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Show 804 MR. F. DAY ON THE FISHES OF YARKAND. [Dec. 5, Among Siluroids the Indian genera Callichrous and ''.Amblyceps have been doubtfully recorded from Afghanistan ; but neither have spread to Turkestan, where, however, the Silurus glanis is found, evidently 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 aud species organized for a mountain-torrent life ; but as we rise, eventually (as was the case in this Mission) an elevation i3 attained which, taken in connexion 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 Callichrous, ascend a short distance ; but this may be considered accidental. Pseudecheneis 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. Glyptosternum has also an adhesive sucker, but of longitudinal 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 stoliczka) belongs to a genus which has only been recorded from hilly regions, neither extending to the waters of the comparatively levels of the high lands, nor descending any distance towards the plains. The following six species are known : - 1. E. stoliczka, from the head-waters of the Indus; 2. E. blythii, from near Darjeeling, where the waters descend to the Ganges ; 3. E. labiatum, from the Mishmi Mountains and Eastern Assam. 4. E. andersonii, from near Bhamo on the confines of China ; 5. E. davidi, from the must easterly portion of Tibet near the head-waters of the Yang-se-kiang ; 6. E. berdmorei, from Tenas-strim. The distribution of the foregoing six species of this genus is interesting, because it is suggestive of whether at some remote period the Himalayan range, the mountains between Tibet and China, and the spur or continuation southwards through Burma and Siam, may not have been connected one with another. Whilst adverting to this point, I would mention another circumstance : the only Siluroid stated to be found in Turkestan is the Silurus glanis, Linn. Three other species of the same genus have |
