534 PHTSOSTOMI. 



head spotted with black. Some dafk spots on the dorsal fin, and sometimes a few light ones on the 

 caudal. 



Habitat. — Head waters of the Indus and Tibet. 



Genus, 8 — DiPTTOHUS, StemdacJmer. 



Abdomen rovrnded: snout obtuse: mouth mferior, transverse, cwrved : lower jcm sharp, with an mtemal 

 homy covering : lips continuous and having an mdnterrvpted labial fold across the mandible. Two maxillary ba/rbels. 

 Gill-opening na/rrow. Pharyngeal teeth compressed 4, 3/3, 4. Dorsal fin without osseous ray, commencing anterior 

 to the vemtrals : anal short : ca/udal forhed. Scales small, not imbricate but scattered along the upper tioo-thvrds of 

 the lody, the thoracic region, the sides and the tail, also a scaly sheath to the vent and base of the anal fm. 

 Lateral-line continued to the centre of the base of the caudal. 



Geographical distribution. — Tibet, Nepaul, and Tarkand. 



SYNOPSIS OF INDIVIDUAL SPECIES. 



1. Diptychus maculatus. D. 10-11, L. 1. 80-90. Tibet, Nepaul, Tarkand. 



1. Diptychus maculatus, Plate CXXIV, fig. 3. 



Steind. Yerh. zool.-bot. Ges. Wien, 1866, p. 788, t. 13, fig. 6 ; Giinther, Catal. vii, p. 171 ; Day, Proo. 

 Zool. Soc. 1876, p. 792. _ ' 



? Diptychus Sewerzowi, Kess. Fish. Turkestan, p. 17, t. iv, f. 12. 



B. iii, D. 10-11 (lis), P. 19, V. 9, A. 7 (|), C. 19, L. 1. 80-90. 



Length of head 5 to 6, of caudal 5 to 6, height of body- 7-5- to 8 in the total length. Hyes — diameter 

 4i in the young to 6 in the adult in the length of the head, I5 to 2 diameters from the end of the snout, and 

 1-^ apart. The greatest width of the head equals its height or its length behind the front edge or middle of 

 the eyes. Mouth inferior, transverse, having an anterior sharp horny covering to the lower jaw. Lower 

 labial fold interrupted in the middle. Ba/rbels — one on the maxilla hardly so long as the eye. Teeth — 

 pharyngeal 4, 3/3, 4, crooked and pointed. Fins — dorsal as high as the body, it arises rather nearer the snout 

 than the base of the caudal fin, its last undivided ray articulated. Pectoral not quite so long as the head and 

 reaching rather above half way to the ventral, which latter commencing below the last dorsal ray extends half 

 way to the anal. Height of anal nearly three times the length of its base, laid fiat it reaches the caudal. 

 Scales — scattered over the upper two-thirds of the body and pectoral region. Tiled row well- developed. Free 

 portion of tail one half longer than high at its base. Colours — ^bluish, lightest interiorly, indistinctly blotched 

 and spotted in the upper half of the body : often a narrow dull band along the lateral-line, and a second below 

 it. In some specimens the dorsal and caudal fins are much spotted. 



Habitat. — Head waters of the Indus, Tibet, Nepaul, and affluents of the Tarkand river. 



Genus, 9 — Labeo, Ouvier. 



Bangana, pt. Ham. Buch. : Bohita, pt. Guv. and Val. : Tylognathus,* Heckel : Nandina, Gray : Hypselo-. 

 barbus, Diplocheilus, Diplocheilichthys, Lobocheilus, Bohitichthys, Morulius, Schismatorhynchus, and Gobionichthys, 

 Bleeker : Gobiobarbus, Dybowski. 



Body moderately elongated, abdomen rounded, mouth sometimes anterior but msstly inferior, transverse, and 

 semi-oval. Lips thick, covering the jaws, continuous at the angle of the mouth, and one or both having am, i/rmer 

 transverse fold. A soft and moveable horny covering with a sharp margin on the inner side of one or both lips. 

 Snout rounded, generally projecting beyond the mouth, mostly covered vnth tubercles, and sometifnes having a lateral 

 lobe or projection. Barbels when present, four or two : if only one pair they are on the maxilla, the second 

 being on the snout, or they may be absent.-^ Pharyngeal teeth hoohed and in three rows, 5, 4, 2/2, 4, 5. Dorsal fin 

 of moderate length or elongated, destitute of any osseous ray, and arising anterior to the commenceviefLt of the ventral. 

 Anal short. Scales of la/rge, moderate, or small size. Lateral-line running along the middle of the side of the tail. 

 Gill-rakers usually short. 



The homy layer, which is so common to the inside of the lips of the Schizothoracitice is still perceptible 

 in the fish of this Genus, in many of those of the plains taking on the character more of thin cartilaginous than 

 a homy covering. The snout has sometimes a deep depression across it as observed in Discognathus. 



The fins frequently increase in height and length more rapidly than do the proportions of the body ; 

 thus in adults we often perceive the upper edge of the dorsal fin more concave than in the young. 



In some species having the least number of dorsal rays, the hps are much thinner than in the typical 

 Labeos : should such have only two barbels they are maxillary, whereas in Ovrrhinas they would be rostral. 



* Dr. Giinther (Catal. vii. p. 62), admitting the division of Tylognathus from Labeo is artipcial, still adopts it for the foUqwing 

 consistent reason, " by uniting these two General should have been obliged to abandon the character of along or short dorsal fin for the 

 definition of other very natural Genera of Cyprinoida." 



t As a rule the barbels in all specimens of a species are not subject to any vw^ifition in nnmhers, but L. cmgra appears to be an 

 exception. ' 



