FRESH- WATER FISHES OF SlAM, OR THAILAND 121 



29a. Suborbital bones enlarged, covering most of cheek; a small post- 

 symphyseal tubercle on lower jaw, mouth wide, with longitudinal 

 folds on palate; lower lip laterally papillate; branched dorsal 



rays S Barbichthys 



29 &. Suborbital bones not enlarged ; no postsymphyseal tubercle on lower 



jaw. 



30o. Lower lip consisting of a deep part continuous with upper lip and 



a superficial part continuous with skin of isthmus; branched 



dorsal rays 8 or 9. 



31a. Superficial part of lower lip thin and covering deep part medianly. 



32a. Lateral line present; upper lip entire, barbels rostral and 



maxillary or only maxillary in Siamese species (absent in 



one local species) Tylognathus 



326. Lateral line absent ; upper lip plicate ; barbels rostral. 



Holotylognathus 



316. Superficial part of lower lip consisting of a thick fleshy pad which 



completely covers the deeper part both medianly and laterally ; 



barbels rostral and maxillary, only maxillary in some Siamese 



species Lobocheilus 



306. Lower lip entirely separated from isthmus by a deep groove ; snout 

 with a lateral lobe ; lips fringed ; barbels rostral and maxillary ; 



branched dorsal rays 15 to 18 Morulius 



30c. Lower lip joined to isthmus by a bridge ; snout with or without a 



lateral lobe; lips fringed, lobate, or entire; barbels rostral or 



maxillary or both. 



33a. Rostral fold not crenulated and not medianly incised ; one or both 



lips with a transverse inner fold ; branched dorsal rays 10 to 15. 



Labeo 



336. Rostral fold crenulated and medianly incised ; no transverse inner 



labial fold ; branched dorsal rays 8 Henicorhynchus 



Genus LEPTOBARBUS Bleeker 



Leptoiarhus Bleekee (261), Nat. Tijdschr. Nederl.-Indie, vol. 20, p. 435, 1859-60. 

 (Type, Barbus hoevenii Bleeker.) 



Fishes of this genus, inhabiting fresh waters of Borneo, Sumatra, 

 and Thailand, may be recognized by their broad head, four well- 

 developed barbels (rostral and maxillary), moderate-sized mouth with 

 maxillary reaching vertical from front of eye, spoon-shaped pharyn- 

 geal teeth in three rows (5, 3, 2), medium-sized scales, continuous 

 lateral line running in lower part of caudal peduncle, and short dorsal 

 and anal fins with seven and five branched rays respectively. Of the 

 two species ascribed to Thailand (keyed below), one is common and 

 the other is of somewhat doubtful status. 



la. Scales in transverse series from midline of back to midline of abdomen 

 4.5-1-3.5; a black longitudinal band on body in young, disappearing in 

 adult hoevenii 



16. Scales in transverse series from midline of back to midline of abdomen 

 5.5-l-i.5 ; a black longitudinal band on body at all ages melanotaenia 



