FRESH-WATER FISHES OF SIAM, OR THAILAND 521 



peculiar generic characters are the compressed body ; greatly depressed 

 head ; large nearly horizontal mouth, with jaws reaching far beyond 

 the eyes; small teeth in several rows in each jaw, none canine; about 8 

 fleshy barbels on each side of the snout, 1 large pair of barbels on the 

 chin, and 1 pair on each side of the lower jaw under the anterior 

 nostrils; body covered with ctenoid scales, about 46 in longitudinal 

 series, opercles and cheeks naked; conspicuous rows of pores on 

 opercles, cheeks, snout, and under side of lower jaw ; dorsal rays VI-I, 

 9 or 10, anal rays I, 9 or 10. 



Locally the fish is found in brackish and fresh water. It was first 

 met with at Paknam on the Menam Chao Phya in June 1927, when two 

 specimens, 6.5 and 7.5 cm. long, were taken. In 1935 Fowler reported 

 one, 7.8 cm. long, from the same place. From the Chantabun Estu- 

 ary in Southeastern Thailand three specimens 6.8 to 8.7 cm. long were 

 collected in July 1928. 



Day's type was 10 cm. long. 



Genus PSEUDOGOBIOPSIS Koumans 



Pseudogobiopsis Koxtmans, Zool. Meded., vol. 18, p. 131, 1935. (Type, Gobiopsis 

 oUgactis Bleeker.) 



PSEUDOGOBIOPSIS OLIGACTIS (Bleeker) 



Gobiopsis oligactis Bleeker (461), Arch. Neerl. Sci. Nat., vol. 10, p. 113, 1875 

 (Amboyna). 



Pseudogobiopsis oligactis Kotjmans, 1935, p. 131, fig. 4 (Bangpakong River, Am- 

 boyna, Indo-Australian Archipelago). — Fowler, 1937, p. 251 (Bangkok). 



The known range of this species is restricted. The type, and the 

 only specimen referred to by Bleeker, was found by Koumans in the 

 Royal Natural History Museum in Leiden, together with five addi- 

 tional specimens in the Bleeker collection, and one without indication 

 of locality in the Zoological Museum in Amsterdam. The only other 

 habitat is Thailand in two of the large rivers debouching into the head 

 of the Gulf of Siam. 



Excellent series of 25 specimens were taken by the writer in the 

 Bangpakong River in June 1928 and 35 specimens in June 1933, and 12 

 specimens were reported by Fowler (1937) as coming from the Menam 

 Chao Phya at Bangkok. Two of the specimens from the Bangpakong, 

 sent to Dr. Koumans in 1934, were used by him in defining the genus 

 PseudogoMopsis. 



The type was 2.6 cm. long. Other Bleekerian specimens were up to 

 5.3 cm. The largest Thailand examples are 4.5 cm. 



In his description of Pseudogohiopsis oligactis^ Koumans (1935) 

 stated that the maxillary extends to the posterior margin of the opercle. 

 In his 1931 paper, p. 66, he described the genus Gobiopsis, which then 

 included oligactis, as having the maxillary "prolonged posteriorly to 



