22 
SECOND YARKAND MISSION. 
of the Himalayas, and sometimes even descending to the plains. Diptychus, Tibet, Yarkand 
and Western Turkestan. Schizopygopsis, Tibet and Yarkand. Etychobarbus, Tibet and 
Yarkand. The remainder are Loaches. 
Diptychus Dybowskii, Kess., would almost seem to be a Schizopygopsis with an articulat- 
ed dorsal ray and a pair of maxillary barbels. Perhaps several of these hill-genera will) at 
some future date, be properly amalgamated, as has been done with the low-country Barbels 
(Barbus). * 
An examination of the genera of spiny-rayed or Aeanthopterygian fishes clearly shows 
that as we proceed inland in India they diminish ; at the Himalayas they cease. Two Indian 
species 1 only have been observed to exist in Afghanistan ; and they are amongst the most 
widely distributed of their respective genera. Neither of these extends in the north-east, either 
to Western Turkestan or Yarkand. In Western Turkestan, it is true, three genera of this 
order are represented ; but they have evidently extended southwards. Yarkand and Tibet 
appear to be unsuited for this order of fishes : and thence none have been brought. 
The Physostomi include all the Yarkand and Tibet fishes. Among Siluroids the Indian 
genera CalUchrous and ? Amblyceps have been doubtfully recorded from Afghanistan ; but 
neither have spread to Western Turkestan, where, however, the Silurus glams is found, evi- 
dently a wanderer from its more northern home. 
It is clear that in India there is a gradual diminution of Siluroids as we proceed inland 
until we arrive at the Himalayas. On the slopes of these mountains we at first obtain a f eVl 
peculiar genera and species organized for a mountain-torrent life ; but as wc rise, eventually 
(as was the case in this Mission), an elevation is attained which, taken in connection with the 
latitude and paucity of food, seems to be beyond the limit of the Indian Siluroids. 
The Siluroids along the slopes of the Himalayas appear to be mostly confined to the 
following : — A few, as Macrones and CalUchrous , ascend a short distance, which may be con- 
sidered accidental. JPseudecheneis is a more distinct hill-form, possessing a sucker formed 0 
transverse folds between its pectorals on the chest, and by the aid of which it prevents it spl 
being carried away by the torrents. Glyptosternum has also an adhesive sucker, but of longitu- 
dinal folds, and likewise placed on the chest. These fishes, however, appear to be moi‘ ( 
intended for rapid rivers in the plains, but some ascend the slopes of the Himalayas. I 
taken large specimens from the rivers at the base of the bills in which the suckers w cr< 
scarcely visible : whether they had outgrown them, or, owing to the suckers not having be*- 11 
primarily well developed, they had been unable to maintain their footing in the hill-stream*’ 
of course, one cannot decide. Amblyceps is a Loach-like form found in the waters of 1 14 
plains and also of the hills ; it is abundant near Kangra, Exostoma, an example of wmj^ 
exists in the Yarkand-Mission collection, is also a remarkable form. It has a broad a* 1 
depressed head and chest, the latter forming a species of sucker to enable it to sustain 
mountain-torrent life. 
This fish ( Exostoma stolicskcc) belongs to a genus which has only been recorded r ° , 
hilly regions, neither extending to the waters of the comparatively level plateaus of the u^ 
lands, nor descending any distance towards the plains. -The following six species arc know n • ^ 
(1) E. stolicskcc , from the head- waters of the Indus; (2) E. blythii, from near Darjee n-,) 
where the waters descend to the Ganges; (3) E. labiatmn, from the Mishmi Mountains 
Eastern Assam ; (4) E. andersonii, from near Bhamo on the confines of China; (5) ^ aCl 
1 Ophiocephalus gachua and Mastacemhelus armatus. 
