18/6. J 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 tbat which causes its 

 necessity. 



It is certainly remarkable that Siluroid forms do not appear to 

 thrive in cold climates ; whereas the CyprinincB 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 them- 

 selves with great rapidity on the approach of danger. 



15. NEMACHEILUS STOLICZK^E. 



Colitis stoliczkce, Steindachner, Verh. z.-b. Ges. Wien, 1866, 

 p. 793, t. xiv. f. 2. 



Cobitis tenuicauda, Steind. I.e. p. 792, t. xvii. f. 3. 

 Nemacheilus stoliczkce, Giinther, Cat. vii. p. 360. 

 Nemacheilus tenuicauda, Giinther, I. c. p. 357. 



B.iv., D.f, 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. 



