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Show 1876.] MR. F. DAY ON THE FISHES OF YARKAND. 795 As we find genera with the air-vessel enclosed in bone decrease in number the further we are from Hindustan proper, it is but natural to conclude that the necessity for this bony capsule is greater in India than in other tropical countries, and also that it is only useful for freshwater forms. When we see that all fishes (except the Nemacheili) from Yarkand have the air-vessel free in the abdominal cavity, it stands to reason that heat or cold can scarcely be that which causes its necessity. It is certainly remarkable that Siluroid forms do not appear to thrive in cold climates ; whereas the Cyprinina of this collection have all small scales, or are more or less destitute of any ; whilst the Loaches of Yarkand and Tibet have none at all, neither have those recorded from the Oxus or the Jaxartes. There is one characteristic of the hill-Loaches which seems almost invariable: the pectoral fins are stiff at their bases, as if employed for adhesive purposes. I have observed the outer ray in some of the Loaches of the plains forming a distinct bony ray with an enlarged and flattened outer extremity; but this is used for the purpose of assisting them to dig into the sand, in which they will bury themselves with great rapidity on the approach of danger. 15. NEMACHEILUS STOLICZKA. Cobitis stoliczka, Steindachner, Verh. z.-b. Ges. Wien, 1866, p. 793, t. xiv. f. 2. Cobitis tenuicauda, Steind. I. c. p. 792, t. xvii. f. 3. Nemacheilus stoliczka, Gunther, Cat. vii. p. 360. Nemacheilus tenuicauda, Gunther, I. c. p. 357. B.iv., D.J, P. 13, V. 8, A. | C. 15. Length of head 6, of caudal 6, height of body 8 in the total length. Eyes: diameter 8 in the length of head, 3 diameters from the end of snout, and 2 apart. Snout rounded, slightly projecting over the mouth. Lips rugose; and in some specimens from Yarkand the edges are fimbriated: lower lip with a lobe on either side, but the lower labial fold interrupted in the middle. The greatest width of the head equals its height, or its length excluding the snout. In some specimens the preorbital has a free lower edge. Barbels six ; the maxillary ones reach beyond the hind edge of the eye ; the rostral ones are shorter. Fins: the dorsal commences midway between the eye and the base of the caudal, it is one third higher than its base is long, and equals the greatest depth of the body; its last ray is divided to its base ; its upper edge is oblique, with a rounded anterior angle. Pectoral nearly as long as the head, and reaching rather above halfway to the ventral; the latter fin arises on a vertical line below the anterior dorsal rays, is almost as long as the pectoral, and reaches above halfway to the anal. Anal with a very narrow base. Caudal slightly emarginate. Free portion of the tail from twice to two and a half times as long as high at its base. Scales absent. Air-vessel in two portions, enclosed in bone. |