), FRESH- WATER FISHES OF SIAM, OR THAILAND 239 



LOBOCHEILUS BO (Popta) 



Tylognathus io Popta, 1904, p. 199 (Borneo). — Koumans, 1937a, p. 03 (inner lake 

 of Tale Sap). 



This species Avas described in 1904 from specimens, 11.1 to 29.4 cm. 

 long, from the Bo River in Central Borneo, and until recently has 

 been known from no other locality. The fish is admitted to the pres- 

 ent catalog because of its discovery in widely separated parts of 

 Thailand. 



One specimen 16.7 cm. long was taken by the writer in the Mekok, 

 a tributary of the Mekong, in Northern Thailand, March 2, 1924. This 

 specimen agrees very closely with the descriptions and figure given by 

 Dr. Popta (1904, 1906, fig. 26). The differences, which are of a minor 

 character and may easily fall within the limits of individual variation, 

 include slightly shorter barbels (0.5 eye in Thailand example as 

 against 0.8 eye in Bornean specimens) ; and there are several obscure 

 dark longitudinal lines following the rows of scales in the posterior 

 part of the body, such lines not being referred to in the descriptions but 

 suggested in Popta's figure reproduced from a photograph. 



A second specimen, 15 cm. long, collected by the writer in the Nakon 

 Nayok River, Central Thailand, July 10, 1930, likewise agrees with 

 Bornean specimens: Scales in lateral line 33, in transverse line to 

 base of ventral fin 5.5-1-3.5, in predorsal region 11, and around nar- 

 rowest part of caudal peduncle 16 ; depth 4 in standard length ; head 

 4.5 in length ; maxillary barbels 0.8 eye; dorsal fin arising over eleventh 

 scale of lateral line, its longest ray longer than head ; caudal fin deeply 

 forked, longer than head ; anal and ventral fins subequal and shorter 

 than pectorals which are 0.9 head. The fish is a female, with well- 

 developed eggs, and has 3 rows of large pores on the snout. On the 

 median line of the side posterioi' to the dorsal fin there is a large dark 

 diffuse spot through which several dark lines extend to the base of the 

 caudal fin. 



A third specimen has been reported from the inner lake of the Tale 

 Sap in Peninsular Siam by Dr. Koumans, who compared his speci- 

 men, measuring 18 cm., with the type, 29.4 cm. long, in the Leiden 

 Museum. 



At Chiengrai this fish is known as pla Mom pah wong (literally,, 

 circular-mouth fish). 



LOBOCHEILUS MELANOTAENIA (Fowler) 



Tylognathus inelanotaenia Fowlek, 1935a, p. 122, figs. 65, 66 (ELhao Nam Poo) ; 

 1937, p. 210 (Kemarat). 



Originally described from a single specimen, 15.8 cm. long, from 

 Khao Nam Poo in Central Thailand, this species was subsequently 

 reported from the Mekong at Kemarat in Eastern Thailand, where 



