430 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



1&. Upper jaw as broad as long. 

 3a. Projection of lower jaw beyond upper jaw 7 to 8 times length of latter. 

 4a. Fifth dorsal ray in male thickened and more than twice length of other 

 rays ; sixth anal ray in male greatly enlai'ged and lengthened, in some 



examples extending to end of caudal fin gilli 



46. Fourth dorsal ray in male broadened, thickened, bowed, and in fully 

 mature examples may be nearly 4 times length of other rays, the end 

 club-shaped ; sixth anal ray in male enlarged, thickened, and twice 



length of other rays dunckeri 



3&. Projection of lower jaw beyond upper jaw 6 times length of latter ; dorsal 

 rays in male unmodified ; sixth anal ray in male enlarged, thickened, and 

 moderately elongated, seventh and eighth rays slender and 

 elongated pappenheimi 



ZENARCHOPTERUS CLARUS Mohr 



Zenarchopterus clarus Mohe, 1926a, p. 241 (Bangkok). 



At the time the original description of this species was published 

 only two females were known ; these, 16.5 and 15 cm. long, were found 

 in the Lubeck Museum and had come from Bangkok. Later in the same 

 year Mohr (1926b) published a notice of three additional specimens 

 found in Vienna, two of them females 15 and 15.2 cm. long, one a male 

 12.2 cm. long, all from Kangoon, Burma. 



The differential features on which the species is based are : Length 

 of upper jaw twice its width at base; length of lower jaw beyond the 

 tip of the upper jaw 4 times the length of the lower jaw; dorsal rays 

 13 or 14, none modified in the male ; anal rays 11 to 13, the middle ray 

 in the male enlarged and thickened but not produced beyond the other 

 rays. Various characters that would be of interest in comparing this 

 species with related forms have not been published. 



The possibility that this species is Z. ectimtio (Hamilton) is to be 

 considered. 



ZENARCHOPTERUS ECTUNTIO (Hamilton) 



Esox ectunfio Hamilton, 1822,, pp. 212, 380 (Gangetic provinces). 

 Hemiramphus horneensis Bleekeb, 1865 (347), p. 35 (Siam) ; 1865 (356), p. 176 



(Siam). 

 Eetnirhamphus mnblyurus GtJNxHER, 1866, vol. 6, p. 273 (Siam). — Karoli, 1882, 



p. 182 (Siam). 

 Zenarchopterus ectuntio Webee and de Beaufort, 1922^ vol. 4, p. 165 (Siam). 

 Xe7iarchoptcrus ectuntio Hora, 1923b, p. 176 (Bangkok). 

 Zenarchopterus amUyurus Mohr, 1926a, p. 243, fig. 11 (Siam). 



This fish is very common and has a wide distribution in Thailand, 

 It occurs in most of the rivers of Central Thailand, ranges at least as 

 far south as the Tale Sap in Peninsular Thailand, and has been ob- 

 served in Southeastern Thailand at Krat. From its habit of swim- 

 ming at the surface and actively darting about in search of food, the 

 fish is conspicuous and easily recognized; the tip of the lower jaw is 

 glistening white. In the Menam Chao Phya at Paknam on July 13, 



