FRESH-WATER FISHES OF SIAM, OR THAILAND 43 



of Chantabun. It enters the inner lake of the Tale Sap. Its adapt- 

 ability to a strictly fresh-water habitat is shown by the fact that in the 

 interior of Java it is reared in fresh-water ponds from young caught 

 along the coast. During 2 years the fish was found on Koh Tao, the 

 isolated island in the Gulf of Siam off Chumporn, which has little or 

 no fresh water except during the rainy season ; on July 19, 1927, Di-. 

 A. F. G. Kerr collected specimens 10 to 11 cm. long in an isolated 

 pool in an otherwise dry stream bed cut off from the sea by a high sand 

 bank; and in September 1928 in a similar pool in the same place the 

 present writer found the fish to be common in two sizes, averaging 

 about 10 and 20 cm. long. 



A length in excess of 50 cm. is attained by this species, but the 

 largest examples actually met with in Thailand have been about 35 

 cm. long. 



The vernacular designation of this fish in Thailand is 'pla taluerk 

 (upturned-eye fish), a name that does not indicate much discrimina- 

 tion, for the same name is applied to various clupeids, such as Ilisha, 

 belonging in another family. In the Chantabun district of South- 

 eastern Thailand, however, this fish is called pla taluerk nam chuet 

 {nam chuet^ fresh water) to distinguish it from the marine species of 

 somewhat similar appearance, with large eyes. 



Family CLUPEIDAE : Herrings, Sardines, Shads 



This very large and commercially important family has many local 

 species, most of them marine but a few either regular migrants into 

 fresh water or wanderers therein at certain times. The Thai forms 

 having a fresh water habitat may be conveniently considered by sub- 

 families, which are distinguishable as follows : 



la. Mouth terminal or superior, toothed or edentulous ; maxillary with 2 supple- 

 mentary bones. 

 2a. Ventral fins well developed; anal fin of moderate length, with 15 to 25 



rays; jaws equal Clupeinae 



2b. Ventral fins small or absent ; anal fin long, with 33 to 92 rays ; lower jaw 



projecting and upturned Pristigasterinae 



16. Mouth inferior, edentulous ; maxillary with 1 supplementary bone. 



Dorosomatinae 



Subfamily Clupeinae 



This subfamily is numerously represented in Thai waters and is 

 economically the most important division of the clupeid fishes. The 

 three local genera that enter fresh water may be distinguished as 

 follows : 



la. A distinct notch in middle of upper jaw formed by intermaxillaries meeting 

 at an acute angle; size large; anadromous Hilsa 



