534 PHYSOSTOMI. 



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



caudal. 



Habitat. — Head waters of the Indus and Tibet. 



Genus, 8 — DiPTTCHUS, Steindachner. 



Abdomen rounded: snout obtuse: mouth inferior, transverse, curved: lower jaw sharp,- with an internal 

 horny covering : lips continuous and having an uninterrupted labial fold across the mandible. Two maxillary barbels. 

 Gill-opening narrow. Pharyngeal teeth compressed 4, 3/3, 4. Borsal fin without osseous ray, commencing anterior 

 to the ventrals : anal short : caudal forked. Scales small, not imbricate but scattered along the upper two-thirds of 

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

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



Geographical distribution. — Tibet, Nepaul, and Yarkand. 



SYNOPSIS OF INDIVIDUAL SPECIES. 

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

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



Stoind. Verb, zool.-bot. Ges. Wien, 1866, p. 788, t. 13, fig. 5; Giinther, Catal. vii, p. 171 ; Day, Proc. 



Zool. Soc. 1876, p. 792. 



fjDiptychus Seiverzowi, Kess. Pish. Turkestan, p. 17, t. w, f. 12. 



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



Leno-th of bead 5 to 6, of caudal 5 to 6, height of body 7i to 8 in the total lengtb. ^(/es— diameter 

 41 in the young to 6 in tlie adult in the length of the head, 1|- to 2 diameters from the end of the snout, and 

 li 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. J5(U?je/s— one on the maxilla hardly so long as the eye. Teeth— 

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

 tban'the base of the caudal fin, its last undivided ray articulated. Pectoral not quite so long as the bead and 

 reachino- 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 flat it reaches the caudal. 

 Seal es—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. Co?o!(rs— bluish, lightest interiorly, indistinctly blotched 

 and spotted in the npper half of the body : often a naiTOW dull band along the lateral-lme, and a second below 

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



Habitat.— Re&d waters of the Indus, Tibet, Nepaul, and aftluents of the Yarkand nver. 



Genus, 9 — Labeo, Cuvier. 

 Banqana, pt. Ham. Buch. : Rohita, pt. Cuv. and Val. : Tylognathus,* Heckel : Nandina, Gray : Hypselo- 

 barbus, Biplocheilus, Diplocheilichthjs, Lobocheilus, Bohitichthys, Mondius, SchismaCorhynchus, and Gohomchthys, 

 Bleeker : Gobiobarbus, Dybowski. 



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

 semi-oval. Lips thick, covering the jatvs, continuous at the angle of the month, and one or both having an mner 

 tran-n'erse fold. A soft and moveable horny covering with a sharp margin on the inner side of one or both lips. 

 Snout rounded, genercdly projecting beyond the mouth, mostly covered with tubercles, and sometimes 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 abse7it.-f Fharyngeal teeth hooked 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 commencement of the ventral. 

 Anal short. Scales of large, moderate, or small size. LateraUine running along the middle of the side of the tail. 

 Gill-rakers usually short. 



The horny layer, which is so common to the inside of the lips of the Schizothoracinm is still perceptible 

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

 a homy covering. The snout has sometimes a deep depression across it as observed m Discognathiis. 



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

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



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

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



* Dr Gunther (Catiil. vii. p. 62), admittinf: the division of Tylognathus from Labeo is artificial, still adopts it for the following 

 consistent reason, " by unitintj- these two Genera I should have been obliged to abandon the character of a long or short dorsal fin for the 

 definition of other very natural Genera of Cyprinoids.'' ... , ^ r » u 



+ As a rule the barbels in all specimens of a species are not subject to any variation in numbers, but L. angra appears to be an, 



exception. 



