FRESH-WATER FISHES OF SIAM, OR THAILAND 75 



1863 [314] made Chela cachius of Hamilton the genotype, but his action 

 seems to have been generally disregarded (Day, Giinther, Weber and 

 de Beaufort). The next available name is Oxygaster of van Hasselt, 

 1823. 



These fishes are easily distinguishable by the extension of the nuchal 

 scales into the interorbital space, in addition to the other features shown 

 in the preceding key. 



Fowler (1934a) described, as new species of Chela from Thailand, 

 C. pointoni, harroni, and stigmabrachiuTn, but only the first of these 

 conformed with the definition of Chela (i. e., Oxygaster). Later 

 Fowler (1935a, 1937) placed them, including pointoni., in Cutter. 



Bleeker (1865 [356]) listed without description Chela castelnaui 

 from Bangkok. The name is based on a drawing in Count Castelnau's 

 album of Siamese fishes and appears to have no standing. 



Following is a key to the species of Oxygaster recorded from 

 Thailand : 



la. Caudal fin with a sharply defined black spot on each lobe ; scales in lateral 



line 42, in transverse series to base of ventral fin 10.5-1-5 maculicauda 



16. Caudal fin veith no black spot on either lobe. 

 2a. Scales in lateral line 50 to 60, in transverse series to base of ventral fin 11 

 or 12^1-5 to 7 ; origin of dorsal fin opposite or slightly in advance of 



origin of anal fin . anomalura 



2&. Scales in lateral line 30 to 43. 



3a. Depth 2.75 to 3.6 in length and greater than head ; pectoral fins extending 

 beyond base of ventral. 

 4a. Scales in transverse series 8-1-3 ; origin of dorsal fin slightly in advance 



of origin of anal siamensis 



4&. Scales in transverse series 6 or 7-1-4 ; origin of dorsal fin opposite or 



behind origin of anal oxygastroides 



3&. Depth about 4.25 in length and equal to head ; scales in transverse series 

 8-1-3 ; origin of dorsal fin far in advance of origin of anal fin ; pectoral 

 fin extending to base of ventral pointoni 



OXYGASTER MACULICAUDA (H. M. Smith) 



Chela maculicauda Smith, 1934b, p. 301 (Tale Sap). 



This strikingly marked little fish is known only from three speci- 

 mens, 5.5 cm. long, taken by the writer in Klong Ranoad, a tributary 

 of the inner lake of the Tale Sap, Peninsular Siam, October 9, 1923. 

 No other species of Oxygaster has a black spot on each caudal lobe. 



The type is U. S. N. M. No. 103372. 



OXYGASTER ANOMALURA van Hasselt 



Oxygaster anomalura van Hassext, 1823, p. 133. 



Chela oxygaster Weber and de Beaufort, 1916, vol. 3, p. 52 ( Sumatra ; Java ; 

 Borneo ; Malacca ) . 



The range of this species includes Java, Borneo, Sumatra, and 

 Malaya, as well as Thailand. Its inclusion in the local fauna rests on 



