150 THE FRESH-WATER FISHES OF EUROPE. 



breadth of the frontal region between the eyes is nearly half the length 

 of the head. The eye is between one-fifth and one-sixth of the length of 

 the head ; its hinder border is in front of the middle of the head. The 

 upper jaw is scarcely longer than the lower, which is thickened at the 

 symphysis in a fold. The nares are rather large, nearer to the snout than the 

 eye, and less widely separated than the orbits. The dorsal profile is similar 

 to the ventral profile, as far as the dorsal and ventral fins. 



The dorsal fin, which begins nearly in the middle of the body, is much 

 higher than long ; its base measures less than half the length of the head. 

 It is somewhat truncate behind, but the last ray is more than half the length 

 of the longest ray. The anal fin is well behind the dorsal ; its base is as long 

 as the base of that fin, but it is not so high, and its margin is slightly convex. 

 The ventral fins are in front of the dorsal, and do not reach back to the vent. 

 The caudal fin is broad and strong, not deeply forked, with the lower lobe 

 slightly the longer, and its longest ray is nearly as long as the head. The 

 jointed rays of the dorsal, anal, and caudal fins sub-divide three or four times. 



The scales are large and strong ; the largest, which are over the lateral 

 line, measure one and a half times the diameter of the eye. On the back, tail, 

 and abdomen, the scales are smaller ; the smallest, which are on the throat, 

 are one-quarter of the size of the largest. The scales are finely marked 

 with concentric lines, and have a fan of eight or ten rays, which scarcely 

 indent the free margins. The lateral line is sub-parallel to the ventral 

 margin, and its mucus-canal opens by short, simple pores. A branch of 

 the cephalic mucus-canal is indicated on the pre-operculum by large pores, 

 and another branch extends over the eye to the nares. 



The number of vertebra) in the skeleton varies ; according to Dr. 

 Giinther, there may be twenty-five or twenty-six thoracic, and eighteen or 

 nineteen caudal vertebrae, so that some varieties have two more than others. 

 The facial bones of the skull are weak, in comparison with its other parts. 

 The ethmoid bone is as broad again as long. The supra-orbital and hind- 

 ermost sub-orbital bones, which in other species of the genus are small, 

 are well developed in this species. The third sub-orbital bone is small. 

 The bones associated with the gill apparatus are strong. The pharyngeal 

 bones are small, elongated, and in the form of a pot-hook. The pharyngeal 

 teeth (Fig. 81) are long, compressed, and hooked, with the formula 5'2 2'5. 



The colour of the back is blackish-green, changing on the sides to yellow 

 or shining-silver ; on the throat it becomes reddish- white. The cheeks and 

 operculum have a brilliant rose- red and golden glimmer, the lips are red ; 

 the iris is golden yellow, with dark green spots. The dorsal fin is blackish, 

 and, like the caudal, red at the base, though the latter is sometimes olive, 



