FRESH-WATER FISHES OF SUM, OR THAILAND 249 



Bangkok May 3,, 1928, weighed 3 pounds each. In Thailand it occurs 

 throughout the basin of the Menam Chao Phya and in various other 

 rivers of the Central region. 



An important breeding ground for this species is Bung Borapet, the 

 large swamp communicating with the Menam Chao Phya and the 

 Menam Nan near Paknampo which, on the writer's recommendation, 

 was converted into a fish preserve and nursery by the Siamese Govern- 

 ment. A series of specimens taken November 19, 1923, as the fish were 

 leaving the swamp with the fall of the flood waters, were 7.1 to 10.5 

 cm. long and were undoubtedly the young of the year. Notwithstand- 

 ing their small size, all had a profuse display of pearl organs on snout, 

 top and sides of head, and on the back as far as the dorsal fin. 



There is little reason to doubt that Fowler's M. erythrostictus is this 

 common and widely distributed species, which shows slight variation 

 in color depending on age and environment. Among specimens col- 

 lected by the writer in different streams of Thailand, including the 

 Ping River from which Fowler's specimens presumably came, there 

 are examples that conform with the color features given for M. ery- 

 throstictus. The transverse rostral fold, which Fowler stresses as a 

 diagnostic point, is to be seen in all specimens at hand and in some is 

 much more strongly marked than in Fowler's figure ; it is shown also 

 in Chevey's plate of a specimen from Cambodia and in Sauvage's 

 figure of Rohita 'pectoralis^ also from Cambodia. Another feature on 

 which Fowler separates M. erythrostictus from M. chrysophekadion 

 is the size (and hence the number) of the scales in the predorsal area, 

 the former being credited with "small predorsal scales." These scales 

 in M. ei^throstictus are stated to number 19 to 22, whereas in M. chry- 

 sophekadion they are given as 20 to 23 by Bleeker and "about 25" by 

 Weber and de Beaufort — in other words, there is no essential differ- 

 ence in this respect. Another feature that is said to separate M. 

 erythrostictus from M. chrysophekadion is the "much smaller scales 

 crowded on the back along the dorsal fin base." The presence of these 

 scales is not mentioned by Bleeker or by Weber and de Beaufort, but is 

 obvious in all specimens of M. chrysophekadion from all parts of 

 Thailand and adjacent countries. 



Sauvage's Rohita pectoralis from Cambodia presents no valid dif- 

 ferential characters and is assignable to M. chrysophekadion. 

 Although the scales in the lateral line are said by Sauvage to number 

 46 to 48, his figure shows only 42 or 43, thus bringing his fish within 

 the scope of M. chrysophekadion., in which the lateral-line scales are 

 given by Bleeker and by Weber and de Beaufort as 41 to 43. Fowler, 

 in identifying as M. pectoralis specimens 9.4 to 15.5 cm. long collected 

 in Bangkok, notes that they have the free edge of the dorsal and anal 

 lins straight, whereas Weber and de Beaufort's figure of M. chryso- 

 phekadion shows these fins with a concave edge. Sauvage, however, 



