258 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



to base of caudal fin ; caudal deeply forked, 1.4 times length of head ; 

 anal rays iii, 5, longest 1.5 in head; ventrals 1.25 in head; pectorals 

 pointed, 0.8 head. 



Coloration: Back and sides greenish, with faint darker longitu- 

 dinal lines following the rows of scales; underparts whitish; inter- 

 radial dorsal membranes medianly blackish, free margin of dorsal 

 fin with a narrow sharply defined black edge. 



/;:. 



/x/' 



x. 



'^ 



Figure 4:9.—HenicoThynchus lobatus, new species: Type (U.S.N.M. No. 119490). Drawn 



by Mrs. Alice C. Mullen. 



Type and other speciviens. — The type (U.S.N.M. No. 119490), a 

 female 13.2 cm. long, was collected in the Mekok near Chiengrai, 

 Northern Thailand, March 2, 1924. A male 14.2 cm. long was taken 

 at the same time. Additional specimens have come from the Menam 

 Pasak at the barrage at Dha Luang, August 20, 1923 ; from the Menam 

 Chao Phya at Paknampo November 19, 1923; from Bung Borapet 

 November 20, 1923 (3 specimens 9.1, 11.7, and 12.6 cm. long) ; and 

 from the Menam Chao Phya at Bangsai November 27, 1923. In the 

 Deignan collection are 28 specimens, 5.9 to 10.6 cm. long, from the 

 upper Nan River at Ban Pa Khwang, Northern Thailand, March 

 31, 1936. Paratypes are U.S.N M. Nos. 108091, 119491-119494. 



Remarks. — From the foregoing record of specimens in hand it ap- 

 pears that this species has a rather wide range, involving both the 

 Mekong and the Menam Chao Phya basins. 



A feature by which the species may be recognized readily is the 

 deep median incision in the rostral flap dividing it into two lobes and 

 the evenly crenulated edge of the lobes, together with the indicated 

 structure of the lower lip and the division of the snout into central 

 and lateral lobes. Specimens 7.8 to 9.3 cm. long, believed to be young 

 of the year, show a small roundish black spot on the caudal peduncle 

 at the base of the caudal fin. This spot seems to be entirely lost by 

 the time the adult staee is reached. 



