520 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



specimens from the islands of Kiushii and Okinawa, Japan. Although 

 the genus Hetereleotris belongs in the family Eleotridae, with ventral 

 fins separated, Snyder's description specifies united ventral fins, which 

 would make the fish one of the Gobiidae. The figure of H. arenarius 

 is strongly suggestive of Pipidonia, in which genus the fish was placed 

 by Tomiyama (Gobiidae of Japan, 1936) , with a question as to whether 

 Pipidonia quinqiiecincta may not be Hetereleotris arenarius. The 

 similarity is close but the differences in structure and coloration are 

 suflScient to separate the two species. 



Genus EUGNATHOGOBIUS H. M. Smith 



Eugnathogo'bius H. M. Smith, Proc. U. S. INat. Mus., vol. 79, art. 7, p. 37, 1931. 

 (Type, Eugnatlxogo'bius microps H. M. Smith.) 



EUGNATHOGOBIUS MICROPS H. M. Smith 

 Eugnathogobius microps Smith, 1931a, p. 37, fig. 18 (Bangpakong River). 



Described from a specimen, 3.3 cm. long, from the lower Bangpa- 

 kong Kiver in Central Thailand, this species has been found in other 

 parts of that river, including the upper reaches where the water is 

 quite fresh. It has not been reported from other localities but should 

 be expected in the lower Menam Chao Phya, the lower Tachin, and 

 other rivers discharging into the head of the Gulf of Siam. 



The fish may be recognized by its small size, very large oblique 

 mouth, which extends nearly to the posterior margin of the preopercle, 

 small eyes on the top of the head, and comparatively plain coloration, 

 together with naked head, dorsal rays V-I, 7, anal rays I, 6, and con- 

 spicuous rows of pores on the top and sides of the head and along the 

 ramus of the lower jaw. 



During a number of years the fish was taken as far up the Bangpa- 

 kong Kiver as the town of Petrieu. The genotype, a male 3.3 cm. long, 

 has the maxillary contained 1.4 times in the head and equal to the 

 postorbital space. In a female 3.1 cm. long from Petrieu, the max- 

 illary is 0.5 the length of the head. Paratypes in the U. S. National 

 Museum bear the numbers 119591 and 119593. 



Genus POGONOGOBIUS H. M. Smith 



Fogonogobius H. M. Smith, Proc. U. S. Nat. Mus., vol. 79, art. 7, p. 37, 1931. 

 (Type, OoMus planifrons Day.) 



POGONOGOBIUS PLANIFRONS (Day) 



OoMus planifrons Day, 1873, p. 108 (Bombay). 



Fogonogobius planifrons Smith, 1931a, p. 37 (Menam Chao Phya at Paknam, 

 Chantabun Estuary). — Fowleb, 1935a, p. 161 (Paltnam). 



The genus Pogonogohius (Smith, 1931a) has a single known species, 

 P, planifrons (Day) (1873) , recorded from India and Thailand. The 



