FRESH-WATER FISHES OF SIAM, OR THAILAND 247 



tion, has less elongate body, very different physiognomy, and no 

 sharply defined black lateral band. Z. melanotaenia is a deeper fish, 

 with arched back, differently shaped snout and mouth, much shorter 

 barbels, and entirely different coloration, the black lateral band being 

 much narrower and each of the scales of back and sides having a dark 

 basal crescent. 



At the place of capture, at Ban Muang Sum, the Menam Mao was a 

 clear mountain torrent. The dorsal fin exhibits a marked develop- 

 ment of dermal flanges on the rays, characteristic of many mountain- 

 stream cyprinoids in Thailand. 



The species is named in honor of Dr. Pierre Chevey, of the Institut 

 Oceanographique de I'Indochine, in recognition of his valuable re- 

 searches on the fish fauna of French Indo-China. 



LOBOCHEILUS GRACILIS (Fowler) 



TylognatJius gracilis Fowlee, 1937, p. 209, figs. 183, 184 (Mepoon, Kemarat). 



Known from both the Menam Chao Phya and the Mekong, this 

 species is characterized by its slender form (depth 4.5 to 4.75 in stand- 

 ard length) ; three scales between the lateral line and the ventral fin; 

 falcate dorsal, anal, ventral, and pectoral fins ; caudal fin deeply forked 

 and 1.5 times length of head ; very slender caudal peduncle, its length 

 more than twice its least depth; and three narrow, sharply defined 

 blackish longitudinal stripes on posterior half of body. 



The numerous specimens examined were 15.3 to 23.3 cm. long. A 

 specimen 15.5 cm. in length was taken by the writer in the Mekok at 

 Chiengrai, Northern Thailand, March 2, 1924. 



LOBOCHEILUS THAVILI, new species 



Description. — Elongate, moderately compressed, depth 5 in stand- 

 ard length, 6.5 in length with caudal fin; least depth of caudal 

 peduncle about 2.5 in its length and 2 in head ; head small, over 5 in 

 standard length, its width equal to its depth at posterior margin of 

 eyes and equal to length of snout and eye; snout broad, obtusely 

 rounded, thickly beset with large pores, which extend as far back as 

 nostrils; eye small, 5.5 in head, 2.5 in snout, 3 in strongly convex 

 interorbital space, its center in midlength of head; maxillary barbel 

 shorter than eye; no rostral barbels; thick, rounded pad on lower jaw 

 as wide as postorbital part of head. 



Squamation : Scales in lateral line 33, in transverse line 5.5-1-3.5 to 

 base of ventral, in predorsal region 10, around narrowest part of the 

 caudal peduncle 14. 



Fins: Origin of dorsal fin well in advance of ventral, over ninth 

 scale of lateral line, midway between tip of snout and posterior end 

 of anal base; dorsal rays iii, 8, first bi'anched ray as long as head; 



