LEUCJSCUS TENELLUS. 



171 



Leuciscus tenellus (HECKEL). 



D. 1011, A. 11. Scales : lat. line 7880, transverse 18/8. 



This species (Fig. 94) has been recorded only from the neighbourhood of 

 Livno, in Bosnia, where it reaches a length of six inches. It has a broad 

 head, which is long and blunt. The lower jaw rises abruptly, the mouth 

 is large, and the scales are smaller than in any of the species hitherto de- 

 scribed. The fish is about four and a half times as long as the head, and 

 the greatest height of the body is two-thirds of the length of the head. The 

 diameter of the eye is between one-fifth and one-sixth of the length of the 



Fig. 94. LEVCISCfS TENELLUS (HECKEL). 



head, and the frontal interspace between the eyes is one and a half times the 

 orbital diameter. The jaws are of equal length ; the angle of the mouth 

 reaches back to below the anterior margin of the orbit. The dorsal fin is 

 behind the middle of the fish, and its longest rays are exceeded only by those 

 of the caudal, which are two-thirds of the length of the head. The pectoral 

 fin is as long as the dorsal, and the ventral as long as the anal. 



The largest scales, which are on the lateral line, are scarcely one-quarter of 

 the diameter of the eye. They are delicate, have a remarkable concentric 

 striping, and each shows on the free edge a fan of six to eight diverging rays. 



The lateral line descends somewhat rapidly, and runs in the lower third of 

 the height. 



The colour of the back and sides shades from iron-grey into steel-blue. 

 The belly is silver- white. All the fins are yellow except the dorsal, which 

 is orev. 



