22 
SECOND YAEKAND MISSION. 
of the Himalayas, and sometimes even descending to the plains. Diptycms, Tibet, Yarkand 
and Western Turkestan. Schizopygopsis , Tibet and Yarkand. Btychobarbus, Tibet and 
Yarkand. The remainder are Loaches. 
Diptychus Bybowskii, Kess., would almost seem to be a S chizopygopsis with an articulat¬ 
ed dorsal ray and a pair of maxillary barbels. Perhaps several of these hill-genera will, at 
some future date, he properly amalgamated, as has been done with the low-country Barbels 
{Barbus). 
An examination of the genera of spiny-rayed or Acanthopterygian 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 he 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 Callichrous and ? Amblyceps have been doubtfully recorded from Afghanistan; hut 
neither have spread to Western Turkestan, where, however, the Silurus glanis 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 few 
peculiar genera and species organized for a mountain-torrent life; hut as we 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 he 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 Callichrous , ascend a short distance, which may be con¬ 
sidered accidental. Bseudecheneis is a more distinct hill-form, possessing a sucker formed of 
transverse folds between its pectorals on the chest, and by the aid of which it prevents itself 
being carried away by the torrents. Clyptosternum has also an adhesive sucker, but of longitu¬ 
dinal folds, and likewise placed on the chest. These fishes, however, appear to be more 
intended for rapid rivers in the plains, but some ascend the slopes of the Himalayas. I have 
taken large specimens from the rivers at the base 'of the hills in which the suckers were 
scarcely visible: whether they had outgrown them, or, owing to the suckers not having been 
primarily well developed, they had been unable to maintain their footing in the hill-streams, 
of course, one cannot decide. Amblyceps is a Loach-like form found in the waters of the 
plains and also of the hills; it is abundant near Kangra. Exostoma, an example of which 
exists in the Yarkand-Mission collection, is also a remarkable form. It has a broad and 
depressed head and chest, the latter forming a species of sucker to enable it to sustain a 
mountain-torrent life. 
This fish {Exostoma stoliczkce) belongs to a genus which has only been recorded from 
hilly regions, neither extending to the waters of the comparatively level plateaus of the high 
lands, nor descending any distance towards the plains. The following six species are known:— 
(1) E. stoliczkce, from the head-waters of the Indus; (2) E. blytliii, from near Darjeeling, 
where the waters descend to the Ganges; (3) E. labiatum , from the Mishmi Mountains and 
Eastern Assam; (4) E. anclersonii, from near Bhamo on the confines of China; (5) E. dcividi, 
1 Opliiocegthalus gacJma and Mastacembelus armatus , 
