or 28 in 

 the latter, with the scales in transverse series 10 in both, but while in 

 javanicus the predorsal scales number 22 or 23, in minutillus they are 19. 



In color pattern this fish conforms with species of the Indo-Austra- 

 lian Archipelago in having a dark stripe along the median line of 

 the back, a very thin dark stripe along the middle of the side, and a 

 similar stripe above the base of the anal fin converging toward its 

 fellow on the opposite side and meeting it just behind the base of the 

 anal fin, the combined line continued along the under side of the caudal 

 peduncle. An additional dark line along each side of the anal fin at 

 the very base of the rays is not referred to in descriptions of any other 

 species of this general region. 



This appears to be the smallest of the described species of Oryzias^ 

 attaining full maturity when only 17 mm. long. It seems altogether 

 probable that it is not uncommon in the Bangkok region and has 

 heretofore been overlooked because of its small size and inconspicuous 

 coloration. 



