(;'230 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



A length of 40 cm. is readied in Thai waters, but examples over 30 

 cm. long are not common. 



The fish is well known to most fisherman in Central Thialand and 

 usually bears a distinctive popular name but sometimes it is not dis- 

 tinguished by name from CyclocheiUchthys. Throughout the basin of 

 the Menam Chao Phya, the common vernacular name is plu ta hierk^ 

 with pla ta min heard in ^me places. In the Pasak Eiver the fish is 

 usually called pla taJcok^ while in the Tapi River a name not heard else- 

 where and not given to any other species is pla ta lun or pla ta Ion. 



Genus XENOCHEILICHTHYS H. M. Smith 



XenoGh.eilichth.ys H. M. Smith, Journ. Siam. Soc, Nat. Hist. SuppL, vol. 9, p. 

 304, 1934. (Type, Xenocheilichthys gudgeri H. M. Smith.) 



XENOCHEILICHTHYS GUDGERI H. M. Smith 



Xenocheilichthys gudgeri Smith, 1934b, p. 305, fig. (Nan River). — Fowler, 1937, 

 p. 174, figs. 110, 111 (Kemarat). 



A rare species, known from three specimens (U.S.N.M. Nos. 103367 

 and 103368, type and paratypes, respectively) from the upper Nan 

 J' River near the town of Nan, Northern Thailand, and from one speci- 

 ' men from the Mekong at Kemarat, Eastern Thailand. 



These specimens measured 13,5, 14, and 14.5 cm. in length. 



The fish bears some resemblance to AmhlyrhyncMchthys truncafios 

 (Bleeker) in such features as an annular eyelid, a postsymphyseal 

 tubercle on the lower jaw, no barbels, peculiar shape of the mouth and 

 lips, and a short dorsal fin with strongly ossified and serrated spine, 

 but it is distinguishable from that species by several characters, in- 

 cluding its rounded, not obliquely truncate snout, by the position of 

 the mouth, which may not reach the perpendicular from the anterior 

 edge of the eye, by the very thick, broad, and soft upper lip. 



In the Nan River this fish is called pla nam fai, apparently mean- 

 ing back-water or damned-water fish. 



PAPILLOCHEILUS, new genus 



Moderately elongate, body rather strongly compressed; snout 

 bluntly rounded, entire, and covering base of upper lip; no rostral 

 pores or tubercles; mouth inferior, strongly arched; lips continuous, 

 thick, papillose throughout; upper lip with a deep posterior groove, 

 lower lip closely adnate to lower jaw and with a posterior groove 

 laterally, the median part continuous with skin of isthmus; rostral 

 and maxillary barbels present; a narrow annular eyelid; gill open- 

 ings extending well forward, gill membranes joined to isthmus; 

 gill rakers few ; pharyngeal teeth triserial ; scales in moderate num- 

 ber, lateral line complete and running to midbase of caudal fin; 



