4-1 2 THE FRESH-WATER FISHES OF EUROPE. 



separated by a median depression. There are the usual four barbels, placed 

 in a transverse row in advance of the middle of the space between the mouth and 

 extremity of the snout. They are rather short. They are divided by a median 

 ridge, which does not extend far behind them, but widens in front, where it is 

 covered by rough shields. When the snout becomes broad and thick, the 

 barbels are midway between the eye and the snout. 



The bony armour on the body is well developed. The number of 

 dorsal shields in the median line of the back is usually eleven, but may be 

 thirteen. Each dorsal shield has a more or less distinct keel, which is more 

 developed in the hinder part of the body than in front, but the form and 

 size of the shields varies with age, though all have their upper surfaces roughly 

 granular and radiate, and ornament is seen only at the margin. The lateral 

 shields have the vertically elongated lozenge-shaped form, and usually number 

 from twenty-nine to thirty- one, though Dr. Giinther finds in some young 

 specimens twenty-six or twenty-seven, and mentions an example from the 

 Black Sea with thirty-four shields. The anterior part of each scale has a 

 process which is embedded in the skin, and is overlapped by the suale in front 

 of it. The keels on the scutes become sharper and higher towards the tail. 

 The ventral shields are nine to ten in number, and similar in shape to the 

 dorsal shields, the first two are smaller than the others. There are three 

 shields behind the ventral fin, the two smaller ones form a pair in front of the 

 single large shield. There are three or four longer shields behind the anal fin. 

 There are three to five pairs of shields behind the dorsal fin, followed by a 

 single larger one, which extends on to the upper lobe of the caudal fin. 



The skin is covered with small bony scales which have almost the character 

 of shagreen. They become larger towards the head, and are sometimes 

 arranged in oblique rows (Figs. 199, 201). 



The pectoral fin is inserted low down at the back of the head. The strong 

 bony ray is only three-quarters of the length of the succeeding jointed rays. 

 The dorsal fin, rather in front of the anal fin, is angularly notched, so as to be 

 nearly divided into a large anterior part and a small posterior lobe. The 

 upper lobe of the caudal fin does not exceed the length of the head ; the lower 

 lobe is moderately developed. 



The colour of the back is usually a dull reddish-brown, but varies to a blue 

 or yellowish-grey ; the belly is white, inclining to silvery ; the shields are grey. 

 The iris is yellow. 



The usual size of the fish in Austria and Italy is from five to six feet, but 

 it may reach a length of eighteen feet, and a weight of two hundred to five 

 hundred pounds ; the size is not larger in France or North Germany. Pen- 

 nant speaks of one taken in the North Sea which weighed four hundred and 



