36 THE FRESH-WATER FISHES OF EUROPE. 



Acerina cernua feeds on the eggs of fishes, on insects, worms, and aquatic 

 organisms, and will also eat grass and earth. It does not attempt to 

 capture large fishes or those that move rapidly. 



It spawns in April and May. The yellow eggs are deposited on the 

 roots of water-plants in connected strings, like those of the Perch. Dr. 

 Day found the roe, weighing four and a half ounces, to contain upwards 

 of 205,000 well-developed eggs. 



In some parts of France there is an absurd popular idea that this fish 

 is a cross between the Perch and the Gudgeon. 



It is easily caught with fine meshed nets in the spring of the year, or may 

 be taken with the rod and line. When storms drive away other fishes, the 

 Ruff remains unaffected. It is easily tamed. Wherever it is abundant, its 

 flesh is highly prized ; it is firm, white, and palatable. But, owing to its 

 small size, it is neglected in districts where it is rare. It is sufficiently tena- 

 cious of life to be easily taken from place to place, and, Lloyd says, may 

 be kept alive a long time .if frozen as soon as captured, and afterwards 

 thawed in cold water. 



Frank Buckland mentions that in the Thames, and in other parts of 

 England, a custom called " plugging a Pope " probably connecting its name 

 of Pope with Roman Catholic persecution consists in pressing a wine-cork 

 on the spines of the dorsal fin. The people of Sheffield, Leeds, and York, 

 to the number of hundreds, go to Crewel Bridge, in Lincolnshire, for fishing 

 matches provided with corks, which they fix on the dorsal spines of this 

 fish, and then return them to the water. He states that it is a funny sight 

 to see the surface of the canal for so many miles covered by these unfor- 

 tunate Popes. In Russia the Pope is dried in ovens to make " soosh." 



Acerina schraetzer (LINN^US). 



The Acenna schratzer (Fig. 13), which is peculiar to the Danube, is 

 regarded by some as a geographical variety of the Kaulbarsch. It has an 

 elongated body, with the snout prolonged forward, and a dorsal fin, which 

 contains eighteen or nineteen spinous rays, and runs nearly the whole length 

 of the back. As compared with the Kanlbarsch {Acerina cernua)) it is more 

 elongated ; the greatest height at the pectoral fin is only one-fifth to one-sixth 

 of the total length, the breadth is barely two-thirds of the height, and is equal 

 to half the length of the head. The diameter of the eye is one-fourth of 

 the length of the head. The snout is more elongated, and the profile 

 nearly straight. The mouth reaches back to the anterior aperture of the nares. 

 The teeth are like those of Acerina cernua. The tongue is round, smooth, 



