2 SECOND YARKAND MISSION. 



nostril. Head depressed, as broad as long, and obtusely rounded. Mouth inferior ; lips 

 thick, and studded with small tubercular elevations ; the upper and lower lips continuous at 

 the angle of the mouth ; but the transverse fold across the lower jaw is interrupted in the 

 middle. Nostrils close together, the anterior round and patent, the posterior tubular : a 

 barbel divides the two nostrils ; it is situated on a bridge of skin, below which the two 

 nostrils are continuous. Barbels : the nasal ones reach the hind edge of the eye ; the maxil- 

 lary ones have a broad basal attachment, and reach the root of the pectoral. Of the mandi- 

 bular barbels the anterior are situated just behind the inner end of the lower labial fold : 

 they are shorter than the outer pair, which latter extend to the gill-opening. Gill-opening 

 situated on the side of the head in front and above the base of the pectoral fin. Teeth : 

 several rows of pointed ones in each jaw, of which the outer is slightly the larger, rather 

 wide apart, and with rather obtuse summits. Fins : the dorsal arises midway between the 

 snout and the commencement of the adipose fin ; its greatest height is one-third more than 

 the length of its base ; its spine is rudimentary and enveloped in skin. Adipose dorsal very 

 long and low. Pectoral nearly as long as the head, having its outer half horizontal and its 

 inner vertical ; its spine is rudimentary, with a broad, striated, cutaneous covering. Ventral 

 of a similar form to the pectoral : its first and a portion of its second ray also with a striated 

 cutaneous covering ; the fin commences on a vertical line falling just behind the base of the 

 dorsal fin ; it is rather nearer the snout than the posterior end of the adipose dorsal, and 

 commences midway between the bases of the ventral and caudal fins ; it is half higher than 

 long. Caudal cut almost square. Free portion of the tail half higher than long. Skin 

 tuberculated from the head, along the lower surface of the body, to nearly as far as the base 

 of the ventrals. Colours : of a dull yellowish green, becoming lightest along the abdomen. 

 Fins yellowish, with dark edges or bands. 



Jfab. Basgo, Snima, and Leh on the Upper Indus. The longest specimen 7 inches in 

 length. 



I propose here to shortly remark upon the distinction between the six species of 

 Exostoma at present known 



A. Teeth in jaws pointed, 



1. Exostoma labiatum, Lower labial fold uninterrupted. The interspace between the 

 first and adipose dorsal fins equals two-thirds the length of the latter. Anal commences much 

 nearer the base of the caudal than the base of the ventral. Mishmi Mountains, East Assam- 



2. E. blythii. Lower labial fold interrupted. Interspace between dorsal fins very 

 slight. Anal commences in last third of distance between ventral and base of caudal. 

 Head- waters or affluents of Ganges. 



3. E, berdmorei. Snout more pointed, Caudal forked. Tenasserim. 



4. E. davidi 1 . The interspace between the first and adipose dorsal fins equals the 

 length of the latter. Pectoral reaches the ventral, Eastern Tibet. 



5. E. stolicskce. Lower labial fold interrupted. Anal commences nearer the base of 

 the ventral than that of the caudal. Pectoral does not extend to the ventral. Upper waters 

 of Indus. 



B. Outer row of teeth flattened. 



6. E, andersonii, Lower labial fold interrupted. Bhamo, Burmah. 



1 ChimarrichtJiys davidi, Sauvage. 



