24 SECOND YARKAND MISSION. 



S. micropogon, Heck. ; S . planifrons, Heck. ; S. esocinus. Heck. ; Cirrhina goliama, 

 Ham. Buch. ; Barbus tor, Ham. Buch. ; Labeo varicorhinus, Heck. ; Nemacheilus 

 marmoratus, Heck. ; Callichrous pabda, Ham. Buch. 



These fishes demonstrate relationship with three districts : 



Schizothorax with Afghanistan and East and West Turkestan ; 



Oreinus with the slopes of the Himalayas in their whole extent ; 



Cirrhina, Barbus, and Callichrous with the neighbouring fauna of Hindustan. 



Having examined what are the ingredient parts of the fish fauna of Western Turkestan, 

 Afghanistan, Hindustan, Yarkand or Eastern Turkestan, Tihet, and Kashmir, it will he inter- 

 esting to endeavour to discover if these localities are possessed of any indigenous forms, and, if 

 so, how far they extend into contiguous countries. 



I do not propose inquiring into whether the great desert region of Central Asia can or 

 cannot he included in one Tartarian subregion ; hut, as the zoology of this portion of the 

 globe is at present rather obscure, I think it will be more useful to limit oneself strictly to 

 ascertained facts. 



Sir D. Forsyth's Mission has led naturalists into the fringe of an ichthyological region of 

 which Yarkand may be the centre ; certainly it is richer in forms of Schizothoracince than 

 Western Turkestan appears to be. 



In the cold and hilly districts of Tibet and Yarkand we observe an absence of spiny- 

 rayed and Siluroid fishes ; whilst amongst Carps we see the genera Schizothorax, Ptycho- 

 barbus, Schizopygopsis, and Diptychm fishes belonging to a peculiar division Schizothoracince, 

 (or Hill-Barbels of M'Clelland), which may be thus defined : 



Carps more or less covered with minute scales, or destitute of any. A membranous sac or 

 slit anterior to the anal Jin, which is laterally bounded by a row of vertically placed scales, like 

 eave-tiles, and which are continued along the base of the anal Jin. 



The fishes composing this are mostly of an elongated form, and are divisible into : 



a. Those with transverse mouths, as Oreinus, Ptychobarbus, Schizopygopsis, Diptychus. 



b. Those with compressed mouths, as Schizothorax. 



The genus Oreinus is spread from the Helmund River and Jellalabad in Afghanistan, 

 along the whole Himalayan and contiguous ranges of hills to at least the confines of China. 

 So far as I know, these fishes appear to be strictly residents of rivers in hilly regions, 

 neither descending far into those of the plains nor found on the level plateaus on the sum- 

 mits of the mountains. This accounts for their absence from the Yarkand collection ; and 

 from the foregoing extracts it appears probable that they are not found to the north of the 

 Oxus. This genus appears to be on the outskirts of the rest of its group ; and its mouth 

 armed with a sucker, to resist its being washed away, makes it well able to sustain a moun- 

 tain-torrent life. 



The other genera are more or less spread in the following districts. From the Helmund 

 River and the eastern portion of Afghanistan, the upper part of the Oxus, and the eastern 

 portion of Western Turkestan, the Tian Shan or Celestial Mountains, and also the Alatau 

 mountains more to the south, they extend along the Himalayan region, certainly as far as the 

 most easterly part of Assam. 



These fishes (SchizothoracintB) are confined to cold regions, as a rule, or at least to local- 

 ities possessing snow-fed rivers, many of which rivers end in lakes and do not go to the sea. 



