154- 



THE FRESH-WATER FISHES OF EUROPE. 



height of the body at the beginning of the dorsal fin is equal to the length of 

 the head, and is one-sixth of the entire length of the fish. 



The head has a bluntly-conical form, but is not quite so broad at the oper- 

 culum as high. The eye is rather small (one-sixth of the length of the head), 

 twice its diameter from the snout, and half the length of the head from the 

 other eye, so that the frontal region, which is convex, is remarkably broad. 



The dorsal contour is arched as far as the dorsal fin, but the ventral 

 contour is nearly straight from the pectoral to the anal fin. 



The dorsal fin commences well in advance of the middle of the body ; it is 

 higher than long, the base being two-thirds of the length of the longest 

 ray ; it is truncate behind, the terminal rays being reduced to about one- 



Fig. 79. LEUCISCUS FRIESII (NORDMAXX). 



third of the height in front. The anal fin is far behind the termination 

 of the dorsal ; it is as high as long, and its base is as long as the base of 

 the dorsal. The ventral fin is broad, of moderate length, a little shorter than 

 the pointed pectoral, and opposite the commencement of the dorsal. The 

 caudal fin is well developed, evenly lobed, and deeply 

 forked. 



The scales are nearly circular, but longer than 

 broad, and marked with many radiating rays. They 

 form a fan of fifteen to twenty lines on the free 

 edge of the scale. The largest scales are smaller than 

 the diameter of the eye. 



The lateral line descends a little below the middle 

 of the fish in a concave curve. Its mucus-canal opens by simple pores. 



During life the colour of the upper part of the head and back is blackish- 

 green, the sides are blue-grey, and the throat and abdomen milk-white. Every 

 scale of the abdomen shows behind the margin where it is over-lapped, a 

 black spot of half-moon shape. The dorsal, pectoral, and caudal fins are 

 blackish, though the two latter become grey towards their extremities. The 



Fig. 80. HEAD OF LEUCIS- 

 CUS FKIESII, SEEN FROM 

 ABOVE. 



